Dissertations / Theses: 'Abrasives'

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Potana, Sandhya Naidu. "Environmental performance of copper slag and barshot as abrasives." ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,216.

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Thesis (M.S.)--University of New Orleans, 2005.
Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering"--Thesis t.p. Vita. Includes bibliographical references.

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Stanley, Matthew E. "The development of a management of change procedure for a process safety management covered web making operation." Online version, 1998. http://www.uwstout.edu/lib/thesis/1998/1998stanleym.pdf.

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Sangameswaran, Sivaramakrishnan. "Evaluation of Productivity, Consumption, and Uncontrolled Total Particulate Matter Emission Factors of Recyclable Abrasives." ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/390.

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Dry abrasive blasting is a commonly used surface preparation operation by many process industries to clean up metallic surfaces and achieve surface finishes suitable for future adhesion. Abrasives used in this process can be recyclable or expendable. This study was undertaken to evaluate the performance of three recyclable abrasives: garnet, barshot and steel grit/shot in terms of productivity (area cleaned per unit time), consumption (amount of abrasive used per unit area cleaned) and uncontrolled total particulate matter (TPM) emission factors (in terms of mass of pollutant emitted per unit area cleaned and mass of pollutant emitted per unit mass of abrasive consumed). Though there have been various attempts in the past to evaluate the performance of these abrasives, there has not been a streamlined approach to evaluate these parameters in the commonly used range of process conditions, or to identify and model the influences of key process variables on these performance parameters. The first step in this study was to evaluate the performance of these three abrasives in blasting painted steel panels under enclosed blasting conditions and using USEPA recommended protocols. The second step was to model the influences of blast pressure and abrasive feed rate, two most critical parameters on productivity, consumption and emission factors. Two and three dimensional models were obtained using multiple linear regression techniques to express productivity, consumption and TPM emission factors in terms of blast pressure and abrasive feed rate. Barshot was found to have high productivities over all and steel grit/shot demonstrated the least emission potential at almost all of the tested pressure and feed rate conditions. The data will help fill the gaps in literature currently available for dry abrasive blasting performance. The models obtained will help industries, the research community and the regulatory agencies to make accurate estimates of the performance parameters. Estimating productivity and consumption will help industries identify best management practices by optimizing the process conditions to achieve high productivity and low consumption rates. Emission factor determination will help in reducing the emissions to the atmosphere by choosing process conditions corresponding to minimum emissions. The performance parameters once optimized can result in reduction in material, labor, energy, emission and disposal costs, lower resource utilization and hence reduction in overall life cycle costs of dry abrasive process. The developed models will help industries in making environmentally preferable purchases thereby promoting source reduction options. PM emissions estimated using the models presented here will aid studies on health risk associated with inhalation of atmospheric PM.

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Ayala, Hugo M. (Hugo Mario). "The effects of soil abrasives on rotary seal effectiveness." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38076.

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Datar, Sanjay. "Environmental Performance of Coal Slag and Garnet as Abrasives." ScholarWorks@UNO, 2003. http://scholarworks.uno.edu/td/48.

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This study was aimed at understanding the environmental performance of two abrasives, coal slag and garnet which are commonly used by shipyards and many other industries in surface preparation of metallic surfaces. Environmental performance evaluated in this study included, (1) productivity (ft2/hr), (2) consumption and or used-abrasive generation rate (ton/2000 ft2; lb/ ft2), (3) particulate emission factors (mg/ft2; mg/lb; lb/lb; lb/kg; lb/ton). In order to achieve the study objectives, an emission test facility was built and necessary equipment and materials were procured. Blasting was performed on rusted steel panels inside the test facility and emissions were measured using EPA Source Test Method to quantify particulate emissions. By measuring the area cleaned, blasting time, and the abrasive consumed, environmental performance of coal slag and garnet was evaluated. Simple mathematical models were developed to predict performance based on feed rate and blast pressure. Garnet was observed to be more productive, less consuming, and more environmentally-friendly compared to coal slag. These study findings will valuable in reducing costs, improving productivity, and protecting the environment.

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Kambham, Kalpalatha. "Performance and Total PM Emission Factor Evaluation of Expendable Abrasives." ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/385.

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Dry abrasive blasting is one of the most widely used methods of surface preparation. Air emissions from this process include particulate matter (PM) and metals. Spent abrasive generated from this process may be hazardous in nature. With increasing concern on health effects due to silica emissions from sand, use of alternative materials is suggested by health and regulatory agencies. The objective of this research was to evaluate performance of expendable abrasives and determine PM emission factors. Dry abrasive blasting was performed in an enclosed chamber and total PM samples were collected. Three commonly used expendable abrasives, coal slag, copper slag and specialty sand, were used to evaluate cleaner alternatives. Blast pressure and abrasive feed rate, two important process conditions were varied to study their effect on performance of an abrasive. Productivity, consumption and emission factors (performance parameters) were calculated and their variation with pressure and feed rate was evaluated. Two dimensional and three dimensional predicted models were developed to estimate the performance at intermediate blast pressure and feed rate conditions. Performance of the three abrasives was compared with respect to emission potential, productivity and consumption. Emission factors developed in this research will help in accurate estimation of total PM emissions and to select cleaner abrasives and optimum process conditions that will results in minimum emissions and reduced health risk. The productivity and consumption models will help is estimating life cycle costs including material cost, equipment cost, energy cost, labor costs, waste disposal cost, and compliance costs. Consumption models will also help in determining the quantity of spent abrasive generated, identify abrasives with lower material consumption, and identify process conditions that generate minimum spent abrasives. In addition, these models will help industries in making environmentally preferable purchasing (EPP), which results in pollution prevention and cost reduction.

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Silvadasan, Xavier. "Environmental performance of steel grit and specialty sand as abrasives." ScholarWorks@UNO, 2004. http://louisdl.louislibraries.org/u?/NOD,175.

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Thesis (M.S.)--University of New Orleans, 2004.
Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Civil and Environmental Engineering."--Thesis t.p. Vita. Includes bibliographical references.

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Johnson, James Ballard. "Characterization of Optical Surface Grinding using Bound and Loose Abrasives." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/203478.

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Large optical systems fabrication is a demanding task due to the tight requirements and big scales. To make mirrors up to 8.4m in diameter necessitates technological development in materials, tooling, and metrology. These advancements are designed to not only produce optics on a near-unheard of scale, but to improve fabrication methods with each piece.For an optical surface to be properly polished, the amount of material removed during polishing must be greater than the volume of damage left behind by the grinding process. Mixed-mode grinding, which combines bound abrasives with a compliant binder material, is a valuable tool at this stage as it creates less damage while maintaining a fast and uniform cutting rate than traditional loose abrasive grinding.These materials are challenging for large optical surfaces due to the honeycomb structures used to lightweight the mirrors. Development is done to adapt the abrasive to handle the very low pressures and speeds required to avoid imprinting structure on the optical surface.We take a comprehensive approach in measuring mixed-mode behavior using 3M Trizact™. Prior works on bound abrasives have focused on specific properties: removal rates, subsurface damage, etc. None have yet to look at the entire scope of the material and its benefits. These properties will be analyzed along with different behaviors regarding surface scattering, Twyman effect bending moments, glazing, manufacturing expenses, and failure mechanisms. This comprehensive understanding of the abrasive allows manufacturers to create better grinding schedules and reduce overall expenses in fabrication.Trizact shows up to a three times faster removal rate while producing 30\% less subsurface damage than loose abrasives of similar size. Additionally, the surface has scatters less light which can be adapted through changes in processing to create a specular reflection for optical surface metrology.Based on our findings, this type of abrasive integrates into current optical fabrication processes as a pre-polishing material. Here, the transition to these abrasives becomes cost effective by rapidly eliminating damage created during the generating of the surface and reducing the amount of polishing required.

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ZOPPE, CARLA C. C. "Estudo do metodo radiometrico para avaliacao da abrasividade de dentifricios." reponame:Repositório Institucional do IPEN, 1997. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10672.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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James, Sagil. "Study of Vibration Assisted Nano Impact-Machining by Loose Abrasives (VANILA)." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1427962995.

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Luíz, Sandro Galisteu. "Preparação e caracterização térmica e mecânica de compósitos de matriz polimérica de alumina e carbeto de silício para aplicação em ferramentas abrasivas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-03122015-155527/.

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As ferramentas abrasivas são largamente utilizadas na indústria, entretanto muito pouco de seu processo de fabricação é cientificamente estudado e publicado. Visando esclarecer a forma como são manufaturados os compósitos de abrasivos, neste trabalho foram realizados vários ensaios de caracterização térmica e mecânica destes materiais. O estudo térmico da cura das resinas fenólicas, utilizadas na produção de compósitos de alumina e carbeto de silício, foi realizado por DSC. As propriedades mecânicas foram analisadas por testes de resistência à flexão e ao impacto; as propriedades termo-mecânicas por DMTA e a estrutura destes compósitos por picnometria de gás hélio, porosimetria de mercúrio e MEV. Os resultados das análises térmicas mostraram eventos importantes durante a cura da resina em 60ºC, 90ºC, 150ºC e 175ºC, para os quais é necessário criar isotermas num tratamento térmico adequado aos compósitos. Os ensaios mecânicos apontaram uma tendência de maior resistência mecânica dos compósitos com grãos menores em função da maior quantidade de resina que contêm. E revelaram a transição vítrea da resina curada em torno dos 230 °C. As análises estruturais por microscopia demonstraram que a resina fenólica fratura de forma frágil em taxas de deformação altas (impacto) e baixas (flexão). E a medida da quantidade de poros apontou divergências entre o esperado e o produto final, indicando uma certa imprecisão no processo de prensagem. Com isso, é possível repensar no processo de produção de compósitos de abrasivos, a fim de melhorar a eficiência desse processo e a qualidade do produto final ao aplicá-lo como ferramenta abrasiva.
Abrasive tool are largely employed in industry, however its manufacturing process are poorly scientifically studied and published. In order to make the abrasive composites manufacturing process clearer, in this work we performed many thermal and mechanical characterization tests. The thermal study of cure of phenolic resins, used in the production of alumina and silicon carbide composites, was done by DSC. We evaluate the mechanical properties in flexural and impact tests, the thermomechanical properties by DMTA and the structure of these composites by pycnometry of helium gas, mercury porosimetry and SEM. The results of thermal analyzes showed significant events during the curing of the resin at 60 ° C, 90 ° C, 150 ° C and 175 ° C, for which it is necessary to create isotherms in a heat treatment to the composite. The mechanical tests showed a trend towards greater mechanical strength of composites with smaller grains due to the greater amount of resin they contain. And showed the glass transition of the cured resin around 230 ° C. Structural analysis by microscopy demonstrated that phenolic resin has a fragile fracture at high (impact) and low (flexion) strain rates. And as the amount of pores presented differences between the expected and the final product, indicating a certain inaccuracy in the pressing process. This work makes it possible to think better over the composite abrasive manufacturing process, in order to improve the efficiency of this process and the quality of the final product to apply it as abrasive tool.

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Faria, Robersio Marinho de. "Estudo da dispersão das propriedades físico-químicas em blocos de alumina marrom obtida por eletrofusão." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-29032017-091850/.

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Tendo em vista a natureza finita dos minerais naturais, torna-se evidente a necessidade de utilizarmos este recurso de maneira estratégica. Desta forma, diversas pesquisas vêm sendo desenvolvidas principalmente nas áreas químicas, metalúrgicas e mineralógicas desde as etapas de extração, beneficiamento, aplicação e reutilização dos resíduos de minérios. Portanto, é extremamente importante a intensificação dos estudos para aumentar o conhecimento quanto às características e propriedades físico-químicas destes minerais, visando melhorar o seu aproveitamento e longevidade das jazidas naturais, como as fontes de bauxita, que é a principal matéria-prima para a produção de óxido de alumínio fundido. Na sua forma cristalina mais comum, denominada coríndon, ou óxido de alumínio ?, sua baixa condutividade elétrica, baixo calor específico, alta condutividade térmica, alto ponto de fusão, elevada dureza e resistência mecânica, o torna adequado para uso em produtos refratários, cerâmicos e abrasivos tais como, lixas, rebolos, ferramentas de corte e de polimento. Na síntese deste produto as principais impurezas que afetam a qualidade dos grãos são Fe, Si, Ca, K, Na e Zr, oriundas da matéria prima bauxita e da carta de mistura, composta por ilmenita, limalha de ferro, carvão vegetal e coque de petróleo. Desta forma, o presente trabalho assumiu o objetivo de estudar a dispersão das propriedades físico-químicas em blocos de alumina fundida marrom obtida em fornos Higgins a arco por eletrofusão, produzidos na Saint-Gobain Abrasivos, unidade de Lorena, SP. Por fim, foram utilizadas técnicas de caracterização físico-químicas de difratometria de raios X (DRX), análises químicas de fluorescência de raios X (FRX), ensaio de dureza Knoop e caracterização microestrutural via (MEV/EDS). Desta forma, foi definido o mapeamento composicional nos blocos de alumina eletrofundida marrom, que servirão como referência técnico-científica para subsidiar ações de melhoria deste produto, em decorrência do avanço do estado da arte deste referido assunto.
The mineral ores are not renewable sources and we need to use it in the best way possible. In this way, a large number of researches are being developed around the world aiming the improvement of current methods of production mainly in chemical, metallurgy, mineralogical from the steps of extraction, processing, application and reuse of waste ore. Therefore, it is extremely important to intensify the studies to increase the knowledge about the characteristics and physicochemical properties of these minerals, in order to improve their utilization and longevity of natural deposits, such as sources of bauxite, which is the main raw material to product aluminum oxide fused. In its most common crystalline form, called corundum or ?-aluminum oxide, its low electrical conductivity, low specific heat, high thermal conductivity, high melting point, high hardness and mechanical strength, making it suitable for use as refractories, ceramics and fine or coarse abrasives. The synthesis of this product major impurities that affect quality of grain is Fe, Si, Ca, K, Na and Zr, derived from the raw material bauxite and the mixture chart consisting of ilmenite, iron filings, charcoal and coke oil. Thus, this shows the dispersion of physicochemical properties of brown fused alumina blocks produced by eletrocfusion at Higgins furnace process in the company Saint Gobain Abrasivos, Lorena- SP. Finally, the samples were physicochemical analyzed by X ray diffraction (XRD), chemical analyses by X ray fluorescence (XRF), hardnes using Knoop method, microstructural characterization by (SEM). The results of this work show a compositional gradient map of the fused alumina block; that shows the main physicochemical differences into the block, to support changes in the alumina production process; and it is also important to improve the actual state of art of this particular theme.

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Филимонов, Е. В. "Анализ используемых в Украине стандартов на шлифовальные материалы." Thesis, Изд-во СумГУ, 2005. http://essuir.sumdu.edu.ua/handle/123456789/20142.

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Wei, Gang. "Development of an abrasive wear resistance test and the study of correlation between two-body and three-body abrasive wear." Thesis, Queensland University of Technology, 1991. https://eprints.qut.edu.au/36472/1/36472_Gang_1991.pdf.

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In this study, a standardized coal abrasive wear resistance (AWR) test has been developed by utilizing a modified YGP test rig (initially developed by Yancey, Geer and Price) and the manufacture of a specified abrasive (CB-Ql abrasive). The later was developed to meet standardized test requirements since coal was not adequate for this purpose. The standardized A WR test was then used to test an as-cast and heat treated 3.5C5Cr5Mo5V white cast iron - an experimental abrasive wear resistant material. To evaluate the ranking ability of the test and to study the three-body wear mechanisms, the above tests were also repeated with coal. The heat treated experimental white cast iron alloy was also tested with the Pin-on-plate Two-body AWR test to study wear mechanisms in two-body situations. Based on these three-body and two-body AWR tests, a comprehensive study was carried out on the correlation between two-body and three-body abrasive wear. It was found that the influence of most comparable factors, such as material hardness, heat treatment of the material, abrasiveness of the abrasive, abrasive particle size, for both two-body and three:-body AWR tests was very similar. The ranking effect of a test was related to the type of abrasive used rather than whether it was two-body or three-body test. The scanning electron microscopic photomicrographs also showed that the grooves which caused material removal were similar for both two-body and three-body tests. It was therefore proposed that the main mechanisms of material removal was the same in both two-body and three-body situations. The difference was that in three-body abrasive wear processes much more "rolling action" of the abrasive particles was involved, while in two-body abrasive wear the process was dominated by "rectilinear action". It was assumed that pure rolling action did not produce material removal but created plastic flow which influenced later material removal. The material removal in both two-body and three-body abrasive wear tests was mainly caused by rectilinear actions which caused microploughing and microcutting. However, depending on the microstructure of the material being tested, the properties of the abrasive and the contact stress involved, the mechanism of material removal in rectilinear actions may vary considerably. An embryonic model of abrasive wear (ignoring the types of two-body and threebody) was built up based on the above studies. A parameter f was introduced, which described the extent of rolling action (or the extent of rectilinear action) involved in an abrasive wear process.

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Дремлюженко, С. Г., З. І. Захарук, В. П. Шафранюк, А. І. Раренко, and П. М. Фочук. "Вплив методів обробки поверхні кристалів Cd[1-х]Mn[х]Te на рельєф і глибину порушеного шару." Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45939.

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Після абразивної обробки поверхні напівпровідника залишається порушений шар тієї або іншої глибини, який істотно впливає на електричні характеристики напівпровідникових приладів. Тому перед виготовленням приладів його вплив необхідно звести до мінімуму.

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Conroy, Ashley Paul. "The development of a high stress abrasive wear tester." Thesis, Queensland University of Technology, 1992.

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Trevisiol, Céline. "Effet de la microstructure et de la rugosité sur le comportement au frottement et à l’usure d’aciers faiblement alliés." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2430.

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Cette thèse est un travail expérimental mettant en évidence les effets de la microstructure et de la rugosité sur le comportement au frottement et à l'usure d'aciers faiblement alliés. Une méthodologie est mise en place pour sélectionner des aciers faiblement alliés et générer des microstructures permettant de répondre à cet objectif. Différents échantillons caractérisés par une composition chimique, une microstructure et une macro-dureté sont générés et caractérisés tribologiquement par des essais de frottement. Une réflexion originale a été menée pour étudier le comportement tribologique d'un même acier avec différentes microstructures pour le même niveau de macro-dureté. Ces essais de frottement permettent également d'étudier l'effet du chargement normal sur la contribution de la microstructure et de la rugosité sur le comportement tribologique. Cette caractérisation est réalisée par des mesures de coefficient de frottement, du taux d'usure, des paramètres de rugosité, d'essais de micro-duretés et de nano-indentation, d'analyses dispersives en énergie, d'observations par microscopie électronique à balayage et d'analyses des mécanismes d'usure. Cette approche a permis d'étudier 273 configurations et de dégager différentes tendances sur cette thématique. Parallèlement, une confrontation entre les résultats issus de l'approche expérimentale et d'une approche de modélisation du comportement tribologique de microstructures dual-phase a été réalisée. Cela a permis de mettre en place une réflexion sur les modes de distribution de la pression appliquée entre les phases lors des essais expérimentaux réalisés en fonction de la rugosité et du chargement normal
This thesis is an experimental work highlighting the effects of microstructure and roughness on friction and wear behavior of low alloy steels. That's why, low alloyed steels are carrefully selected in order to generate precise microstructures. Thus, different samples characterized by a chemical composition, a microstructure and a macro-hardness are generated and characterized tribojogically by performing friction tests. An original reflection was conducted to study the tribological behavior of the same steel with different microstructures for the same level of macrohardness. In addition, the effect of normal load on the contribution of microstructure and roughness on tribological behavior is investigated. This characterization is carried out by measurements of friction coefficient, wear rate, roughness parameters, micro-hardness and nanoindentation tests, energy dispersive analyzes, observatibns by using scanning electron microscopy and analysis of wear mechanisms. Finally, 273 configurations are studied and different trends are identified, Moreover, a comparison between the results from an experimental approach and a modeling approach of the tribological behavior of dual-phase microstructures was carried out. From this study, reflections are performed as regards the modes of the applied pressure pressure between the phases as function of roughness and normal load during the experimental friction tests

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Avey, Karen D. "Development of a standardized abrasive scale an analysis of commercial prophylaxis pastes /." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3698.

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Thesis (M.S.)--West Virginia University, 2004.
Title from document title page. Document formatted into pages; contains viii, 74 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 55-57).

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Mercer, A. P. "The effects of atmospheric humidity and oxygen on the wear of metals by fine abrasives." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356659.

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Kermel, Christine. "Fabrication et caractérisation de micro- et nano-composites alumine-carbure de silicium pour des applications abrasives." Valenciennes, 2003. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/51965ee9-5586-4c60-af60-c2ac6bc16715.

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Le but de ce travail était de rendre possible la production industrielle de grains abrasifs micro- et nanocomposites alumine-SiC aux propriétés supérieures à celles des abrasifs commerciaux en alumine. La synthèse hydrothermale (à partir de nitrate d'aluminium), suivie d'un pressage à chaud, a d'abord permis d'obtenir des nanocomposites Al2O3-SiC par voie aqueuse. Le produit intermédiaire de ce procédé est une poudre boehmite-SiC, qui présente une vitesse maximale de densification sans pression appliquée vers 1500°C. Or le boehmite est la matière première des grains abrasifs "alumine sol-gel" fabriqués industriellement, aussi avons nous choisi d'adapter ce procédé de fabrication par l'ajout d'une suspension de SiC avant l'étape de gélification. Les conditions de frittage naturel ont été étudiées en fonction de la taille et de la quantité de SiC ajouté. Les meilleures performance d'usure, otenues pour 1 vol. % SiC 200 nm (1500 °C) et 1 vol. % de SiC 14µm (1400 °C), sont supérieures à celles des abrasifs commerciaux en alumine. Pour de bonnes propriétés d'usure, les grains abrasifs doivent avoir une densité apparente ≥ 95 %, une dureté ≥ 20 GPa, et une matrice à grains fins (1 à 2µm)
This work aimed to make possible the industrial production of alumina-SiC micro- and nanocomposite abrasive grits of better wear properties than commercial alumina grits. The hydrothermal synthesis (starting from aluminium nitrate) followed by a hot pressing, initially made it possible to obtain nanocomposites Al2O3-SiC by an aqueous route. The intermediate product of this process is a boehmite-SiC powder, which has a maximum densification rate without pressure towards 1500 °C. As boehmite is the raw material for commercial "alumina sol-gel" abrasive grains, we chose to adapt this fabrication process by the addition of a SiC suspension before the stage of gelation. The conditions of pressureless sintering were studied according to the size and quantity of added SiC. The best wear performances, obtained for 1 vol. % SiC 200 nm (1500 °C) and 1 vol. % of SiC 14µm (1400 °C), are higher than those of the commercial alumina abrasives. For good wear properties, the abrasive grains must have a bulk density ≥ 95 %, a hardness ≥ 20 GPa, and a fine grain matrix (1 to 2 µm)

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Manocha, Chhavi. "Chemical Mechanical Planarization: Study of Conditioner Abrasives and Synthesis of Nano-Zirconia for Potential Slurry Applications." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002741.

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Zhong, Yu Mechanical &amp Manufacturing Engineering Faculty of Engineering UNSW. "A study of the cutting performance in multipass abrasive waterjet machining of alumina ceramics with controlled nozzle oscillation." Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2008. http://handle.unsw.edu.au/1959.4/41216.

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An experimental investigation has been undertaken to study the depth of cut in multipass abrasive waterjet (AWJ) cutting of an 87% alumina ceramic with controlled nozzle oscillation. The experimental data have been statistically analysed to study the trends of the depth of cut with respect to the process parameters. It has been found that multipass cutting with controlled nozzle oscillation can significantly increase the depth of cut. Within the same cutting time and using the same cutting parameters other than the jet traverse speed, it has been found that multipass cutting with nozzle oscillation can increase the depth of cut by an average of 74.6% as compared to single pass cutting without nozzle oscillation. Furthermore, a multipass cutting with higher nozzle traverse speeds can achieve a larger depth of cut than a single pass cutting at a low traverse speed within the same cutting time. A recommendation has been made for the selection of appropriate process parameters for multipass cutting with nozzle oscillation. In order to estimate the depth of cut on a mathematical basis, predictive models for the depth of cut in multipass cutting with and without nozzle oscillation have been developed using a dimensional analysis technique. The model development starts with the models for single pass cutting which are then extended to multipass cutting where considerations are given to the change of the actual standoff distance after each pass and the variation of kerf width. These predictive models has been numerically studied for their plausibility by assessing their predicted trends with respect to the various process variables, and verified qualitatively and quantitatively based on the experimental data. The model assessment reveals that the developed models correlate very well with the experimental results and can give adequate predictions of this cutting performance measure in process planning.

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Golanda, Alexandre Dutra. "Preparação e caracterização de compósitos abrasivos resinoides reforçados com alumina reciclada." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-20112017-172318/.

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A iminente escassez de recursos naturais e de fontes energéticas não renováveis são forças motrizes para a adoção de práticas sustentáveis. Dentre os processos industriais que fazem uso intensivo de recursos naturais, estão os que utilizam processos de usinagem baseados em ferramentas abrasivas para desbaste, esmerilhamento, corte, entre outros. A partir deste panorama geral, é possível enxergar a necessidade de estudar os processos de usinagem com ferramentas abrasivas a fim de aumentar a compreensão sobre eles e de torná-los sustentáveis. Sendo assim, o objetivo deste trabalho é avaliar, por meio do comportamento mecânico de compósitos abrasivos resinoides, o potencial de reciclagem de grãos de alumina oriundos de ferramentas abrasivas. No presente trabalho, foi estudada a preparação e caracterização de compósitos abrasivos resinoides reforçados com grãos alumina reciclada e virgem. Uma das aluminas recicladas é oriunda de rebolos e discos de corte resinoides, outra alumina é oriunda de rebolos vitrificados, e a última, composta por alumina branca, é recuperada de rebolos vitrificados refugados ou usados. As amostras de grãos de alumina reciclada e a de grãos de alumina marrom virgem foram caracterizadas por meio das técnicas de fluorescência de raios X (FRX), difratometria de raios X (DRX), microscopias óptica (MO) e eletrônica de varredura (MEV). Corpos de prova de compósitos utilizando os quatro tipos de alumina foram preparados por meio da mistura, prensagem e tratamento térmico de grãos de alumina e resinas fenólicas resol e novolaca. Por fim, os compósitos foram caracterizados por meio das técnicas de calorimetria exploratória diferencial (DSC), módulo elástico por excitação por impulso, impacto Izod, flexão em quatro pontos, análise térmica dinâmico-mecânica (DMTA), dureza por Sand Blasting Penetration (SBP), porosidade pelo método de Arquimedes e microscopias óptica e eletrônica de varredura. Os resultados dos ensaios mecânicos mostraram que os compósitos de alumina reciclada apresentaram depreciação em todas as propriedades estudadas em relação ao compósito de alumina virgem, exceto a resistência ao impacto Izod, no qual todas as amostras apresentaram baixa resistência. A razão desta baixa resistência ao impacto deveu-se à estrutura formada pelo grão de alumina, ligante (resina fenólica) e porosidade, na qual a baixa proporção de resina fenólica (10% m.) foi a responsável pelo resultado. Por outro lado, a causa da depreciação nas propriedades mecânicas apresentadas pelos compósitos de alumina reciclada foi a menor concentração em alumina e a presença de impurezas oriundas da produção das ferramentas abrasivas. Neste caso, o compósito de alumina branca reciclada apresentou melhores resultados das propriedades mecânicas em relação aos compósitos de alumina oriunda de rebolos vitrificados e os de alumina oriunda de rebolos e discos resinoides. Concluindo, o potencial de reciclagem dos grãos de alumina oriundos de ferramentas abrasivas visando o seu reaproveitamento no processo de fabricação destas ferramentas é limitado pela sua pureza, de modo que se no processo de reciclagem dos grãos for aumentada a concentração de alumina haverá possibilidade de seu reaproveitamento.
The imminent scarcity of natural resources and nonrenewable energy sources are driving forces for the adoption of sustainable practices. Among the industrial processes that make intensive use of natural resources, there are those that use machining processes based on abrasive tools for roughing, grinding, cutting, among others. From this general panorama, it is possible to see the need to study the machining processes with abrasive tools in order to increase the understanding about them. Thus, the objective of this work is to evaluate, through the mechanical behavior of resin-bound abrasive composites, the recycling potential of alumina grits from abrasive tools. In the present work, the preparation and characterization of resinoid abrasive composites reinforced with recycled and virgin alumina grits was studied. One of the recycled aluminas comes from resin-bound grinding wheels and thin wheel cut-off discs, another alumina comes from vitrified grinding wheels, and the latter, composed of white alumina, is recovered from scrapped or used glazed grinding wheels. The samples of recycled alumina grits and virgin brown alumina grits were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffractometry (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). Composite test bodies using the four types of alumina were prepared by mixing, pressing and heat treatment of alumina grits and resol and novolak phenolic resins. Finally, the composites were characterized by differential scanning calorimetry (DSC), impulse excitation elastic modulus, Izod impact, four-point flexing, dynamic-mechanical thermal analysis (DMTA), Sand Blasting Penetration hardness (SBP), porosity by the Archimedes method and optical and scanning electron microscopy. The results of the mechanical tests showed that the recycled alumina composites presented depreciation in all the studied properties in relation to the virgin alumina composite, except the Izod impact resistance, in which all the samples presented low resistance. The reason for this low impact strength was due to the structure formed by the alumina grit, binder (phenolic resin) and porosity, in which the low proportion of phenolic resin (10% m) was responsible for the result. On the other hand, the reason for the depreciation in the mechanical properties presented by the recycled alumina composites was the lower concentration in alumina and the presence of impurities from the production of the abrasive tools. In this case, the recycled white alumina composite presented better mechanical properties in relation to alumina composites from vitrified grinding wheels and those from alumina from grinding wheels and resinoid disks. In conclusion, the recycling potential of the alumina grits from abrasive tools aiming at their reuse in the process of manufacturing these tools is limited by their purity, so that if in the grit recycling process the alumina concentration increases it will make possible its reuse.

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Bianchi, Eduardo Carlos. "Estudo do comportamento de discos abrasivos, em operações do tipo "Cut-off" por mergulho basculante, submetidos à diversas condições de corte sem lubrificação /." Bauru : [s.n.], 1997. http://hdl.handle.net/11449/116081.

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Resumo: O corte de aços por disco abrasivo é um dos processos que apresentam as melhores características de economia, eficiência e rapidez, e ainda hoje é muito utilizado no meio industrial se comparado a outros processos tradicionais de corte como o cisalhamento (tesourão), torneamento (sangramento), serragem com serras metálicas, serragem por atrito com lâminas circulares sem dentes e chama oxi-acetileno. Da literatura formal mais recente, nota-se que durante os últimos anos as máquinas para a realização dos cortes foram inovadas. Entretanto, esta atenção não foi dada à ferramenta de corte abrasiva. A falta de literatura técnica dificulta a escolha das condições de corte e da sua otimização no meio industrial. Este fato é agravado pela grande diversidade de discos abrasivos disponíveis no mercado, com diferentes qualidades e preço. As decisões sobre as condições de corte são baseadas em experiências pessoais, sem critério definido, e freqüentemente desprezam os aspectos de segurança inerentes ao processo. A concorrência estrangeira, através da globalização da economia, está obrigando as indústrias nacionais a atenderem os padrões internacionais de qualidade e desempenho. Uma forma das indústrias nacionais tornarem-se mais competitivas é através do conhecimento detalhado das operações de corte com discos abrasivos. Neste trabalho é apresentado um estudo sobre o comportamento de discos abrasivos, submetidos a diversas condições de corte. Os resultados são discutidos em função da análise da velocidade de corte, velocidade de mergulho do disco abrasivo na peça, força tangencial de corte média, tempo de corte e relação G.
Abstract: The cut-off operation shows the best savings, efficiency and quickness caracteristics and nowadays it is very used in the industrial environments if compared to other traditional cutting operations like shearing, turning, sawing with metalic hacksaws, friction sawing with non-tooth circular blades and oxi-acetylene torch cutting. In the most recent bibliography, it is noted that the new cutting machines have been improved. However, this fact did not happen in the abrasive cut-off tools. The lack of technical bibliography led the cutting conditions and optimizations choices to be a hard action. Such difficulties are worsen because there are many kinds of abrasive cutting wheels available with different qualities and prices. So, these choices are based on personal experiences, without parameters, and frequently despise the security aspects of the operations. The foreign competition, through the economy globalization, is forcing the national industry to attend the international quality and performance standards. One way for the national industries become more competitives (improving the productivity and decreasing the production costs) it is by the detailed knowledgment of the cut-off operations with abrasive wheels. This work shows a research about the abrasive wheels behavior, under several cutting conditions. The results are discussed in function of the cutting speed, downfeed of the abrasive wheel, average of tangencial cutting force, time per cut and G parameter analysis.

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25

Söderwall, Patrik. "Procedur för delning av casing offshore med hjälp av vattenskärning." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-37052.

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Within the oil and gas industry on offshore installations in the North Sea, several oil wells are closing in on the brink where they no longer are being profitable to keep producing from. When that day comes the oil wells are closed off and the boreholes are plugged with cement. Before the holes can be cemented shut the companies need to remove all their equipment that has been used for underwater exploitations of the well and if applicable remove the above water installation as well. This includes removing the casing that the holes are lined with which main purpose is to prevent the hole from collapsing on the production line and to prevent oil and gas leaks into the surroundings. This thesis focuses on removal of the borehole casing. When performing this task problems have been raised regarding corrosion on the casing couplings, making them very hard to separate. When this problem occurs, the need for an alternative method to split them is necessary. As of today this operation is performed by cold cut sawing or with a beveling machine. This is a highly time consuming task and an alternative method to perform a faster cut is wanted. This degree work investigates the possibilities of doing this using the benefits of abrasive water jet (AWJ) cutting. The major concerns on using this technic is whether it is fast enough and if it is possible to perform in accordance with the fire and explosive hazards on a hydrocarbon producing installation. As a reference the maximum cut time is set to one minute. Calculations on theoretical cutting speeds as well as physical testing on the AWJ method has been performed and evaluated. The investigations show that the method does have the possibilities of making the cut within the target time. The work also contains a simple concept model on how the equipment could be constructed.
Inom olje- och gasindustrin på offshoreanläggningar i Nordsjön, närmar sig flera reservoarer randen där de inte längre är lönsamma att fortsätta producera från. När den dagen kommer pensioneras borrhålen och pluggas med en cementblandning. Innan hålen pluggas måste företagen ta bort all utrustning som har använts vid utvinningen av brunnen, både ovan och under ytan. Detta innefattar avlägsnande av casingen, som hålen är fodrade med, och vars huvudsakliga syfte är att förhindra att hålet kollapsar och skadar produktionsledningen, men även för att förhindra olje- och gasläckor till omgivningen. Denna avhandling fokuserar på borttagandet av casingen. När detta görs upplevs problem med att casingskarvarna är kraftigt korroderade vilket gör dem mycket svåra att separera. Detta är ett problem som efterfrågar en alternativ delningsmetod. I dag utförs den här operationen med antingen kallsågning eller med en avfasningsmaskin. Detta är en mycket tidskrävande uppgift och en metod för att utföra en snabbare delning önskas. Detta examensarbete är tänkt att undersöka möjligheterna att göra detta genom att använda fördelarna med abrasiv vattenskärning för att kapa rören. De största frågorna gällande denna metod är om den är tillräckligt snabb och om det är möjligt att utföra i enlighet med de brand- och explosionsrisker som finns på en kolväteproducerande installation. Som referens är målet för maximal skärtid satt till en minut. Beräkningar på teoretiska skärhastigheter samt fysiska tester på metoden har utförts och utvärderats. Undersökningarna visar på att metoden har möjligheter att göra snittet inom utsatt tid. Arbetet innehåller också en enkel konceptmodell på hur utrustningen skulle kunna konstrueras.

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Ide, Mark. "Investigations of dentine sensitivity : an in vitro investigation of the role of abrasives and the development and testing of improved methods of clinical measurement." Thesis, King's College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309242.

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27

Tazibt, Abou-el-Foutouh. "Étude théorique et expérimentale du processus d'accélération de particules abrasives dans un jet d'eau sous très haute pression : interaction avec le matériau à découper." Lille 1, 1995. http://www.theses.fr/1995LIL10003.

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L'utilisation de la technologie du jet d'eau abrasif comme procédé de découpage à froid de matériaux tels que les composites et métaux, trouve des champs d'applications divers (aéronautique, industrie de l'automobile, génie civil). Bien que ce procédé soit utile, son support théorique est loin d'être maîtrisé quant à l'optimisation du grand nombre de paramètres de travail (pression hydraulique, débit d'abrasif, profondeur de coupe). La résolution de ce problème ne peut être effective que si l'on considère les facteurs qui conduisent principalement au phénomène de coupe. En effet, grâce à l'énergie cinétique des particules abrasives, le matériau est découpé par arrachement de matière. Ce qui a conduit à la modélisation du processus d'accélération du jet d'eau abrasif selon la démarche macroscopique de la mécanique des milieux continus appliquée aux écoulements biphasiques solide/liquide. En exploitant l'hypothèse de conservation de la quantité de mouvement du mélange, la résolution de l'équation différentielle, non linéaire et à deux inconnues (vitesses de la particule et de l'eau), du mouvement a donné deux solutions analytiques exactes. Celles-ci représentent la variation de la vitesse des phases en fonction de la distance sur l'axe du jet à l'intérieur du tube de focalisation. La méthode utilisée permet non seulement de tenir compte des actions simultanées des forces interfaciales (traînée, masse virtuelle), mais aussi des conditions réelles de fonctionnement du jet, à savoir l'aspiration de particules qui s'accompagne d'air par effet venturi. La validation expérimentale de la modélisation théorique a été menée avec succès en développant une corrélation expérimentale donnant la vitesse des particules à l'impact indépendamment de la modélisation théorique. Cette corrélation repose sur l'interaction du jet avec le matériau et débouche sur un modèle intègre qui donne la profondeur de coupe et la vitesse d'avance en fonction de la vitesse théorique de modélisation et les paramètres de travail.

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ZAMATARO, CLAUDIA B. "Estudo in situ da resistência à desmineralização do esmalte dental submetido à irradiação com laser Er, Cr:YSGG associada ao uso de produtos fluoretados." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10508.

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Made available in DSpace on 2014-10-09T12:41:18Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:06:03Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Rosso, Tiago Alexandre. "Uso do ensaio de desgaste por micro abrasão para avaliação da abrasividade de partículas de alumina e carbeto de boro." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2732.

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Processos de fabricação que fazem uso de abrasão como modo de remoção de material são discutidos constantemente pela literatura. Entretanto, a abrasividade, ou a capacidade de remoção de material pelos abrasivos pouco tem sido abordada na literatura especificamente para partículas micrométricas. Esta capacidade de remoção pode ser atribuída a variações da concentração, geometria, dureza e distribuição de tamanho das partículas no fluido abrasivo. Logo, um melhor entendimento acerca da abrasividade das partículas faz-se necessário para uma melhor caracterização dos modos e mecanismos atuantes no processo, visto que a seleção do abrasivo é um fator econômico significativo em diversos processos de fabricação, tais como retificação e hidroerosão. Esta dissertação tem por objetivo utilizar-se do ensaio de desgaste por micro abrasão para a avaliação da abrasividade de partículas de alumina e carbeto de boro. Como corpos-de-prova foram utilizadas amostras de aço AISI D2 (677 HRC) e as esferas de 25,4 mm de diâmetro foram de aço AISI 52100 temperado e revenido. Foram realizados ensaios com abrasivos diferentes de tamanhos semelhantes e ensaios com o mesmo abrasivo de tamanhos diferentes para verificar a influência da concentração do abrasivo, da rotação e do desgaste da esfera e do tempo de ensaio. As distribuições de tamanho das partículas foram determinadas através da técnica de difração a laser na forma de distribuição de frequência em volume e na forma de frequência acumulada. Além disso, a caracterização quanto à geometria, por meio do fator SPQ (parâmetro de ponta), foi realizada utilizando um programa computacional desenvolvido no Matlab. As distribuições de tamanho mostraram uma percentagem de volume de partículas finas maior nas amostras de carbeto de boro e uma percentagem de volume de partículas mais grossas superiores para a alumina. O valor de SPQ médio apresentou-se maior para o carbeto de boro do que para a alumina, quando com tamanhos médios diferentes. Porém para os abrasivos diferentes com tamanho médio semelhante, a alumina apresentou um valor maior para o parâmetro. Esse valor maior sugere uma maior capacidade de remoção de material. Os resultados mostraram que a variação do tempo de ensaio é responsável por uma mudança no modo de desgaste e que os abrasivos de Al2O3 apresentam menor abrasividade quando comparados aos abrasivos de B4C, pois o coeficiente de desgaste mostrou-se maior para este após o alcance do regime permanente. Um aumento da concentração do abrasivo e um acréscimo no tempo de ensaio levaram a um crescimento no volume de desgaste do material para ambos os abrasivos, enquanto que um aumento na rotação da esfera de ensaio não proporcionou um aumento significativo no volume de material removido. As durezas das partículas abrasivas e do corpo de prova e o tamanho e a angularidade dos abrasivos são utilizados para discussão das causas do regime permanente ter ocorrido em diferentes tempos para os dois abrasivos.
Manufacturing processes that use abrasion for material removal are constantly discussed in the literature. However, the abrasiveness, or the ability of material removal by particles has not been widely discussed in the literature specifically for micrometric particles. This removal capacity can be attributed to changes in the particle concentration, geometry, hardness and size distribution in the fluid abrasive. Therefore, a better understanding of the particles abrasiveness is necessary for a proper characterization of the modes and mechanisms acting in the process, since the abrasive selection is a significant economic factor in several manufacturing processes, such as grinding and hydroerosive grinding. The purpose of this work is to use the micro abrasion wear test to evaluate the abrasiveness of alumina and boron carbide particles. Samples of AISI D2 steel (677 HRC) and balls with 25.4 mm diameters quenched and tempered AISI 52100 steel were used. Tests were performed with different abrasives of similar sizes and with the same abrasive of different sizes to verify the influence of the abrasive concentration, ball rotation and wear and test time. Particle size distribution was determined by laser diffraction in terms of frequency distribution and cumulative frequency volumes. Moreover, the particle geometry characterization was also determined using the SPQ factor (Spike value) using a Matlab computer program. The size distribution indicated a higher percentage of fine particles for boron carbide and a higher percentage of coarse particles for alumina. The mean SPQ value was higher for boron carbide than for alumina with different average sizes. However, for different abrasives with similar average size, the alumina presented a bigger value for the parameter. This bigger value suggests a higher material removal capacity. The results show that test time is responsible for a change in the wear mode. Al2O3 particles presented a lower abrasiveness when compared to B4C particles because the wear coefficient was bigger for B4C after reaching the steady state regime. An increase in abrasive concentration and in test time led to a growth in material volume wear for both abrasives, while an increase in the ball rotation did not provide a significant increase in the material volume removed. The particles and specimen hardness and the abrasives size and angularity were used to discuss the causes of the steady state regime occur at different times for the two abrasives.

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Betrabet, Chinmay Suresh. "Inorganic-organic hybrid materials and abrasion resistant coatings based on a sol-gel approach." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40188.

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Novel inorganic-organic hybrid materials made previously in the laboratory have utilized acids catalysts such as HCI, acetic acid, toluene sulfonic acid and polystyrene sulfonic acid to catalyze the sol-gel reaction. The sol-gel reaction can also be catalyzed under near neutral (i.e. 5 < pH < 7) and basic conditions. The effects of synthesizing hybrid materials under near basic and basic conditions has not been studied. Attempts to synthesize hybrid materials from polytetramethylene oxide (PTMO) end functionalized with triethoxy silyl groups and, tetraethylorthosilicate (TEOS) under basic conditions met with only partial success. The films obtained had low mechanical stability. This was attributed to the low reactivity of the triethoxy species under neutral and basic conditions. In contrast, films with good mechanical stability were obtained when the TEOS was replaced with titanium tetraisopropoxide (TIOPR). The microstructure of the TIOPRlPTMO hybrid synthesized under near neutral conditions was generally similar to the acid catalyzed PTMOffIOPR hybrids.
Ph. D.

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Yahiaoui, Malik. "Comportement tribologique de diamants polycristallins et de carbures cémentés WC-Co avec traitements de graduation : application aux inserts et taillants d'outils pour le forage de formations rocheuses fortement abrasives." Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0052/document.

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La performance des inserts d’outils tricône et des taillants d’outils PDC commerciaux est soumise au compromis dureté/ténacité principalement régi par la proportion de cobalt et la taille des grains de carbures cémentés WC-Co et du PDC. Les traitements de graduation basés sur l’imbibition de cobalt et les revêtements de nitrure de bore des carbures cémentés permettent d’augmenter la résistance à l’abrasion au niveau de la surface active des inserts et des taillants tout en générant une ténacité accrue au cœur des carbures cémentés. Des essais d’usure à l’aide d’un tribomètre rotatif avec une contreface en alumine pour les inserts WC-Co et à l’aide d’un tour d’usure avec une contreface en béton à forte teneur en silice pour les taillants ont permis d’étudier leur comportement tribologique. Pour les inserts, le coefficient de frottement et les cinétiques d’usure (modèle d’Archard), mais aussi l’évaluation de la température de contact et de l’émission acoustique générée au contact, ont permis de mieux comprendre l’effet des traitements réalisés sur les carbures cémentés. Pour les taillants PDC un modèle de qualité, basé sur un compromis usure/efficacité de coupe, a été développé afin de caractériser la résistance à l’usure des taillants. Des analyses physicochimiques (EDX, DRX, Raman) ont permis d’associer l’évaluation de la résistance à l’abrasion des échantillons à des mécanismes d’usure en considérant les éléments constitutifs des systèmes tribologiques et la formation de troisièmes corps. Les résultats ont ainsi montré l’importance de la proportion de cobalt générée dans les débits d’usure sur la stabilité des débris abrasifs (alumine et silice) et ainsi sur la résistance à l’usure des inserts et taillants. Les mécanismes de rupture des microstructures WC-Co et PDC sont aussi mis en avant afin d’expliquer leur influence sur la résistance à l’abrasion des échantillons. Enfin, des mesures de ténacité des inserts ont permis de juger de l’apport des traitements d’imbibition sur la résistance à la propagation de fissures des carbures cémentés WC-Co. Aussi, des essais complémentaires de chocs ont permis de montrer que les traitements améliorant la résistance à l’abrasion des taillants ne se traduisent pas par la chute de leur résistance aux chocs
The performance of commercial tricone bit inserts and PDC bit cutters is defined by the compromise between hardness and fracture toughness controlled by the cobalt proportion and the grain size of WC-Co cemented carbide and PDC. On one hand, graduation treatments based on reactive imbibition of cobalt and boron nitride coating of cemented carbides lead to an improvement of abrasive wear resistance of inserts and cutters active surfaces. On the other hand, greater fracture toughness is obtained in the cemented carbides core as a result of imbibition. Wear experiments were performed with a rotary tribometer using an alumina contreface for the WC-Co inserts and with a lathe and its silica based concrete contreface for the PDC cutters. For the inserts, the friction coefficient and wear kinetics (Archard model), but also contact temperature measurement and acoustic emission consideration, permitted to clarify the treatments effects on cemented carbides tribological behaviour. For PDC cutters, a quality model, based on wear/cutting efficiency compromise, was developed in order to characterize the wear resistance. Physicochemical analyses (EDX, XRD, Raman) made a link between mechanical results and wear mechanisms considering the tribological systems and the third body formation. These analyses highlighted the influence of the proportion of cobalt generated in the wear flows on the stability of abrasive debris (alumina and silica) and thus on the wear resistance of inserts and cutters. The Fracture mechanisms of WC-Co and PDC microstructures have also been studied and their effects on the wear resistance have been demonstrated here. At last, fracture toughness measurements showed that the imbibition treatments could maintain a good resistance to cracks propagation of inserts. In addition, complementary impacts experiments prove that the improvement of wear resistance of PDC cutters did not produce reduction of impact strength

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Gomes, João Jorge de Faria. "Identificação em processo de mecanismos de desgaste de rebolos." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-20032017-113947/.

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O objetivo deste trabalho é o desenvolvimento de um sistema de monitoramento capaz de identificar em processo o mecanismo de desgaste ao qual o rebolo está sendo submetido durante a retificação. Assim, inicialmente foram pesquisados os meios físicos, os tipos de sensores e estratégias utilizadas nos sistemas de monitoramento, o estágio atual de desenvolvimento e suas aplicações. Para que este sistema seja confiável e eficiente foi necessário estudar detalhadamente a fenomenologia dos mecanismos de desgaste do rebolo. Este estudo permite definir parâmetros para identificação do tipo de desgaste que está ocorrendo, baseado em indicações fornecidas pelo monitoramento de variáveis cujo comportamento é conhecido, como potência consumida pelo motor do rebolo e vibração ou ainda por medições metrológicas. Dois sistemas ópticos de mapeamento da superfície do rebolo são apresentados e estes sistemas serviram como base para o desenvolvimento de um novo sistema de mapeamento da Distribuição da Energia Acústica de Retificação no rebolo, DEAR. Realizaram-se experimentos com o novo sistema, monitorando simultaneamente outros meios físicos. Procurou-se desta forma relacionar o padrão gráfico do mapa gerado pelo novo sistema com o tipo de desgaste que estava ocorrendo, baseado nas informações obtidas no estudo dos mecanismos de desgaste. A análise dos resultados mostraram que o mapa DEAR pode ser utilizado para identificar o tipo de mecanismo de desgaste predominante que está ocorrendo no rebolo, em processo. Esta informação é muito útil na escolha de ações corretivas para problemas da retificação.
The objective of this work is the development of a monitoring system able to identify in process the grinding wheel wear mechanism. Thus, initially the physical quantities, sensors types and monitoring systems strategies, developing status and their applications were researched. To get a reliable and efficient system was necessary a detailed study of the grinding wheel wear mechanism phenomenology. This study allows to define parameters in order to identify which type of wear is occurring, using indication obtained by the monitoring variables whose behavior is known, such as grinding power, vibration or metrological measurement. Two grinding wheel surface optical mapping systems are presented, those systems were utilized as base to developing a new mapping system of Grinding Acoustic Energy Distribution (DEAR). Experiments have been done with the new system, monitoring simultaneously other physical quantities, looking for a way to link the mapping graphic patterns generates by the new system with the wear type which was occurring, based on information obtained from the wear mechanism study. The results and analysis have shown that the DEAR map can be used to identify the predominant wear mechanism type which is occurring on a grinding wheel, in process. This information is very useful in the corrective actions when facing a grinding problem.

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Araújo, Gilberto de Lima 1967. "Uma contribuição ao brunimento de precisão." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265869.

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Orientador: Amauri Hassui
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-26T13:17:57Z (GMT). No. of bitstreams: 1 Araujo_GilbertodeLima_M.pdf: 4592521 bytes, checksum: 2e679dc1a192c0f7897695fb43c81107 (MD5) Previous issue date: 2014
Resumo: Os processos de brunimento visam buscar precisão de usinagem mais acentuada em superfícies cilíndricas, principalmente em diâmetros internos, em que tais tolerâncias não podem ser obtidas por um processo de retificação cilíndrica. As operações anteriores deste processo também contribuem na qualidade final em termos de obtenção de características geométricas mais precisas. A determinação dos parâmetros de corte de usinagem, o tipo de ferramenta, neste caso a pedra de brunimento ou brunidor, as condições de fixação da peça a ser usinada e o fluido de corte também afetam tais requisitos de especificação geométrica no produto final. Quando as especificações do produto em erros de forma de circularidade e retilineidade demandam valores abaixo de 0,001mm e rugosidade média máxima de 0,10 µm Ra, para sua produção seriada é necessário a realização de uma operação complementar de lapidação, que em muitas aplicações são manuais e utilizam pastas de difícil remoção na superfície da peça. O presente trabalho busca estudar as operações de brunimento e lapidação, tendo como objetivo: realizar experimentos em busca de alternativas de processo para substituir a operação de lapidação diretamente pelo brunimento de precisão, aplicado em aços-liga de alta dureza. Como resultado final, obter erros de forma estatisticamente aceitáveis em produção seriada, inferiores à 0,001mm e rugosidade média abaixo de 0,10 µm Ra, através de experimentos planejados de todo sistema máquina e ferramenta. Os primeiros ensaios comprovaram a forte influência da baixa granulometria dos brunidores na rugosidade da peça, alcançando valores similares ao da lapidação. Os demais ensaios mostraram que a rotação do fuso da brunidora e o avanço dos brunidores em valores baixos, nos limites inferiores dos que foram definidos nos ensaios, proporcionaram melhores características geométricas de circularidade e retilineidade. A estabilidade dimensional do diâmetro da peça também foi melhorada nestas condições. A conclusão desta pesquisa foi de que é possível substituir uma operação de lapidação pelo brunimento de precisão. Palavras Chave: Brunimento, brunidor, brunidora, lapidação, circularidade, retilineidade, rugosidade
Abstract: Honing process is used when a high precision machining is required to correct bore errors on a cylindrical surface, mainly in internal diameters, which is more accurate than grinding process. The operations carried out before honing affect directly the final quality in order to achieve tighter tolerances. The specification of the cutting parameters, such as the tool type, in this case the honing stone, the fixturing condition and the honing coolant affect the geometric results on the final product. In some products applications when roundness and straightness specification is very tight, around or less than 0,001mm and surface finishing of 0,10 ?m Ra maximum, it is necessary a complementary operation of lapping, which is manual and uses the lapping paste, difficult to remove from the piece surface. The objective of this research is to analyze the behavior of the above parameters on precision honing process for hardened steels and suggest process alternatives to achieve the above tolerances directly from honing without lapping. The results must be statistically accepted in production environment by planned experiments in the machine and tooling system. The experiments confirmed the influence of lower honing stones grit size in the roughness quality and it was achieved equivalent surface from the lapping operation. In addition, it was demonstrated that lower spindle speed and stones feedrate figures, in the bottom limit from the range adopted in the trials resulted in a better geometry quality in the roundness and straightness. Also the diameter capability improved with this cutting condition. The conclusion of this research was that it is possible to replace a lapping operation to a precision honing. Keywords: Honing, honing stones, honing machine, lapping, cylindricity, roundness, straightness, surface finishing
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica

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Cristine, Hedlund, and Alexander Tasevski. "Design of bucket teeth." Thesis, Mälardalens högskola, Innovation och produktrealisering, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-33079.

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For many years, buckets have been equipped with teeth to help penetrate, gouge and breakout materials. The teeth also works as wear parts and can be replaced when they are worn down, and thus increase the service life of the bucket. The first teeth were made like a one-piece design and to replace such tooth required both cutting and welding which was very time consuming. Today’s modern teeth consist of an adapter that is welded on the bucket and a tooth with a locking system that makes it easy to replace the tooth when needed. The teeth on the market today are cast, which means that the hardness cannot be guaranteed through the whole cast and the hardest tooth is measured to be around 500 HB. SSABs brand Hardox is the toughest steel on the market. It is extremely wear resistant and has a three time longer service life than ordinary steel. To increase the use of Hardox the possibility to manufacture bucket teeth of three or more plates are examined. This thesis has applied a product development process to mainly develop concepts of the locking system that holds the adapter and tooth together. The locking systems main requirement is to be hammerless, meaning that it is not hammered in, due to the high risk of injury and longer assembly time. Apart from, the geometry of the tooth will be developed to give a better wear resistance. The result is a tooth with at least twice as long service life than the cast competitors and two concepts of locking system. Both locking systems meet the requirement of being hammerless and the sustainability is ensured with calculations of shear force. The geometry of the tooth is design to be self-sharpening, which allows it to stay sharper throughout its service life. Wear test using DEM analysis assure a positive outcome.

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Riofano, Rosamel Melita Muñoz. "Efeito das variáveis de nitretação por plasma na resistência à abrasão de um aço \"maraging\"." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-16092016-113006/.

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Visando-se a avaliação do desempenho de um sistema de nitretação por plasma que se construiu bem como a determinação da influência das variáveis do processo sobre o desempenho das camadas nitretadas ionicamente, foram nitretadas amostras do aço \"maraging\" com a seguinte composição: Fe - 18Ni - 4.2Mo - 12.3Co - 1.7Ti - 0.15Al - 0.03C. Foram variadas as seguintes condições de processo: tempo, temperatura, freqüência do pulso e condição de tratamento térmico prévio. Foram realizadas análises metalográficas, difração de raios-X, microdureza e ensaios de abrasão do tipo \"pino-sobre-disco\" para caracterização das camadas obtidas. O equipamento de nitretação apresentou excelente desempenho no tratamento das amostras utilizadas e o aço \"maraging\", excelente resposta ao tratamento de nitretação. O tempo de tratamento de 3 horas produziu as camadas mais resistentes à abrasão. Os tratamentos com corrente contínua produziram resistências à abrasão superiores às obtidas com corrente pulsada. As amostras nitretadas após o envelhecimento apresentaram resistências superiores às envelhecidas simultaneamente com a nitretação.
Pursuing the evaluation and performance of a nitration system via plasma for us constructed, as well as the determination of the influence of variables of the process on the performance of ionically nitrated layers, it was nitrated maraging steel samples with the next compositions: Fe -18Ni - 4,2Mo - 12,3Co - 1,7Ti - 0,15AI- 0,03C. The following processing conditions were modified: time, temperature, pulse frequency end previous thermal treatment condition. Metallografic analyses, X-ray diffraction, microhardness and pin-on-dick type abrasion test were practised on samples for characterization of their layers. The nitration equipment had excellent performance in the treatment of samples used while the \"maraging\" steel showed excellent answer to the nitration treatment. A treatment time of three hours produced the more resistant layers to abrasion. The treatments with continuous current produced abrasion resistance higher than in treatment with pulsed current post-aged nitrated samples showed higher resistances than those aged during the nitration.

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Dias, Marcia Fernanda Martins. "Avaliação dos parâmetros de soldagem na resistência ao desgaste abrasivo de revestimentos duros." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-20092016-113125/.

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Este trabalho apresenta uma análise das condições de soldagem sobre o desgaste abrasivo de um revestimento duro. O revestimento foi feito pela deposição metálica por arco submerso variando os parâmetros de soldagem e utilizando fluxos comerciais. Foram utilizados dois conjuntos de parâmetros de soldagem (conjunto 01 com velocidade de soldagem de 55 cm/min, extensão do eletrodo de 35,0 mm, tensão de 30V, corrente de 450A e o conjunto 02 com velocidade de soldagem de 50 cm/min, extensão do eletrodo de 25,5 mm, tensão do arco de 26V e corrente de 440A) e quatro fluxos comerciais (identificados como E, M, L e R) formando assim oito condições de soldagem. Foram feitas duas camadas com três cordões de solda cada sobre uma chapa base de aço SAE 1020. Corrente contínua com polaridade direta (CC-) foi utilizada em ambas condições. A resistência ao desgaste abrasivo a baixa-tensão foi avaliada pelo ensaio de desgaste do tipo Roda de borracha/areia seca conforme a norma ASTM G65-94. A análise microestrutural foi feita por microscopia óptica e a análise da região desgastada por microscopia eletrônica de varredura. A resistência ao desgaste abrasivo dos revestimentos do conjunto 01 foi superior em comparação com os revestimentos do conjunto 02, para todos os fluxos utilizados. Os fluxos E e R proporcionaram os melhores desempenho e a martensita de agulhas foi a microestrutura com a qual foram obtidos os melhores resultados de desgaste abrasivo a baixa-tensão neste estudo realizado.
This work presents an analysis of the welding conditions and its effects in the abrasive wear of hardfacings. The hardfacings were obtained by submerged arc surfacing. The welding variables were changed and the commercials fluxes were used. Two groups of welding variables were used (group 01: a traveI speed of 55 cm/min, an electrode extension of 35,0 mm, a voltage of 30V and an amperage of 450A; group 02: a traveI speed of 50 cm/min, an electrode extension of 25,0 mm, a voltage of 26V and an amperage of 440A) and four commercials fluxes (E, M, L e R designated) establishing eight welding conditions. Double-Iayered ot three beads were deposited (applied) on a SAE 1020 base metal plate. Direct current electrode negative polarity (CC-) were used in both groups of welding. The low stress abrasion resistance evaluation was carried out by dry sand/rubber wheel apparatus according to the ASTM G65-94. The microstructural analysis were done by optical microscopy and the worn surface analysis were done by scanning electronic microscopy. The abrasion resistance of the group 01 was superior as compared to the group 02, independent of the fluxe was used. The fluxes E and R presented the best results and the befter abrasion resistant microstructure was lath martensite.

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Giarollo, Daniela Fátima. "Influência do metal de adição na resistência ao desgaste abrasivo de dois aços estruturais." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/178798.

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O presente trabalho teve por objetivo realizar ensaios de desgaste abrasivo em juntas soldadas pelo processo MAG, em dois aços estruturais de alta resistência e baixa liga utilizados no transporte ferroviário de minério, os quais apresentavam diferentes propriedades mecânicas. No aço de menor resistência (Aço A) foram utilizados os metais de adição AWS ER70S-G (Aço A-70) e AWS ER80S-G (Aço A-80), enquanto no aço de maior resistência (Aço B) os metais de adição AWS ER80S-G (Aço B-80) e AWS ER110S-G (Aço B-110). Os conjuntos soldados foram caracterizados quanto às suas microestruturas, dureza e resistência ao desgaste abrasivo em ensaios de degaste roda de borracha e ensaios de desgaste por deslizamento a seco e com adição de um meio corrosivo (NaCl 0,05M, água arti cial ). Os resultados obtidos a partir dos ensaios de desgaste roda de borracha mostraram que para o Aço A a junta soldada do Aço A-70 apresentou melhor resistência ao desgaste, enquanto para o Aço B a maior resistência ao desgaste foi obtida na junta soldada Aço B-110. Dos resultados dos ensaios de desgaste por deslizamento a seco, as zona afetada pelo calor de grãos grosseiros (ZAC-GG) foram as regiões que apresentaram a maior resistência ao desgaste. Das condições soldadas no Aço A, o metal base (MB) apresentou a menor resistência ao desgaste, entre os metais de solda (MS), o MS do Aço A-80 apresentou a maior resistência ao desgaste. No Aço B, o MS do Aço B-80 apresentou a menor resistência ao desgaste, e o MS do Aço B-110 apresentou a resistência ao desgaste similar ao MB. Foi observado um maior desgaste para as amostras que foram submetidas ao ensaio de desgaste por deslizamento com solução, comparativamente às amostras submetidas aos ensaios a seco, o que, de acordo com a literatura, está associado ao efeito sinérgico entre corrosão e desgaste.
The present work had the objective perform abrasive wear tests on GMA welded joints in two high strength low alloy structural steels used in rail transport of ore, which presented di erent mechanical properties. The AWS ER70S-G and AWS ER80S-G wires were used in the lower strength steel (Steel A), whereas the AWS ER80S-G and AWS ER110S-G wires were used in the higher strength steel (Steel B). The welded joints were characterized in terms of their microstructures, hardness and abrasive wear resistance in dry sand/rubber wheel tests and sliding wear tests dry and with a corrosive medium (0.05M NaCl, arti cial water ). The results obtained from the dry sand/rubber wheel tests showed that for Steel A the welded joint with the wire AWS ER70S-G showed better wear resistance, while for Steel B the highest wear resistance was obtained with the AWS ER110S-G wire. From the results of dry sliding wear tests, the coarse grained heat a ected zone were the regions that presented the highest wear resistance. In Steel A, the base metal (BM) showed the least resistance, and between the weld metals (WM), the WM Steel A-80 showed the highest wear resistance. In Steel B, WM Steels B-80 showed the least wear resistance, while the WM Steels B-110 showed the wear resistance similar to BM. It was observed a higher wear for the samples that were submitted to the sliding wear test with solution, compared to the samples submitted to the dry wear test, which, according to the literature, is associated with the synergic e ect between corrosion and wear.

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Leprat, Etienne. "Contribution de la rhéologie aux propriétés tribologiques d'un nontissé abrasif." Ecully, Ecole centrale de Lyon, 2007. http://www.theses.fr/2007ECDL0021.

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La société Spontex fabrique des non-tissés abrasifs destinés au récurage ménager et à l’entretien des sols. Ils sont constitués d’une structure fibreuse liée tridimensionnelle sur laquelle des grains abrasifs en corindon sont fixés au moyen d’un deuxième liant. La capacité à enlever de la matière et à fournir une surface rénovée en fonction du comportement des liants est mal comprise et constitue l’objectif de ce travail. Les récurants de l’étude sont basés sur une nappe de fibres et des grains abrasifs identiques liés avec une résine et/ou des latex au comportement viscoélastique varié. Les propriétés mécaniques sont analysées directement sur les échantillons au moyen d’un rhéomètre en torsion. Les propriétés tribologiques sont déterminées grâce à un tribomètre original, conçu pour l’étude et adapté aux récurants. Ce dispositif mesure l’énergie fournie à un échantillon immergé dans l’eau qui abrase une surface en aluminium 1050 ou en acier inoxydable 304L et qui est soumis, pendant l’expérimentation, à une pression constante et un mouvement trochoïdal typique du nettoyage. Sous l’effet de la densification des structures, qui s’opère pendant les mesures, le comportement des récurants évolue en permanence. Pourtant, l’action abrasive reste stable car la densité surfacique d’abrasifs en contact n’évolue pas avec la densification. Les mesures d’abrasion montrent que le volume abrasé est proportionnel à l’énergie fournie aux échantillons. L’efficacité abrasive, qui correspond à la pente du volume en fonction de l’énergie, dépend uniquement de la raideur du liant des grains abrasifs. Ainsi, à liant des grains identique, l’efficacité n’est pas affectée par la souplesse du liant de la nappe de fibres, souplesse qui augmente la densité d’abrasifs en contact. En revanche, l’augmentation de la densité d’abrasifs diminue considérablement la rugosité des surfaces abrasées. On constate finalement qu’un récurant efficace peut générer une surface peu rugueuse. Ce comportement inhabituel dans le domaine de l’abrasion peut être en partie lié à la particularité des mécanismes d’abrasion engendrés par les mouvements trochoïdaux. Le processus abrasif des récurants est modélisé grâce à une approche énergétique qui se décompose en une partie due aux longueurs de glissement et une partie due aux efforts d’abrasion dépendante de la nature des liants
Spontex is a company which manufactures non-woven scourers for domestic uses such as cleaning dishes and floors. The scourers consist of a three-dimensional structure of bonded fibres, onto which abrasive corundum particles have been bonded. The way in which this material acts to remove material and clean a surface, and the influence of the bonds on its performance, are poorly understood and are the object of this study. The scourers used here are formed from a layer of fibres and identical abrasive grains, bonded with either resin or latex, with varying visco-elastic properties. The mechanical properties of the materials have been measured directly, using a torsion rheometer. The tribological properties of the surface have been measured using a tribometer that was designed specifically for this study and adapted to the characteristics of the scourers. This device measures the energy supplied to a scourer (immersed in water) which is subject to a constant applied pressure and undergoes a trochoidal motion similar to that used in cleaning. Experiments have been performed on two substrates: aluminium 1050 and stainless steel 304L. During the experiments, the scourer undergoes compaction and its behaviour changes over time. However the abrasive action remains almost constant because the compaction does not change the surface density of the abrasive grains. Abrasion measurements show that the volume of material removed by abrasion is proportional to the supplied energy. The abrasive efficiency, defined as the slope of the eroded volume when plotted versus the supplied energy, depends only on the stiffness of the bonds holding the abrasive grains. Thus the abrasive efficiency does not depend on the flexibility of the bonds in the fibre layer, provided the grain bonding does not change, even though increasing the flexibility of the fibre bonds increases the number of abrasive grains in contact with the substrate. On the other hand, increasing the surface density of the abrasive grains produces a significantly smoother abraded surface. Finally, we observe that an efficient scourer can produce a relatively smooth surface. This is an unusual result for surface abrasion, which can possibly be explained by the rather special abrasion mechanisms generated by the trochoidal motion of the scourer. The abrasive action of a scourer has been modelled using an energy approach, based on two effects – one linked to the slip lengths and the other linked to the abrasive forces, which depend on the characteristics of the bonds

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Vendrame, Saimon. "Integridade superficial do aço-rápido AISI M3:2 após o processo de retificação /." Bauru, 2019. http://hdl.handle.net/11449/191113.

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Orientador: Eduardo Carlos Bianchi
Resumo: Aços-rápidos são materiais que exibem elevada resistência ao desgaste abrasivo, aliada a uma tenacidade relativamente alta, propriedades estas que os tornam adequados para se fabricar ferramentas de corte. Grande parte de suas propriedades se deve a presença de carbonetos na microestrutura. Ao mesmo tempo que estas propriedades mecânicas são favoráveis para a utilização como ferramentas, tornam-se desafios na sua fabricação. O processo de retificação é empregado nas últimas etapas de fabricação de ferramentas de corte como machos e brocas e a presença dos carbonetos afetam a eficiência dos rebolos. Neste contexto, este trabalho visa investigar o quanto a diferença de microestrutura de aços-rápidos classe AISI M3:2, obtidos de diferentes fornecedores, influencia na retificação, levando em consideração a integridade superficial. Os materiais, aqui nomeados como M-A, M-B e M-C, foram avaliados sob três aspectos: características da microestrutura, resistência à abrasão e integridade da superfície após a retificação. Da microestrutura os carbonetos tipo MC e M6C, foram descritos quanto à forma e a distribuição, utilizando para isso MEV e EDS. A resistência à abrasão dos materiais foi medida recorrendo ao método de ensaio tribológico pino-lixa. Após esta caracterização, foram realizados ensaios de retificação tangencial plana com rebolo de Carboneto de Silício (SiC) em várias penetrações de trabalho (entre 10 µm e 30 µm). As superfícies das amostras foram avaliadas mensurando a rug... (Resumo completo, clicar acesso eletrônico abaixo)
High-Speed Steels are materials that exhibit high abrasive wear resistance coupled withrelatively high toughness, properties that make them suitable for making cutting tools. Much ofits properties are due to the presence of carbides in the microstructure. While these mechanicalproperties are favorable for use as tools, they impose challenges in their manufacture. Thegrinding process is employed in the final stages of the cutting tools manufacturing, such as tapsand drills and the presence of carbides affects the efficiency of the grinding wheels. In thiscontext, this work aims to investigate how the microstructure difference of class AISI M3: 2steel, obtained from different suppliers, influences the grinding, taking into consideration thesurface integrity. The materials, here named M-A, M-B, and M-C, were evaluated under threeaspects: microstructure characteristics, abrasion resistance, and surface integrity after grinding.From the microstructure, carbides type MC and M6C were described regarding the shape anddistribution, using for this purpose SEM and EDS. The abrasive wear resistance of the materialswas measured using the pin-abrasive tribological test. After this characterization, flat tangentialgrinding tests were performed, using silicon carbide grinding wheel (SiC), in various workdepths (between 10 μm and 30 μm). The ground samples surfaces were evaluated by measuringthe roughness parameters, evaluated by SEM, and the microhardness profil
Doutor

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Doan, Yen The. "Experimental investigation and wear simulation of three-body abrasion." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2015. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-158239.

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The wear process in three-body contact causes problems of abrasion such as volume loss and changes of geometry of the triboelements. The wear problem leads to increased failure and high costs for repairing or replacing equipment. To understand the nature of the wear behaviour and to predict the wear rate in advance, experimental investigation and numerical simulation of the wear process are required. In this work, the wear process is analysed and the influencing parameters governing the wear behaviour are investigated experimentally to develop a new wear model. Main influential factors are considered such as kinematics of abrasive particles, contact stiffness of the particle layer, friction characteristics, and wear factors. The experiments to study kinematics of particle layers are performed on a new observation tester. To define the contact stiffness of abrasive particles, experiments are conducted by the uniaxial spindle compression tester. Moreover, a tribometer test rig with applied load up to 200 N and velocity up to 1000 mm/s is used to investigate the friction characteristics and the wear behaviour of three-body tribosystem. Analyses of influential factors on the wear behaviour in dependency of predefined process parameter are carried out. Additionally, based on the results of the experimental investigations, approximation equations representing the relation of the influential factors and the process parameters are determined. A three-body wear model is build up to represent the wear behaviour by physical wear laws. Furthermore, these approximation equations and the relevant parameters obtained by experimental investigations are included in the Fleischer’s wear equation to simulate the wear process. With the coupled model the wear process of the sample can be simulated twodimensional over the sliding distance. It is possible to predict the wear depth and the wear intensity, which can be used to estimate the wear rate. Additionally, from the results of the wear simulation the worn surface and the local contact pressure in the contact region are determined which provide a deeper insight into the wear process. With this simulation the understanding of the wear behaviour can be improved which is important to solve wear problems.

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Vignola, Alex. "Abrasive water jet (AWJ): tecnologia, impianto e ruolo dell’abrasivo." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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La tecnologia water jet è una tecnologia piuttosto recente che però, negli ultimi decenni, ha avuto uno sviluppo davvero elevato; uno sviluppo continuo, a partire dagli anni 50, che non accenna ad arrestarsi, e che ha progressivamente migliorata la tecnologia, portandola ad essere una delle più versatili presenti sul mercato odierno. All’inizio fu utilizzata su materiali morbidi e con spessori limitati, come carta o plastica. La successiva introduzione dell’abrasivo, in aggiunta al getto d’acqua pressurizzato, ha portato alla possibilità di lavorare materiali e spessori di interesse ingegneristico.

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Andrade, Gustavo Tressia de. "Resistência à abrasão de aço Hadfield para britadores: efeito do tamanho do abrasivo e do pH do meio." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-11072016-102946/.

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Neste trabalho, foi investigado o efeito do tamanho do abrasivo e do pH do meio na resistência ao desgaste abrasivo do aço H-13 com matriz martensítica e do aço Hadfield com matriz austenítica. Ensaios de abrasão foram realizados utilizando o equipamento roda de borracha a úmido, variando o tamanho do abrasivo entre 0,15 e 2,40 mm e o pH do meio entre 5,5 e 12,8. As microestruturas dos materiais estudados foram analisadas utilizando microscopia óptica, as superfícies de desgaste e as partículas de desgaste foram analisadas em microscópio eletrônico de varredura. A macrodureza e a microdureza, antes e após os ensaios, foram obtidas utilizando durômetro Vickers. A topografia da região central da superfície de desgaste foi obtida utilizando Perfilometria 3D, visando obter valores de profundidade de penetração do abrasivo. Os resultados mostraram que o aço Hadfield é mais resistente do que o aço H-13 em todos os valores de pH e tamanhos de abrasivo utilizados. Para os dois materiais, a perda de massa aumenta linearmente até um tamanho crítico de abrasivo (TCA) e, após este, a mesma continua a aumentar, mas com uma intensidade menor. Para os dois materiais e para todos os tamanhos de abrasivo, o aumento do pH do meio resultou em menores perdas de massa, sendo este efeito maior para os dois menores tamanhos de abrasivo. Para maiores valores de pH, foram observadas menores profundidades de penetração do abrasivo. A microdureza da superfície de desgaste do aço H-13 sofreu um pequeno aumento com o aumento do tamanho do abrasivo enquanto que para o aço Hadfield esse aumento foi mais intenso. A análise das partículas de desgaste mostraram que, para todas as condições ensaiadas, os debris do aço H-13 tinham duas morfologias, contínuas e descontínuas enquanto que os cavacos do aço Hadfield foram sempre descontínuos. Para os dois materiais, foram observados dois micromecanismos de desgaste, sendo eles microcorte e microsulcamento. Por fim, os resultados apresentados neste trabalho sugerem que a análise de desempenho do aço Hadfield em serviço deve considerar o pH do meio bem como a granulometria do abrasivo em contato.
In this work, the effects of abrasive particle size and pH value of the aqueous solution on abrasive wear resistance of the H-13 steel with martensitic matrix and the Hadfield steel with austenitic matrix were investigated. Abrasive wear tests, using a wet rubber wheel abrasion tester, were carried out using abrasive sizes between 0.15 and 2.40 mm and pH values of the aqueous solution between 5.5 and 12.8. The microstructures of the materials studied were analyzed by optical microscopy and the wear surfaces and wear particles were analyzed by scanning electron microscopy. The hardness and microhardness before and after the tests were measured using a Vickers hardness tester. The topography of the middle of wear scars, were obtained by a noncontact 3D profiler in order to measure the depth of abrasive penetrations.The results show that the Hadfield steel is more wear resistant than the H-13 steel at all pH values and abrasive sizes conditions tested. For both materials, mass loss increases linearly up to a critical abrasive size, and after this the mass loss continues to increase, but with a lower intensity. Moreover, for both materials and all the abrasive sizes, increases in the pH values of the aqueous solution resulted in lower mass losses, and this effect is greater for the two smaller grain sizes. For higher pH values, lower depths of penetration of abrasive were observed. The microhardness in the wear scar surface of the H-13 steel presented a slight increase with the abrasive size, while for the Hadfield steel, this microhardness increases in a more intense form with the abrasive size. The analysis of the wear particles showed that, for all test conditions, the chips of H-13 steel has two types of morphologies, continuous or discontinuous, and for Hadfield steel only discontinuous. For both materials, two abrasive wear micromechanisms were observed, microcutting and microploughing. Finally, the results presented in this work suggest that the wear performance analysis of the Hadfield steel, to be used in an abrasive environment, must consider the effects of pH of the aqueous solution and particle size.

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Ferreira, Renata Prata. "Estudo do efeito da força, do módulo de elasticidade e do envelhecimento termomecânico no desgaste abrasivo da borracha de polibutadieno baixo cis." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-19072016-115907/.

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Esta Dissertação de Mestrado tem como Objetivo estudar a influência da tangente delta, envelhecimento termomecânico e força no comportamento de uma borracha de polibutadieno baixo cis perante o desgaste abrasivo através de experimentos em roda de borracha, utilizando planejamento fatorial completo em dois níveis (DOE 2k). A literatura possui muitas informações em relação à força indicando uma relação exponencial com a taxa de desgaste, todavia em relação à tangente delta e ao envelhecimento termomecânico quase não há dados. Ao final do trabalho foi possível verificar que todos os fatores estudados são significativos com relação ao desgaste da borracha, sendo a força a variável com maior influência, seguida pelo envelhecimento. A histerese medida pela tangente delta, apesar de ser um fator importante, só exerce influência no desgaste quando a borracha se encontra no estado envelhecido. Além disto, este trabalho também apresenta informações complementares sobre propriedades que são características da borracha e pouco difundidos, como o smearing, características de ondas de abrasão (abrasion pattern), comprimento de onda (Schallamach wavelength) e ondas de destacamento (waves of detachment).
This goal of this Master thesis is the study the influence of loss factor, thermomechanical aging and applied load to the abrasion behavior of low cis polibutadiene rubber through rubber wheel testing machine experiments using 2k factorial experiment design in two levels (DOE 2k). The literature has many information involving action of force showing exponential relationship between wear rate with applied load, almost no data related to the influence of loss factor and the thermomechanical aging. It was observed that all the studied factors are significant to the wear of rubber, the force being the variable with the greatest influence, followed by aging. The loss factor, despite being an important factor, only influences the wear behavior of aged rubber. In addition, this work presents some information regarding to the typical properties only for rubber and rubber products, such as smearing, abrasion pattern and Schallamach wavelength.

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Machado, Paulo Cordeiro. "Análise multiescala da abrasão de aços austeníticos ao manganês aplicados em britadores de minério." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-28112017-073503/.

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O desgaste abrasivo de dois aços austeníticos ao manganês, materiais com grande utilização na mineração, foi estudado empregando metodologia multiescala (escalas: macro, meso e micro). Na macroescala foram estudados os mecanismos de dano e de desgaste de revestimento de britador utilizado em campo. Na mesoescala foram realizados ensaios de britador de mandíbula e de esclerometria linear. Na microescala o ensaio de esclerometria linear foi utilizado para avaliar os efeitos da camada encruada em campo e da orientação cristalográfica dos grãos austeníticos dos aços com 12 %Mn e 20 %Mn. As técnicas de caracterização utilizadas nesta pesquisa foram: macro e microdureza, nanodureza instrumentada, MO, MEV, DRX, EBSD, FIB e MET. A pesquisa foi dividida em três Capítulos, intitulados: \"Desgaste abrasivo dos aços austeníticos com 12 %Mn e 20 %Mn via ensaio de britador de mandíbula\"; \"Efeito do encruamento e da orientação cristalográfica no desgaste por riscamento dos aços austeníticos 12 %Mn e 20 %Mn\"; e \"Microestrutura da subsuperfície do aço austenítico com 12 %Mn deformado por desgaste abrasivo\". O primeiro Capítulo mostrou, a partir do ensaio de britador de mandíbulas (mesoescala), que o aço com 20 %Mn tem tendência de maior resistência ao desgaste que o aço com 12 %Mn. Este resultado foi obtido para a mandíbula fixa do britador, na qual a severidade de desgaste foi superior a mandíbula móvel, por apresentar microcorte e microsulcamento como micromecanismos predominantes, enquanto na mandíbula móvel o micromecanismo predominante foi a microendentação. No segundo Capítulo observou-se que o desgaste por riscamento (mesoescala e microescala) não depende do perfil de encruamento gerado em campo. Entretanto, foi identificado o efeito da orientação cristalográfica, planos (001), (111) e (101), no desgaste por riscamento dos aços com 12 %Mn e 20 %Mn. No último Capítulo a análise multiescala mostrou que a microestrutura deformada na subsuperfície sofre alterações semelhantes em diferentes intensidades. Nas três escalas de análise foram observadas uma camada com grãos ultrafinos (nanométricos), na subsuperfície, e uma de transição com maclas de deformação. A formação dos grãos ultrafinos foi associada à recristalização dinâmica por deformação plástica, na qual faz parte do mecanismo de auto reparação superficial. Além dos resultados apresentados, o desenvolvimento desta pesquisa de doutorado permitiu a elaboração de duas metodologias: i. análise do efeito da orientação cristalográfica no desgaste por microesclerometria; e ii. análise de microestrutura revelada por ataque iônico - FIB.
The abrasive wear of two manganese austenitic steels, materials broadly used in mining industry, was studied using multiscale methodology (scales: macro, meso and micro). In the macroscale the mechanisms of damage and wear of in-service crusher liner were studied. In the mesoscale, jaw crusher and linear scratch tests were performed. In the microscale the linear scratch test was used to evaluate the effects of the hardening layer and the crystallographic orientation of the austenitic grains of steels with 12 %Mn and 20 %Mn. The characterization techniques used in this research were: macro and microhardness, instrumented nanohardness, OM, MEV, DRX, EBSD, FIB and TEM. The research was divided into three chapters, entitled: \"Abrasive wear of steels with 12 %Mn and 20 %Mn via jaw crusher test\"; \"The effect of the in-service workhardening and crystallographic orientation on the micro-scratch wear of austenitic steels with 12 %Mn and 20 %Mn\"; and \"Subsurface microstructure of the deformed austenitic steel with 12 %Mn by abrasive wear\". The first chapter showed, from the jaw crusher tests (i.e. mesoscale), that the steel with 20 %Mn tends to be more wear resistant than the steel with 12 %Mn. This result was obtained to the fixed jaw crusher, in which the wear severity was superior to the movable jaw, since it presents microcutting and microploughing as predominant micromechanisms, whereas in the mobile jaw the predominant micromechanism was microendentation. In the second chapter, it was observed that scratch wear (i.e. meso and microscale) does not depend on the in-service work-hardening profile. However, it was identified the effect of crystallographic orientation, (001), (111) and (101) planes, on the scratch wear of the steels with 12% Mn and 20% Mn. In the last chapter, the multiscale analysis showed that the subsurface deformed microstructure changes with different intensities. At the three analysis scales, a layer with ultrafine grains was observed in the subsurface and mechanical twins. The formation of this layer, with nanometric grains, was associated with dynamic recrystallization by plastic deformation, in which it is part of the self healing effect. In addition to the results found, the development of this doctoral research allowed for the elaboration of two methodologies: i. Analysis of the effect of crystallographic orientation on the scratch wear; and ii. Microstructure analysis revealed by ion etching - FIB.

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Reichenwallner, Christopher, and Erik Tegevall. "Skivbytesrobotik i tuff miljö : Utvärdering och förslag på förbättringsåtgärder." Thesis, Uppsala universitet, Industriell teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325064.

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Examensarbetet har utförts under 10 veckor i uppdrag av Outokumpu Stainless AB via Uppsala universitet. Outokumpus produktion i Avesta tillverkar rostfritt stål, där en del av det producerade stålet slipas för att få en finare yta och minska defekter. I sliphallen finns 8st slipmaskiner som alla måste servas med nya slipskivor när de gamla är nedslipade. Detta utförs av två robotar som automatiskt ska åka ut i sliphallen och byta ut de gamla slipskivorna. Problematiken ligger i dessa robotar, vars automation endast fungerar fullt ut ett fåtal av gångerna. Examensarbetet gick således ut på att utvärdera dessa robotar samt generera förslag på förbättringsåtgärder. En stor del av arbetet fokuserades på analys av den befintliga skivbytesprocessen. Efter att förståelse erhållits för dagens process utfördes undersökningar i syfte att finna de faktorer som orsakar stopp i automationen samt dess konsekvenser. Till sist genererades lösningsförslag vars syften är att öka andelen automatiska byten. De huvudsakliga orsakerna till stoppen i automationen grundar sig i processens utformning, dess krav på precision och att ett flertal komponenter måste harmoniera för att byten ska fungera automatiskt. Bortsett från processens utformning är smuts, slitage, ej anpassad reglering och bristande rutiner faktorer som sätter stopp för automationen. Konsekvenser av problemet är säkerhetsrisker, frustration, tidsförluster för operatörer och ekonomiska förluster. Den instabila skivbytesprocessen påverkar i dagsläget inte nödvändigtvis ledtider på produkterna, men tvingar operatörer att byta slipskivor för tidigt vilket resulterar i outnyttjade slipskivor. Att öka andel automatiska byten är möjligt men kräver mycket arbete. Rutiner är viktigt, särskilt angående linjering av slipmaskinerna, vilket är en förutsättning för att det ska fungera. Även utbyte av slitna komponenter, optimering av reglertekniken och mindre programändringar är lösningar till en ökad andel automatiska byten. För att minska kostnaden för outnyttjade slipskivor krävs det att processen kan utföras snabbare och utan att påverka produktionen. Om företaget ska implementera en alternativ lösning är det viktigt att denna lösning inte kräver att operatörer behöver befinna sig i sliphallen. Detta grundar sig i säkerhetsrisker och minskad produktionskapacitet. Lösningen bör vara adaptiv för att ej behöva förlita sig på linjerade maskiner eller snäva toleranser.
This thesis in Mechanical engineering has been performed at the stainless steel manufacturer Outokumpu Stainless AB, through Uppsala University. At the company's production site some of the produced steel slabs are going through hot grinding in order to get the required surface finish, depending on the customer's demand on quality. There are 8 grinding machines in the grinding station, each of those needs to be provided with new abrasives when the old ones get to worn out. Two robots are installed to execute the abrasives change operation automatically, where each robot maintains 4 grinding machines, two coarse and two fine. This changing process is currently working fully automatically around one percent of the times which constitutes a problem. The thesis is about evaluation and improvement suggestions of this process, where the proportion of succeeded automatically replaced abrasives is in focus. A big part of the work has been based on analysing the existing process in purpose of understanding it fully. After enough knowledge about the process was achieved, investigations about the deficiencies of the process were conducted. Finally improvement suggestions were generated. The main cause of the automation failure is based on the process design and its precision requirements. The environment is tough and the forces are big which affects the process negatively. In addition there are a several components that need to harmonize in order for the abrasives replacement to work properly. Aside from the design of the process other critical factors are dust, component wear, deficient adapted regulation and lacking of alignment routines. Consequences of the failed automatically abrasive replaces are reduced safety, frustration among operators, time loss and economical losses. When the automation stops, the operators have to manually correct the errors alongside the grinding machines in the grinding area. The unstable processes does not necessarily affect the value-adding lead time but forces operators to change the abrasives too early which results in losses in form of non-fully utilized abrasives. Increasing the proportion of automatically fulfilled replaced abrasives is possible but requires much work. Routines are important, especially with alignment of the grinding machines which is a prerequisite for the process to succeed. Replacing of wear damaged components, optimizing the regulation and smaller programming changes are also solutions that contribute to an increasing proportion. To minimize the cost of unutilized abrasives the process is required to perform faster and without interfering with the production. If the company wants to implement a different solution in form of an investment it is important that the solution does not require operators to be inside the grinding area. This is based on safety issues, also the risk of interrupting the production and creating a bottleneck, which can be crucial under more demanding periods. The solution should be a faster, more adaptive system and should not have to rely on alignment and narrow tolerances.

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Pereira, Marcio Henrique. "Caracterização do desgaste em punção de forjamento a quente em prensa horizontal automática de múltiplos estágios." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-03082017-095236/.

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Concebido há milhares de anos, o forjamento passa por melhorias contínuas, mantendo-se como um processo de fabricação moderno, capaz de agregar características importantes a produtos forjados que são utilizados em inúmeras aplicações. Na indústria automobilística, responsável pelo consumo de cerca de 60% de todos os produtos forjados, o forjamento mostrou-se como um processo de conformação plástica eficaz no atendimento das especificações de resistência mecânica e nos quesitos de produtividade. Esta demanda por produtos forjados estimulou a busca por processos mais robustos, nos quais as ferramentas de forjamento possuem papel fundamental para possibilitar a produção de lotes maiores sem paradas de máquina devido a falhas. Cerca de 70% das falhas estão relacionadas ao desgaste das ferramentas. Este trabalho buscou identificar no ambiente industrial, os modos de desgaste responsáveis pela degradação da superfície de contato de um punção, fabricado em aço H-10. Um conjunto de punções foi utilizado no forjamento a quente em prensa mecânica excêntrica horizontal e automática de múltiplos estágios, que utiliza água na refrigeração das ferramentas, durante a fabricação de porcas de roda, em aço SAE 1045. Os resultados obtidos basearam-se: (i) nas análises da superfície e da seção transversal de seis punções em microscópio eletrônico de varredura, (ii) na análise da nanodureza e (iii) na variação dimensional e da massa dos punções. Os resultados apontaram para o desgaste da superfície dos punções logo nas primeiras peças forjadas devido à transferência de óxidos do blank para a superfície da ferramenta. Nesta camada transferida para a superfície dos punções, foram encontrados danos causados pelo desgaste abrasivo e pela fadiga térmica.
Since the initial development, thousands of years ago, forging has faced continuous improvements, remaining as a modern manufacturing process, capable of adding important characteristics to forged products that are used in numerous applications. In the automotive industry, responsible for the consumption of approximately 60% of all forged products, the forging has proved to be an effective metal forming process in terms of mechanical strength specifications and productivity requirements. This demand for forged parts has stimulated the search for more robust processes in which the forging tool has a fundamental role to enable the production of larger batches without downtime due to failures. Approximately 70% of these failures are related to tool wear. This work aimed identifying, in an industrial environmental, the wear modes responsible for the degradation of the contact surface of a punch, made of H-10 steel. A series of punches was used for hot forging in a horizontal and automatic multi-stage eccentric mechanical press which uses water for tool cooling, during the manufacture of wheel nuts, made of SAE 1045 steel. Results were based: (i) on the analysis of the surface and cross section of six punches in a scanning electronic microscope, (ii) on nanohardness analyses and (iii) as well as on mass and dimensional variations. Results pointed to the punch wear in the first forged pieces, due to oxides transferring from blank to the punch surface. On this transferred layer to punch surface, have also found damage caused by abrasive wear and thermal fatigue.

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Pontel, Henrique Ferreira. "Estudo do desgaste abrasivo e propriedades mecânicas de um aço Hardox 500 soldado por MAG convencional." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/156494.

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Os aços Hardox possuem microestrutura de martensita revenida e são caracterizados pelas elevadas dureza e resistência à tração, sendo empregados em situações que requerem alta resistência ao desgaste. Entretanto, os processos de soldagem alteram significativamente a sua microestrutura e propriedades. Assim, o objetivo deste estudo foi avaliar a resistência ao desgaste de juntas soldadas de um aço Hardox 500 produzidas através do processo MAG convencional e, juntamente, com o Hardox sem soldagem (metal base), para comparação. A soldagem ocorreu utilizando dois consumíveis, um recomendado pela empresa fabricante do aço, o AWS ER80S-G, e outro de maior resistência mecânica, o consumível AWS ER120SG. As propriedades mecânicas das juntas soldadas foram avaliadas através de perfis de microdureza, ensaios de tração e dobramento. Ainda, foi realizada uma análise da superfície de fratura dos corpos de prova do ensaio de tração, em microscópio eletrônico de varredura. Foram executados ensaios de desgaste por um abrasômetro do tipo roda de borracha. Análises através de microscopia óptica e microscopia eletrônica de varredura foram utilizadas para verificar os mecanismos de desgaste nas superfícies submetidas à abrasão Nos ensaios de dobramento, constatou-se que a condição soldada com o arame de menor resistência apresentou maior ductilidade. Verificou-se, também, que com a soldagem houve uma diminuição da resistência mecânica das juntas em comparação ao metal sem soldagem. Em relação aos ensaios de desgaste, com o uso do arame de maior resistência foi atingido um melhor desempenho no desgaste abrasivo em comparação ao de menor resistência, pois as taxas de desgaste foram de 0,058 e 0,083 mm³/m, respectivamente, mas o comportamento foi ainda inferior ao exibido pelo aço Hardox 500 sem soldagem, que apresentou uma taxa de desgaste de 0,031 mm³/m. Constatou-se, também, que os mecanismos de desgaste foram dúcteis em todas as condições estudadas, pois as superfícies desgastadas mostravam predominantemente micro sulcamento e regiões com micro fadiga; essa última parece ter aumentado de tamanho à medida que a dureza do material testado aumentava.
The Hardox steels have a martensite microstructure and are characterized by high hardness and tensile strength. This steel has been used in situations that require high resistance to wear. However, the welding processes significantly alter their microstructures and properties. Thus, the purpose of this study was to evaluate the wear resistance of welded joints of Hardox 500 steel produced by the conventional MAG process and with Hardox without welding (base metal), for comparison. The welding took place using two consumables, one recommended by the steel manufacturer, the AWS ER80S-G and another with higher resistance, the consumable AWS ER120S-G. The mechanical properties of welded joints were evaluated through micro hardness profiles, tensile and bending tests. In addition an analysis of the fracture surface of the tensile test specimen was carried out by scanning electron microscopy. Wear tests were performed by a rubber wheel type abrasometer. Analyses by optical microscopy and scanning electron microscopy were used to verify the mechanisms of wear on surfaces subjected to abrasion In the bending tests, it was verified that the welded condition with the filler metal of lower resistance presented greater ductility. It was also verified that with the welding, there was a decrease in the mechanical strength of the joints in comparison with the base metal. In relation to the wear tests, with the use of the higher strength wire, a better performance was obtained when compared to the lower one, since the wear rates were 0.058 and 0.083 mm³/m respectively, but the behavior was lower in the Hardox 500 steel without welding, which presented a wear rate of 0.031 mm³/m. It was also observed that the wear mechanisms were ductile in all the studied conditions, since the worn surfaces showed predominantly micro plowing and regions with micro fatigue, the latter seem to have increased in size as the hardness of the tested material increased.

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Silva, Joélson Vieira da. "Estudo da influência do tratamento térmico de austenitização seguida de resfriamento ao ar forçado na resistência ao desgaste abrasivo do ferro fundido branco ASTM A532 II D." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/170956.

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O objetivo desta pesquisa é realizar um estudo sobre o desgaste abrasivo do ferro fundido branco alto cromo de acordo com a norma ASTM A532 II D, submetidas à diferentes faixas de temperatura de austenitização, decompondo a faixa de 950 a 1.150 ºC, amplamente usada nas fundições, em intervalos de 50 ºC. Esta liga foi escolhida para estudo em virtude de sua extensa aplicação na indústria de mineração, possuindo como principal característica a utilização em revestimentos de moinhos e martelos de britadores, onde a resistência ao desgaste abrasivo é exigida. Os corpos de prova foram caracterizados através de análise química, dureza, e estrutura metalográfica, avaliando as mudanças na microestrutura, e consequentemente, alterações nas propriedades de resistência ao desgaste abrasivo do material. Na avaliação das amostras, foi utilizada a microscopia ótica e, para simular a condição de desgaste abrasivo, determinando a perda de massa, foi empregando o abrasômetro do tipo roda de borracha, seguindo a norma ASTM G65. Os testes práticos demostraram que o ciclo de temperatura é uma etapa importante na determinação da dureza, que por sua vez, é uma característica fundamental à resistência ao desgaste abrasivo, visto que para o material estudado, quanto maior a dureza, maior foi a resistência ao desgaste abrasivo.
The objective of this research is to perform a study on the abrasive wear of high chromium white cast iron according to ASTM A532 II D, submitted to different austenitizing temperatures, in the range of 950 to 1150 ºC with 50 ºC steps, widely used in foundries. This alloy was chosen for study because of its extensive application in the mining industry, having as main characteristic the use in mill and hammer coatings of crushers where abrasive wear resistance is required. The specimens were characterized by chemical analysis, hardness, and metallographic analysis, evaluating the changes in the microstructure, and consequently changes in the abrasive wear properties of the material. In the evaluation of the samples, optical microscopy was used and, to simulate the abrasive wear condition, determining the mass loss, the rubber wheel type abrasive test was used, following the ASTM G65 standard. The practical tests demonstrated that the temperature cycle is an important step in determining the hardness, which in turn is a fundamental characteristic to the abrasive wear resistance, since for the material studied, the higher the hardness, the higher the resistance to abrasive wear.

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Morris, Tom. "Abrasive machining with MQSL." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7012.

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Grinding and polishing of engineered components are critical aspects of the precision manufacturing of high performance, quality assured products. Elevated process temperatures, however, are a common and for the most part undesirable feature of the grinding process. High process temperatures increase the likelihood of microstructural change within the immediate subsurface layer and are detrimental to the strength and performance of the manufactured products. Increasing processing costs and tighter environmental legislation are encouraging industry to seek innovative fluid application techniques as significant savings in production can be achieved. In this context, and with sponsorship from three industrial partners, namely; Fives Cinetic, Fuchs Lubricants plc and Southside Thermal Sciences Ltd, and also from the Engineering and Physical Science Research Council (EPSRC), this research aimed to develop an understanding of Minimum Quantity Solid Lubrication (MQSL) as a method for abrasive machining, with particular reference to the control of surface temperatures. Improving the lubricity of Minimum Quantity Lubrication (MQL) fluids reduces the frictional source of process heat and controls the finish surface temperature. The application of effective solid lubricants is known as Minimum Quantity Solid Lubrication (MQSL). Molybdenum Disulphide (MoS2), Calcium Fluoride (CaF2), and hexagonal Boron Nitride (hBN) were compared against a semi-synthetic water soluble machining fluid (Fuchs EcoCool). A series of Taguchi factorial experimental trials assessed their performances through ANOVA (ANalysis Of VAriance) statistical method. The hBN produced the lowest grinding temperatures of the solid lubricants tested, although they still remained higher than those achieved using the EcoCool control. The reduction of the machining fluid enabled a Charged Coupled Device (CCD) sensor to be fitted into the grinding machine. The recorded movement in the emitted spectrum from the grinding chips was compared to experimental and modelled process temperatures. This showed that the wavelengths of the chip light correlated to the temperature of the finish grinding surface. This greatly contributed to determining the feasibility of constructing a non-destructive, non-invasive, thermally-adaptive control system for controlling grinding surface temperatures.

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Selbee, Amber. "Activated charcoal; too abrasive?" The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619127299234152.

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Dissertations / Theses on the topic 'Abrasives'

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