Dissertations / Theses: 'Scratch tests'

1

Krupicka, Andreas. "Use and interpretation of scratch tests on organic coatings." Doctoral thesis, KTH, Polymer Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3357.

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Akono, Ange-Therese. "Scratch tests : a new way of evaluating the fracture toughness of materials." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/64571.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 126-130).
This thesis develops, validates and implements a fracture mechanics model for the assessment of the fracture toughness of materials from scratch tests. Dimensional Analysis highlights two major processes at work during scratch tests: plastic yielding and fracture dissipation. An original set-up of controlled laboratory tests on paraffin wax allows us to identify fracture processes as predominant. An analytical model for scratch tests with a rectangular blade and a back-rake angle is then developed. This model applies to linear elastic isotropic brittle materials and links the fracture toughness to the average horizontal and vertical forces recorded in the scratch test, and to the width and depth of the scratch. Finite Element simulation show that the model is highly accurate for back-rake angles smaller than 25'. From the model, an inverse technique to predict the fracture toughness is developed and implemented. This technique is validated for scratch tests on cement paste, Jurassic limestone, red sandstone and Vosges sandstone. and applied to oil cements hydrated at high temperature and pressure. The application shows that the scratch tests is highly reproducible. almost non-destructive, and not more sophisticated than classical strength-of-materials tests; which makes this *old' technique highly attractive for both materials research and industrial applications.
by Ange-Therese Akono.
S.M.

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3

Seriacopi, Vanessa. "Evaluation of abrasive mechanisms in metallic alloys during scratch tests: a numerical-experimental study in micro-scale." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-12032018-144239/.

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The abrasion can have some approaches, such as: (i-) the manufacturing processes and the production of different surface features and finishing of workpieces and components; and (ii-) in terms of the wear and failure, which occur in tools materials. The present thesis consists in developing a numerical model by Finite Element Method (FEM) validated by experimental tests, aiming to evaluate microstructural influences on the abrasion of metallic alloys. Therefore, objectives are related to define rules focused on ductile material design to obtain cutting resistance. Regardless of their applications, the abrasive micro-mechanism depends on mechanical and damage properties of the materials and their microstructure. A simplified abrasion study is developed considering a single abrasive over a microstructure to evaluate from ploughing to cutting. Thus, scratch tests are performed in micro-scale, applying different ranges of constant normal force. Moreover, the specimen characterization was conducted using optical and electronic microscopy techniques, optical interferometry, conventional hardness, and instrumented indentation. By the developed numerical approach, the results were: (a-) in terms of apparent coefficient of friction (COF), the found numerical and experimental mismatches are assigned to the effects of adhesion, anisotropy, grain boundaries and twinning, for instance, which were not taken into account on the modelling; (b-) the hard precipitates have a prevailing effect over the matrix regarding the apparent COF, whereas the matrix effect is dominant of the soft precipitates on the COF behavior; (c-) as a consequence of the reduced strain energy and tangential load, the local COF decreased when the abrasive scratches the hard precipitates; (d-) regarding the depth of penetration and removed volume, the numerical results are in accordance with the experimental results; (e-) there is not a remarkable micro-mechanism transition using the approach of the dimensional wear coefficient as a function of normal load, which indicates that several abrasive micro-mechanisms can occur in a single scratching; however, a predominance of a certain micro-mechanism can be observed; (f-) hard precipitates often decreases the local depth of penetration and, as a consequence, they cause the reduced of removed volume and increased the local specific energy; (g-) considering the studied range of the normal load, soft precipitates follow the matrix mass removal behavior, but these particles can show fluctuations of the local specific energy in the less severe abrasion; and, finally, (h) the map of the abrasive resistance x deformed hardness/attack angle is an important tool to point out the dominant ductile or brittle effect on the microstructure (mechanical properties); and it delineates frontiers for the abrasive micromechanisms.
A abrasão pode ser tanto tratada do ponto de vista de processos de manufatura e geração de características superficiais distintas em peças e componentes, quanto pode ser abordada em termos de desgaste e falha em diferentes ferramentas aplicadas em processos de fabricação. A presente tese remete ao desenvolvimento de um modelo numérico pelo Método dos Elementos Finitos (MEF), validado por ensaios experimentais, com o objetivo de avaliar influências de aspectos microestruturais na abrasão de ligas metálicas. Portanto, o objetivo desta tese é focado na construção de regras que auxiliem no projeto de materiais dúcteis para terem resistência ao corte. Independentemente da aplicação, os estudos da ocorrência dos micro-mecanismos de abrasão incorporam propriedades mecânicas e de dano dos materiais e suas fases. A avaliação do micro-sulcamento ao micro-corte foi realizada a partir de um estudo simplificado de abrasão, considerando o riscamento de microestruturas por um único abrasivo. Dessa forma, ensaios de riscamento em micro-escala aplicando força normal constante dentro de uma faixa específica. Em adição, as caracterizações das amostras são realizadas a partir de técnicas de microscopia óptica e eletrônica, interferometria óptica, dureza convencional e indentação instrumentada. Por meio da abordagem numérica desenvolvida, os principais resultados obtidos foram: (a-) in termos de coeficiente de atrito aparente (COF), as divergências numérica e experimental encontradas foram decorrentes principalmente do efeito da adesão, anisotropia, contornos de grão e maclação que não foram levadas em conta na simulação; (b-) os precipitados duros tendem a ter efeito predominante sobre a matriz no que diz respeito ao COF aparente, ao passo que a influência da matriz é predominante sobre o comportamento dos precipitados moles; (c-) como consequência das reduções de energia de deformação e força tangencial, o COF local tende a ser diminuído quando o abrasivo passa por precipitados duros durante o riscamento; (d-) os resultados numéricos de profundidade de penetração média e volume removido total são consistentes com os resultados experimentais; (e-) não há uma transição marcante de micro-mecanismo em função de coeficiente de desgaste dimensional em função da carga, indicando uma predominância de um certo micro-mecanismo em um dado risco e, não ocorrendo transições bruscas; (f-) precipitados duros, em geral, diminuem a profundidade de penetração local e, assim, eles reduzem o volume removido e aumentam a energia específica; (g-) para a faixa de força normal avaliada, os precipitados moles seguiram o comportamento de remoção de material de sua matriz, mas podem apresentar oscilações na energia específica local nas condições menos severas de abrasão; e, por fim, (h-) o mapa de resistência à abrasão x dureza após deformação/ângulo de ataque é uma importante ferramenta para definir efeitos dominantes de propriedades mecânicas (dúctil e frágil) na microestrutura submetida à abrasão, e faz o delineamento de fronteiras de micro-mecanismos abrasivos.

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Bernardes, Rodrigues Guilherme. "Friction anisotropy of metallic thin films deposited by Glancing Angle Deposition (GLAD) : Morphological and crystallographic aspects." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCD065.

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Une technique prometteuse pour introduire une anisotropie de frottement dans une surface est la Glancing Angle Deposition (GLAD). Cette méthode a démontré un large éventail de possibilités pour créer des films avec diverses morphologies et caractéristiques structurelles, qui peuvent induire une anisotropie dans diverses propriétés physiques. Cependant, l'étude de l'anisotropie de frottement des films GLAD reste limitée, ce qui peut conduire à une sous-utilisation de cette technique dans les applications tribologiques. Dans ce contexte, cette thèse vise à étudier l'utilisation potentielle du GLAD pour induire une anisotropie de frottement, en se concentrant particulièrement sur l'influence des facteurs morphologiques et cristallographiques. Deux métaux, le tungstène (W) et le molybdène (Mo), ont été sélectionnés pour être déposés dans différentes conditions. Des essais de rayure ont été effectués à différentes charges normales et à différentes directions de rayage afin de déterminer si l'anisotropie de frottement pouvait être systématiquement obtenue et comment elle se manifeste. Les résultats indiquent qu'il est non seulement possible d'obtenir une anisotropie de frottement grâce au GLAD, mais aussi que différents types d'anisotropie peuvent être observés. Ce comportement anisotrope semble être principalement régi par la morphologie du film, en particulier par le contrôle de la déformation plastique et des interactions colonne-colonne. En outre, le type de matériau et l'angle de dépôt influencent considérablement l'anisotropie du frottement, les films de Mo présentant des caractéristiques anisotropes plus complexes que les films de W. Bien que l'impact significatif de la morphologie sur le comportement de la plupart des films soit évident, un film de Mo a démontré que d'autres facteurs peuvent également contribuer à des réponses de frottement atypiques
One promising technique for introducing friction anisotropy in a surface is the Glancing Angle Deposition (GLAD). This method has demonstrated a wide range of possibilities for creating films with diverse morphologies and structural characteristics, which may induce anisotropy in various physical properties. However, the study of friction anisotropy in GLAD films remains limited, potentially leading to the underutilization of this technique in tribological applications. In this context, this thesis aims to investigate the potential use of GLAD to induce friction anisotropy, with a particular focus on the influence of morphological and crystallographic factors. Two metals, tungsten (W) and molybdenum (Mo), were selected for deposition under varying conditions. Scratch tests were conducted with different normal loads and scratching directions to determine whether friction anisotropy could be consistently achieved and how it manifests. The results indicate that not only is it possible to obtain friction anisotropy through GLAD, but also that different types of anisotropy can be observed. This anisotropic behavior seems to be primarily governed by the film’s morphology, particularly through the control of plastic deformation and column-column interactions. Furthermore, the type of material and deposition angle were found to significantly influence friction anisotropy, with Mo films exhibiting more complex anisotropic characteristics than W films. Although the significant impact of morphology on the behavior of most films was evident, a Mo film demonstrated that other factors may also contribute to atypical frictional responses

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5

Damarla, Gowrisankar. "Determination of Wear in Polymers Using Multiple Scratch Test." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4627/.

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Wear is an important phenomenon that occurs in all the polymer applications in one form or the other. However, important links between materials properties and wear remain illusive. Thus optimization of material properties requires proper understanding of polymer properties. Studies to date have typically lacked systematic approach to all polymers and wear test developed are specific to some polymer classes. In this thesis, different classes of polymers are selected and an attempt is made to use multiple scratch test to define wear and to create a universal test procedure that can be employed to most of the polymers. In each of the materials studied, the scratch penetration depth s reaches a constant value after certain number of scratches depending upon the polymer and its properties. Variations in test parameters like load and speed are also studied in detail to understand the behavior of polymers and under different conditions. Apart from polystyrene, all the other polymers studied under multiple scratch test reached asymptotes at different scratch numbers.

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Browning, Robert Lee. "Quantitative characterization of polymer scratch behavior using a standardized scratch test." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/5988.

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The lack of a widely-accepted quantitative methodology for evaluating the scratch behavior of polymeric materials has resulted in the development and establishment of a new methodology recently standardized as ASTM D7027-05. Using a custom-built instrumented scratch machine, it is possible to produce controlled, repeatable scratches on polymer surfaces under constant or linearly increasing loading conditions at constant or increasing scratch rates. Software-aided digital image analysis along with material science tools (SEM, OM, FTIR, etc.) allows polymer scratch behavior to be analyzed without the ambiguity inherent in the past. The current work will serve to describe the motivation for the development of this methodology as well as illustrate the effectiveness of the increasing load/constant rate test mode in three case studies. First, it will be shown that an acrylic coating on a steel system exhibits three zones of scratch damage: adhesive delamination, transverse cracking and finally buckling failure. It will be discussed how increases in ductility and thickness serve to improve the scratch resistantance of this coating/substrate system. Improvements in the scratch behavior of thermoplastic olefins (TPOs) through the use of surface-treated talc fillers and the slip agent erucamide will be shown in the second case. It was found that the surface-treatment of the talc likely allows for enhanced migration of the erucamide to the TPO surface, thus lowering the surface friction and greatly increasing scratch resistance. Finally, the effects of processing conditions, namely injection molding, on the scratch behavior of neat i-polypropylene will be represented by the results of scratch tests conducted where the scratch direction was oriented both along and transverse to the polymer melt flow direction. Based on the findings of the study, there appears to be a high degree of surface anisotropy introduced to injection-molded polymers due to complex fluid flow regimes as well as non-uniform cooling properties.

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7

Wong, Min Hao. "The development of scratch test methodology and characterization of surface damage of polypropylene." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1194.

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A new scratch test methodology is proposed. The new test methodology is developed based on the principles of materials science and solid mechanics, which include the consideration of material parameters, use of microscopy for image analysis and the finite element method (FEM). The consistency and reproducibility of test results are shown using a new scratch test device on two sets of neat and talcfilled polypropylene (PP) systems. Three different test conditions, i.e., linear load increase under constant rate, constant load under constant rate, and linear rate increase under constant load, have been conducted to determine the most effective, informative test conditions for evaluation of scratch resistance of polymers. Experimental observations and FEM results show a good qualitative correlation. The unique advantages of the new scratch test method for evaluating scratch resistance of polymers are discussed. A systematic study of surface damage effected by a progressive scratching load is performed on model polypropylene (PP) systems. Mar-scratch and stress -whitening transitions can be readily observed, and the corresponding critical loads determined. Distinctive scratch hardnesses and surface damage features are found for different material systems. Visibility of scratched surface is quantified using gray level analysis via a flatbed scanner and a commercial image analysis tool. It is found that the onset of scratch visibility can be determined accurately and reproducibly using the custom -built scratcher under progressive loading condition. Talc particles are found to be responsible for the increased light scattering, leading to greatly increased visibility. The observed scratch visibility is also found to be related to the measured frictional force profiles. Approaches for producing scratch resistant PP are discussed.

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Bard, Romain (Romain M. ). "Analysis of the scratch test for cohesive-frictional materials." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61521.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 143-148).
In this thesis we develop analytical solutions for the relations between scratch hardness and strength properties of cohesive-frictional materials of the Mohr-Coulomb and Drucker-Prager type. Based on the lower-bound yield design approach, closed form solutions are derived for frictionless scratch devices, and validated against computational upper bound and elastoplastic Finite Element solutions. The influence of friction at the blade{material interface is also investigated, for which a simple computational optimization is proposed. The model is extended to porous cohesive-frictional materials through the use of a homogenized strength criterion based on the Linear Comparison Composite theory. Relations between scratch hardness, porosity and strength properties are proposed in the form of fitted functions. Illustrated for scratch tests on cement paste, we show that the proposed solutions provide a convenient way to determine estimates of cohesion and friction parameters from scratch data, and may serve as a benchmark to identify the relevance of strength models for scratch test analysis.
by Romain Bard.
S.M.

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9

Atroshenkova, Anastasiia, and Анастасія Олександрівна Атрошенкова. "Strength properties investigation of glass by scratch test method." Thesis, National Aviation University, 2021. https://er.nau.edu.ua/handle/NAU/54160.

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Робота публікується згідно наказу Ректора НАУ від 27.05.2021 р. №311/од "Про розміщення кваліфікаційних робіт здобувачів вищої освіти в репозиторії університету". Керівник роботи: доцент, к.т.н. Закієв Вадим Ісламович
This master thesis is dedicated to the сomparative study of glass strength using scratch test technique. The methods of investigation are scratch tests, nanoindentation and calculation methods for results analysis.
Ця магістерська робота присвячена порівняльному вивченню міцності скла за допомогою методики випробування дряпанням. Методами дослідження є скретч-тести, наноіндентування та розрахункові методи аналізу результатів.

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Dyrda, Katia Marjolaine. "Adhesion characterization of hard ceramic coatings by the scratch test." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ37948.pdf.

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CHAKRAVARTY, SRINIVAS L. N. "DEVELOPMENT OF SCRATCH RESISTANT PECVD SILICA-LIKE FILMS." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973542599.

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12

Browning, Samuel Frank. "Using Dr. Scratch as a Formative Feedback Tool to Assess Computational Thinking." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6659.

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Scratch is one of the most popular ways to teach younger children to code in K–8 throughout the U.S. and Europe. Despite its popularity, Scratch lacks a formative feedback tool to inform students and teachers of a student's progress in coding ability. Dr. Scratch was built to fill this need. This study seeks to answer if using Dr. Scratch as a formative feedback tool accelerates the students' progress in coding ability and Computational Thinking (CT). Forty-one 4th-6th grade students participated in a 1-hour/week Scratch workshop for nine weeks. We measured pre- and posttest results of the Computational Thinking Test (CTt) between control (n = 18) and treatment groups (n = 23) using three methods: propensity score matching (treatment = .575; control = .607; p = .696), information maximum likelihood technique (treatment effect = -.09; p = .006), and multiple linear regression. Both groups demonstrated significant increased posttest scores over their pretest (treatment = +8.31%; control = +5.43%), though which group improved the most varied depending on which test was run. We discuss the implications of using Dr. Scratch as a formative feedback tool and recommend further research on the use of such tools in elementary coding experiences.

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13

Secor, E. Daniel. "A constant-depth scratch test for the measurement of adhesion at film-substrate interfaces." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283660.

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Campbell, John C. "The measurement of adhesion at film-substrate interfaces using a constant depth scratch test." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA289940.

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Russell, Andrew James Reksten. "Design of a Mine Roof Strata Analyis Device." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/73210.

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Because the roof lithology in an underground coal mine is typically variable and poorly known, the safety and efficiency of these mines is reduced. To address this shortcoming, a device for analyzing rock properties by way of scratching a mine roof borehole was designed and tested in multiple different media with the goal of determining in situ mine roof properties with a nondestructive technique. Tools were developed for measuring extraction force and position of the scratching mechanism and those values were compared versus time for multiple tests to look for changes in applied force over changing positions. Because of signal stability and inconsistencies in scratch depths the data were found to contain too much variation to determine any rock properties or changing rock conditions from the simulated roof material in the concrete block. However, further scratch tests in a sandstone block indicated that increasing the diameter of the wire scratchers (and therefore increasing their stiffness and accompanying normal force) from 0.045 inches to 0.055 inches increased the average pull force from 6.24 to 9.96 lbs. Similar to that test, a scratch test was performed in a PVC pipe where it was found that increasing the scratcher diameter from 0.045 inches to 0.051 inches increased the pull force from a 2.81 lb average to a 36.46 lb average, with considerably better gouging of the host material.
Master of Science

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Pálesch, Erik. "Charakterizace adheze tenkých vrstev plazmových polymerů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216641.

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The diploma thesis deals with characterization of adhesion of plasma polymer films deposited on silicon wafers. The samples included organosilicon thin films based on tetravinylsilane monomer prepared by plasma-enhanced chemical vapour deposition. Scratch test was used to characterize film adhesion employing nanoindentation measurements. Adhesion of plasma polymer films of different mechanical properties and film thickness was analyzed by normal and lateral forces, friction coefficient, and scratch images obtained by scanning probe microscope working in atomic force microscopy mode.

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Pálesch, Erik. "Povrchové a mechanické vlastnosti tenkých vrstev." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-233386.

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The doctoral thesis deals with the study of morphology and mechanical properties of thin plasma polymer films based on tetravinylsilane monomer and its mixtures with oxygen and argon. Thin films were prepared by plasma-enhanced chemical vapour deposition on silicon and glass substrates. Atomic force microscopy was used for characterization of thin film surface and for depiction of composite interphase with functional interlayer. Mechanical properties of thin films, namely Young’s modulus and hardness, were studied by cyclic nanoindentation technique. Nanoindentation device was also used to carry out scratch test, which was helpful to describe adhesion of films to substrate. In this thesis the influence of deposition conditions on surface and mechanical properties of thin films prepared in continual and pulse wave on planar substrates is discussed. Also, the suitability of few atomic force microscopy techniques for depiction of composite interphase was reviewed.

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Rodriguez, Régis. "Influence de la microstructure du nitrure de silicium sur son aptitude à la rectification." Valenciennes, 2003. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/406e32e7-f701-425f-8f4a-a96453b90783.

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Cette thèse CIFRE se penche sur l'influence de la microstructure de nitrures de silicium (Si3N4) commerciaux sur leur aptitude à la rectification en vue d'une application d'éléments roulants dans un roulement. La première partie concerne une étude des conditions de densification de différentes nuances de Si3N4, avec MgO/Al2O3 et Y2O3/Al2O3 comme additifs de frittage, par GPS et HIP. La seconde partie traite des effets générés par une rectification sur les propriétés mécaniques de Si3N4 commerciaux. Une estimation de l'endommagement créé par les grains abrasifs a été réalisée par les techniques d'indentation et de scratch test. Les variables testées lors des essais de rectification sont la vitesse d'avance, la prise de passe, la taille et la nature des grains abrasifs. L'analyse par microscopie électronique à balayage des surfaces rectifiées révèle le passage d'un mode d'enlèvement de matière ductile à un mode pseudo-ductile. Les essais de flexion, corroborés par la mesure des contraintes résiduelles montrent que le matériau n'est pas perturbé, par rapport à un état de référence, quels que soient les paramètres de rectification utilisés
This CIFRE thesis concerns the influence of silicon nitride microstructure on its grinding ability. The first part concerns the densification of different silicon nitride (Si3N4) commercial powders with MgO/Al2O3 or Y2O3/Al2O3 as sintering aids through GPS and Post HIP. The second part is devoted to effects produced by grinding on the mechanical properties of materials. An approach of the damage created by the abrasive grains is tempted by techniques of indentation and scratch test techniques. The grinding variables are : the depth of cut, the workpiece rate, the size and the nature of diamond grits. The observation of surfaces by SEM reveals the passage of a ductile matter removal mode to a pseudo-ductile mode. Tests of bending, corroborated by the residual stresses measurements, show that the material doesn't present any modification related to a state of reference, whatever are the studied grinding parameters

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Palkovic, Steven D. (Steven David). "Development of a portable scratch test device for probing strength, ductility and structural distress in metal materials." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90157.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Practicing civil, mechanical, aerospace, petroleum and structural engineers are often faced with the complexity of evaluating the quality and integrity of new or existing structures. Recent academic research has demonstrated that instrumented scratch testing is a viable alternative for determining the strength and ductility of metals without the use of destructive methods involving the extraction of tensile testing specimens. Although the scientific basis for scratch testing is well established, there is a necessity for a simple and robust implementation that avoids the complexities of current methods which require expensive laboratory equipment and sophisticated data processing. A detailed description of the instrumented scratch testing method for characterizing ductile metals is provided, as well as comparisons with existing alternatives. An innovative scratch testing method is proposed and validated to perform a displacement controlled scratch experiment. A portable scratch testing device is designed and developed to utilize the displacement control technique along with specific instrumentation to allow for the continuous measurement of material properties along the length of a scratch during the experiment. The scratch testing device and method are implemented in a scratch experiment on a welded connection. For the first time, a simple experimental procedure allows for the measurement of changes in mechanical properties through the weld, from the base metal, heat-affected zone (HAZ) and filler weld metal. This novel application highlights the unique ability of the scratch testing method to monitor the evolution of localized mechanical properties in areas of interest to practicing engineers. Recommendations for future iterations of the portable scratch tester are provided.
by Steven D. Palkovic.
S.M.

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20

Lionti, Krystelle. "Élaboration d’un revêtement dense et protecteur sur polycarbonate." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10225/document.

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Ce travail s’intéresse a la synthèse et à la caractérisation de revêtements hybrides O/I à base de silice, préparés par voie sol-gel et déposés sur polycarbonate (PC), pour des applications en milieu chaud et humide dans le domaine culinaire. Le PC étant connu pour sa sensibilité à l’hydrolyse dans ce type de milieux (provoquant sa dépolymérisation progressive et ainsi la libération de bisphénol A, molécule suspectée comme étant toxique), le rôle du revêtement est donc de protéger le PC et d’éviter son vieillissement prématuré, tout en améliorant ses propriétés mécaniques. Dans un premier temps, de nombreux sols ont été synthétisés et optimisés, principalement en termes de nature et quantités de précurseurs, et de pH, dans le but d’obtenir des revêtements homogènes et transparents. Un suivi des réactions d’hydrolyse et de condensation des sols a également été réalisé afin de déterminer le temps minimal de maturation de ces derniers. Apres dépôt des revêtements par dip-coating, les propriétés mécaniques des films ont été étudiées par de nombreuses techniques. D’un point de vue général, les propriétés des échantillons revêtus ont été trouvées supérieures à celles du PC nu. L’influence de nombreux paramètres de synthèse comme le ratio organoalcoxysilane(s)/silice colloïdale, l’ajout d’additifs, le type de traitement de surface du PC pré-dépôt ou encore les conditions de recuit, a également été étudiée. L’ensemble de ce travail a permis d’obtenir, à partir de deux systèmes sol-gel différents, des revêtements performants en termes de transparence, d’adhésion au substrat, de non-toxicité, couplés à des valeurs élevées de dureté, de densité et de module de Young
This work deals with the synthesis and the characterization of hybrid O/I silica coatings prepared by the sol-gel route and deposited on polycarbonate (PC), for applications in hot and humid environment in the alimentary field. PC is well-known for undergoing hydrolysis in such conditions (causing its progressive depolymerization and thus leading to the release of bisphenol A, a molecule suspected to be toxic): the function of the coating would thus consist in preventing PC from this kind of premature ageing, along with the enhancement of its mechanical properties. As a first step, a lot of different sols were synthesized and optimized, mainly in terms of type and quantity of precursors, along with the pH, in order to obtain transparent and homogeneous coatings. The hydrolysis and condensation reactions were monitored in order to determine the minimum ageing time to be waited before any film deposition. After deposition by dip-coating, the mechanical properties of the films were assessed by using many different techniques. Basically, the coated-PC samples display higher properties than the uncoated one. The influence of numerous synthesis parameters such as the organoalkoxysilanes/colloidal silica ratio, the presence of additives, the kind of surface treatment of PC before film deposition, or the annealing conditions was also studied. This whole work led to the synthesis, from two different sol-gel systems, of superior quality coatings in terms of transparency, adherence to the substrate, non-toxicity, along with elevated hardness, density and Young’s modulus values

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Seok, Jin Woo. "SPUTTER DEPOSITED CR/CRN NANOCRYSTALLINE THIN FILMS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin985901057.

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Handrk, Jiří. "Úprava oxidačních vlastností TiAl intermetalik kovovými multivrstvami na bázi Al-Y." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231716.

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Mechanické vlasnosti intermetalika na bázi titan hliník Ti-46Al-7Nb-0.7Cr-0.1Si-0.2Ni jsou konstatní do teploty 700 °C. Nad touto teplotou slitina oxiduje. Cílem této práce bylo zlepšit oxidační vlastnosti pomocí kovové multivrstvy na bázi yttrium hlinik. Pro depozici vrstev byla použita metoda PVD. Na vzorky byly naneseny vrstvy čistého ytria nebo kombinace yttrium, hliník. Vzorky byly následně žíhány v inertní atmosféře na 700°C a 900°C nebo nebyly. Kvalita nanesených vrstev byla zkoumána pomocí scratch testu a EDS analýzi. Dále byly vzorky izotermicky oxidovány na 900°C po dobu 100 hodin. Na vzorcích byly po oxidaci prováděny měření pevnosti v tříbodovém obybu a měření hmotnosti. Chemické složení oxidické vrstvy bylo vyhodnoceno pomocí EDS. Žádná z vrstev s nebo bez žíhání neprokázaly zlepšení oxidických vlastností. Vyšší teplota žíhání prokýzala zlepšení mechanických vlastnotí vrstvy, ale zhoršení materiálu.

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Jammula, Chaitanya Krishna. "Correlating the microstructure with wear properties of aluminium silicon carbides." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Industriell produktutveckling, produktion och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-45820.

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Aluminium is one of the metals playing a prominent role in automobile industry after cast iron. Because of its light weight property and good mechanical properties. When aluminium reinforced with silicon carbide showing good tribological properties and improved strength. Aluminium silicon carbide needs some good wear and frictional properties to use it as break disc. Aluminium reinforced with 15% and 20% silicon carbide and casted in two different ways, liquid casting and stir casting. Four different composites are compared in this paper. Hardness test was carried out on the samples. Increase in the Vickers hardness with increase in silicon carbide reinforcement for both the castings is observed. Rockwell C hardness is showing decreasing trend with increase in SiC reinforcement. The scratch resistance of the surface under micro level was analysed with the help of nano scratch test. The SiC particles in the aluminium matrix are resisting the indenter from deep deformation of the surface. Frictional forces are dropped whenever the indenter met the SiC particles. In other cases, SiC particles are deforming the aluminium matrix in the form of broken particles. The plastic deformation of aluminium is observed, and material is piled up on sideways of groove at high load.Sliding wear behaviour of the composites are investigated by means of reciprocating pin on plate wear rig. The test was carried out at load of 20N for five different sliding duration. Aluminium with 20% silicon carbide of liquid casting is used as a base metal. The worn-out surface of the samples is analysed in SEM. The metallography of the worn-out samples is showing some deep grooves and abrasion of the material. Wear debris from both the surfaces are forming into a cluster of layers. These layers are protecting the surface from wear in some areas were observed. Composition of tribo layer formed during the test was investigated with the help of EDS analysis. The tribo layer are rich in aluminium and silicon elements because both the samples are made of aluminium silicon carbide.

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Ventura, Aline Cristina Ferreira. "Seleção de materiais plásticos resistentes a riscos para componentes automotivos." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3149/tde-04052018-092848/.

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Este estudo se refere a um método para selecionar os materiais plásticos resistentes a riscos mais adequados para peças automotivas. Estabelecer este procedimento é fundamental para as montadoras devido à versatilidade, qualidade e custo competitivo que os polímeros apresentam. Contudo, essa é uma atividade árdua, pois nota-se a ausência de profissionais familiarizados em trabalhar com materiais plásticos e a existência de milhares de materiais disponíveis para utilização. Deste modo, formular um processo estruturado para facilitar a seleção de plásticos tem como objetivo minimizar os riscos e erros do projeto. Portanto, o processo concebido para esta pesquisa foi gerado a partir da estratégia de seleção desenvolvida por Ashby, método tido como referência na área. Além deste, também foram utilizados conceitos da matriz de decisão de Pahl & Beitz, incluindo índice de mérito. Dois exemplos de aplicação da metodologia são apresentados através de estudos de caso, com os componentes tampa do porta-luvas e base do espelho lateral.
This dissertation work is focused on a method to select the most suitable plastic material with scratch resistance for automotive parts. This process is essential for the automakers due to the versatility, improved quality and cost competitiveness of resin materials. Nonetheless, the lack of professionals specialized in plastic materials and the large variety of polymeric materials makes the proper material selection challenging. In this way, it is necessary to define a systematic method to simplify polymeric materials selection in order to reduce the project risks and errors. For this reason, the process proposed in this study was generated based from the selection strategy developed by Ashby, as this is a reference in the field. In addition, two other concepts were adopted: Pahl & Beitz decision matrix and merit index. In order to evaluate this systematic method, two case studies were analyzed: glove compartment and side mirror base.

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Prandato, Emeline. "Relations structure-propriétés et résistance à l’endommagement de vernis acrylate photo-polymérisables pour substrats thermoplastiques : évaluation de monomères bio-sourcés et de nano-charges." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0103/document.

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L’objectif de ces travaux a été de développer des vernis acrylate photo-polymérisables à 100% d’extrait sec, destinés à protéger des pièces thermoplastiques en polycarbonate contre les endommagements mécaniques, en particulier contre la rayure. Les relations entre la composition, la structure et les propriétés de ces revêtements ont été explorées. Pour ce faire ont été étudiées la morphologie, les propriétés thermomécaniques ainsi que la résistance à la rayure des matériaux. Cette dernière a été évaluée par des tests de micro-scratch. La cinétique de formation des réseaux polymères a elle aussi été étudiée, par photo-DSC. Tous les matériaux étudiés présentent, en analyse thermomécanique dynamique, un module élevé à l’état caoutchoutique ainsi qu’une large relaxation mécanique. Un vernis pétro-sourcé à 100% d’extrait sec, qualifié de standard, a servi de point de départ à ces travaux. Il a tout d’abord été comparé à un vernis commercial solvanté photo-polymérisable, spécialement conçu pour la protection de pièces thermoplastiques. Celui-ci s’est avéré être plus efficace en termes de résistance à la rayure. Dans un deuxième temps, a été étudiée l’influence sur les propriétés du vernis standard pétro-sourcé d’un monomère multicyclique entrant dans sa composition. La modification de son pourcentage n’a permis d’apporter aucun bénéfice en termes de résistance à la rayure. Des nanoparticules de silice, d’alumine ou de zircone, disponibles sous forme de dispersion dans un monomère acrylate, ont ensuite été incorporées dans le vernis standard pétro-sourcé. Une organisation particulière de la nano-silice et de la nano-alumine au sein des matériaux étudiés a pu être observée par microscopie électronique en transmission. Il a été constaté que le taux de charge doit être élevé pour observer une augmentation du module élastique et une amélioration de la résistance à la rayure du vernis (≥15% massique dans le cas de la nano-silice). Par ailleurs, l’ajout de 5% massique de nano-silice dans le vernis n’a conduit à aucune modification de sa cinétique de photo-polymérisation. Enfin, une partie des composés acrylate pétro-sourcés du vernis standard a été substituée par des acrylates bio-sourcés disponibles industriellement. La cinétique de photo-polymérisation des deux types de vernis est similaire. Les conclusions de la comparaison entre les vernis bio-sourcés et le vernis standard pétro-sourcé en termes de résistance à la rayure dépendent de l’épaisseur des revêtements étudiés. L’ajout d’un composé monoacrylate bio-sourcé à la formulation des vernis tend à améliorer la recouvrance élastique des revêtements de faible épaisseur. L’acrylate d’isobornyle est en particulier intéressant, car il a aussi tendance à retarder l’apparition des craquelures au cours de la rayure
The aim of this work was to develop 100% solids photo-polymerizable acrylate coatings, intended to protect thermoplastic pieces made of polycarbonate against mechanical damage, in particular scratches. The relationships between the composition, the structure and the properties of these coatings were examined. For this purpose the morphology, the thermomechanical properties and the scratch resistance of the materials, assessed by micro-scratch tests, were studied. The kinetics of the polymer network formation was also studied by photo-DSC experiments. All the materials feature a high elastic modulus and a broad mechanical relaxation in dynamic thermomechanical analysis. A 100% solids petro-based coating (standard) constituted the starting point of this work. First it was compared to a commercial photo-polymerizable coating containing solvents, specially designed to protect thermoplastic pieces. This commercial coating turned out to be more efficient against scratches. In a second time was studied the influence of the percentage of a multicyclic monomer, taking part in the composition of the standard petro-based coating, on the properties of the latter. The modification of its proportion does not bring any advantage concerning the scratch resistance. Silica, alumina and zirconia nanoparticles, dispersed in an acrylate monomer, were then incorporated in the standard petro-based coating. A particular organization of the silica or alumina nanoparticles in the materials could be observed by transmission electron microscopy. A high filler content is required to observe an increase in the elastic modulus and an enhancement of the scratch resistance of the coating (≥15% by weight for the nano-silica). Moreover, no change of the photo-polymerization kinetics was noticed through the addition of 5% by weight of nano-silica in the coating. Finally, some of the petro-based acrylate compounds of the standard coating were substituted by commercially available bio-based acrylate monomers. Both types of coatings feature similar polymerization kinetics. The conclusions concerning the comparison of the scratch resistance of the bio-based and standard petro-based coatings depend on their thickness. The incorporation of a bio-based monoacrylate compound in low thickness coatings tends to improve the elastic recovery. Isobornyl acrylate is particularly interesting since it also tends to delay the apparition of cracks along the scratch

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Vieceli, Felipe Monteleone. "Clonagem e análise da expressão do fator de transcrição Scratch2 durante a embriogênese inicial de galinha." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/42/42134/tde-02022010-112918/.

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Em invertebrados, os genes Scratch (Scrt) codificam fatores de transcrição que promovem a neurogênese durante o desenvolvimento. A função de Scrt em vertebrados é desconhecida, mas em camundongos Scrt1 e Scrt2 são especificamente expressos em neurônios pós-mitóticos no embrião e no sistema nervoso central adulto. Neste trabalho, nós clonamos a sequência codificante de Scrt2 de galinha (cScrt2) e caracterizamos seu padrão de expressão no embrião por PCR quantitativo e hibridação in situ. A sequência codificante completa foi clonada no vetor de expressão pMES-GFP e o produto previsto da tradução é uma proteína com 276 aminoácidos. A sequência de aminoácidos compartilha identidades de 70% com Scrt2 de rato e 58% com Scrt de zebrafish. Transcritos cScrt2 são detectados primeiramente na periferia do tubo neural do rombencéfalo em HH 15 e da medula espinhal em HH 17, coincidindo com os locais onde alguns dos primeiros neurônios se diferenciam durante a embriogênese. Entre HH 19-23, a expressão no domínio motor da medula espinhal se concentra progressivamente na interface entre as zonas ventricular e do manto. Além disso, a expressão de cScrt2 também é observada nos gânglios da raíz dorsal a partir de HH 22-23, principalmente no domínio dorsomedial. O campo de expressão de cScrt2 no tubo neural é complementar aos de Notch1, que é expresso em células-tronco neurais, e SCG10, marcador de neurônios diferenciados. Nossos resultados sugerem que durante a embriogênese da medula espinhal cScrt2 é especificamente expresso em neurônios pós-mitóticos indiferenciados. A construção pMES-GFP(cScrt2) possibilita futuras análises funcionais diretas por interferência gênica no embrião de galinha, que serão de grande valor para um melhor entendimento da função dos genes Scrt em vertebrados.
In invertebrates, the Scratch (Scrt) genes encode transcription factors that promote neurogenesis during development. The Scrt function in vertebrates is unknown, but in mice Scrt1 and Scrt2 are specifically expressed in post-mitotic neurons in the embryo and in the adult central nervous system. In this work, we have cloned the coding sequence of chicken Scrt2 (cScrt2) and characterized its expression pattern in the embryo with quantitative PCR and in situ hybridization. The complete coding sequence was cloned in the expression vector pMES-GFP and the predicted translation product is a 276-aminoacids protein. The aminoacid sequence shares identities of 70% with rat Scrt2 and 58% with zebrafish Scrt. cScrt2 transcripts are firstly detected in the periphery of the neural tube in the hindbrain by HH 15 and in the spinal cord by HH 17, coinciding with the places where some of the first neurons differentiate during embryogenesis. Between HH 19-23, the expression in the motor domain of the spinal cord is progressively concentrated in the interface between the ventricular and mantle zones. Furthermore, cScrt2 expression is also observed in the dorsal root ganglia after HH22-23, particularly in the dorsomedial domain. The expression pattern of cScrt2 in the neural tube is complementary to that of Notch1, which is expressed in neural stem cells, and SCG10, a marker for differentiated neurons. Our results suggest that during embryogenesis cScrt2 is specifically expressed in post-mitotic undifferentiated neurons. The construction pMES-GFP(cScrt2) makes possible future direct functional analysis by genetic interference in the chick embryo, which will be of great value for better understanding the Scrt genes function in vertebrates.

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Rudolf, Miroslav. "Depozice a analýza tenkých vrstev DLC." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228535.

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Diplomová práce nastiňuje problémy spojené s výrobou a analýzou tenkých vrstev DLC:H. Tyto vrstvy jsou ve středu zájmu mnoha vědeckých pracovníků již po několik desetiletí. V současné době existuje mnoho technik pro přípravu a analýzu. Příprava DLC vrstev má zásadní vliv na jejich vlastnosti a možnosti použití. Je zde mnoho kritérií jak vrstvy posuzovat. V této práci jsou studovány vlastnosti DLC:H vrstev připravených na substrát krystalického křemíku metodou RF-PECVD a následně jsou studovány mechanické, tribologické a optické vlastnosti. Jsou zde využity techniky jako XPS, Ramanova spektroskopie, reflektometrie, měření tvrdosti a adheze. Část práce se zabývá modelováním DLC z prvních principů. Pro tento účel je využito prvoprincipiálního programu Abinit který je šířen pod GPL. Je studována otázka přípravy vstupních dat s ohledem na konvergenci výsledků. Pozornost je také věnována výpočtu vibračních spekter ve středu Brillouinovy zóny ( bod) a celkové hustotě elektronových stavů clusteru DLC v supercele tvaru krychle. Tyto výsledky mohou být porovnány s experimentálně získanými daty z Ramanovy spektroskopie, respektive z XPS spektra valenčního pásu

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Agudelo, Juan Ignacio Pereira. "Analysis of the microstructure transformation (wel formation) in pearlitic steel used in relevant engineering wear systems." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-04092018-131559/.

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In this thesis, the behavior of pearlitic steel was characterized under controlled wear conditions in the laboratory and service conditions in two ore mining stages, comminution and transportation. The thesis consists in three experimental chapters, divided according to the tribosystems analyzed. On all the chapters Electro Microscopy techniques for the microstructural analysis were employed. Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB-SEM), Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM) were used. The first experimental chapter shows the analysis of the pearlite under abrasive wear with loose abrasive particles in multi-events conditions. The sample was taken from Semi-Autogenous Grinding mills (SAG) and experimental simulation was carried out in laboratory using the Dry Sand Rubber Wheel Abrasion Test (DSRW). The results show a polycrystalline layer formation in both cases, characterized by ultra-fine grains of ferrite in the layer closer to the surface. It was also concluded that the DSRW can simulate the wear produced on field (superficial and microstructural features) in conditions of higher normal load than recommended by the ASTM Standard G65. The second experimental chapter explores the characterization of the microstructure after the indenter pass in scratch test using two conditions of normal load applied and five sequences of scratch. The microstructural analysis shows the formation of two subsuperficial layers identified by the level of the microstructural alterations. In the subsuperficial layer (close to the surface), the formation of new ultra-fine grains of ferrite was observed. A second layer was observed deeper in the sample and denominated as layer of the microstructure transition, characterized by the combination of deformed (reduction of the interlamellar spacing) and pearlite colonies not affected plastically by the mechanical loading. On this layer, the crystallographic texture in RD // in samples tested at 4 N (normal load) and one-pass scratch was determined. Later, on this chapter, the microstructure in a ground rail (industrial procedure characterized as a multi-event scratch test) was analyzed. Two grinding conditions were used for the analysis with variation of the grinding linear speed and load on the grinding stones (discs). The combination of low grinding speed and high load promotes a higher deformed layer formation beneath the patch zone and low randomized orientation of the pearlite colonies. Finally, in the third experimental chapter, the pearlitic characterization was concluded with the study of samples of railway wheel and rail under wear in service and Rolling Contact Fatigue (RCF) in laboratory. The laboratorial simulation was carried out using the twin-disc rolling contact tribometer with a variation of number of cycles. The characterization of railway wheel shows that the WEL is characterized by levels of breaking and aligned cementite and zones with dissolution of the carbon atom in the ferrite to form the supersaturated carbon ferrite. The polycrystalline ferrite formation (ultra-fine grains) in the sub-superficial layer and it was identified a preferential orientation of RD // in the layer of microstructural transition. The results of the laboratory test show surface crack nucleation and propagation at low angle in the more severe deformed layer. The microstructure of the layer consists in polycrystalline ferrite and the cementite dissolution.
Nesta tese foi caracterizado o comportamento do aço perlítico em condições controladas de desgaste em laboratório e em serviço em dois estágios do processo de mineração de minério, cominução e transporte ferroviário. A tese consiste em três capítulos experimentais divididos segundo o tribosistema analisado. Em todos os capítulos do trabalho foi utilizada a técnica de microscopia eletrônica para análise microestrutural. Foi utilizado Microscopia eletrônica de varredura (MEV), Focused Ion Beam (FIB-SEM), Electron Backscatter Diffraction (EBSD) e Microscopia eletrônica de transmissão (MET). O primeiro capítulo experimental mostra a análise da perlita in condições de desgaste abrasivo com partículas soltas em eventos múltiplos. As amostras foram tiradas de um moinho semi-autógeno (SAG) e realizada uma simulação experimental do desgaste em condições controladas usando o tribômetro de roda de borracha (RWAT). Os resultados mostraram a formação de camada branca em ambas as condições de análise, consistindo em uma camada poli cristalina caracterizada pela formação de grãos ultrafinos na camada mais próxima da superfície de desgaste. Também foi concluído que a roda de borracha pode simular o desgaste produzido nos moinhos SAG tanto nas características superficiais quanto microestruturais em condições de maior severidade as comumente utilizadas na norma ASTM G65 (procedimento B). O Segundo capítulo experimental explora a caracterização da microestrutura depois da passagem do endentador no ensaio de riscamento (scratch test) utilizando duas condições de carga normal aplicada e 5 sequências de riscamento. A análise microestrutural mostrou a formação de duas camadas subsuperficiais identificadas pelo nível de alteração microestrutural. Na camada mais próxima da superfície de desgaste foi observada a formação de grãos ultrafinos de ferrita. A segunda camada identificada mais profundamente na amostra, denominada como camada de transição, é caracterizada pela combinação de colônias deformadas (redução do espaçamento interlamelar) e camadas não afetadas pelos esforços produzidos no contato. Nesta camada foi determinada a texturização em direção RD // nas amostras testadas a 4 N (carga normal aplicada) e uma passada. Posteriormente à análise de riscamento foi caracterizada a microestrutura de uma amostra tirada de um trilho esmerilhado (processo industrial que pode ser considerado como aplicação do ensaio de riscamento). Foram consideradas duas condições de esmerilhamento com variação de velocidade de esmerilhamento (deslocamento linear do veículo esmerilhador) e potência dos motores dos rebolos usada no procedimento. A combinação de baixa velocidade de esmerilhamento e alta potência nos motores controladores dos rebolos promoveu uma grande deformação nas camadas subsuperficiais na região de contato e uma baixa aleatoriedade das orientações cristalográficas das colônias de perlita. Finalmente, no capítulo três, a caracterização da microestrutura perlitica foi finalizada com o estudo de amostras de roda e trilho em condições de desgaste em campo e de Rolling Contact Fatigue (RCF) em ensaios de laboratório. A simulação experimental foi realizada utilizando o tribômetro twin-disc rolling (configuração disco-disco) com variação do número de ciclos. A caracterização da roda ferroviária mostrou a formação da camada branca caracterizada por níveis de cementita fraturada e alinhada em direção do movimento de rolamento/deslizamento com áreas de dissolução do átomo de carbono na ferrita formando uma ferrita supersaturada. Foi identificado a formação de policristais de ferrita (grãos ultrafinos) na camada mais superficial e uma orientação preferencial RD // na camada de transição. Os resultados dos ensaios de laboratório mostraram a nucleação de trincas superficiais se propagando a baixo ângulo na camada branca. A transformação microestrutural dessa camada após ensaios de laboratório consiste em policristais de ferrita e dissolução da cementita.

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Angelo, Isabela Martins. "Recomendações para o desenvolvimento de ambientes de programação inclusivos para crianças cegas." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-27082018-090956/.

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A inclusão de crianças com deficiência em escolas regulares, ocorrida seguindo a Lei 13.146 de 06 de julho de 2015, que institui a Lei Brasileira de Inclusão da Pessoa com Deficiência, exige que as atividades escolares sejam acessíveis a todas as crianças. Entre as atividades escolares, as atividades de programação têm se espalhado nas escolas devido aos benefícios gerados nas habilidades dos alunos, como criatividade e pensamento lógico. Atualmente, essas atividades utilizam principalmente ambientes de programação em blocos, como o Scratch, que focam em aspectos visuais para interação, contando com cores, formatos e utilização do mouse. Nesse contexto, e de grande importância o estudo de interfaces de programação para que crianças com deficiência visual possam ser incluídas e participem em conjunto com as outras crianças. Este projeto busca investigar este tema, bem como propor e avaliar um sistema para atividades de introdução à programação para crianças cegas e videntes. Foi proposto um sistema formado por peças tangíveis, em que os blocos digitais foram substituídos por peças físicas com formas para reconhecimento tátil e respostas auditivas. Foi adotado um modelo cíclico para o desenvolvimento do protótipo que garantiu duas etapas de testes com usuários. Na primeira etapa foram 4 participantes videntes, sendo que três participaram vendados, e a partir das observações foram gerados novos requisitos e modificações no protótipo. Na segunda etapa participaram 2 crianças cegas e os resultados destes testes geraram requisitos específicos para a utilização do sistema por crianças cegas. Este trabalho traz como contribuição final um conjunto de recomendações para o desenvolvimento de sistemas que permitam a crianças cegas e videntes brincarem juntas em atividades de programação.
The inclusion of children with disabilities in regular schools, following Law 13,146 of July 6, 2015, which establishes the Brazilian Law on the Inclusion of Persons with Disabilities, requires that school activities be accessible to all children. Among school activities, programming activities have spread in schools because of the benefits generated in students\' skills such as creativity and logical thinking. Currently, these activities mainly use blocks programming environments, such as Scratch, that focus on visual aspects for interaction, counting on colors, shapes and mouse usage. In this context, it is of great importance to study programming interfaces so that children with visual impairment can be included and participate together with other children. This project seeks to investigate this theme as well as to propose and evaluate a system for introductory programming activities for blind and sighted children. It was proposed a system formed by tangible pieces in which the digital blocks were replaced by physical pieces with forms for tactile recognition and auditory responses. It was adopted a cyclical model for the development of the prototype that guaranteed two stages of testing with users. In the first stage, four sighted participants, three were blindfolded among them, and and from the first observations were generated new requirements and modifications in the prototype. The second stage involved 2 blind children and the results of these tests generated specific requirements for the use of the system by blind children. This work brings as final contribution a set of recommendations for the development of systems that allow blind and sighted children to play together in programming activities.

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Cui, Xiaoyun. "Electroless metallisation of glass for electrical interconnect applications." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/10303.

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The microelectronics industry requires continuous advances due to ever-evolving technology and the corresponding need for higher density substrates with smaller features. Specifically, new dielectric materials with enhanced electrical properties are needed. At the same time, adhesion must be maintained in order to preserve package reliability and mechanical performance. As a result, this research investigates the use of thin glass sheets as an alternative substrate material as it offers a number of advantages including coefficient of thermal expansion similar to silicon, good dielectric properties and optical transparency to assist in the alignment of buried features. As part of this project it was necessary to deposit metallic coatings onto the glass sheets to create electrical tracks, pads and microvias. In order to meet these requirements, the metallisation of both smooth as received glass surfaces and surfaces roughened by laser machining using electroless copper and nickel deposition were investigated. This study resulted in a number of important conclusions about the roles of chemical bonding and mechanical anchoring in both the adhesion and catalyst adsorption, that are key factors in the electroless metallisation process.....

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Prieto, Nieto Claudia L. "Mechanical Characteristics and Adherence of Corrosion Products on Mild Steel." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1574678745737727.

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Morais, Anuar Daian de. "O desenvolvimento do raciocínio condicional a partir do uso de teste no squeak etoys." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/164383.

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A presente tese apresenta uma investigação acerca do desenvolvimento do raciocínio condicional, considerado um componente chave do pensamento lógico-dedutivo, em crianças e adolescentes que participaram de uma experiência de programação com o software Squeak Etoys. O desenvolvimento do raciocínio condicional é classificado em etapas relacionadas à composição e reversão de transformações que operam sobre a implicação, culminando com a plena reversibilidade que corresponde, na teoria piagetiana, à construção e mobilização do grupo de transformações INRC (Identidade, Negação, Recíproca, Correlativa). Tais etapas são identificadas a partir de entrevistas realizadas segundo o método clínico piagetiano, através da aplicação de três desafios de programação com complexidade crescente, cuja solução envolvia o uso da operação lógica da implicação. As entrevistas foram realizadas com oito crianças, com idades entre 10 e 16 anos, que cursavam as séries finais do Ensino Fundamental de duas escolas públicas. Com base nos dados, a análise revela a importância do pensamento combinatório, que permite aos adolescentes testarem, sistematicamente, todas as possibilidades de ordenamento e inclusão dos comandos sugeridos, e a obterem as conclusões lógicas adequadas, enquanto que as crianças mais novas não obtém o mesmo êxito. Além disso, na tese é realizada uma discussão sobre a inclusão da escola numa cultura digital sob uma perspectiva construtivista de construção do conhecimento. Nesse contexto, a metodologia de projetos de aprendizagem foi apresentada como sendo adequada e o software Squeak Etoys despontou como uma possibilidade interessante de se desenvolver projetos e de promover a aprendizagem de matemática. Por último, neste trabalho também é realizado um debate sobre a importância de se aprender a programar na escola.
The present thesis presents an investigation into the development of conditional reasoning, considered a key component of logical-deductive thinking, in children and adolescents who participated in a programming experience with the software Squeak Etoys. The development of conditional reasoning is classified into stages related to the composition and reversal of transformations that operate on the implication, culminating in the full reversibility that corresponds, in Piaget’s theory, to the construction and mobilization of the Transformations INRC (Identity, Negation, Reciprocity and Correlation). These steps are identified from interviews conducted according to Piaget’s clinical method, through the application of three programming challenges with increasing complexity, whose solution involved the use of the logical operation of the implication. The interviews were conducted with eight children aged 10-16, who attended the final series of the Elementary School of two public schools. Based on the data, the analysis revealed the importance of combining thinking, which allows teenagers to systematically test all the possibilities for ordering and inclusion of the suggested commands, and to obtain the appropriate logical conclusions, while younger children do not achieve the same results. Moreover, in the thesis a discussion is conducted on the inclusion of the school in a digital culture under a constructivist perspective of building knowledge. In this context, the methodology of learning through projects has been presented as being appropriate and the Squeak Etoys software has appeared as an interesting possibility of developing projects and promoting the learning of mathematics. Finally, in this study a debate is also conducted on the importance of learning to plan in the school.

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Шовкопляс, Оксана Анатоліївна, Оксана Анатольевна Шовкопляс, Oksana Anatoliivna Shovkoplias, О. В. Соболь, and В. М. Береснєв. "Фізико-механічні властивості іонно-плазмових покриттів квазібінарних систем TiB[2]-WB[2] і TiC-WC." Thesis, Сумський державний університет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40810.

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У роботі досліджено вплив умов формування іонно-плазмових покриттів квазібінарних систем TiB2-TiB2 і TiC-WC із різним вмістом металічних складових на їх механічні властивості: твердість і адгезійну міцність під час відриву в процесі скретч-тестування.

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Sanjuan, Luis Armando Espitia. "Comportamento em desgaste por erosão cavitação, erosão - corrosão e em ensaios de microesclerometria linear instrumentada de um aço inoxidável martensítico AISI 410 nitretado a plasma em baixa temperatura, utilizando a tecnologia de tela ativa." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-29062016-154350/.

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Amostras de um aço inoxidável martensítico AISI 410 temperado e revenido foram nitretadas a plasma em baixa temperatura usando o tratamento de nitretação plasma DC e a nitretação a plasma com tela ativa. Ambos os tratamentos foram realizados a 400 °C, utilizando mistura gasosa de 75 % de nitrogênio e 25 % de hidrogênio durante 20 horas e 400 Pa de pressão. As amostras de aço AISI 410 temperado e revenido foram caracterizadas antes e depois dos tratamentos termoquímicos, usando as técnicas de microscopia óptica, microscopia eletrônica de varredura, medidas de microdureza, difração de raios X e medidas de teor de nitrogênio em função da distância à superfície por espectrometria WDSX de raios X. A resistência à erosão por cavitação do aço AISI 410 nitretado DC e com tela ativa foi avaliada segundo a norma ASTM G32 (1998). Os ensaios de erosão, de erosão - corrosão e de esclerometria linear instrumentada segundo norma ASTM C1624 (2005) somente foram realizados no aço AISI 410 nitretado com tela ativa. Ensaios de nanoindentação instrumentada forma utilizados para medir a dureza (H) e o módulo de elasticidade reduzido (E*) e calcular as relações H/E* e H3/E*2 e a recuperação elástica (We), utilizando o método proposto por Oliver e Pharr. Ambos os tratamentos produziram camadas nitretadas de espessura homogênea constituídas por martensita expandida supersaturada em nitrogênio e nitretos de ferro com durezas superiores a 1200 HV, porém, a nitretação DC produziu maior quantidade de nitretos de ferro do que o tratamento de tela ativa. Os resultados de erosão por cavitação do aço nitretado DC mostraram que a precipitação de nitretos de ferro é prejudicial para a resistência à cavitação já que reduziu drasticamente o período de incubação e aumentou a taxa de perda de massa nos estágios iniciais do ensaio; entretanto, depois da remoção desses nitretos de ferro, a camada nitretada formada somente por martensita expandida resistiu bem ao dano por cavitação. Já no caso do aço nitretado com tela ativa, a resistência à erosão por cavitação aumentou 27 vezes quando comparada com o aço AISI 410 sem nitretar, fato atribuído à pequena fração volumétrica e ao menor tamanho dos nitretos de ferro presente na camada nitretada, às maiores relações H/E* e H3/E*2 e à alta recuperação elástica da martensita expandida. A remoção de massa ocorreu, principalmente, pela formação de crateras e de destacamento de material da superfície dos grãos por fratura frágil sem evidente deformação plástica. As perdas de massa acumulada mostradas pelo aço nitretado foram menores do que aquelas do aço AISI 410 nos ensaios de erosão e de erosão corrosão. O aço nitretado apresentou uma diminuição nas taxas de desgaste em ambos os ensaios de aproximadamente 50 % quando comparadas com o aço AISI 410. O mecanismo de remoção de material foi predominantemente dúctil, mesmo com o grande aumento na dureza. Os resultados de esclerometria linear instrumentada mostraram que a formação de martensita expandida possibilitou uma diminuição considerável do coeficiente de atrito em relação ao observado no caso do aço AISI 410 sem nitretar. O valor de carga crítica de falha foi de 14 N. O mecanismo de falha operante no aço nitretado foi trincamento por tensão.
Specimens of a quenched and tempered AISI 410 martensitic stainless were low temperature plasma nitrided using DC pulsed plasma treatment and the pulsed plasma active screen technic. Both treatments were carried out at 400 °C in a mixture of 75 % of nitrogen and 25 % of hydrogen during 20 hours and 400 Pa of pressure. Nitrided and non-nitrided AISI 410 specimens were characterized by optical and scanning electron microscopy, micro and nanohardness measurements, X ray diffraction and determination of the nitrogen content as a function of the depth using wavelength dispersive spectroscopy WDSX. Cavitation erosion tests were carried out according to ASTM G32 (1998) standard for both DC nitrided steel and active screen nitrided steel, whereas, the erosion, erosion - corrosion tests and scratch tests according to ASTM C1624 (2005) were conducted only for active screen nitrided steel. Nanoindentation tests were carried out in order to assess the hardness (H), the reduced elastic modulus (E*) the H/E* and H3/E*2 ratios and the elastic recovery (We) of the active screen nitrided steel according to the procedure proposed by Oliver and Pharr. Both nitrided treatments produced thick nitrided cases composed of nitrogen supersaturaded expanded martensite and iron nitrides, however, the DC treatment promoted the precipitation of large quantities of iron nitrides in comparison to the active screen technic. The cavitation erosion results of the DC nitrided steel showed that iron nitrides precipitation is harmful for the cavitation resistance as it drastically reduced the incubation period, despites this, after the removal of those iron nitrides, the nitrided case composed solely of expanded martensite resisted the cavitation damage. On the other hand, the active screen technic increased 27 times the cavitation erosion resistance of the AISI 410 steel. The increase in cavitation erosion resistance was attributed to minor quantities of smaller size iron nitrides, the higher H/E* and H3/E*2 ratios and to the higher elastic response of the expanded martensite. The material removal mainly comes from the formation of craters and from debris detachment from the grain surfaces due to brittle fracture, without plastic deformation. The active screen nitrided steel showed the lower cumulative mass losses in erosion and erosion - corrosion tests. The nitrogen addition decreased around 50 % the erosion rate in both tests. The active screen nitrided steel showed a ductile behavior despite the intense increase in hardness. The scratch tests showed that expanded martensite formation led to a significant decrease of the friction coefficient. The critical load was 14 N and the failure mechanism acting in the nitrided case was tensile cracking.

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Cének, Lukáš. "Stanovení vlastností původních a EB-modifikovaných nástřiků deponovaných technologiemi tepelného nanášení pomocí vrypové zkoušky a testování nano-indentací." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231364.

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Properties of samples and their coatings may be affected by the electron beam. This paper deals with the analysis of the microstructure, phase and chemical composition and the determination of mechanical characteristics of inconel steel substrate and CoNiCrAlY coatings deposited via different types of thermal spraying (HVOF, cold spray), in combination with modifications by the electron beam technology. During the study it was found that the deposition did not change the chemical composition. Further it was found that the interaction of the electron beam with the material did not change the chemical composition, but there is a change in the structure and a reduction of porosity and surface roughness, resulting in a change of mechanical properties such as decreasing hardness or increase of the modulus of elasticity.

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Ruiz, Eduardo Alberto Pérez. "Comportamento mecânico de sistemas revestidos submetidos a esforços de contato normais e tangenciais." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-30092016-100322/.

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A deposição de filmes finos resistentes ao desgaste é uma prática realizada com bastante frequência para melhorar o comportamento tribológico (atrito, desgaste, lubrificação) de diferentes peças e componentes. Afim de se garantir o adequado funcionamento do sistema revestido (substrato+filme), é importante avaliar o comportamento mecânico do mesmo. Um método para avaliação e estudo do comportamento mecânico destes sistemas é o ensaio de riscamento. O ensaio é utilizado para analisar a fratura superficial do revestimento (falha chamada coesiva), ou a resistência à adesão (falha chamada adesiva), e os modos de falha de revestimentos duros (HV>=5 GPa) e finos (<=30 ?m), depositados sobre substratos cerâmicos ou metálicos. A caracterização de alguns modos de falha nos sistemas revestidos está relacionada com modelos qualitativos de tensões presentes na região de contato e nas bordas do riscamento. Neste trabalho, foi estudado o comportamento das tensões Sxx e Szz desenvolvidas durante o riscamento de sistemas compostos por combinações de revestimentos/substratos. O trabalho foi baseado no desenvolvimento de modelos de simulação em 3D e 2D, utilizando o método dos elementos finitos (MEF), nos quais, uma partícula rígida com características de indentador Rockwell C, aplica carga progressiva até 2 N, ao longo de uma distância de 0,5 mm. No estudo, variou-se a dureza, traduzida em valores de tensão de escoamento do revestimento e do substrato, da mesma forma, analisou-se o efeito da tensão residual do revestimento, o efeito da espessura, o atrito, e a rugosidade, na superfície e na interface do sistema. O fato de obter valores de tensão que ultrapassam o valor do escoamento do revestimento pressupõe a possível ocorrência de falhas nos sistemas revestidos. Os resultados obtidos por simulação indicaram que as combinações de revestimento com tensão de escoamento baixa (Sy<3000 MPa) levam a experimentar tensões ao nível da tensão de escoamento do revestimento. Os revestimentos com tensão de escoamento Sy>5000 MPa apresentaram valores de tensão inferiores aos da tensão do revestimento, bem como o uso de tensão residual de -3 GPa no revestimento, assim como o aumento da espessura do revestimento têm grande importância nos sistemas revestidos, em particular nos casos em que a tensão de escoamento no revestimento é Sy>=5000MPa. O efeito do coeficiente de atrito leva à obtenção de valores de tensão (Sxx ou Szz) suficientemente altos na maioria das combinações, sendo esta a variável de estudo que levou ao maior número de vezes que foi atingido o valor da tensão de escoamento do revestimento. Da mesma forma, a rugosidade afeta os valores de tensão Sxx (interior do sulco). Ao aumentar a rugosidade do sistema aumenta a possibilidade de ultrapassar valores da tensão do revestimento na superfície e na interface do conjunto. Finalmente, pela complexidade do número de variáveis que afetam o ensaio, a simulação numérica sugere que o fato de analisar unicamente a dureza dos materiais, assim como as diferentes variáveis de forma isolada, não permite a reprodução de um mapa de falhas próximo ao proposto na literatura.
The deposition of wear resistant thin films is a common practice to improve the tribological behavior (friction, wear, lubrication) of several mechanical components. In order to guarantee the adequate performance of the coated systems, it is important to evaluate the mechanical behavior. A method for evaluation and study of the coated systems is the scratch test. The test is used to analyze the fracture of the coating (cohesive failure), or the adhesion of the coating (adhesive failure), and the failure modes of hard coatings (HV>=5 GPa) and thin (<=30 ?m) deposited on ceramic or metallic substrates. The characterization of some failure modes in coated systems is related to qualitative stress models at the contact region and the scratch edges. In this work, the behavior of the Sxx and Szz stresses developed during the scratch test was analyzed in different combinations of coatings/substrates. The work was based on the development of 3D and 2D simulation models using the finite element method (FEM). In the simulation, a rigid particle (with the geometry of Rockwell C indenter) applied progressive load to 2N along a 0.5 mm distance. In the study, the hardness was expressed as yield stress values in the coating and the substrate. In addition, it was examined the effect of coating residual stress (-3 GPa), as well as the effect of the thickness, the friction coefficient, and roughness of the surface and interface in the stresses behavior. The fact of obtaining tension values, which exceed the yield stress of coating implies the possible occurrence of failure. The results obtained by simulation indicated that the coating combinations with low yield stress (Sy < 3000 MPa) lead to Sxx and Szz stress values in the level of the coated yield stress. The coatings with yield stress Sy > 5000 MPa enable to obtain low Sxx and Szz values. The use of the residual stresses (-3 GPa) as well as increasing the thickness of the coating are very important factors in the coated systems, especially in the case of coatings with Sy > 5000 MPa. The effect of the friction coefficient leads to stress values (Sxx or Szz) sufficiently high in most of the combinations. This factor is the most important variable leading to the greater number of times that the value of the coating yield stress was reached. The roughness is responsible for Sxx stress values (inside groove). Increasing the roughness of the system increased the possibility of exceeding stress values in the surface and interface coating. Finally, by the complexity of the number of variables that affect the scratch test, the numerical simulation suggests that the fact of only analyzing the hardness of materials, as well as other isolated variables of the scratch test does not allow reproduction of a map of failures similar to that proposed in the literature.

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Plichta, Tomáš. "Povrchová topografie a mechanické vlastnosti tenkých vrstev na bázi tetravinylsilanu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2016. http://www.nusl.cz/ntk/nusl-240521.

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Proposed diploma thesis is focused on preparation and characterization of the plasma polymer thin films based on tetravinylsilane monomer (TVS). Plasma enhanced chemical vapour deposition (PECVD) method involving pulse and continual plasma discharge modes were used for thin film deposition on silicon wafer pieces. Reactive plasma composition was containing pure TVS or mixtures of TVS and argon or oxygen gas. Atomic force microscopy was used for surface topography and roughness characterization. Cyclic nanoindentation was involved to measurements to determine the Young’s modulus and hardness of prepared films and scratch test was performed to evaluate the degree of adhesion. Special attention was drawn to the characterization of films with a Young’s modulus below 10 GPa. Tip geometry of indenter influence on scratch test was also commented. Surface and mechanical properties of thin films in relation to the deposition conditions were correlated to the obtained results and final analysis of deposition conditions influence is proposed.

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Balášová, Patricie. "Příprava a charakterizace moderních krytů ran." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449701.

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This diploma thesis is focused on the study of bioactive wound dressings. During the thesis, hydrogel, lyophilized and nanofiber wound dressings were prepared. Hydrogel and lyophilized wound dressings were prepared on basis of two polysaccharides – alginate and chitosan. Nanofiber wound dressings were prepared by spinning polyhydroxybutyrate. All prepared wound dressings were enriched with bioactive substances, which represented analgesics (ibuprofen), antibiotics (ampicillin) and enzymes (collagenase). Into hydrogel and lyophilized wound dressings were all the mentioned active substances incorporated, whereas nanofiber wound dressings were only with ibuprofen and ampicillin prepared. The theoretical part deals with the anatomy and function of human skin. There was explained the process of wound healing and also there were introduced available modern wound dressings. The next chapter of the theoretical part deals with materials for preparing wound dressings (alginate, chitosan, polyhydroxybutyrate) and with active substances, which were used during the experimental part of this thesis. In the theoretical part, the methods of preparation of nanofiber wound dressings and also the methods of cytotoxicity testing used in this work were presented. The first part of the experimental part of this thesis was focused on preparing already mentioned wound dressings. Then, their morphological changes over time and also the gradual release of incorporated active substances into the model environment were monitored. The gradual release of ampicillin was monitored not only spectrophotometrically, but also by ultra-high-performance chromatography. In wound dressings, in which collagenase was incorporated, was also the final proteolytic activity of this enzyme monitored. The effect of the active substances was observed on three selected microorganisms: Escherichia coli, Staphylococcus epidermidis and Candida glabrata. The cytotoxic effect of the active substances on the human keratinocyte cell line was monitored by MTT test and LDH test. A test for monitoring the rate of wound healing – a scratch test – was also performed.

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Císařová, Michaela. "Vliv morfologie povlaku Zn na mezní podmínky při tažení tenkých plechů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234011.

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The doctor thesis deals about the influence of zinc coating morphology on limit conditions formability of a thin sheet metal. In the introduction of the thesis is discusesed about current problems searching the most suitable morphology of the steel sheet metals, a method of appliing to the zinc sheet metal. The hot dip zinc coating is discussed in next chapter, the topical knowledges about the influence of the individual factors have some effect to coat calibre and quality. In literary researchs are discussed the concrete technological tests of zinc coating to harder sheet metal forming, the theory of the bend and the basic theory of pressing sheet metal. In following chapter is devoted interpretation selected technological tests, according to that is described behaviour, characteristics, influence of zinc coating formability of basic material and his morphology.

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Barcellos, Robson. "Detecção de riscos em lentes esféricas, por luz refletida, através de descritores de Fourier." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-04092007-162846/.

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Este trabalho apresenta uma metodologia para inspeção de lentes oftalmológicas orgânicas esféricas durante seu processo de polimento. A metodologia consiste na obtenção de uma imagem em uma câmera de vídeo CCD, usando-se luz ultravioleta, da lente a ser inspecionada, e posterior processamento desta imagem para discriminar a presença de riscos de outros artefatos que poderão aparecer na imagem capturada. Para a detecção da presença de riscos foram utilizados os descritores de Fourier. Atenção especial foi dada à iluminação da lente, que é fator determinante na obtenção de uma boa qualidade de imagem. Os resultados mostram a eficiência do método e permitem sua utilização durante o processo de fabricação de lentes.
This work presents a methodology for inspection of spherical organic ophthalmic lenses during the polishing process. The methodology encompasses the capture of an ultraviolet image of the lens under inspection by a CCD video camera and associated processing of the image to discriminate between scratches on the lens and artifacts that can appear on the image. Fourier descriptors were used to detect the existence of scratches. Special attention was given to illumination which is a determining factor in grabbing an image with good quality. The results show that the method is efficient and that it can be used in the lens manufacturing process.

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Prandato, Emeline. "Relations structure-propriétés et résistance à l'endommagement de vernis acrylate photo-polymérisables pour substrats thermoplastiques : évaluation de monomères bio-sourcés et de nano-charges." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00995108.

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L'objectif de ces travaux a été de développer des vernis acrylate photo-polymérisables à 100% d'extrait sec, destinés à protéger des pièces thermoplastiques en polycarbonate contre les endommagements mécaniques, en particulier contre la rayure. Les relations entre la composition, la structure et les propriétés de ces revêtements ont été explorées. Pour ce faire ont été étudiées la morphologie, les propriétés thermomécaniques ainsi que la résistance à la rayure des matériaux. Cette dernière a été évaluée par des tests de micro-scratch. La cinétique de formation des réseaux polymères a elle aussi été étudiée, par photo-DSC. Tous les matériaux étudiés présentent, en analyse thermomécanique dynamique, un module élevé à l'état caoutchoutique ainsi qu'une large relaxation mécanique. Un vernis pétro-sourcé à 100% d'extrait sec, qualifié de standard, a servi de point de départ à ces travaux. Il a tout d'abord été comparé à un vernis commercial solvanté photo-polymérisable, spécialement conçu pour la protection de pièces thermoplastiques. Celui-ci s'est avéré être plus efficace en termes de résistance à la rayure. Dans un deuxième temps, a été étudiée l'influence sur les propriétés du vernis standard pétro-sourcé d'un monomère multicyclique entrant dans sa composition. La modification de son pourcentage n'a permis d'apporter aucun bénéfice en termes de résistance à la rayure. Des nanoparticules de silice, d'alumine ou de zircone, disponibles sous forme de dispersion dans un monomère acrylate, ont ensuite été incorporées dans le vernis standard pétro-sourcé. Une organisation particulière de la nano-silice et de la nano-alumine au sein des matériaux étudiés a pu être observée par microscopie électronique en transmission. Il a été constaté que le taux de charge doit être élevé pour observer une augmentation du module élastique et une amélioration de la résistance à la rayure du vernis (≥15% massique dans le cas de la nano-silice). Par ailleurs, l'ajout de 5% massique de nano-silice dans le vernis n'a conduit à aucune modification de sa cinétique de photo-polymérisation. Enfin, une partie des composés acrylate pétro-sourcés du vernis standard a été substituée par des acrylates bio-sourcés disponibles industriellement. La cinétique de photo-polymérisation des deux types de vernis est similaire. Les conclusions de la comparaison entre les vernis bio-sourcés et le vernis standard pétro-sourcé en termes de résistance à la rayure dépendent de l'épaisseur des revêtements étudiés. L'ajout d'un composé monoacrylate bio-sourcé à la formulation des vernis tend à améliorer la recouvrance élastique des revêtements de faible épaisseur. L'acrylate d'isobornyle est en particulier intéressant, car il a aussi tendance à retarder l'apparition des craquelures au cours de la rayure.

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Trivedi, Rutul Rajendra. "Studium povrchů tenkovrstvých materiálů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233343.

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Disertační práce se zabývá studiem povrchových vlastností jedno a vícevrstvých filmů deponovaných z vinyltriethoxysilanových a tetravinylsilanových monomerů. Zabývá se také charakterizací adheze jednovrstvých filmů z tetravinylsilanu. Plazmaticky polymerizované tenké vrstvy byly připraveny na leštěných křemíkových substrátech pomocí plazmové depozice z plynné fáze za ustálených podmínek. Povrchové vlastnosti vrstev byly charakterizovány pomocí různých metod rastrovací sondové mikroskopie a nanoindentačních technik jako je konvenční a cyklická nanoindentace. Vrypový test byl použit pro charakterizaci vlastností adheze vrstev. Jednovrstvé filmy připravené za různých depozičních podmínek byly charakterizovány s ohledem na povrchové morfologie a mechanické vlastností (modul pružnosti, tvrdost). Výsledky morfologie povrchu, analýzy zrn, nanoindentace, analýzy konečných prvků a modulů mapování pomohly rozlišit hybridní charakter filmů, které byly deponovány při vyšších výkonech RF-výboje. Nový přístup byl použit v povrchové charakterizaci vícevrstvého filmu pomocí rastrovací sondové mikroskopie a nanoindentace. Adhezívní chování plazmaticky polymerizovaných vrstev různých mechanických vlastností a tloušťek bylo analyzováno pomocí normálních a laterálních síl, koeficientu tření, a snímků vrypů získaných pomocí mikroskopie atomárních sil.

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Albo, Zieme Louise, and Pontus Bergstedt. "A pre-study for functional coatings evaluated on light metals to be applied on a new HPDC Mg-alloy : Investigating tribological and thermophysical properties, as-cast and coated." Thesis, Jönköping University, JTH, Industriell produktutveckling, produktion och design, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-53096.

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Magnesium with two-thirds of the density compared to aluminium and one-quarter of steel, intrigues product developers and material scientists due to the light metal’s excellent combination of strength to weight ratio as well as their capability of being produced as a High Pressure Die Cast component compared to other ferrous or light metal alloys. However, a magnesium alloy inherits some concerning drawbacks, limiting the exploitation in structural applications and mechanical design such as automotive, heavy machinery and aerospace components. The need for a magnesium alloy that could withstand a sufficient amount of wear, temperature and corrosive environment, leads towards the investigation and evaluation of a suitable, functional coating as a solution to exploit the evident advantages a magnesium alloy exhibits. A substantial amount of research is required in order to reduce an existing knowledge gap that is the ongoing development in the search for a sufficient functional coating and adherence capability to the highly reactive substrate that is a magnesium alloy. This industrial master thesis is an early stage investigation to evaluate how the currently used aluminium substrate with an electrodeposited coating relate and compares to a heat-treated electroless deposited coating through tribological and thermophysical induced stresses. These properties are tested with proven industrial standard methods resulted in a comprehensive conclusion and discussion regarding the feasibility of applying the coating onto a commercial magnesium alloy closely related to the Mg-alloy developed by Husqvarna and thereby contributing to technological advances to the highly relevant topic within product development in materials engineering.

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Anyanwu, Ezechukwu John. "The Effect of Flow on the Development and Retention of Iron Sulfide Corrosion ProductLayers." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1547118739941844.

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45

Laurent, Sabine. "Développement et études de l’influence des procédés d’application et de réticulation de vernis acrylates photo-polymérisables (à 100% d’extrait sec)." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0006/document.

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Le travail présenté porte sur l’étude de la résistance à la rayure d’un vernis acrylate liquide à 100% d’extrait sec et photo-réticulable, en fonction des conditions de réticulation et d’application. Ce vernis est destiné à être appliqué sur des substrats thermoplastiques. Une première étude réalisée sur support polycarbonate a permis de mettre en évidence l’interaction entre le supporte et les monomères du vernis. La photo-polymérisation nécessite une source de rayonnement UV afin de former le réseau 3D. L’évolution de l’énergie (dose UV) et de la puissance (pic d’irradiance UV) a été décrite en fonction des différents paramètres de réglages (vitesse de défilement et position de l’échantillon sous la lampe, distance entre ces deux derniers, focalisation du rayonnement,). La résistance à la rayure des revêtements a été caractérisée par le test de microscratch qui permet de mettre en évidence la transition ductile/fragile, ainsi que le comportement élastique du système feuil/substrat et donne une information sur le travail d’adhésion, selon le mode de rupture. Ces analyses ont été complétées par la mesure du taux de conversion. Le réglage du rayonnement UV permet de modifier les propriétés finales du revêtement. Il existe également un lien entre l’angle d’incidence du rayonnement, l’épaisseur de vernis, et un préchauffage des matériaux avant l’application ou la réticulation, sur le taux de conversion et la résistance mécanique du film. La rhéologie du vernis, en vue d’une application au bol rotatif avec effet électrostatique, a été étudiée. Nous avons montré l’influence du chauffage du vernis sur la viscosité. Les essais en conditions semi-industrielles ont permis de mettre en évidence les paramètres procédés impactant l’aspect et le tendu de la pièce
This research aimed to study the impact of the application and the curing process conditions on the UV-cured coating properties. The UV formulation is a high solid content clear-coat, containing acrylates oligomer and monomers, and developed for thermoplastics substrate, to protect them against scratches. The characterization of the coating and the polycarbonate substrate showed the interaction between the two polymers. UV irradiation is the key to create the polymer network. Several parameters can affect the evolution of its energy and intensity: the conveyor speed, the position of the sample under the bulb, the distance between the last two, and the focalisation of the UV rays. The coating is then analysed in terms of scratch resistance, by the microscratch test. This test gives information about the ductile/brittle transition, the elastic behaviour and the adhesion work. It is completed by the reticulation rate measure. These properties can be modified by the UV radiation setting and the process conditions, like the angle of the support, the coating thickness, and the thermic pre-treatment of the materials before the application or the curing. The clear coat is aimed to be sprayed by electrostatic rotary deposition. The study of the rheological behaviour of the liquid coating showed an impact of the heating on its viscosity. Semi-industrials tests allowed highlighting the process parameters in order to improve the coating levelling and appearance

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Chmela, Ondřej. "Pokovování polyetylentereftalátu mědí a realizace vodivých struktur." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220081.

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The content of this master’s thesis are methods of pretreatment and coating of the surface of PET to produce conductive copper structure and quality control. Thesis also includes theoretical analysis of these methods. Physical and chemical techniques of surface pretreatment methods are discussed in the theoretical part as well as methods making surface of substrate conductive, the subsequent galvanic copper plating and quality control of coating and testing of the adhesion between layers. The experimental part focuses on two methods of the polymer material surface pretreatments. The properties of these pretreatments were evaluated by using the atomic force microscopy and detection of surface energy by wetting and contact angle measurements. The surface is making conductive with cathode sputtering and electrochemical coating of copper. Adhesion of layers is tested mainly with scratch test and other methods. The results of these sub-operations are used for the realization of multi-layer conductive structures.

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Hare, Brian. "Evaluation of Packaging Film Mechanical Integrity Using a Standardized Scratch Test." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-9796.

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Polymeric packaging films see widespread use in the food packaging industry, and their mechanical integrity is paramount to maintaining product appearance, freshness, and overall food safety. Current testing methods, such as tensile or puncture tests, do not necessarily correlate well with field damages that are observed to be scratch-like. The standardized linearly increasing load scratch test is investigated as a new means of evaluating the mechanical integrity of packaging films. Mechanical clamp and vacuum fixtures were considered for securing the films to a set of backing materials and tested under various testing rates and film orientation conditions. Film performance was evaluated according to their puncture load. Based on the above study, the vacuum fixture offers the most consistent and meaningful results by providing a more intimate contact between film and backing and minimizing uncontrolled buckling of the film during testing. Additional testing was also carried out on a commercial film to confirm similarity between damage observed in the scratched films and that from the field. The scratch test gives good correlation between field performance and scratch test results on a set of commercial films. The usefulness of the scratch test methodology for packaging film mechanical integrity evaluation is discussed. Scratch-induced damages on multi-layer commercial packaging films are investigated using cross- and longitudinal-sectioning. Scratch test results show clear distinction between the two tested systems on both the inside and outside surfaces. Microscopy was performed to investigate the feasibility of utilizing this methodology as a tool for packaging film structure evaluation by determining the effect each layer has on the resistance of scratch damages. It is shown that the film showing superior scratch test results also shows significantly better stress distribution through its layers during the scratch test, as well as better layer adhesion during severe deformation. The scratch test shows good ability to provide more in-depth film mechanical integrity testing by allowing for layer-by-layer analysis of damages and layer adhesion after testing.

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Lay, Sange-Ping, and 賴聖評. "Adhesion characterization of diamond-like carbon films using scratch test technique." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/57711403435508829793.

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碩士
元智大學
機械工程學系
95
In order to characterize the adhesion of Diamond-like carbon (DLC) coatings on Tungsten Carbide (WC) substrate, the scratch test was used. The scratch test is the most popular method of measuring adhesion. It was performed on a unit equipped with sensors of normal and tangential force, and acoustic emission (AE) signals. The failure occurs during scratch testing was examined by an optical microscope (OM) and a scanning electron microscope (SEM), if this failure event represents coating detachment than which is called the critical load. In this paper, we used the finite element method to simulate the scratch process. The distributions of the stress field in the coating, and at the interface of the coating/substrate system were investigated. The results of the finite element can be used to simulate bonding strength of coating tool.

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Huang, Shin Wei, and 黃士瑋. "The Probe and Scratch Theoretical Analysis of the Pad on High Temperature Wafer Test." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/37559330389488769989.

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碩士
國立高雄應用科技大學
模具工程系
99
In industry application, to test the electrical nature of wafer during manufacture is very important. Probe will be contact the pad and produce the scratch in wafer testing process. Formerly literature demonstration, that the overdriver (OD), the probe geometry and the temperature will influence the scratch size. This study use the finite element software ANSYS to analysis the scratch size on the pad. First of all, comparing the scratch sizes on pad of the experimental and the analysis data on the temperature is 25℃are in good agreement. Secondly, using the Taguchi method to analyze the scratch sizes on pad of the tungsten probe contact the pad on wafer, the testing conditions will change are: (a) the probe geometry sizes are the tip diameter, the bending angle and the beam length, respectively., (b) the temperatures are 75℃, 150℃ and 300℃, respectively., And, (c) the materials of the pad are aluminum, copper and iron, respectively. And, the noise factors (overdrive) are 10, 30, 50, 70 and 90μm, respectively. Lastly, we analysis the results of Taguchi method, and bring up the optimization probe geometry sizes under the noise factors.

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Chiu, Chien Chang, and 邱建彰. "The application of finite element analysis and abductive network modeling for the scratch test." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/fc549x.

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碩士
國立虎尾科技大學
機械與機電工程研究所
96
Today the scratch test is an important tool, widely used for the development of some industrial sectors (anti-scratch coating, glass industries, automobile industries, . . .). The mechanical analysis of this test is very intricate. The elastic recovery angle has the difference very much as the different properties of materials, it must be taken the analysis of the numerical simulations for the scratch test in different properties of material by finite element method(FEM), observing the rheological forms of materials of different elastic and plastic. This paper combine the finite element analysis(FEM) with AIM to perform the scratch tests for bulk materials and coating. The first to simulate the scratch test with FEM then compare the elastic recovery, hardness and shape ratio with index, and discuss the effect of different material parameters, for example the yield stress, Young’s modulus and tangent modulus with conical indenter and spherical indenter. The abductive network is then utilized to synthesize the data sets obtained from numerical simulations, to predict the shape ratio, hardness and elastic recovery by AIM traning. Finally research the basis effect of the scratch test of coating/substrate.

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Dissertations / Theses on the topic 'Scratch tests'

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