Dissertations / Theses on the topic 'Microhardness'
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Riches, Philip Edward. "Knoop microhardness of diaphyseal bone." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285817.
Full textShtefan, V. V., A. S. Yepifanova, I. S. Berezovskyi, and T. V. Shkolnikova. "Study of Morphology and Microhardness of Со-Мо Alloys Films." Thesis, Прикарпатський національний університет ім. Василя Стефаника, 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/31678.
Full textSmith, Mackenzie Boeing J. "Developement of a Microhardness Acceptance Criterion for TB Weld Qualification." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu153175273381454.
Full textCOUTO, ANTONIO A. "Transformacoes de fase e propriedades da liga FECO-2V." reponame:Repositório Institucional do IPEN, 1989. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10246.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energetica e Nucleares IPEN/CNEN-SP
Majeed, Abdul. "An in vitro study of microleakage and surface microhardness of nanocomposite restorative materials." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
Full textToker, Sidika Mine. "An Investigation Of Microstructure, Microhardness And Biocompatibility Characteristics Of Yttrium Hydroxyapatite Doped With Fluoride." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611540/index.pdf.
Full text#61616
C for 1 hour. Increased densities were achieved upon Y3+ doping while F- doping led to a decrease in densities. For structural analysis, XRD, SEM and FTIR spectroscopy examinations were performed. No secondary phases were observed in XRD studies upon doping. Lattice parameters decreased due to substitutions of ions. In SEM analysis, addition of doping ions was observed to result in smaller grains. In FTIR analysis, in addition to the characteristic bands of HA, novel bands indicating the substitution of F- ions were observed in F- ion doped samples. The highest microhardness value was obtained for the sample doped with 2.5%Y3+, 1%F-. Increased F- ion contents resulted in decreased microhardness values. For biocompatibility evaluation, in vitro tests were applied to the materials. MTT assay was performed for Saos-2 cell proliferation analysis. Y3+ and F- ion incorporation was found to improve cell proliferation on HA discs. Cells were found to attach and proliferate on disc surfaces in SEM analysis. ALP assay showed differentiation of cells on the discs can be improved by doping HA with an optimum amount of F- ion. Dissolution tests in DMEM revealed that structural stability of HA was improved with F- ion incorporation. The material exhibiting optimum structural, mechanical and biocompatibility properties was HA doped with 2.5%Y3+, 1%F-.
Godel, Jeffrey Harold. "Diametral Tensile Strength, Microhardness, Surface Modulus, and Surface Morphology of Novel,Antibacterial Orthodontic Adhesives." Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/410293.
Full textM.S.
Objective: Prior to the advent of bonded orthodontic appliances each tooth was fitted with a band made from stainless steel. Traditionally they were cemented to the tooth with a zinc phosphate cement. This acted more as a luting agent then adding to the actual adherence of the band to the tooth. In addition, often times the cement would wash out and upon the band removal white spot lesions and or carious lesions were present. The development of glass monomer cements had a traumatic improvement over both the adhesion to the tooth and a diminishing of white spot lesions in part due to the release of fluoride. Since the advent of the acid-etch technique and the bonding of orthodontic brackets directly to the enamel various bonding adhesives were developed. The first and most popular bonding resins were chemical curing bonding systems. The general class of self-adhesive and/or self-etching orthodontic adhesives are of several types, including resin-modified cements, such as resin-modified glass ionomer cements, that exhibit self-adhesive properties to enamel, as well as self-etching primers that combine the conditioning and priming agents into one acidic, polymerizable composition for application to the tooth surface, and do not require separate etching and rinsing steps. Not only do resin modified glass ionomers have the benefit of chemically bonding to a clean and un-etched enamel surface, but these self-adhesive cements also release significant and continuous levels of fluoride ion. Recently investigators have explored adding antimicrobial agents in addition to fluoride in orthodontic adhesives. One such approach has been the addition of ZnO powder, a known compound with anti-microbial properties, to an orthodontic resin modified glass ionomer adhesive. It should also be noted that zinc ions and compounds have been shown to positively influence enamel remineralization and enhance apatite formation. The objective of this research is to evaluate the effect of the addition of an antimicrobial agent, zinc oxide powder, on selected mechanical properties of a resin modified glass ionomer orthodontic adhesive. Methods: A resin modified glass ionomer (Fuji Ortho LC), in its two-component, powder/liquid format were utilized in this study. Control specimens, according to manufacturer's directions for use, were prepared for both diametral tensile and microhardness testing with be prepared. Using the powder component provided in the marketed product; powder blends containing both 10 and 20 percent Zinc Oxide (by weight) will be added to the RMGI powder, and thoroughly mixed and blended to create a uniform powder blend. The mechanical testing will be performed on 8-10 disc specimens, approximately 6.2 mm diameter by 3.1 mm in height, using a standardized mixing and molds for each material. The specimens will be tested using the Instron 5569 testing machine at a crosshead speed of 0.75 mm/minute for DTS until failure occurs. Data was recorded in Newton’s (N) force. The microhardness testing was performed on 12 disc specimens, approximately 6.2 mm diameter by 3.1 mm in height, using a standardized mixing and molds for each material. A CSM microindentation testing device was used to measure theVickers microhardness. The surface morphological evaluation of the specimens both control and experimental will be examined at 50 X magnification for comparison of surface characteristics and morphology. One-way ANOVA for comparison of time- and material-specific mean Vickers microhardness values and post hoc pair-wise comparisons was employed to assess statistically significant differences in the mean values (p<0.05). Results: The diametral tensile strength test of all specimens including the modified control and experimental showed incremental decreases in the DTS as compared to the control mixed as per the manufacturer’s specifications. The Vickers values illustrated minimal variation of Vickers microhardness for the control and experimental group. The surface morphological evaluation illustrated various differences between the control, modified control and the Zinc Oxide formulations. Conclusions: Alterations in the liquid powder ration of the orthodontic resin modified glass ionomer adhesive resulted in a reduction of the DTS. The addition of both 10% and 20% zinc oxide powder also resulted in a significant reduction of the DTS as compared to the manufacturers mix proportions of liquid and powder. The Vickers microhardness did not illustrate a significant alteration in any of the specimens. The addition of both 10% and 20% zinc oxide powder to the mixture reduced the modulus and stiffness as compared to both of the control groups. Lastly, the morphology of the experimental samples with the zinc oxide showed a more irregular surface at the fracture site.
Temple University--Theses
Silva, Jo?o Moreno Vilas Boas de Souza. "Adapta??o de um sistema automatizado para medi??o de microdureza." Universidade Federal do Rio Grande do Norte, 2006. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15543.
Full textThe hardness test is thoroughly used in research and evaluation of materials for quality control. However, this test results are subject to uncertainties caused by the process operator in the moment of the mensuration impression diagonals make by the indenter in the sample. With this mind, an automated equipment of hardness mensuration was developed. The hardness value was obtained starting from the mensuration of plastic deformation suffered by the material to a well-known load. The material deformation was calculated through the mensuration of the difference between the progress and retreat of a diamond indenter on the used sample. It was not necessary, therefore, the manual mensuration of the diagonals, decreasing the mistake source caused by the operator. Tension graphs of versus deformation could be analyzed from data obtained by the accomplished analysis, as well as you became possible a complete observation of the whole process. Following, the hardness results calculated by the experimental apparatus were compared with the results calculated by a commercial microhardness machine with the intention of testing its efficiency. All things considered, it became possible the materials hardness mensuration through an automated method, which minimized the mistakes caused by the operator and increased the analysis reliability
O ensaio de dureza ? amplamente empregado em pesquisa e avalia??o de materiais para controle de qualidade. Entretanto, os resultados desse ensaio est?o sujeitos a erros causados pelo operador do processo no momento da medi??o das diagonais da impress?o deixada pelo penetrador na amostra ensaiada. Desse modo, fora desenvolvido um equipamento de medi??o de dureza automatizado. O valor de dureza foi obtido a partir da medi??o da deforma??o pl?stica sofrida pelo material a uma carga conhecida. A deforma??o do material foi calculada atrav?s da medi??o da diferen?a entre o avan?o e o recuo de um penetrador de diamante sobre a amostra utilizada. N?o foi necess?rio, portanto, a medi??o manual das diagonais, excluindo-se a fonte de erro causada pelo operador. Gr?ficos de tens?o versus deforma??o puderam ser analisados a partir de dados obtidos dos ensaios realizados, assim como tomou-se poss?vel um completo monitoramento de todo o processo. Em seguida, as durezas calculadas pelo aparato experimental foram comparadas com as durezas calculadas em um microdur?metro comercial com o intuito de testar sua efici?ncia. Desse forma, tornou-se poss?vel a medi??o de dureza de materiais atrav?s de um m?todo automatizado, que excluiu os erros causados pelo operador e aumentou a confiabilidade dos ensaios
Watts, D. Y. "An investigation of the mechanical properties of InGaAsP and related materials using microhardness indentation techniques." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373576.
Full textGromov, V. E., N. A. Soskova, S. V. Raikov, E. A. Budovskikh, A. V. Ionina, I. V. Lushina, and S. V. Konovalov. "Nanosize Structure Phase States of Ti Surface Layer Formed During Electroexplosive Carboborating." Thesis, Сумський державний університет, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34804.
Full textMilot, Timothy S. "Establishing Correlations for Predicting Tensile Properties Based on the Shear Punch Test and Vickers Microhardness data." Thesis, University of California, Santa Barbara, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1536555.
Full textA series of mechanical tests was performed on a matrix of pressure vessel alloys to establish correlations between shear punch tests (SPT), microhardness (Hv), and tensile data. The purpose is to estimate tensile properties from SPT and Hv data. Small specimen testing is central to characterization of irradiation-induced changes in alloys used for nuclear applications. SPT have the potential for estimating tensile yield and ultimate strengths, strain hardening and ductility data, by using TEM disks, for example. Additional insight into SPT was gained by performing finite element analysis (FEA) simulations.
Noriega, Motta Julio Amilcar. "Portable transparent indenter instrumentation for material surface characterization." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4765.
Full textTitle from document title page. Document formatted into pages; contains xiii, 105 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 97-98).
Nunes, Margareth Calvo Pessutti. "Avaliação da microdureza e desgaste por escovação simulada de uma resina composta, em função de diferentes fontes de luz e energias de ativação." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/25/25131/tde-20062007-105425/.
Full textThis in vitro study evaluated comparatively, the superficial microhardness and wear of a resin composite, FiltekTM Z-250 (3M/ESPE) under the influence of different light sources (LED Ultrablue IS/DMC, LED Ultralume 5/Ultradent and halogen VIP/BISCO); with power (300, 600 and above 800mW/cm2) and energy density (6, >8, 12, >16, 24, >32J/cm2) variations. Rectangular specimens (15 x 5 x 4 mm) were polymerized, as the variation factors, totalizing 15 groups (n=6). After, they were ground flat with water-cooled carborundum discs in decreasing abrasive order (300, 600, 1200 and 2000) and stored for seven days, before the tests, in deionized water at 37º C. The Knoop microhardness measurements were carried out using a microhardness tester (Shimadzu HMV-2), with a 100g static load applied for 5s on specimens\' top and lateral surfaces (50µm under surface). In sequence the specimens were taken to a machine for brushing simulation, using soft nylon bristles (Oral B 30 Indicator) and dental paste (Colgate) diluted in deionized water in the ratio of 1:2 in weight. After 100,000 cycles, the hardness of the lateral surface was again measured and the wear profile of the brushed area was determined by a profilometer (Hommel Tester T 100 basic/Hommelwerke). The microhardness and superficial wear data were submitted to the analysis of variance (ANOVA) and Tukey test (p<0.05). The results showed that the superficial microhardness of the evaluated resin composite was significantly lower when photoactivated with VIP-300 mW/cm2, being the biggest values observed for the Ultralume 5 device. The superficial wear was significantly influenced by the low power density (300 mWcm2) and energy density of 6 J/cm2. This was for both, VIP and Ultrablue IS, which demonstrated greater effectiveness when a density of energy above 12J/cm2 was used. In general, a negative correlation was observed between the two tests (wear and microhardness). In other words, there was an increase of hardness with the decrease in wear values, which demonstrates that only microhardness values do not constitute a parameter to qualify resin composite wear resistance behavior.
Polydorou, Olga. "The effect of two bleaching products on microhardness and surface texture of different dental aesthetic restorative materials." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972521119.
Full textAmambal, Altamirano Jessenia. "Estudio In Vitro del efecto erosivo de las bebidas industrializadas en el esmalte de dientes permanentes humanos." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2013. https://hdl.handle.net/20.500.12672/3228.
Full textIn this study we measured the Vickers microhardness of enamel after exposure to three industrialized beverages more consumed in the city of Lima, and a control beverage; we want to evaluate the erosive effect of the acidic beverages and their relation with the titratable acidity, the level of pH and buffer effect of this beverages. 60 blocks of surface enamel were made of 2mm thickness, and 2-4mm in length, were placed in fast curing acrylic circumferential mold of 10mm in diameter and 5mm in height, in different colors (blue for the carbonated drink, orange for the drink refreshing, green for the drink isotonic and white for the control beverage; to be differentiated); we gave them that the free surface being parallel with the base of the mold, then they were given a mirrorpolished for microhardness after that, they were being taken to Buehler where microhardness was measured. The data were analyzed by the statistical test T-STUDENT, ANALYSIS OF VARIANCE ANOVA, HSD TUKEY, YU WALLIS KRUSKAL WHITNEY MANN. It was concluded that the enamel surface microhardness decreases significantly after being subjected to the action of acidic drinks and the erosive effect is immediate and increases with each exposure. The result was that the isotonic beverage is more erosive than other drinks, and it was concluded that there is not a relationship between the erosive effect of pH values, titratable acidity and buffer effect of the beverages.
Tesis
Bordin, Ângelo Rafael de Vito. "Estudo do shelf life da quitosana armazenada em diferentes tipos de embalagem, por meio de colorimetria e análise da microdureza dentinária." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-22042014-144350/.
Full textThe aim of this study was evaluate, through the colorimetric titration method and analysis of the dentine microhardness, the shelf life of the solution of chitosan 0,2% stored in flasks of glass and plastic. Thirty human superior canines had their crown discarded and the cervical portion of the root sectioned, obtaining 3 sections. The second and the third sections were divided in half and included in acrylic resin resulting in 4 specimens per tooth. The chitosan solution 0,2% (pH 3,2) was prepared and distributed in 3 flasks of glass (v1, v2, v3) and in 3 of plastic (p1, p2, p3) to perform the test in triplicate. The tests of microhardness and colorimetry were performed during 6 months in the period of 0, 7, 15, 30, 45, 60, 90, 120, 150 and 180 days after the preparation of the solution. For the measurement of microhardness Knoop, it was used a load of 10 grams for 15 seconds. The test object received 50 μL of the test solution for 5 minutes and after washing and drying, it was taken out for measurement. The analysis was performed with the solutions v1, p1, EDTA 17% and distilled water (control); v2, p2, EDTA 17% and control; v3, p3, EDTA 17% and control, for each proposed time. Three indentations were performed with a 200μm space. Measurements were noted and filed in a database. For the colorimetric test, a standard solution of calcium carbonate 0.3% was used and a predetermined volume of chitosan solution was inserted to it by using a micropipette. The color changes observed in the carbonate solution, from violet to blue, indicated the chelation of calcium Ions, detected through visible ultraviolet absorbance spectrophotometry. The instrument generated a specific value of absorbance for each coloring solution analyzed, expressed through the graphic (wavelength/absorbance). Variation of analysis was used (One-Way ANOVA) (α= 0,05) to compare the microhardness among the solutions, the different time for each solution, as well as the interaction microhardness/time for each solution. The time of study was similar among the tested solutions (p=0,113), as well as the interaction between microhardness/time (p=0,329). The tested solutions showed, individually, the same effect over the dentine microhardness, from time zero until 180 days. When compared among each other the results were different (p<0,0001). The Tukey test demonstrated that chitosan (v1, v2, v3, p1, p2 and p3) and EDTA reduced the microhardness in a similar pattern among them (p>0,05) and different from the control (p<0,001). The graphics of the colorimetric analysis showed that either chitosan in glass or plastic presented medium values of absorbance in the same wave length (234nm) for all the different times, meanwhile the standard solution of calcium carbonate wavelength was 206 nm. It was concluded that independently of storing methods, the chitosan presents chelating property for a minimum period of six months.
Irikura, Sandra Ilka [UNESP]. "Estudo da influência da microestrutura no comportamento mecânico de juntas soldadas de um aço estrutural." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/94486.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Como se sabe dureza e resistência mecânica dependem da microestrutura do aço. Em aços multiestruturais é importante compreender a influência individual da estrutura do microconstituinte. O único ensaio prático que pode ser realizado individualmente no microconstituinte estrutural em aços multiestruturais é o ensaio de dureza com pequenas indentações sob cargas baixas ou ensaio de microdureza. Já que é possível obter a resistência ou a curva tensão-deformação da dureza de um aço mono estrutural, tal como ferrita, perlita, bainita ou martensita, também é possível estimar a resistência ou a curva tensão-deformação para aços multiestruturais conhecendo-se a fração volumétrica de cada constituinte estrutural individualmente presente. O trabalho tem como objetivo analisar o comportamento de microestruturas de um cordão-de-solda sob ensaio de microdureza com a tentativa de se recompor o valor de dureza Vickers (HV) obtido no ensaio de (macro) dureza, observando-se assim o comportamento individual dos constituintes. O material ensaiado foi a junta soldada por arco submerso do aço estrutural COS Civil 300. Tratamentos térmicos foram realizados para que se pudessem obter microestruturas variadas. As amostras foram analisadas metalograficamente e também por anális...
It is well known that both hardness and strength depend on the microstructure of steels. In multistructure steels, it is important to understand the influence of individual structure microconstituent. The only practical test that can be performed on the individual microstrutural constituents in multistructure steels is a hardness test with a small indentation under low load or microhardness test. If is possible to obtain strength or the stress-strain curves from the hardness of single structure steels, such as ferrite, perlite, bainite or martensite, it is may possible to estimate the strengths or stress-strain curves of multistructure steels by knowing the volume fraction of the individual structural constituents present. The purpose of the present work is analyzing the microstrutural behaviour of weld joint under microhardness test with the attempt of recomposing the Hardness Vickers (HV) value obtained on the (macro) hardness test, observing then the individual behaviour of the constituents. The material tested was the joint welded by submerge- arc welding of the structural steels COS Civil 300. Heat treatment had been carried out to obtain different microstrutures. The specimens were analyzed by metallography and quantitative analysis... (Complete abstract click electronic access below)
Challapalli, Dharmendra, and Ahmad El-masri. "Study and analysis of surface layer characteristics of lead brass and lead free brass." Thesis, Högskolan i Halmstad, Maskinteknisk produktframtagning (MTEK), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-32207.
Full textLead free brass
Flamini, Luís Eduardo Souza. "Estudo morfológico e análise da microdureza da dentina na área de furca de dentes molares inferiores." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-04122012-161754/.
Full textThe aim of this study was to evaluate the dentin microhardness in furcation areas of mandibular molars and to study the dentin morphology in these regions by scanning electron microscopy (SEM). The crows of ten specimens were transversely sectioned and the occlusal portions were discarded. The mesial and distal roots were cut near to the cervical third ignoring the middle and apical thirds. The remaining teeth were included in rapid polymerization acrylic stubs and cut longitudinally resulting in two hemi-sections. One was designed to study the morphology in which was possible to observe characteristics of the dentin and dentinal tubules direction. The other one was used to perform analysis of the microhardness using a Knopp device with load of 10g/15s. The furcation areas were established as the regions between two orthogonal lines drawn from the point of maximum concavity of the outer surface of the bifurcation. Microhardness was measured in the superficial layers of dentin (next to the floor), middle and inner (closest to the concavity of the external furcation), as well as in the three axes: mesial (parallel to the straight line along the mesial furcation), central (parallel to the bisectrix between the lines) and distal (parallel to the line drawn along the distal). Five measurements were performed for each axis yielding an average in each one. The measurements were subjected to statistical analysis (one way - ANOVA) (α = 0.05). The results showed no significant difference (p> 0,05) between the microhardness of the mesial (46.5±6.4), central (47.3±8.1) and distal portions (49.7±6.5). In relation to the layers, the Tukey test showed significant differences only between the inner (51.7±2.5) and outer (41.4±2.4) layers (p <0.05). The SEM images showed that the dentinal tubules assumes centripetal trajectory toward the inner portion. These ones, in the outer layer, presents larger and more evident. In the middle layer are thinner and in the inner layer the dentin is similar to sclerotic dentin. In this study was possible to observe that the microhardness of dentin in the furcation areas is uniform across to the three axes. The inner layer is harder than the outer. The dentin of the furcation areas appears to be a very mineralized tissue having a bigger calcification as it approaches to the inner layer.
BONK, PAULO A. "Avaliacao da mudanca da microdureza na superficie de esmalte dentario irradiada com laser de holmio e modelamento das microexplosoes." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10778.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Irikura, Sandra Ilka. "Estudo da influência da microestrutura no comportamento mecânico de juntas soldadas de um aço estrutural /." Ilha Solteira : [s.n.], 2006. http://hdl.handle.net/11449/94486.
Full textBanca: Cecília A. de C. Zavaglia
Banca: Vicente Afonso Ventrella
Resumo: Como se sabe dureza e resistência mecânica dependem da microestrutura do aço. Em aços multiestruturais é importante compreender a influência individual da estrutura do microconstituinte. O único ensaio prático que pode ser realizado individualmente no microconstituinte estrutural em aços multiestruturais é o ensaio de dureza com pequenas indentações sob cargas baixas ou ensaio de microdureza. Já que é possível obter a resistência ou a curva tensão-deformação da dureza de um aço mono estrutural, tal como ferrita, perlita, bainita ou martensita, também é possível estimar a resistência ou a curva tensão-deformação para aços multiestruturais conhecendo-se a fração volumétrica de cada constituinte estrutural individualmente presente. O trabalho tem como objetivo analisar o comportamento de microestruturas de um cordão-de-solda sob ensaio de microdureza com a tentativa de se recompor o valor de dureza Vickers (HV) obtido no ensaio de (macro) dureza, observando-se assim o comportamento individual dos constituintes. O material ensaiado foi a junta soldada por arco submerso do aço estrutural COS Civil 300. Tratamentos térmicos foram realizados para que se pudessem obter microestruturas variadas. As amostras foram analisadas metalograficamente e também por anális... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: It is well known that both hardness and strength depend on the microstructure of steels. In multistructure steels, it is important to understand the influence of individual structure microconstituent. The only practical test that can be performed on the individual microstrutural constituents in multistructure steels is a hardness test with a small indentation under low load or microhardness test. If is possible to obtain strength or the stress-strain curves from the hardness of single structure steels, such as ferrite, perlite, bainite or martensite, it is may possible to estimate the strengths or stress-strain curves of multistructure steels by knowing the volume fraction of the individual structural constituents present. The purpose of the present work is analyzing the microstrutural behaviour of weld joint under microhardness test with the attempt of recomposing the Hardness Vickers (HV) value obtained on the (macro) hardness test, observing then the individual behaviour of the constituents. The material tested was the joint welded by submerge- arc welding of the structural steels COS Civil 300. Heat treatment had been carried out to obtain different microstrutures. The specimens were analyzed by metallography and quantitative analysis... (Complete abstract click electronic access below)
Mestre
Kushnerov, O. I., and V. F. Bashev. "Structure and mechanical properties of Al-Co-Cr-Fe-Mn-Ni-Si-V high-entropy films obtained by splat-quenching." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42650.
Full textProzorova, M. S., O. V. Kolisnishenko, M. G. Kovaleva, M. Yu Arseenko, and Yu N. Tyurin. "Structure and the Physico-Mechanical Properties of the Ceramic Coatings Obtained by the Cumulative -Detonation Device." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35467.
Full textTrivedi, Yash Nipun. "Investigation of Mechanical Properties of Bulk and Additively Manufactured Ni-Mn-Ga Shape Memory Alloy using Nanoindentation and Microhardness Techniques." Youngstown State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1558656191440726.
Full textNascimento, Tiago Elias do. "Estudo morfológico e da microdureza dentinária da região da furca e adjacente de pré-molares superiores com raízes divergentes." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-13082013-104359/.
Full textThe aim of this study was to study the morphology of furcation areas of maxillary premolars, by confocal laser scanning microscopy (CLSM), and to evaluate comparatively the microhardness in these regions to those adjacent on vestibular and palatine. Ten maxillary premolars with divergent roots had the crowns transversely sectioned and the occlusal portions were discarded. The vestibular and palatine roots were cut near to the cervical third ignoring the middle and apical thirds. The remaining teeth were included in rapid polymerization acrylic stubs and cut longitudinally resulting in two hemi-sections. One was designed to the morphology study and the other one to the microhardness using a Knoop device with load of 10g/15s. The furcation area was established as the region between two orthogonal lines drawn from the point of maximum concavity of the outer surface of the bifurcation. Microhardness was measured by layers (superficial, middle and inner) and by regions (vestibular, central and palatine) of furcation and adjacent (vestibular and palatine). The average for the five measurements for each region was subjected to statistical analysis (one way - ANOVA) (α = 0.05). The results showed no significant difference between the analyzed regions (p> 0,05), however the inner layer presented to be harder than the superficial one (p < 0,05). The CLSM images showed that the superficial layer is quite tubular with large and visible tubules while in the inner one the tubules are completely calcified. The middle layer showed a lower amount of visible dentin tubules than the superficial layer. From the chamber floor toward the inner layer, the tubules initially assume a winding trajectory, tending to form an interweaving among them as they approach to the middle layer.
Jiménez, Pereira Cláudia. "Influência de imersões em vinagre sobre a rugosidade e a dureza de uma resina acrílica de termoativação." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/102540.
Full textSeveral substances have been used for the disinfection and hygiene of acrylic resin devices, however, many of these substances are used empirically. Thus, the aim of this study was to evaluate the influence of immersion in vinegar, sodium hypochlorite and hydrogen peroxide on the surface roughness and hardness of thermo-cured acrylic resin Meliodent® Heat Cure (Heraeus Kultzer, Germany). 130 specimens of acrylic resin were produced and randomly divided into 13 groups (n = 10). The control group remained dry without immersion. The test groups were immersed in vinegar, 1% sodium hypochlorite, hydrogen peroxide 10V and distilled water during different times (30h, 150h and 300h). The solutions were protected from light and changed every 24 hours. After the immersion period, Knoop hardness and surface roughness of the acrylic resin were evaluated. The Knoop hardness of the specimens were obtained through an automatic microhardness tester HMV-2 (Shimadzu, Japan) with five measurements on each specimen with a load of 25g for 10 seconds. The roughness was determined by five readings on each specimen using a Surface Roughness Tester SJ-201 (Mitutoyo, Japan). The results showed a statistically significant difference in microhardness after immersion for 30h, 150h and 300h in vinegar, 1% sodium hypochlorite, hydrogen peroxide and distilled water 10V, compared with the control group. The results of roughness showed no statistically significant difference after immersion for 30h, 150h and 300h in vinegar and distilled water when compared with the control group. Based on the experimental design and results of this study it can be concluded that vinegar can eventually become an option for homemade disinfecting apparatus of acrylic resin.
Vodoriz, O. S., T. V. Tavrina, and O. I. Rogachova. "Thermoelectric Properties of PbSe₁₋ₓTeₓ Solid Solutions." Thesis, Прикарпатський національний університет ім. Василя Стефаника, 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/44863.
Full textRose, Scott Anthony. "The Effect of Cooling Rate of Friction Stir Welded High Strength Low Alloy Steel." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4181.
Full textMartins, Kandice Valente. "Avaliação da microdureza e rugosidade do esmalte bovino submetido ao clareamento com géis de alta e baixa concentração com ou sem adição de cálcio na sua composição." Universidade de Taubaté, 2015. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=858.
Full textObjective: To evaluate the effects of bleaching with hydrogen peroxide 40% (HP 40%) and carbamide peroxide 20% (CP 20%), with and without the addition of calcium (2000ppm), in enamel through the Knoop microhardness and roughness tests. Method: bovine enamel blocks (3mm2) were prepared and included and randomly divided into five experimental groups (n=12) and subjected to different treatments. The Group 1 and 2 were bleached carbamide peroxide with or without calcium, and G3 e G4 were bleached HP 40% with or without calcium. The group 5 were immersed in saliva artificial (control group). The samples were washed and stored in artificial saliva to the next bleaching session. The treatments were carried out for 14 days. The analysis of the enamel surface was performed with test surface roughness and Microhardness, before and after treatment. An exploratory analysis of the data and the groups were subjected to analysis of variance was performed (ANOVA) and Tukey test (5% significance). Results: All specimens were subjected to testing Knoop microhardness before the treatment (initial reading), after the bleaching treatment. The bleached group with 40% PH had the lowest values of microhardness. There was a statistically significant difference between the initial and final readings. For surface roughness were no differences between the tested materials; but there was an increase of roughness for all groups after bleaching. Conclusion: It was concluded that there was decrease of microhardness for all tested bleaching agents. There was an increase in surface roughness after tooth whitening.
Nogueira, Juliane Cristina Ciccone. "Influência de métodos de esterilização nas propriedades físicas do substrato dental." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-19032010-113044/.
Full textThe aim of this study was to evaluate the influence of sterilization methods (ethylene oxide, steam autoclave and 10% formalin) on microhardness of extracted human teeth (enamel and root dentin) submitted to pH cycling, and to determine the influence of these methods on shear bond strength (enamel, coronary and root dentin). For microhardness test, 40 root dentin and 40 enamel blocks were prepared from freshly-extracted third molars. Specimens were randomly assigned to 4 groups according to sterilization method: control group no sterilized, ethylene oxide (7h- EtO gas cycles and 48 degassing period), steam autoclave (30´ at 121oC) and 10% formalin (7 days). After sterilizing, specimens were rinsed, moisten and submitted to pH cycling. Microhardness test in different depths (30, 60, 90, 120 and 300µm) was realized on sound and demineralized areas. For shear bond strength test, 60 enamel, coronary and root dentin fragments were randomly divided into 4 groups according to sterilization method: control group, ethylene oxide, steam autoclave and 10% formalin. The bonding site was delimited and a resin composite cylinder was built. After 24h, the specimens were tested to failure. Data were analyzed using ANOVA and Fishers test (α=0.05). Sound enamel microhardness showed the highest values for control group, followed by ethylene oxide and steam autoclave, while the 10% formalin provided the lowest values. For depths, ANOVA showed no statistical difference among them. For demineralized enamel, control group was similar to steam autoclave group and higher than formalin and ethylene oxide (control ≈ steam autoclave > formalin ≈ ethylene oxide). Comparing depths, it was observed that 30µm < 60µm ≈ 90µm ≈ 120µm < 300µm. For sound root dentin, control group was similar to formalin and ethylene oxide and higher than steam autoclave, being formalin similar to ethylene oxide and different from steam autoclave. It was not verified statistical difference for depths in this substrate. For desmineralized root dentin, ANOVA showed no statistical difference among the methods. For depths, 30µm was similar to 90µm and different from 300 and 120µm. 300µm provided the highest values. For bond strength in root dentin, it was observed statistically significant difference among sterilization methods, presenting formalin the highest values. However, when enamel and dentin were evaluated, ANOVA showed no statistical difference among sterilization methods. It can be concluded that, the sterilization methods employed in this study affect the microhardness of sound and demineralized enamel and sound dentin. On the other hand, the sterilization methods did not affect the microhardness of demineralized root dentin. Shear bond strength was affected by the sterilization methods only in root dentin.
CUBAKOVIC, IVANA A. "Caracterizacao microestrutural, mecanica e eletroquimica de acos inoxidaveis austeniticos utilizados no acondicionamento de rejeitos radioativos de alto nivel." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10883.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Liu, Lizhi. "Surface Hardening of Titanium Alloys by Gas Phase Nitridation under Kinetic Control." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1094223428.
Full textJúnior, Agnaldo Rocha de Souza. "Efeito dos processos de cristalização nas propriedades mecânicas e morfologia do sistema cerâmico de dissilicato de lítio." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-03022015-081237/.
Full textDue to the crescent appreciation for esthetic, the use of lithium disilicate glass ceramic has excelled because of their esthetic and mechanical properties. However, this system requires a complex process of crystallization which restricts his use to sophisticated and expensive ovens. This study aimed to evaluate the effect of two crystallization processes in hardness, flexural strength and morphology of the IPS e.max CAD lithium disilicate. Ten blocks of IPS e.max CAD generated 60 specimens that were divided between the Knoop micro hardness test (n = 30) and flexural strength (n = 30). Each trial had the bodies of evidence separated into 3 groups according to the crystallization process: G1-crystallization process recommended by the manufacturer; G2-simplified process of crystallization; G3 without crystallization. It was performed a morphological analysis, qualitatively, by confocal laser scanning microscopy on one sample taken randomly from each group for the flexural strength test. The data obtained by the micro hardness test were statistically analyzed Friedman tests, while the flexural strength data were analyzed by analysis of variance and Tukey-Kramer test, both analysis with significance set at p≤ 0.05. The results showed that the average micro hardness of the specimens in group G3 (862.13 KHN) was similar to G2 (818.9 KNP) and these were significantly higher than the G1 group (645.13 KHN). The flexural strength of the specimens showed a higher value for G1 (302.95 MPa), but statistically similar to G2 (277.7 MPa), which were significantly higher than the G3 group (155.2 MPa). Morphologically G3 exhibited a more irregular surface followed by G1, with a surface more regular for G2. Both of crystallization processes promoted a gain in flexural strength. However, the simplified crystallization process promoted a greater hardness and more regular surface.
Aivazoglou, Marcos Uyeda [UNESP]. "Influência de soluções de armazenamento, métodos de esterilização e suas associações sobre a microdureza dentinária radicular em dentes humanos: estudo in vitro." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/90382.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo deste trabalho foi avaliar a ação das soluções de armazenamento: água destilada (G1), solução de timol a 0,05%(G2), formalina a 10%(G3), e hipoclorito de sódio a 1%(G4), bem como os métodos de esterilização por autoclave (A) e radiação gama (B), e as associações dos dois fatores, sobre a microdureza da dentina radicular de terceiros molares extraídos. Os dados obtidos foram submetidos aos testes t de Student, ANOVA a 2 e 3 fatores, e teste de Tukey, todos com α=0,05. Quanto ao armazenamento, o G1(nos dois períodos avaliados) foi o único grupo que não alterou significantemente a microdureza, sendo seguido pelos grupos G2 e G3 (7 dias), G2 e G3 (28 dias), e G4 (7 e 28 dias), tendo estes dois últimos subgrupos apresentado as maiores perdas de microdureza. Na análise da esterilização isoladamente, não houve diferença significante para os 2 métodos quando comparadas as microdurezas iniciais e após a esterilização (autoclave: p=0,144; raios gama: p=0,827), apesar da esterilização por autoclave ter induzido diferenças significantes no grupo armazenado por 28 dias em água destilada. Entretanto, estudada a interação de todos os fatores, encontraram-se diferenças significantes quanto à solução empregada, método de esterilização e interações entre eles (p<0,05). Com base nos dados analisados pôde-se concluir que o armazenamento em água destilada não alterou a microdureza dentinária radicular, e sua associação à esterilização por radiação gama foi o melhor método para o armazenamento e esterilização de dentes, no que diz respeito às influências sobre a variável estudada, sendo indicados para dentes extraídos a serem utilizados em pesquisa.
The aim of this study was to evaluate the effect of storage solutions: distilled water (G1), 0.05% thymol solution (G2), 10% formalin (G3), and 1% sodium hypochlorite (G4); sterilization methods- steam autoclaving (A) and gamma irradiation (B)- and the associations between the two factors on the root dentin microhardness of extracted human third molars. Data were subjected to student’s t test for dependent samples, Two and Three-way ANOVA, and Tukey’s test (α = 0.05 for all tests). Regarding storage, only the G1 (in both periods) did not alter the dentin microhardnes significantly. In the analysis of sterilization methods, there were significant differences on the solution employed, storage time and sterilization method (p <0.05). Based on the results, it was concluded that the storage in distilled water did not change the root dentin microhardness, and association of this storage solution with sterilization by Gamma radiation did not produce alterations by means of the studied variable, thus consisting in the best methods regarding storage and sterilization of teeth to be used in research.
Silva, Luciana Maria da. "Influência das dimensões e do modo de fotoativação do corpo de prova sobre os testes de sorção, de solubilidade e de microdureza Knoop." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/23/23140/tde-02052011-121941/.
Full textThis study evaluated the influence of the dimensions and the light-cure mode of specimens in the tests of sorption, solubility and Knoop microhardness. This research was divided into two phases. In the first stage, disc shaped samples of an experimental composite resin (15 mm in diameter x 1 mm in thickness) were fabricated using a teflon split mold., The composite was inserted in one increment and then flattened by a polyester strip adhered to a glass plate. All groups had the same dimensions, however, were polymerized in three different ways: G1-five exposures for each side of the specimen, according to the standard specified by ISO 4049, G2-removing the tip of the curing unit and allowing light to reach all the surface of the specimen, and G3-distancing the tip of the curing unit 1.5 cm with the same intention (n=5). Anova and Tukey test (p<0.05) for the means comparisons showed no statistically significant differences among groups for the sorption test (p=0.517). The values in g/mm3 with their standard deviation were: G1 = 22.58±1.20, G2 = 23.51±0.61 and G3=22.16±1.39. The solubility test showed statistically significant differences (p=0.002), according to the superscript letters. The values in g/mm3 with their respective standard deviations were G1=0.54±0.14B, G2=0.37±0.14B and G3=1.04±0.09A. For the microhardness test, statistical analysis showed significant differences among groups (p=0.003). The KHN values with their standard deviation were: G1 = 78.9±2.74A, G2 = 69.4±4.77B and G3 = 67.4±4.94B. The conclusion of this first phase was that the best way of light-curing was G1 (according to ISO), which showed lower solubility and the higher Knoop microhardness. The second research stage was performed using only the best way of light-curing achieved in the first round, which was corresponding to Group 1 (ISO 4049), varying the dimensions of the specimens with the sizes most used in the literature of sorption and solubility. The experimental groups were divided into: (Diameter x thickness) g1=15x1 mm (ISO), g2=5.8x0.8 mm and g3=6x0.5 mm, prepared in the same way as the samples of the first phase. The specimens were then submitted to the sorption, solubility and Knoop microhardness tests. ANOVA and Tukey test (p<0.05) showed no statistically significant differences for the sorption test (p=0.915).The values in g/mm3 with their respective standard deviations were: g1=22.58±1.2; g2=22.28±2.26 and g3=22.78±2.02. The solubility test showed statistically differences among groups (p=0.006). The values in g/mm3 with their respective standard deviations were: g1 = 0.54±0.14B, g2=3.2±2.07A, and g3=2.16±1.06AB. The Knoop microhardness test showed no statistically significant differences among groups (p=0.106). The values in KHN with their respective standard deviations were: g1=62.12±0.86, g2=64.88±4.21 and g3=66.20±2.33. Taking into consideration the studied factors, it can be concluded that the size and the shape of photoactivation recommended by ISO 4049 seems to be the best way of preparing the specimens for sorption and solubility tests, associated with the Knoop microhardness test.
Pinheiro, Helena Burlamaqui. "Influência de cinco géis clareadores e de um gel remineralizante sobre a ultra-estrutura e microdureza do esmalte e da dentina de dentes humanos." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/23/23140/tde-29092009-092041/.
Full textObjective: The aim of this in vitro study was to evaluate, through ultrastructural analysis and microhardness test, the influence of a remineralizing gel and five bleaching gels on enamel and dentin of human teeth. Material and Method: 10 third molars crowns had occlusal and cervical portions removed (5 crowns used for ultrastructural analysis and 5 for microhardness test). Each remaining coronary structure were cut in 7 slices (ultrastructural analysis) and 6 slices (Knoop hardness test). For ultrastructural analysis, the slices were divided into 6 groups (n=5), one being the control group. The other 6 slices were distributed into 6 experimental groups, one remineralizing gel, Relief ACP (Rel ACP); 2 conventional bleaching gels, Opalescence PF (Opal) and Whiteness Perfect (WP); 2 gels with Ca and PO4, Nite White ACP (NW ACP) and Day White ACP (DW ACP) and a bleaching gel with calcium, White Class Ca (WC Ca). After each session of remineralizing or bleaching treatment, the specimens were stored in distilled water (37º C). After 24 hours of completed treatments, the specimens were examined by field emission in-lens scanning electron microscopy (FEISEM) and then, final values were determined for enamel (Ef) and dentin (Df) microhardness. Results: The conventional bleaching gels and the bleaching gel with calcium, caused demineralization in enamel and dentin and reduce the hardness values of these two tissues (Opal: Ei=308,9; Ef=278,5; Di= 51,7; DF=44,0 / WP: Ei=316,8; Ef=291,2; Di=50,3; DF=34,8 / WC Ca: Ei=315,7; Ef=289,7; Di=52,1; DF=44,8) (p <0.05). Already, the bleaching with calcium and phosphate (NW ACP and DW ACP) and the remineralizing gel (Rel ACP) did not cause demineralization or reduction in the enamel and dentin hardness values (NW ACP: Ei=313,8; Ef=315,7; Di=51,7; DF=48,2 / DW ACP: Ei=320,7; Ef=316,2; Di=53,7; DF=52,6 / Rel ACP: Ei=310,1; Ef=314,8; Di=48,9; DF=46,5). Conclusion: The remineralizing gel (Rel ACP) and the bleaching agents with Ca and PO4 (DW ACP and NW ACP) did not cause changes in the ultrastructure nor the enamel and dentin microhardness. The conventional bleaching gels (Opal and WP) and the bleaching gel with calcium, WC Ca, promoted changes in enamel and dentin and reduction of the microhardness values in the two tissues.
Franzon, Renata. "Avaliação clínica e laboratorial da dentina de dentes decíduos após remoção parcial de tecido cariado." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/12134.
Full textThe aim of this study was longitudinally to investigate the clinical and radiographic performance of the Partial Caries Removal (PCR) in deciduous teeth and evaluate the remaining carious dentin through the microhardness after exfoliation. The sample of this study comes from a randomized clinical controlled study in 20 patients with age between 4 and 7 years. Thirty nine primary molars with deep acute carious lesions, without irreversible signs of pulp pathology were submitted to PCR. The teeth were divided in two groups in accordance with capping material: calcium hydroxide (CH) - 20 teeth or gutta-percha (GP) - 19 teeth, both restored with composite resin. After 36 months of follow-up, 29 teeth (15 patients) had been reevaluated; of these, 23 teeth had clinical and radiographic success: 11 CH (73.3%) and 12 GP (85.7%). The overall success in this stage of the evaluation was 79.3% and it did not have difference between the capping material. These teeth were follow-up evaluated until its exfoliation (37 - 71 months of permanence in mouth), when 18 teeth (6 CH and 12 GP) were collected for laboratorial analysis. The aim of this analysis was to verify if PCR provides conditions for dentin remineralization in primary teeth. The 18 teeth submitted to PCR were grouped (treated group). Additionally, ten sound molars and ten molars with deep acute carious lesions were selected to serve as positive and negative control groups, respectively. In the treated group, restorations and pulp-capping materials were removed. In the positive control group, 3 to 4 mm deep cavities were prepared and in the negative control group the carious tissue was removed according to the same in vitro PCR criteria. All teeth were prepared for microhardness analysis to be performed in three linear points with 100 μm between each one and at 10, 35, 60, 85 and 110 μm from the cavity floor resulting in 15 indentations for each sample. Furthermore, thickness of remaining dentin was measured to estimate cavity depth. There were no significant differences in the thickness of the remaining dentin between the three groups (means 921, 852, 833 μm for sound, carious and treated, respectively; p≤0.01). There was a statistically significant difference among the groups sound, carious and treated, for microhardness in all distances: 10 μm (54.8, 12.5, 38.3), 35 μm (62.0, 13.0, 38.0), 60 μm (56.8, 12.3, 39.1), 85 μm (58.9, 13.0, 40.3), 110 μm (55.7, 14.2, 42.0), p≤0.01. The results showed hardness increase in treated teeth when compared to carious teeth in all dentin depths investigated, (p≤0.01) suggesting mineral gain after treatment.
Majeed, Abdul. "Efficacy and safety of various tooth-whitening products, with special reference to the three dimensional colour space (L*a*b*) measurements and the microhardness tests." Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6162_1319790550.
Full textRodžianskas, Tomas. "Elektrolankinio purškimo skirtingomis vielomis tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140619_092224-76020.
Full textIn the final master thesis examined coatings by arc spraying with different solid wires. The review of thermal spray coatings technology and research methods are described. The metal surface coating was applied to modify it‘s mechanical and physical properties, also resistance to external impact and improve aesthetics view. The research of stainless steel, marine bronze and combined coating microstructures, microhardness modulus of elesticity and adhesion were carried out. The results are presented graphically. The experimental and numerical results of thermal spray coatings were analysed and conclusions were given. Structure of work: introduction, literature review and analysis, research of coatings by arc spraying, coclusions, references. Thesis consist of – 59 p. text, 55 pictures, 14 tables, 18 bibliografical entries.
Cardia, Guilherme Saintive. "Avaliação da profundidade de polimerização através de testes de microdureza de duas resinas compostas de matrizes distintas em diferentes densidades de energia e períodos, utilizando LED como fonte fotoativadora." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/25/25148/tde-05122011-160411/.
Full textThis study aimed to evaluate the depth of cure through microhardness tests on two types of resin composite with different matrices using LED curing unit, using different energy densities and are assessed during the initial (baseline) and after 7 days. Knoop hardness test was performed in samples made of two light cured composites (P 90, 3M/ESPE, A2; Z 250, 3M/ESPE, A2). The specimens were divided into 8 groups (n=10), and half of them were made with each composite resin tested. Each group was defined by different power densities (600 mW/cm2 x 40s, 1000 mW/cm2 x 40s, 1000 mW/cm2 x 20s; mW/cm2 1400 x 20s), each specimens obtained four measures, different depths (0, 1, 2 and 3 mm). Each specimens was made with the aid of a metal matrix, consisting of 3 parts, superior, intermediate and bottom, each with 1 mm thickness and center hole diameter of 5 mm. On each side filled with resin, was placed a piece of polyester strip, on which, with a glass slide was exerted pressure to promote a flat surface. A unit LED curing was used and to achieve different power densities, plastic rings were attached at the tip of the curing unit. The polymerization was carried out with the tip of the curing unit in contact with the polyester strip placed on top of the specimen (0 mm). Thus, each specimen was composed of three parts, each part with 1 mm thick. Immediately after curing, the parts of the specimens were separated and held up five impressions of Knoop hardness (initial hardness), with a load of 50g for 30s on 4 surfaces, which were: 1) the upper surface of the upper specimen directed to the light source (0 mm), 2) lower surface of the upper specimen (1 mm); 3) lower surface of the middle section of the specimen (2 mm) and 4) lower surface of the bottom of the specimen (3 mm). After 7 days of storage in an oven at 37°C, new hardness re adings were made (final hardness). It was found that: 1) The composite P 90 had lower average values of Knoop hardness in relation to the other studied composite, Z 250, 2) The greater the depth, lower Knoop hardness values were measured, 3) Final values of Knoop hardness were higher after 7 days compared with initial hardness, 4) In accordance with the increase of power density, higher average values of Knoop hardness were measured. These results indicate that: 1) The resin improves the hardness property over a period of 7 days, 2) The greater the depth, the lower the hardness, 3) the higher the power density used in this study, higher hardness was evaluated; 4 ) P 90 resin obtained values less than Z 250 resin, evaluated under the same conditions.
Medeiros, Igor Studart. "Dispositivos LED para polimerização de resinas compostas dentais: comparação com outras fontes de luz." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-07042010-155505/.
Full textThe improvement of composite resins polymerization through visible light has been an important research topic. The majority of the studies, however, are restricted only to the conventional light sources and little has been made to viable new sources, introducing new technologies in this area of the knowledge. In intention to develop new light sources for dental composite resins polymerization, the Optics Groups is one of the pioneers in the development and characterization of devices, using blue LEDs for this purpose. In this work, it was verified the viability of a new device based in blue LEDs, executing a comparative analysis with the conventional polymerization device and the argon laser. It was executed the test of thermal analysis during the process of exposure to the polymerization light, to verify the thermal variation in the pulpal chambers of third molars caries free. After that, it was determined the variation of microhardness and diametral tensile strength properties when composite specimens were storaged in chemical agents found in the oral cavity. The results have demonstrated that the LEDs based device present is viable for polymerization of dental composites with some advantages in relation to other used light sources.
ALMEIDA, FILHO AMERICO de. "Influencia da preparacao previa de amostras de aco AISI H 13 no comportamento a nitretacao." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10775.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP
FAPESP:97/04424-5
Mecelis, Guilherme Rosati. "Caracterização mecânica e microestrutural de aços microligados processados industrialmente /." Ilha Solteira, 2017. http://hdl.handle.net/11449/151453.
Full textResumo: Os aços microligados são materiais já tradicionais e muito versáteis por suas propriedades mecânicas superiores, sendo sua evolução diretamente ligada com a otimização da composição química e do processamento termomecânico. É um tipo de aço que apresenta uma microestrutura refinada, alta resistência mecânica, boa usinabilidade e soldabilidade e tem substituído aços comuns por atingir essas propriedades mecânicas a partir de processos de fabricação mais baratos. Os aços estudados são comerciais, apresentam limite de escoamento entre 419 MPa e 646 MPa e grãos ferríticos finos com tamanhos inferiores a 3,70 μm. Neste trabalho são investigadas chapas industriais produzidas por laminação controlada, visando analisar a correlação entre a microestrutura ferrítico-perlítica e as propriedades mecânicas encontradas nas diferentes secções longitudinal, transversal e normal da chapa laminada. As diferenças entre as diferentes secções não são bem exploradas atualmente, então este estudo contribui para uma melhor compreensão da anisotropia introduzida pelo processamento termomecânico industrial. Foram feitas correlações entre as propriedades, confirmando a existência de diferenças estatisticamente significativas entre as secções, constatando que esses aços podem apresentar variações em suas propriedades de acordo com a secção de análise adotada. Foi confirmada a correlação de Hall-Petch nos aços estudados, e a influência dos mecanismos de endurecimento foi avaliada para estes materiais.
Abstract: Microalloyed steels are traditional materials and very versatile due to their superior mechanical properties, being its evolution directly linked with an optimization of the chemical composition and the thermomechanical processing. It is a type of steel that has a fine microstructure, high mechanical strength, good machinability and weldability, and has substituted common steels for achieving these mechanical properties with a cheaper manufacturing process. The studied steels are commercial and have yield strength between 419 MPa and 646 MPa and fine ferritic grains with size smaller than 3.70 μm. In this work are investigated industrial plates produced by controlled lamination, aiming to analyze the correlations between ferrit-perlitic microstructure and the mechanical properties found in the different sections of the hot rolled plate (longitudinal, transverse and normal). The differences between the different sections are not well explored, so this study contributes to a better understanding of the anisotropy introduced by industrial thermomechanical processing. Correlations were made between the properties, confirming the existence of significant differences between the different sections, finding that these steels may show different properties according to the section of analysis adopted. The Hall-Petch correlation was confirmed in the studied steels, and the influence of the hardening mechanisms was also evaluated.
Mestre
Šoulák, Petr. "Aplikace CMT Advanced v průmyslové praxi." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401050.
Full textAivazoglou, Marcos Uyeda. "Influência de soluções de armazenamento, métodos de esterilização e suas associações sobre a microdureza dentinária radicular em dentes humanos : estudo in vitro /." São José dos Campos : [s.n.], 2009. http://hdl.handle.net/11449/90382.
Full textBanca: Samira Esteves Afonso Camargo
Banca: Carlos Rocha Gomes Torres
Resumo: O objetivo deste trabalho foi avaliar a ação das soluções de armazenamento: água destilada (G1), solução de timol a 0,05%(G2), formalina a 10%(G3), e hipoclorito de sódio a 1%(G4), bem como os métodos de esterilização por autoclave (A) e radiação gama (B), e as associações dos dois fatores, sobre a microdureza da dentina radicular de terceiros molares extraídos. Os dados obtidos foram submetidos aos testes t de Student, ANOVA a 2 e 3 fatores, e teste de Tukey, todos com α=0,05. Quanto ao armazenamento, o G1(nos dois períodos avaliados) foi o único grupo que não alterou significantemente a microdureza, sendo seguido pelos grupos G2 e G3 (7 dias), G2 e G3 (28 dias), e G4 (7 e 28 dias), tendo estes dois últimos subgrupos apresentado as maiores perdas de microdureza. Na análise da esterilização isoladamente, não houve diferença significante para os 2 métodos quando comparadas as microdurezas iniciais e após a esterilização (autoclave: p=0,144; raios gama: p=0,827), apesar da esterilização por autoclave ter induzido diferenças significantes no grupo armazenado por 28 dias em água destilada. Entretanto, estudada a interação de todos os fatores, encontraram-se diferenças significantes quanto à solução empregada, método de esterilização e interações entre eles (p<0,05). Com base nos dados analisados pôde-se concluir que o armazenamento em água destilada não alterou a microdureza dentinária radicular, e sua associação à esterilização por radiação gama foi o melhor método para o armazenamento e esterilização de dentes, no que diz respeito às influências sobre a variável estudada, sendo indicados para dentes extraídos a serem utilizados em pesquisa.
Abstract: The aim of this study was to evaluate the effect of storage solutions: distilled water (G1), 0.05% thymol solution (G2), 10% formalin (G3), and 1% sodium hypochlorite (G4); sterilization methods- steam autoclaving (A) and gamma irradiation (B)- and the associations between the two factors on the root dentin microhardness of extracted human third molars. Data were subjected to student's t test for dependent samples, Two and Three-way ANOVA, and Tukey's test (α = 0.05 for all tests). Regarding storage, only the G1 (in both periods) did not alter the dentin microhardnes significantly. In the analysis of sterilization methods, there were significant differences on the solution employed, storage time and sterilization method (p <0.05). Based on the results, it was concluded that the storage in distilled water did not change the root dentin microhardness, and association of this storage solution with sterilization by Gamma radiation did not produce alterations by means of the studied variable, thus consisting in the best methods regarding storage and sterilization of teeth to be used in research.
Mestre
Abouelnaga, Mohamed Ahmed Anis. "A comparison of gingival marginal adaptation and surface microhardness of class II resin based composites (conventional and bulk fill) placed in layering versus bulk fill techniques." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/1281.
Full textFERRARI, RICARDO B. "Caracterizacao de liga metalica a base de aluminio-magnesio obtida por metodo convencional apos tratamentos termomecanicos visando estruturas microcristalinas." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11775.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Moura, Altair Soares de. "Influência de diferentes protocolos de tratamento da dentina de raízes fragilizadas sobre a resistência de união de pinos fibrorreforçados: avaliação por meio de microscopia confocal, push-out e microdureza." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-17032015-111245/.
Full textThe present study aimed to evaluate, in vitro, the influence of different treatment protocols of weakened root dentin on the bond strength (BS) of glass fiber reinforced post luted with different resin cements. Forty two upper human canines were sectioned and the root length was standardized on 17-mm after coronary portion was removed. Biomechanical preparation was performed via Reciproc system with R 50.05 instrument and 2.5% NaOCl. The roots were flared using diamond bur #4137 and #720G at a depth of 12mm and filled by the lateral condensation technique with AH Plus sealer modified with 0.1% Rhodamine B. After 3 times the time required to the setting reaction of the sealer the filling was removed and the glass fiber post was relined with composite resin. The roots were divided into 3 groups (n = 14) according to the treatment of dentin surface: 2.5%NaOCl; 2.5%NaOCl + 17% EDTAand 2.5% NaOCl+ 17% EDTA+ ultrasound. Half of the samples of each group had the post luted with RelyX U200 and the other half with Panavia F. Both cements were added with 0.1% fluorescein. The roots were transversely sectioned obtaining two slices of each third, one for the push-out test and the other for the confocal analysis and measurement of knoop hardness. Data were submitted to ANOVA test with sub-divided portion followed by Tukey test (α= 0.05). The highest BS values were observed for 2.5% NaOCl + 17% EDTA and 2.5%NaOCl + 17% EDTA + ultrasound (p> 0.01) compared to 2.5%NaOClalone (p <0.0001). Panavia F showed higher BS than RelyX U200 in specimens treated with 2.5%NaOCl + 17% EDTA and 2.5% NaOCl + 17% EDTA + ultrasound (p <0.0001) in the three root thirds. There was no difference between the luting materials in specimens treated only with 2.5% NaOCl(p> 0.01). The protocols did not affect the BS of RelyX U200. Overall the higher incidence of failure was adhesive (38.83%) followed by mixed (34.72%) and cohesive (26.45%) failure. Dentin treatment with 2.5%NaOCl+ 17% EDTA + ultrasound promoted the greatest reduction in microhardness. It was concluded that the Panavia F presented the highest BS in the three root thirds and the protocols did not influence the BS of the specimens filled with RelyX U200
Gabriel, Aline Evangelista de Souza. "Progressão da lesão de cárie no esmalte dental após aplicação de compostos fluoretados e irradiação com laser de CO2." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-19032010-093036/.
Full textThis thesis was divided into 2 studies whose specific objectives were: 1) To compare the ability of CO2 laser and fluoride sources to inhibit caries-like lesions in human enamel and to test whether a similar pattern of response would hold for bovine enamel. 2) Evaluate in situ the progression of caries lesions in bovine enamel and to verify the amount of fluoride present in biofilm and enamel after treatment with fluoride varnish combined with CO2 laser. In the first study, 96 enamel slabs (48 from bovine and 48 from human teeth) were randomly distributed into 4 groups (n=12): CO2 - CO2 laser, FV - 5% fluoride varnish, APF - 1.23% acidulated phosphate fluoride gel, or WT - without treatment (control). Specimens were subjected to a 14-day in vitro cariogenic challenge. Microhardness (SMH) was measured at 30 µm from the surface. Additional 20 slabs of each substrate (n=5) received the same treatment described above and were analyzed by scanning electron microscopy (SEM). In the in situ study (crossover and performed in 2 phases of 14 days each), 14 (n = 14) wore palatal appliance with bovine enamel blocks that were previously submitted to one of the 4 treatments: FV + CO2 - 5% fluoride varnish + CO2 laser, FV - fluoride varnish, PV - placebo varnish without fluoride, PV + CO2 - placebo varnish + CO2 laser. Dental biofilm was allowed to accumulate on the blocks and 6 times a day a drop of sacarose solution was dispensed into emamel blocks by volunteers, simulating a cariogenic challenge. After each phase, the blocks were removed to evaluate enamel demineralization (microhardness test) and concentration of fluoride in biofilm and enamel after cariogenic challenge. Microhardness was evaluated by ANOVA and Tukey test, and the amount of fluoride present in biofilm and enamel were analysed by non-parametric Friedman test (α = 5%). CO2 laser promoted the least mineral loss. Treatment with FV resulted in the second highest values, which was followed by APF. Untreated specimens performed the worst (p < 0,05), in summary: CO2 > FV > APF > WT. Bovine teeth presents higher values of microhardness than human, although the performance of both substrates were the same. SEM showed a granulate precipitate on FV group and fusion ang fissures on lased-specimens. In in situ study, regardless of the application of fluoride or placebo varnish, the microhardness of enamel was statistically superior (p < 0.05) when the substrate was irradiated with CO2 laser. When the varnishes application were not followed by the irradiation of CO2 laser, no significant statistical diference were observed in the bovine enamel (p > 0.05). When analyzing the dental biofilme, it was observed that the group treated with VF presented larger amount of fluoride, statistically different from the other groups (p < 0.05), which were statistically similar among themselves (p > 0.05). In the enamel, the largest amount of fluoride was found in the FV + CO2 group (p < 0.05), which was not statistically different from FV (p > 0.05). It was concluded that: 1) CO2 laser may control caries progression more efficiently than fluoride sources and bovine teeth may be a suitable substitute for human teeth in studies of this nature; 2) CO2 laser promoted larger inhibition of the caries progression, in in situ model, independently of the application of fluoride or placebo varnish. The use of fluoride varnish fluoretado resulted in larger amount of fluoride in dental biofilme, while, the association of fluoride varnish and CO2 laser provided larger fluoride uptake in the enamel.
Левіцький, Анатолій Миколайович. "Структура та властивості сплавів систем Nb-Si-B, Nb-Si-Cr, Nb-Si-Ti, Nb-Si-Mo для високотемпературних застосувань." Master's thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/31364.
Full textThe object of study: the alloys of the system Nb-Si-(B, Cr, Mo, Ti) at. %: Nb-25Si-13B, Nb-Si-25Cr, Nb-6Si-30Cr, Nb-6Si-35Cr, Nb-20Si-2Mo, Nb-20Si-4Mo, Nb-20Si-6Mo, Nb-20Si-22Ti, Nb-20Si-24Ti obtained by electron beam sintering. The purpose of the work is to study the structure and properties of alloys of the Nb-Si-(B, Cr, Mo, Ti) system obtained by electron beam sintering. Research methods and equipment: the alloys of system Nb-Si-(B, Cr, Mo, Ti) were obtained by ELA-6. The micro- and macrostructure, the chemical composition of the phase components of the resulting Nb-Si-(B, Cr, Mo, Ti) alloys, was studied using a set of highly informative methods of physical material science (electron microscopy, chemical analysis). It was measured is microhardness and crack resistance.
Объект исследования: сплавы систем Nb-Si-(B, Cr, Mo, Ti) ат. %: Nb-25Si-13B, Nb-Si-25Cr, Nb-6Si-30Cr, Nb-6Si-35Cr, Nb-20Si-2Mo, Nb-20Si-4Mo, Nb-20Si-6Mo, Nb-20Si-22Ti, Nb- 20Si-24Ti, полученные электронно-лучевым оплавлением. Целью работы является изучение структуры и свойств эвтектических сплавов систем Nb-Si-(B, Cr, Mo, Ti), полученных электронно-лучевым оплавлением. Методы исследования и аппаратура: получение сплавов систем Nb-Si-(B, Cr, Mo, Ti) осуществлялось в установке Эла-6. С помощью комплекса высокоинформативных методов физического материаловедения (электронной микроскопии, микрорентгеноспектрального анализа) исследованы микро- и макроструктура, химический состав фазовых составляющих сплавов систем Nb-Si-(B, Cr, Mo, Ti). Также измерена микротвердость и трещиностойкость на Микротвердомере ПМТ-3.