Mémoire (M.Sc.T.)-- Université du Québec à Chicoutimi, 1991. / Bibliogr.: f. 61-65. Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Eng.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--The University of Michigan, 1986. / Also issued in print.

Mémoire (M.Ing.)--Université du Québec à Chicoutimi, 2000. / Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--The University of Michigan, 1986. / eContent provider-neutral record in process. Description based on print version record.

Thesis (M.S.)--University of Alabama at Birmingham, 2009. / Title from PDF title page (viewed on Sept. 3, 2009). Includes bibliographical references.

Thesis (M.S.D.)--Indiana University School of Dentistry, 2010 / Title from PDF t. p. (viewed May 12, 2010) Advisor(s): Michael A. Cochran, Chair of the Research Committee, Jeffrey A. Platt, Bruce A. Matis, Carlos Gonzalez-Cabezas, Sopanis D. Cho. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 64-69).

Made available in DSpace on 2014-06-11T19:28:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-10-31Bitstream added on 2014-06-13T19:37:33Z : No. of bitstreams: 1 rocha_ss_me_arafo.pdf: 674518 bytes, checksum: 9888e8462ea32b3c607f867bc951afd1 (MD5) / O objetivo desta investigação foi determinar se os tratamentos térmicos podem alterar a resistência à tração e a dureza Vickers do Ti c.p. e da liga Ti-6Al-4V. Trinta corpos-de-prova na forma de halteres com 3,0 mm no segmento central e 42 mm de comprimento, obtidos por meio de uma matriz de alumínio, foram fundidos no sistema Rematitan. Os corpos-de-prova de Ti c.p. e Ti-6Al-4V foram divididos aleatoriamente em três grupos de 10 cada, e submetidos às seguintes condições de tratamento térmico: (1) controle; (2) T1 - aquecimento a 750ºC/2 h; (3) T2 - recozimento a 955ºC/1 h e envelhecimento a 620ºC/2 h. Ambos, aquecimento e resfriamento, foram realizados em atmosfera controlada de argônio. O ensaio de tração foi efetivado na máquina de testes mecânicos MTS modelo 810 à velocidade de 1,0 mm/min. Após o teste de tração uma das extremidades do corpo-de-prova foi embutida em resina acrílica, regularizada e polida antes da medida da dureza Vickers no durômetro Micromet 2100. As médias de resistência à tração e dureza Vickers foram comparadas estatisticamente usando o teste não-paramétrico de Kluskall-Wallis. Nos grupos de Ti c.p. não foram observadas diferenças significativas na resistência à tração, entretanto, na dureza Vickers os resultados do grupo T2 foram significativamente maiores que os outros grupos, que se mostraram iguais entre si. Na liga Ti-6Al-4V os grupos controle e T1 revelaram igualdade estatística em relação à resistência à tração, e significativamente superiores ao grupo T2. Quanto à dureza Vickers, diferenças estatisticamente significantes foram observadas entre os três grupos de tratamento térmico: T2>T1>controle. Não foi observada correlação entre as propriedades de resistência à tração e dureza Vickers.... / The aim of this investigation was to determine whether heat treatments could change the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy castings. Thirty dumbbell rods, 3.0 mm in diameter at the central segment and 42 mm in length, obtained from an aluminum matrix, were cast for each metal in the Rematitan system. The specimens of CP Ti and of alloy Ti-6Al-4V, were divided randomly into three groups of ten each; then submitted to the following heat treatments: (1) control group, without heat treatment; (2) T2 - heat at 750ºC for 2 h; (3) annealing at 955ºC for 1 h and aged at 620ºC for 2 h. The heat treatments, as well as the cooling process were conducted in the furnace with argon atmosphere. The tensile strength was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile testing the specimens were embedded in acrylic resin, grounded and polished prior to hardness measurements, using the Vickers tester Micromet 2100. The means and standard deviations of tensile strength and Vickers hardness were statistically compared using Kruskal-Wallis non-parametric test at a=0.05 significance level. In CP Ti groups, no statistically significant differences in tensile strength were observed; however, in Vickers hardness the results of group T2 were significantly higher than the other groups, which showed similar mean values among themselves. In Ti-6Al-4V alloy, the control and T1 groups revealed statistically higher tensile strength when compared to T2 group, with no significant difference between control and T1 group. Regarding Vickers hardness, statistically significant differences were observed among the three heat-treatment groups: T2>T1>control...(Complete abstract, click electronic access below)

Made available in DSpace on 2014-06-11T19:28:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-13Bitstream added on 2014-06-13T20:58:46Z : No. of bitstreams: 1 schalch_mv_me_arafo.pdf: 500459 bytes, checksum: bbb8a40c8cbaedcfd8d25a115259987e (MD5) / O objetivo deste estudo foi comparar a resistência à flexão, a resistência à tração diametral e a dureza do material de infra-estrutura dos sistemas cerâmicos IPS-Empress 2/Ivoclar (dissilicato de lítio, processado por injeção) e In-Ceram Zirconia/Vita (óxidos de alumínio e zircônio, processados por dupla sinterização). Foram confeccionadas dez amostras de cada material para o ensaio de flexão (em forma de barra, 25mm de comprimento, 5mm de largura, 2mm de espessura - ISO 6872) e 15 amostras para o ensaio de tração diametral (em forma de disco, 6mm de diâmetro, 3mm de espessura). Os testes foram realizados em equipamento MTS 810 (Material Test System - EUA), com célula de carga de 10kN e velocidade de 0,5mm/minuto, gerenciado por programa Test Star II (IBM, EUA). Para o ensaio de dureza, na escala Vickers, cinco fragmentos de cada cerâmica foram incluídos em resina acrílica autopolimerizável JET (Artigos Odontológicos Clássico, Brasil), polidos e submetidos ao teste no durômetro Buheler (EUA), com carga de 1,0kgf por 30 segundos. Os resultados mostraram maior resistência à flexão do material In-Ceram Zirconia (439,88MPa) em relação ao IPS-Empress 2 (226,13MPa). Entretanto, observou-se maior resistência à tração diametral do IPS-Empress 2 (175,08MPa) em relação ao In-Ceram Zirconia (150,47MPa). Para a dureza Vickers, o material In-Ceram Zirconia (972,0VHN) mostrou-se superior em relação ao IPS-Empress 2 (488,33VHN). / The aim of this study was to compare flexural strength, diametral tensile strength and hardness of infra-structure ceramic systems IPS-Empress 2/Ivoclar (litium dissilicate, heat-pressed) and In-Ceram Zirconia/Vita (aluminum and zirconium oxides, Slip casting). Ten especimens were made for flexural test (25mm length; 5mm width; 2mm thick - ISO 6872), and 15 especimens for diametral test (6mm diameter; 3mm thick). The tests were done in a MTS 810 machine (Material Test System - USA), with load cell of 10kN and crosshead-speed of 0.5mm/minute, managed by Test Star II software (IBM, USA). Five samples of each ceramic were included in autocured resin JET (Artigos odontológicos Clássico, Brazil), polished and submitted to Vickers hardness test in duromer Buheler (USA), with load of 1.0kgf for 30 seconds. In flexural test, In-Ceram Zirconia (439.88MPa) showed greater strength than IPS-Empress 2 (226.13MPa). However, the IPS-Empress 2 (175.08MPa) showed greater diametral strength than In-Ceram Zirconia (150.47MPa). For hardness, the In-Ceram Zirconia (972.0VHN) showed greater than IPS-Empress 2 (488.33VHN).

Compared with most construction materials, concrete is considered as a brittle material, and its brittleness increases with the compressive strength. For super-high-strength concrete, failure can be sudden, explosive and disastrous. Also the tensile strength is not proportionally increased. Therefore, it is necessary to carry out research on the brittleness of concrete in order to establish parameters for assessing the brittleness, find ways to improve the brittleness and tensile strength, and eventually design and manufacture concrete materials with high strength and low brittleness. In this study, strengthening and toughening effects of polymer materials on the high performance concrete (HPC) were investigated. The HPC was manufactured using ordinary Class 52.5 N Portland cement, silica fume and superplasticizer. The adopted polymers included the styrene-butadiene-rubber (SBR) latex, polyvinylidene chloride (PVDC), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) with contents of 1.5%, 3% and 5% in weight of cement content. The measured material and fracture properties included compressive and tensile strengths, modulus of rupture, Young's modulus, fracture energy, fracture toughness and brittleness. The test results at 28 days indicate that the addition of 1.5% and 3% SBR, PVDC, LLDPE and HDPE into the HPC could largely improve the compressive strength by up to 15.7%, while the addition of 5% SBR, LLDPE and HDPE did not show any enhancement except for 5% PVDC which increased the compressive strength by 10.9%. The tensile strength was considerably increased for all dosages of polymers, with the maximum increases of 72.7% and 83.2% for 3% SBR and 1.5% LLDPE, respectively. The fracture energy were also enhanced by adding 1.5% SBR and all dosages of LLDPE, with a maximum increase of 24.3%, while there were no indications of enhancement for other dosages of polymers. The modulus of rupture, fracture toughness and Young's modulus were not improved for lower dosages of polymers but slightly decreased for higher dosages. The brittleness decreased monotonically with increasing amount of LLDPE, but it increased with increasing amounts of SBR, PVDC and HDPE.