995 resultados para Fatica confronto fresatura elettroerosione EDM acciaio titanio


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pós-graduação em Engenharia Mecânica - FEG

Relevância:

10.00% 10.00%

Publicador:

Resumo:

O sucesso das restaurações metálicas indiretas depende, dentre outros fatores, de uma união eficaz entre a estrutura metálica e o cimento dentário empregados. Sabe-se que os primers para metal atuam com comprovada eficácia na resistência adesiva dos cimentos resinosos às ligas nobres. Entretanto, pouco foi estudado sobre o efeito de tais materiais em ligas não nobres. O propósito deste estudo foi avaliar a eficácia de primers para metal na resistência ao cisalhamento da união entre cimentos resinosos e metais não nobres. Discos (9 mm de diâmetro e 3 mm de altura) foram fundidos em liga de NiCr (n=80) e em titânio comercialmente puro (Ti c.p.) (n=80) e foram incluídos em anel de PVC com resina acrílica quimicamente ativada. As superfícies dos discos foram regularizadas com lixas de carbeto de silício de granulação 320, 400 e 600 e jateadas com partículas de óxido de alumínio de 50 µm. Espécimes de cada metal foram divididos em quatro grupos (n=20). Uma matriz metálica bi-partida (5 mm de diâmetro interno e 2 mm de altura) foi posicionada na superfície do espécime. As áreas adesivas receberam um dos seguintes tratamentos: 1) Panavia F; 2) Alloy Primer e Panavia F; 3) Bistite DC e 4) Metaltite e Bistite DC. Para evitar a exposição dos cimentos à luz, estes foram espatulados e inseridos na matriz dentro de uma câmara de revelação radiográfica. Quarenta minutos após a confecção, os espécimes foram armazenados em água destilada a 37ºC por 24 horas e então termociclados (1.000 ciclos, 5ºC e 55ºC, 30 segundos cada banho). Após a termociclagem, os espécimes foram armazenados novamente nas mesmas condições descritas anteriormente por um período de 24 horas (n=10) ou de 6 meses (n=10) antes do ensaio de cisalhamento em uma máquina de ensaios mecânicos (Material Test System 810).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Atualmente o titânio é empregado como biomaterial devido à sua biocompatibilidade e resistência à corrosão. Entretanto, íons fluoretos, freqüentemente empregados em dentifrícios bucais, podem interferir no processo de corrosão. O objetivo deste estudo foi analisar a influência de um meio fluoretado com diferentes pH nas propriedades mecânicas e na resistência à corrosão dos conjuntos implantes/componentes protéticos à base de Ti c.p., a partir dos testes de fadiga, microscopia eletrônica de varredura (MEV) e dureza. Foram simulados cinco anos de uso regular de meios de higiene oral com conteúdo de 1500 ppm de NaF, com dois diferentes pH, 7,4 e 5,3, mediante imersão das amostras nesses meios durante 184 horas e também em água destilada, grupo controle. As amostras foram testadas num durômetro Micromet 2001 (500gf/30s). Os dados dos testes de dureza foram analisados pelo teste de Wilcoxon, demonstrando que as amostras sofreram influência negativa na dureza após a ação dos íons fluoreto. Entretanto, essa influência não ocorreu nos testes de fadiga realizados em uma máquina de ensaios mecânicos MTS-810, fixada a 100.000 ciclos, 15Hz e programada com força de fadiga a 150 N. Pela análise de MEV foram constatadas evidências de corrosão na superfície das amostras após ação de íons fluoretos, entretanto pelo EDS não se verificou incorporação de íons fluoretos sobre a superfície dos conjuntos. Concluiu-se que a concentração de flúor e o pH das soluções não exerceram influência nas propriedades mecânicas.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This paper proposes a reflection on processes of variation and change that occurred with the portuguese prepositions a, ate, em and para, taken as a parameter for answers in a broader context, the confrontation between the norm and use and between standard and linguistic variation. We conducted the study based on a corpus composed of all occurrences of the prepositions in question removed news of the newspaper O Combate and O Estado de Sao Paulo. Whereas the main objective of the study is to present and describe the use of these particles in newspaper articles of the Imprensa Paulista, data were collected and quantified by using the statistical package GOLDVARB, and interpretation of results relied (i) assumptions regarding the process variation in the use of prepositions and prepositions replace weak, as the preposition to, for strong prepositions (para, em, até), (ii) in comparison with the grammatical rule in effect at the time, (iii) and in the search for the existence of some historical factor that justifies the selection of a preposition rather than another. Among the hypotheses, we investigate the relationship between these prepositions and whose kind of preachers they introduce supplements: the direction of motion (abstract or concrete) or transfer (material and verbal / perceptual). This theoretical perspective was the Labovian sociolinguistics (Labov, 1972, 1994), which defines the linguistic variable as a representation of two or more different ways to convey a certain information content, being necessary to define it the following criteria set exact number of variants to establish all the multiplicity of contexts in which it appears; develop a quantitative index for measuring the values of variables

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This research attempts to analyze the relationship between the National Secondary Education Examination and the design of teaching, specifically in the way of defining what should be taught, in the present National Curriculum identifying clues that help us in the explanation of a conception of teaching and making the confrontation between the evaluation device in this ENEM. We intend to identify, even if there is consistency between what is taught and what is learned in schools, whether it public or private, and it evaluates the evidence as ENEM. This work is part of the Bachelor's Degree in Education Full theme is a critical analysis of the evaluation system ENEM regarding their school pedagogical practices. The overall goal is to bring to light the evaluative perspective envisaged in secondary education as a training practice, regarding the evaluation method levied by the National Examination of Secondary Education, seeking to raise the following reflection: The evaluation addressed in high school according to the National Curriculum meets view of the National Middle School? To answer this question, the work specified in a field research through analysis of evidence applied to the Portuguese Language School students in two schools, one in public and one private school, both in the city of Rio Claro, São Paulo, the analysis on the Matrix Reference ENEM in order to show whether the school pedagogical practice meets the demand of this evaluation system. Methodology as part of the job search literature, taking for himself the main theoretical assessment as Luckesi (2005), Hoffman (1996) Saviani (1986) and Curriculum Proposal of the State of São Paulo

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Titanium and its alloys have been used for biomedical applications due their excellent properties such as high corrosion resistance, biocompatibility and mechanical properites. In this study, microstructural and mechanical properties of Ti-30Ta alloy was evaluated during its processing. Ti-30Ta alloy ingots were produced from sheets of commercially pure titanium (99.9%) and tantalum (99.9%). Its melting was realized in arc melting furnace in an argon atmosphere. After homogenizing at 1200ºC, ingots were cold worked by swaging. Samples with 13 mm in diameter were obtained. They were forging at the reduction ratios of 15%. After deformation, microstructure was evaluated by optical microscopy in each condition. Also, Vickers microhardness of samples was measured and phase constitution was evaluated using XRD analysis

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The research aims to analyze the main changes in the concepts of the processes of production and consumption of news content information. The theoretical framework used will be the new consequent social, economic and technological paradigms of the current scenario of convergence of platforms, content and languages. The research aims to investigate the changes in the macro environment of journalistic production and, therefore, examine whether the local flow of news content meets the requirements of a new public consumption target set by the new Brazilian generations, composed of young people influenced by the cultures of computing, audiovisual communication and also by economic and cultural globalization. As expansion of the analyzes sought to verify the impact of these changes in the current models of traditional media, as well as the interference caused and trends in models of existing production. Also a case study is performed on this production flow in comparison with current market research of Jornal da Cidade (JC) of the city of Bauru (SP), the main media of the Grupo Comunicação. The intent of the approach will be to establish some preambles to assist in bringing the theory with the practical impacts on journalistic production, its agents, institutions and the workplace

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Disputas agressivas são comuns em peixes ciclídeos, tanto em indivíduos juvenis quanto adultos. Quando os indivíduos estão maduros sexualmente o efeito do gênero na resolução e perfil dos confrontos é mais claro. Em geral, os indivíduos machos são mais agressivos que as fêmeas e defendem agressivamente territórios reprodutivos e outros recursos. Contudo, o efeito desta variável não é bem conhecido em confrontos entre indivíduos juvenis em peixes. Assim, neste estudo foi testado o efeito do gênero na expressão do comportamento agressivo da tilápia-do-Nilo, Oreochromis niloticus, uma espécie de peixe comumente utilizado como modelo para o estudo do comportamento agressivo. Analisamos em pares de tilápia a latência para início do confronto, a frequência de interações agressivas e a duração da disputa e probabilidade de ser dominante. Após o pareamento, o sexo de cada indivíduo foi verificado histologicamente e comparamos os valores obtidos para pares de fêmea vs fêmea, macho vs macho e fêmea vs macho. Apenas em confrontos macho vs macho, a frequência de exibições frontais foi maior em relação aos pares monosexo de fêmeas. Concluímos que o gênero influencia muito discretamente as disputas agressivas em juvenis de tilápia-do-Nilo e não afeta a probabilidade de se tornar dominante em um par

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The objective of the present work was to evaluate surface of experimental alloy Ti-7.5Mo after hydrothermal treatment. Ingots were obtained in arc melting furnace under an argon atmosphere and then homogenized under vacuum at 1100ºC for 86.4 ks to eliminate chemical segregation and after cold worked discs were cutting and grinding. For surface treatment, samples were immersed in a container with NaOH aqueous solution 5M, autoclaved, washed with distilled water. Followed, samples were heat treated and they were soaking in 5xSBF to form an apatite layer on the surface. Surfaces were investigated by, scanning electron microscopy, X-Rays powder diffraction, atomic force microscopy and contact angle, in order to evaluate the wettability of the alloy surface. The results were compared with our previous studies using the group of chemical surface treatments and results shows better condition is 120 minutes in the autoclave

Relevância:

10.00% 10.00%

Publicador:

Resumo:

O enriquecimento ambiental tem sido proposto como uma prática para melhoria do bem-estar de animais de cativeiro ou de produções zootécnicas. No caso de animais territoriais e agressivos, ao se enriquecer o ambiente, aumenta-se a quantidade de recursos a se defender, bem como o valor do território em disputa, aumentando as interações agressivas. Esse aspecto foi mostrado recentemente para o peixe ciclídeo tilápia-do-Nilo (Oreochromis niloticus). Do ponto de vista comparativo, isso pode ser um fenômeno espécie-específico. Para avaliar isso devemos observar se em condições similares outro peixe ciclídeo sofre a mesma influência do enriquecimento do ambiente. Assim, seguindo a lógica do confronto obtido para tilápia-do-Nilo, aventamos a hipótese de que as atividades agressivas aumentam em função do enriquecimento. Este estudo avaliou essa hipótese para a tilápia do Congo Tilapia rendalli. Como principal resultado, observamos que a latência para iniciar a luta é menor no ambiente enriquecido, mas a frequência de ataques é maior no ambiente não enriquecido (controle). Além disso, observamos clara definição hierárquica por meio da sinalização de submissão (corpo com listras escuras) e dominância (corpo claro sem listras) na condição sem enriquecimento do ambiente. Concluímos que ao contrário da tilápia-do-Nilo, na tilápia do Congo o enriquecimento do ambiente leva a diminuição da agressividade sem clara definição da hierarquia de dominância

Relevância:

10.00% 10.00%

Publicador:

Resumo:

As they have excellent mechanical properties, corrosion resistance and biocompatibility, much research has been conducted with respect to biomedical applications of titanium alloys. This work aims to study the experimental system binary alloy Ti-15Mo, in the raw state of fusion and heat treatment after homogenization, solubilization and calcination (simulating conditions employed for nanotube growth) targeting biomedical applications. Samples were obtained by casting the components in an electric arc furnace with inert atmosphere of argon. After obtaining the alloy, it was heat treated at three different heat treatments, namely homogenizing, calcining and simulation solubilization. The phases present were analyzed by X-ray diffraction, optical microscopy and microhardness testing

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study aims to conduct a comparative analysis of the cover stories of magazines Atrevida, published by Escala, Capricho, published by Abril, and Todateen, published by AltoAstral, published between 2008 and 2012, which give prominence to the phenomena with more recurring presence on the covers. The objective of the research is to analyze the criteria for newsworthiness adopted by publications targeting a teenage audience, relating them to cover highlights involving idols of that audience. As object, we study the press coverage given to four magazines phenomena of cultural industry: the actors in the Twilight saga, the actors of the Disney Channel series, singer Justin Bieber and actors of Brazilian soap opera Rebelde. The work begins with a history of magazine journalism, from its origin to the journalism geared toward teenage readers, through the history of women's magazines and variety. Then, we present the theoretical concepts from the Theory News (Traquina) in confrontation with the notions of consumption (Canclini) and behavior (Featherstone). Finally, analysis of the corpus, which was defined by a cutout thematic within this period, divided into two major groups of news reports: those in which the idol is the news, and those in which he serves as a guide for the reader

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Titanium and its alloys has been widely used as materials for metallic biomaterials implants are usually employed to restore the hard tissue function, being used for artificial joints and bones, synthetic plates, crowns, dental implants and screws . Objective of this work was the surface modification of Ti-alloy 25Ta from biomimetic surface treatment of employment and deposition of polymer by electrospinning. The league was obtained from the fusion of the pure elements in the arc furnace with controlled atmosphere. The ingots were subjected to heat treatment, cold forged and sectioned discs with 13 mm diameter and 3 mm thick. Two surface treatments was evaluated, biomimetic and electrospinning with PCL fiber. The biomimetic treatment was performed involving alkaline treatment for three molarities 1.5M, 3M and 5M with immersion in SBF. The electrospinning was performed using PCL polymer alloy surface after the alkali treatment Ti25Ta 1M. For this group the polymer coated surfaces were immersed in calcium phosphate containing solution for immobilization of apatite. The results were compared with previous studies using surface treatment group to verify hydroxyapatite formation on the sample surface and it is concluded that the best condition is biomimetic treatment with 5M alkali treatment and heat treatment at 80 ° C for 72 hours

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Several alloys present the shape memory effect and among them, the equiatomic NiTi alloy, nitinol, is the most important one. It is usually used in several engineering applications and also in biomedical devices, in the fabrication of orthodontic wire, stents and Judet staples. Although a considerable amount of these biomedical devices is utilized in Brazil and a fraction of it is already made here, all nitinol used is bought abroad. Thus, it is important to develop the necessary know-how to fabricate NiTi wire and sheet. It would mean less importation with job creation and wealth generation for the country. In this work nitinol was obtained powder metallurgy from elemental powders of Ti and Ni using uniaxial compression and uniaxial compression followed by isostatic compression. The final densities achieved were determined by the Archimedes method. The precipitation of intermetallic secondary phases was studied and the samples were characterized by metallographic analysis, optical microscopy and X-ray diffraction. Results indicated that 50 hours sintering route showed a low amount of intermetallics, and no trace of unreacted powder. XRD and metallography at room temperature indicated B19’ as the predominant phase, which corresponds to martensite. Although density results showed little dispersion, the most dense sample was compacted under uniaxial compression and presented 4.8 g/cm3, corresponding to 20.84% porosity. Density variation was considered normal to the measurement process and independent of the compaction mode