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Previous issue date: 2010-04-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Present work proposed to map and features the wear mechanisms of structural polymers of engineering derived of the sliding contact with a metallic cylindrical spindle submitted to
eccentricity due to fluctuations in it is mass and geometric centers. For this it was projected and makes an experimental apparatus from balancing machine where the cylindrical
counterbody was supported in two bearings and the polymeric coupon was situated in a holder with freedom of displacement along counterbody. Thus, the experimental tests were
standardized using two position of the two bearings (Fixed or Free) and seven different positions along the counterbody, that permit print different conditions to the stiffness from
system. Others parameters as applied normal load, sliding velocity and distance were fixed. In this investigation it was used as coupon two structural polymers of wide quotidian use, PTFE (polytetrafluroethylene) and PEEK (poly-ether-ether-ketone) and the AISI 4140 alloy steel as counterbody. Polymeric materials were characterized by thermal analysis (thermogravimetric, differential scanning calorimetry and dynamic-mechanical), hardness and rays-X diffractometry. While the metallic material was submitted at hardness, mechanical resistance tests and metallographic analysis. During the tribological tests were recorded the heating response with thermometers, yonder overall velocity vibration (VGV) and the acceleration using accelerometers. After tests the wear surface of the coupons were analyzed using a Scanning Electronic Microscopy (SEM) to morphological analysis and spectroscopy EDS to microanalysis. Moreover the roughness of the counterbody was characterized before and after the tribological tests. It was observed that the tribological response of the polymers were different in function of their distinct molecular structure. It were identified the predominant wear mechanisms in each polymer. The VGV of the PTFE was smaller than PEEK, in the condition of minimum stiffness, in function of the higher loss coefficient of that polymer. Wear rate of the PTFE was more of a magnitude order higher than PEEK. With the results was possible developed a correlation between the wear rate and parameter (E/ρ)1/2 (Young modulus, E, density, ρ), proportional at longitudinal elastic wave velocity in the material. / O presente trabalho prop?s-se a mapear e caracterizar os mecanismos de desgaste de pol?meros estruturais de engenharia oriundos do contato de deslizamento com um eixo-?rvore cil?ndrico rotativo met?lico submetido a excentricidades decorrentes de flutua??es em seu centro de massa e centro geom?trico. Para isso projetou-se e confeccionou-se uma bancada experimental a partir de uma m?quina balanceadora, onde o contracorpo cil?ndrico era apoiado em dois mancais e o corpo-de-prova polim?rico era posicionado em um portaamostra
com liberdade de deslocamento ao longo do contracorpo. Desta forma, os ensaios experimentais foram parametrizados utilizando duas posi??es dos mancais (Fixos ou livres) e sete posi??es distintas ao longo do contracorpo, o que permitiu imprimir condi??es diferentes para a rigidez do sistema. Demais par?metros como carga normal aplicada, velocidade e dist?ncia de deslizamento foram mantidas constantes. Nesta investiga??o utilizou-se como corpos-de-prova dois pol?meros estruturais de engenharia de largo uso cotidiano, PTFE (politetrafluoretileno) e PEEK (poli-?ter-?ter-cetona) e o a?o liga AISI 4140 comocontracorpo. Caracterizou-se os materiais polim?ricos atrav?s de an?lises t?rmicas (termogravim?trica, calorimetria explorat?ria diferencial e din?mico-mec?nica), dureza e
difra??o de raios-X. J? o met?lico foi submetido a ensaios de dureza, resist?ncia mec?nica e an?lise metalogr?fica. Durante os ensaios tribol?gicos eram coletadas as respostas de
aquecimento com o aux?lio de termopares, al?m da velocidade global de vibra??o (VGV) e a acelera??o utilizando aceler?metros. Ap?s os ensaios, as superf?cies de desgaste dos corposde- prova foram analisadas utilizando um Microsc?pio Eletr?nico de Varredura (MEV) para an?lise morfol?gica e espectroscopia EDS para microan?lise, juntamente com a rugosidade do contracorpo, caracterizada antes e ap?s os ensaios tribol?gicos. Observou-se que as respostas
tribol?gicas dos pol?meros foram diferentes e que eram fun??o de suas estruturas moleculares e capacidades de amortecimento distintas. Foram identificados mecanismos de desgaste predominantes em cada pol?mero. A VGV do PTFE foi menor que a do PEEK, na condi??o de m?nima rigidez e atribu?do ao maior coeficiente de perda daquele pol?mero. A taxa de
desgaste do PTFE foi mais de uma ordem de grandeza maior que a do PEEK. Os resultados permitiram desenvolver uma correla??o entre a taxa de desgaste e o par?metro (E/ρ)1/2
(m?dulo de elasticidade, E, massa espec?fica, ρ), proporcional ? velocidade de propaga??o de uma onda el?stica longitudinal no material.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15565 |
| Date | 29 April 2010 |
| Creators | Silva, Ruthilene Catarina Lima da |
| Contributors | CPF:10973370491, http://lattes.cnpq.br/3206952338356447, Silva, Jo?o Bosco da, CPF:13163191487, http://lattes.cnpq.br/3305848313356239, Lima, Severino Jackson Guedes de, CPF:09445110404, http://lattes.cnpq.br/1045652409149134, Matamoros, Efrain Panteleon, CPF:21896458831, Barbosa, Cleiton Rubens Formiga, CPF:22174443449, http://lattes.cnpq.br/8673332414572221, Medeiros, Jo?o Tel?sforo N?brega de |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Mec?nica, UFRN, BR, Tecnologia de Materiais; Projetos Mec?nicos; Termoci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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