Made available in DSpace on 2014-12-17T14:58:12Z (GMT). No. of bitstreams: 1 RuthileneCLS_ate_pag60.pdf: 1874994 bytes, checksum: 2732ad431aa2941e3dd9f4abbe75c29d (MD5) Previous issue date: 2006-02-13 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Wear mechanisms and thermal history of two non-conforming sliding surfaces was investigated in laboratory. A micro-abrasion testing setup was used but the traditional rotative sphere method was substituted by a cylindrical surface of revolution which included seven sharp angles varying between 15o to 180o. The micro-abrasion tests lead to the investigation on the polyurethane response at different contact pressures. For these turned counterfaces with and without heat treatment. Normal load and sliding speeds were changed. The sliding distance was fixed at 5 km in each test. The room and contact temperatures were measured during the tests. The polyurethane was characterized using tensile testing, hardness Shore A measurement, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Thermomechanical Analyze (TMA). The Vickers micro-hardness of the steel was measured before and after the heat treatment and the metallographic characterization was also carried out. Worn surface of polyurethane was analysed using Scanning Electron Microscope (SEM) and EDS (Electron Diffraction Scanning) microanalyses. Single pass scratch testing in polyurethane using indenters with different contact angles was also carried out. The scar morphology of the wear, the wear mechanism and the thermal response were analyzed in order to correlate the conditions imposed by the pressure-velocity pair to the materials in contact. Eight different wear mechanisms were identified on the polyurethane surface. It was found correlation between the temperature variation and the wear scar morphology. / Os mecanismos de desgaste e a historia t?rmica de duas superf?cies n?o-conformes foram investigados em laborat?rio. Um equipamento de ensaios de microabras?o foi usado, mas a configura??o tradicional com esfera rotativa foi substitu?da por uma com superf?cie cil?ndrica de revolu??o, na qual a geratriz incluiu sete formas com ?ngulos variando de 15o a 180o. Os ensaios de microabras?o foram conduzidos investigando-se a resposta do pol?mero a diferentes press?es de contato. Para isso, projetaram-se e foram torneados corpos antagonistas, tratados termicamente, ou n?o, lixados, ou n?o. Variou-se a carga normal e a velocidade de deslizamento. A dist?ncia de deslizamento foi fixada em 5 km ininterruptos em cada ensaio. As temperaturas de contato e ambiente foram medidas e registradas durante os ensaios. O poliuretano estudado foi caracterizado atrav?s de ensaios de tra??o, medidas de dureza Shore A, An?lise Termogravim?trica (TGA), Calorimetria Diferencial Explorat?ria (DSC) e An?lise Termomec?nica (TMA). A Microdureza Vickers do a?o foi medida antes e ap?s o tratamento t?rmico, e a caracteriza??o metalogr?fica realizada. A superf?cie desgastada do poliuretano foi analisada por microscopia eletr?nica de varredura (MEV) e microan?lise-EDS. O estudo foi complementado por ensaios esclerom?tricos de um ?nico passe em poliuretano utilizando indentadores com diferentes ?ngulos de contato. A morfologia da cratera, os mecanismos de desgaste e a resposta t?rmica foram discutidos buscando-se correlacion?-los ?s solicita??es impostas pelo par press?o-velocidade aos materiais em contato. Sete diferentes mecanismos de desgaste foram identificados na superf?cie do poliuretano. Encontrou-se correla??o entre a varia??o da temperatura e a morfologia da cratera de desgaste.