bachelorThesis
Efeito da diluição de etanol em óleo lubrificante de baixa viscosidade no comportamento tribológico do contato anel do pistão/ cilindro
Fecha
2017-10-26Registro en:
CREPALDI JUNIOR, Jesuel. Efeito da diluição de etanol em óleo lubrificante de baixa viscosidade no comportamento tribológico do contato anel do pistão/cilindro. 2017. 118 f. Trabalho de Conclusão de Curso (Graduação) - Universidade Tecnológica Federal do Paraná, Londrina, 2017.
Autor
Crepaldi Junior, Jesuel
Resumen
With the worldwide trend towards sustainable thinking, renewable biofuels such as ethanol are gaining further importance, and its application in Flex Fuel engines provides several benefits such as the lowering of CO2 emissions. However, the use of ethanol as a fuel brings some significant tribological drawbacks. With this in mind, the present work had as its main goal the analysis of both anhydrous and hydrated ethanol dilution effect in a low viscosity engine oil lubricant 0W-20 API SN on the tribological behavior of piston ring/cylinder liner contact with aid of a reciprocating test conducted by a SRV tribometer. Honed gray cast iron cylinder liner and PVD ring samples were taken directly from an internal combustion engine. The tribological behavior was evaluated with regard to the results acquired in two independent tests: short and long duration tests, representative of friction and wear sequences, respectively. With this procedure, CoF was judged from both tests by means of its characterization depicted on Stribeck-like curves, as well as of its behavior as a function of time, recorded from the long duration tests. Wear was discussed according to its response based on the liner worn surfaces measures. Relating to the results obtained, it was found that, with the addition of the Friction Modifier to the base oil formulation, both friction and wear reduced substantially, which attests the superior performance of such oil in mixed and boundary friction regimes due the FM influence. However, when anhydrous or hydrated ethanol were present in this lubricant, the tribological behavior was changed notably – friction and wear increased markedly, mainly in conditions representative of urban cycle, i. e., cold-start, warm-up and short-trips occasions, with the presence of hydrated ethanol lasting longer. After the tests, the tribolfilm presence provided by the FM was found on the surfaces for all tested liners, and a correlation between the measured wear volumes and the area covered by the tribofilm was encountered. Hereby, the anhydrous and hydrated ethanol presence influences the tribological behavior of the piston ring/cylinder liner contact critically, mainly at low temperatures, when ethanol and water might alter the lubricant properties and performance by increasing both CoF and wear.