Efeito da contaminação do óleo lubrificante por combustíveis na lubrificação para motores-flex

Abstract

Engines that use alcohol and gasoline as fuel are known as flexible fuel engines, they have a great tribological challenge, which is related to no suitable lubrication and severe tribochemical wear. Thus an optimization of flex-fuel engines has become an urgent technological challenge as vehicular ethanol increasingly asserts itself as an alternative to reducing CO2 and other pollutants. The present work aimed to contribute to a better understanding of the lubrication phenomena, friction and wear in flex-fuels engines. For that, the effects of the addition of fuels percentages (ethanol and common gasoline) to the synthetic oil on the tribological performance of the lubricants were analyzed. The lubricants were prepared from synthetic oil, with 1, 2 and 5% of the fuel by weight. Knowing what that the contact with engine parts or hydraulic equipment is by sliding, the tribometer HFRR (High Frequency Equipment) was used to measure the lubricating capacity, or the ability of a fluid to reduce wear and tear between surfaces relative movement under load. Based on this: during the tribologial tests coefficient of friction (COF) and percentage of film formation were measured. At the end of the test a wear characterization was performed through MEV/EDS analysis. The results showed that the contamination of the lubricant with the studied fuels decreased its lubrication capacity. This effect is more pronounced for larger proportions of ethanol. Then the lubricants were analyzed by FTIR (Infrared Spectroscopy with Fourier Transform) and X-Ray Fluorescence without verification of the oil degradation, but with the increase of iron and the decrease of zinc, calcium and phosphorus, contribution for performance in reducing friction and wear.