Estudo do comportamento tribológico do lubrificante mineral 15W40 contaminado por Biodiesel e suas misturas com Diesel

Abstract

The use of biodiesel as fuel is growing in the world, so it is necessary to study the effects caused by this new fuel to internal combustion engines. Thus, this study aimed to study the contamination of a commercial mineral oil 15W40 with biodiesel (B100) and its blends with diesel (B10 and B20), in terms of their impact on the physicochemical and tribological properties of the lubricating oil. Based on studies, it was determined that for each contaminant was used in percentages of contamination between 1% and 2%. Several physical-chemical analyzes were performed to ascertain the behavior of the contaminated lubricating oil, comparing them to the specifications required by the quality organs. Some techniques (DSC, acidity index and FTIR) were also applied in order to investigate their behavior when aged. Contaminated lubricants also underwent lubricity analyzes on the HFRR tribometer, using AISI 52100 steel as test specimens. These specimens at the end of the test underwent a superficial analysis in order to understand the extent of wear and tear suffered by this type of contamination. The results showed that contaminated lubricants do not present great risks to their properties, but when aged, they increase the number of saturated esters, reduce the oxidative stability and increase the acidity. The behavior of the contaminated lubricants aged was different than expected, as it caused a better performance in the lubricity, thus the antioxidant additives, contrary to expectations.