Evaluation of tribological perfomance of liquid ionic as additive for vegetable-based lubricant

Abstract

Given the growing current demand for more efficient and sustainable lubricants, the study of ionic liquids (ILs) appears as an alternative with a great potential for success. ILs stand out concerning conventional lubricants, for forming tribofilm better, being less aggressive to the environment, and having great applicability. These are constituted of organic cations and anions, so they do not generate environmental impacts like current lubricants. ILs can be used both as a neat lubricant and as an additive, to increase lubrication efficiency in metal sliding pairs, decreasing friction and wear. In order to understand how ILs behave as additives for vegetable-based lubricant, tribological characterizations were carried out in the high-frequency reciprocating rig (HFRR) tests of ionic liquid as an additive in vegetable-based oil in different concentrations. These tests were carried out by a lubricated contact of a sliding pair ball-on-disk made of AISI 52100 steel, during the test the coefficient of friction (COF), the wear scar diameter (WSD), and the film percentage were measured, according to ASTM D6079-11. Based on the results it was possible to observe improvements in lubrication, with reduced coefficient of friction, reduced wear, and better formation of tribofilm, when used as an additive compared to the pure base oil.