The anti-wear enhancement of boric acid + molybdenum disulfide derived tribofilm

Abstract

Additives are important components to reduce friction and wear of tribological systems. Zinc dithiophosphate (ZDDP), the most commonly used anti-wear additive prevents the tribological system from the friction and wear loss without any commercially available antagonist additive. However, its environmentally harmful content enforces to lubricating oil manufacturers to replace it with an alternative one. Therefore, in this study, the H3BO3 + MoS2 combination was tested in the boundary lubrication regime in a tribometer with a pin on flat reciprocating test module to be a possible alternative anti-wear additive against ZDDP. The friction and wear behavior of Boric acid (H3BO3) + Molybdenum Disulfide (MoS2), ZDDP, MoS2, and H3BO3 evaluated in terms of friction coefficient (COF), wear rate, surface energy and tribo-chemical analysis of tribofilms. SEM/EDX and XPS were employed to explore tribofilm formations on the wear scars. According to the results, the addition of MoS2 into H3BO3 presented a similar tribological performance to ZDDP by forming a strength tribofilm on the surface containing B2O3, MoO3, and metal sulfate.