Lubricities of environmentally acceptable lubricants with zinc dialkyldithiophosphate and dibenzyl disulfide on tribological properties of plasma electrolytic oxidation coated A6061-T6 alloy under mixed/boundary lubrication

Abstract

3 different base-stocks (poly-α-olefin, polypropylene glycol and unsaturated TMP ester) and additionally formulations with 2 different additives (1 mass% ZnDTP or 1 mass% dibenzyl disulfide (DBDS)) were used as lubricants to evaluate the tribological properties of A6061-T6 treated by means of plasma electrolytic oxidation in a SRV tribometer (Toil = 80°C, FN = 50 N, v = 50 Hz, 2 mm stroke, 2 hrs). The base oils of PPG and the TMP-ester had better lubricities than the PAO with/without the additives. ZnDTP tend to reduce wear, but when added to PAO and PPG increased the friction. The unsaturated TMP-ester +1 mass% DBDS showed 45% lower friction than PAO + ZnDTP (reference), whereas PPG + DBDS had 30% lower friction.