Abstract:

The PDSC, crankcase simulation test and four ball tests were employed to investigate the oxidation stability and triboligical properties of lubricating oil with MoDDP additive. The oil samples before and after the crank simulation test and the worn scar surfaces were characterized by FTIR, ICP, UV fluorescence sulfur determinator, SEM, and EDS techniques. The results show that MoDDP additive has a good anti-oxidation ability that effectively enhances oil initial oxidation temperature and lower the oxidation extent of oil in the crankcase simulation test. It is found that the addition of MoDDP cause obvious deposits at high temperature in crankcase simulation test and that the triboligical properties of oil samples decrease significantly after crankcase simulation test. The element analysis indicates that the characteristic elements of MoDDP (S, P, Mo) are important components of deposits. The results of element analysis of oils and worn scar surfaces characterization suggest that the loss of element S, P, Mo in oil samples during test is the main reason.

Key words: MoDDP, anti-oxidation, tribological property, PDSC, crankcase simulation test