Mechanism of wear at extreme load and boundary conditions with ashless anti-wear additives: Analysis of wear surfaces and wear debris

In this study the wear behavior of ashless antiwear additives is examined. For the very first time extensive use of transmission electron microscopy was used to evaluate the characteristics of wear debris that is generated in a tribological test and the nature of crystalline phases in the wear debris was examined. The importance of sulfur in the ashless antiwear additives was proved by comparing the wear performance of an amine phosphate to that of a dialkyl dithiophosphate. In addition, in this study the several phosphorothionates were compared to dialkyl dithiophosphates. Lastly, it was shown that an acidic dialkyl dithiophosphate exhibited the best wear performance under boundary lubrication conditions.