The tribological behaviors of some rear earth complexes as Part2-the antiwear and extreme pressure properties in lithium grease

摘要

The antiwear and extreme pressure (EP) properties of rare earth 8-hydroxyquinolinates and of rareearth di-n-hexadecyldithiophosphates as additives in lithium grease were evaluated on an OptimolSRV friction and wear tester. The morphologies of the worn surfaces and the elemental distributionsin the worn surfaces were observed and determined with an electron probe microanalyzer. Then theaction mechanisms of these compounds as additives in lithium grease were discussed. It was foundthat rare earth di-n-hexadecyldithiophosphates in lithium grease exhibited better antiwear andextreme pressure properties than zinc di-n-butyldithiophosphate (ZDDP), while rare earth 8-hydroxyquinolinates registered antiwear and extreme pressure properties comparable to ZDDP.Moreover, the different tribological behaviors of the compounds as additives in lithium grease wereclosely related to different mechanisms. That is, rare earth 8-hydroxyquinolinates as additives inlithium grease exhibited physisorption action only, while copper 8-hydroxyquinolinate in lithiumgrease functioned by both physisorption and coordination ligand exchange reaction. The tribologicalbehaviors of ReDDP was closely related to tribochemical reaction.