TRIBOLOGICAL PROPERTIES OF SILICON-NITRIDE CERAMICS COATED WITH MOLYBDENUM FILMS UNDER BOUNDARY LUBRICATION

The tribological behaviour of Si3N4 ceramics, with and without molybde num films deposited by means of ion beam mixing (IBM), was investigate d on a reciprocating friction tester under boundary lubrication. Paraf fin oil containing 3 wt.% tricresyl phosphate (TCP), sulfide olefin (S O), chlorinated paraffin (CP) and zinc dialkyldithiophosphate (ZDDP) a dditives were used to lubricate the ceramics. SEM, EPMA and XPS were u sed to examine the rubbed surfaces. It was found that concurrent use o f the IBM modification and additives reduced the friction of the tribo system and wear of blocks, and in particular reduced the wear volume o f blocks by a factor of 30 with SO lubrication. The wear mechanism and synergistic effects are discussed.