Role of Bulk Additions in Solid Lubricant Compacts

摘要

Oxide and sulfide additions to molybdenum disulfide and graphite solid lubricants were evaluated experimentally. Results indicate that the tribologically beneficial effect of bulk additions to solid lubricants originates in the ability of the additive to deform under asperity contact conditions to permit the solid lubricant to attain and retain preferred tribological orientation for overall improvement in tribological condition. Such improvement is evident in scanning electron microscopic examination of worn compact surfaces. Thermal mechanical analyses of solid lubricant compacts and calculated asperity flash temperatures indicate that the mechanism proposed is plausible. Studies of antimony trioxide as an additive to molybdenum disulfide support the hypothesis. Previous hypothesis offered to explain the beneficial effect of Sb2O3, retardation of MoS2 oxidation by Sb2O3, or formation of a eutectic of antimony and molybdenum oxides to improve transfer film formation are refuted. In summary, lubricant compact properties and selection of bulk additions for improved tribological performance are hypothesized to be determined by the test or application conditions, the shear strength at asperity contact temperature of the additive and properties of the solid lubricant. Keywords: Solid Lubricant Additives.