Organoamine and organophosphate molybdenum complexes as lubricant additives

Abstract

The friction and wear characteristics of molybdenum complexes, from which sulphur is absent, were examined under reciprocating sliding conditions by adding them to a paraffinic base oil with, and without, sulphur and phosphorus compounds as additives. Two kinds of molybdenum complex were used, i.e. an alkylamine complex and an alkylphosphate complex. The complexes were capable of forming MoS 2 despite the absence of sulphur in their constituents when they were added to the base oil containing sulphur compounds. The friction was reduced by the formation of a surface film comprising MoS 2 but the wear performance was little improved by combining the alkylamine complex with a sulphur compound. Both the friction and the wear performance were improved markedly by the formation of FePO 4 besides MoS 2, i.e. it was effective for the alkylamine complex and the alkylphosphate complex to be used together with sulphur and phosphorus compounds and with sulphur compounds respectively.