The antiwear mechanism of zddp's. Part II

Abstract

The solution breakdown of zddp's to zinc polyphosphates and mixed alkyl sulphides has been discussed. In this paper, their interaction with metal surfaces is pursued using esca. Zinc phosphate is demonstrated to arrive in the surface oxide layer of engine cams and tappets by physical adsorption and FeS is formed via the oxide layer and elemental sulphur generated from alkyl sulphides with Fe2O3. It is hypothesized that their presence there as fusible glassy compounds, phosporus as polyphosphate and iron sulphide as a ternary eutectic with iron oxide, provides the antiwear function of zddp. © 1982.