Films formed by antiwear additives and their incidence in wear and scuffing

Abstract

Lead naphthenate, zinc dithiocarbamate, antimony dithiocarbamate and zinc dithiophosphate have been tested as antiwear additives in the four-ball machine. The chemical nature, thickness and distribution of the films formed on the wear track have been determined by X-ray energy dispersive spectroscopy using a method for analysing films. It has been found that the film thickness arises from a balance between the rate of growth, depending on the type of additive, its concentration in the base oil, the contact temperature and the rate of removal determined by wear. Under mild conditions the first process dominates and thicker films are formed which reduce wear. With increasing severity the films are strongly thinned until scuffing occurs when the films have been worn off. © 1987.