Wear property of silicon nitride in steel-on-Si 3N 4 and Si 3N 4-on-Si 3N 4 systems

Abstract

A ball-on-three-disc modification of the four-ball wear tester was utilized to evaluate the wear property of Si 3N 4 lubricated with mineral oil, containing additives such as oleic acid, stearic acid and zinc dialkyldithiophosphate (ZDP). For comparison, the wear of a steel ball on Si 3N 4 discs and an Si 3N 4 ball on Si 3N 4 discs was investigated for identical test conditions, and the worn surfaces of the discs were analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The study indicates that the steel ball-on-Si 3N 4 disc system usually gives less wear of the Si 3N 4 disc compared with the Si 3N 4 ball-on-Si 3N 4 disc system. XPS results reveal that a protective surface film containing the products of degraded ZDP was formed on the rubbed surfaces.