Effect of calcium compounds in lubrication oil on the frictional properties of Fe2O3-Al2O3 ceramics under boundary lubricating conditions

Abstract

Calcium sulfonate, a detergent/dispersant component in lubricating oils, greatly increase the friction coefficient of TiO2 added Fe 2O3-Al2O3 ceramics under boundary lubricating conditions. ESCA studies showed that the average thickness of an organic thin film sticking to the surface of wear tracks was thicker than that away from wear tracks, and the concentrations of Ca, S and P were much higher in the wear track than those off the wear track, suggesting that most of the -SO3-Ca-OH groups in sulfonate remained unchanged. It is concluded that oil containing rich calcium compounds possibly formed a layer, blocking other oily additives with which the surface would have been wettable. This is assumed to increase the friction coefficient of the TiO2 added Fe2O3-Al2O3 ceramics.