Effects of temperature and sliding velocity on the dry tribological characteristics of high purity, high density polycrystalline aluminium oxides

Abstract

The effects of temperature (up to 600 °C) and sliding velocity on the tribological properties, i.e. volumetric wear rates and friction coefficients, of high density (greater than 97% theoretical density) and high purity alumina (99.7% Al 2O 3) were investigated using a pin-on-disc tribometer. Increases in volumetric wear rates with temperatures were noticed, while the friction coefficient values decrease. The formation of smooth agglomerated compacted layers of water debris is thought to be responsible for the decrease in the friction coefficient. The wear of alumina couples is a complex process which may involve brittle fracture and plastic deformation which are active in different degrees depending on the operating conditions and material properties, e.g. microstructure and composition. The compressive stresses, exerted on the wear debris at the interface between pin and disc during sliding, caused a reduction in the crystallite size, as revealed by the peak broadening of X-ray diffraction patterns.