Wear in metal/silicon nitride sliding pairs

Ball-on-rotating disc tests were conducted to assess the relative wear behaviour of various disc materials in contact with silicon nitride under lubricated environment at room temperature high load and high speed conditions. Some selected tests were also performed under unlubricated conditions for comparison. The discs were made of grey cast iron, Al-bronze, bronze, aluminium and stainless steel. The lubricant was commercial additive free mineral base oil having a viscosity grade of 68. The applied normal load ranged between 16 and 300 N. The sliding speed changed from 0.5 to 4.0 m/s. The behaviour of grey cast iron and Al-bronze in sliding contact with silicon was characterised by a decrease in wear with an increase in sliding speed. Bronze and aluminium experienced very high wear rates as sliding speed increased. Stainless steel exhibited high wear and also caused significant damage to silicon nitride. Severity of wear between stainless steel and silicon nitride increased with the speed. High wear occurred at both low and high sliding speeds, which were accompanied by high wear track temperatures on the disc surface. This phenomenon resulted in considerable wear on both mating surfaces.