Effect of Surface and Mechanical Properties on Silicon Nitride Bearing Element Performance

Abstract : The report discusses the importance of understanding the extent of surface damage caused during the manufacture of bearing surfaces on ceramics. The likely impact of the damaged surface on the usefulness of ceramics as rolling bearing materials is presented. The results of flat-washer rolling- contact fatigue tests signify the role of surface interactions in a steel- silicon nitride contact on the life of the contact. The variables evaluated include lubricant viscosity, surface finish of the silicon nitride washer, type of contact (line or point) and hardness of the steel rollers. The effect of the lower density and higher elastic modulus of silicon nitride on bearing fatigue life was analytically evaluated. The analysis shows that silicon nitride rolling elements can improve the fatigue life of very high speed bearings.