Friction and wear of HPSN bearing materials

Silicon nitride-based ceramics are used as high-performance materials for roller bearings. Its low specific gravity (about one-third that of ball-bearing steel), retention of strength at high temperature and corrosion resistance make Si3N4 ideal for this application. The first study of hot-pressed silicon nitride (HPSN) was made by Baumgartner. Later works were reviewed by Cranmer. Most previous work was related to the evaluation of HPSN in contact with itself. In this paper, the authors present work on wear and friction of HPSN and its composites in contact with ball-bearing steel. HPSN was made by sintering a nitrogen-rich Si3N4 liquid phase. The effect of sintering aids on the wear behavior of HPSN and its composites was investigated. The composites were made by adding either a high-temperature lubricating material, e.g., hexagonal boron nitride (BN) or harder particulates, e.g., titanium carbide (TiC)