Rolling contact silicon nitride bearing technology: a review of recent research

The paper reviews some of the extensive research in the field of ceramic rolling element bearings that has been carried out over the past decade or so. As a result of this work hot isostatically pressed silicon nitride (HIPed Si3N4), has emerged as an extremely promising material for fabricating high performance all-ceramic or hybrid steel/ceramic rolling contact bearings. Compared with conventional steel bearings silicon nitride bearings have been shown to offer significant benefits in terms of rolling contact fatigue life, and the lower density of the material greatly reduces the dynamic loading at ball/raceway contacts in very high speed applications such as machine tool spindles and gas turbine engines. Investigations have shown the particular benefits of using silicon nitride bearings in severe lubrication and wear conditions such as extreme temperature, large temperature differential, high speed, ultra-high vacuum and in safety-critical applications where, for example, they can respond to the requirements of short periods of oil-off operation in an aircraft engine. Other benefits which have been demonstrated are corrosion resistance and tolerance of contaminated lubricants. As a result of their sustained development and testing it is expected that silicon nitride bearings will continue to achieve wide acceptance in all types of applications.