... steel (Gcr15) or stainless steel (9cr18), mainly silicon nitride ceramic balls (Si3N4), Zirconia (ZrO2), alumina (Al2O3) and so on. ... , wear-resistant, self-lubricating and rigidity and good. Ceramic ball bearings have become the preferred material. Si3N4 ceramics ... choice for high-speed operation, self-lubricating properties of ceramic balls, ceramic ball bearings so you can use high-temperature short ...