... chrome steel and stainless steel ball material :Si3N4 and ZrO2 Hybrid ceramic ball bearings inside and outside the ring material is ... Gcr15) or stainless steel (9cr18), mainly silicon nitride ceramic balls (Si3N4), Zirconia (ZrO2), alumina (Al2O3) and so on. Si3N4 which ... for high-speed operation, self-lubricating properties of ceramic balls, ceramic ball bearings so you can use high-temperature short ...