Ceramic Ball Bearings Ceramic Ball Bearings The hybrid ceramic ball bearing features bearing rings made of bearing steel (Gcr15) or stainless steel (9cr18). The ceramic ball bearing is mainly made of silicon nitride (Si3N4), rconia (ZrO2) or alumina (Al2O3), among which Si3N4 is of excellent overall erformance and has become the preferred material for ceramic ball bearing. The density of Si3N4 ceramic is 3.20g/cm3, much lower than that of bearing steel (7.85g/cm3).