... level:Z1,Z2. 5,C2,C0,C3. high Performance ceramic ball bearing-china bearingWe have 2 types of ... most common ceramic materials are Si3N4 that stands for the silicon nitride ceramic material and is black ... colored, SiC stands for the silicon carbide material and also is black ... colored. and the ZrO2 that stands for the zirconium dioxide, also known as zirconia or ...