Ceramic bearings are rotary bearings constructed of ceramic.  Ceramic hybrid bearings, the most common type of ceramic bearing, are constructed of steel inner and outer rings with ceramic (typically Si3N4) balls in place of steel.  Common types of ceramic bearings are angular contact and Conrad.  These bearings have several advantages over all steel bearings, such as higher speed and acceleration capability, increased stiffness, higher accuracy, lower friction and heat generation, reduced lubrication requirements, low thermal expansion, and extended operation life. Bearings containing all ceramic balls are also nonconductive and are commonly used in electric motor applications.
It's lighter, smoother, stiffer, harder, corrosion resistant, and electrically resistant. The fundamental characteristics of ceramics allow for a wide range of performance enhancements in bearings. Ceramic bearings dissipate heat quickly, reducing friction and wear while maintaining a precision smooth surface.