Silicon nitride ceramic ball is a high-temperature sintered precision ceramic in non-oxidizing atmosphere, with high strength, high wear resistance, high temperature resistance, corrosion resistance as well as acid and alkali resistance. Si3N4 ball can use in seawater over a long period of time. It also has good performance of absolute power and magnetic field. At 800 ℃, the strength and hardness of Si3N4 ball is almost constant. Its density is 3.20g / cm3 and the weight is almost 1/3 of bearing steel. When rotating the centrifugal force is small, so Si3N4 ball can achieve high-speed operation. Because of its self-lubricating, it can be used in the environment of non-lubricating medium and high pollution. Si3N4 ball become a preferred ball in the ceramic ball bearings.