For many years, ceramic materials have been the most interesting material for engineers engaged in bearing research. The term "ceramic bearings" usually reminds people of bearings made entirely of ceramics that operate red and hot without lubrication. Many early works focused on the study of all ceramic bearings in high-temperature environments, such as air turbine engine bearings. At present, the development of such bearings is still ongoing, but the lubrication system needs to be improved. Recent development work has focused on hybrid bearings composed of steel rings or raceways and ceramic balls. Hybrid bearings have been used in urgently needed situations such as machine tool spindles, and their applications are becoming increasingly widespread.

There are many types of ceramic materials, each with different compositions, microstructures, and properties. It has been proven that silicon nitride material has the best comprehensive physical and mechanical properties when used in bearings. At present, the annual production of silicon nitride balls worldwide is estimated to be in the millions.

The most important feature of hybrid ceramic bearings compared to all steel bearings of the same model is:

1. The operating speed increases because the low density of silicon nitride balls means a decrease in centrifugal force.

2. The rigidity increases because the elastic modulus of silicon nitride is 50% higher than that of bearing steel.

3. Heat generation is reduced because silicon nitride balls have the characteristics of low friction coefficient and good sports performance.

4. Better thermal stability, as the thermal expansion coefficient of silicon nitride is one-third of that of steel.

5. The design flexibility is greater because the performance of silicon nitride material allows bearing designers to change different parameters without considering the impact.

When applied to machine tools, these characteristics improve productivity and machining accuracy, resulting in improved product quality. Traditionally, lubrication devices used for high-speed spindle bearings generally use oil air or oil mist lubrication systems, as grease lubrication can reduce the performance of all steel bearings. On the other hand, hybrid bearings can be safely lubricated with grease. For machine tool manufacturers, eliminating the oil air lubrication system can significantly reduce costs.

Hybrid ceramic bearings for aircraft engines are also under development. When an air turbine engine operates at high speed, the centrifugal load generated by the balls in its bearings often becomes the main factor restricting the maximum engine speed. Hybrid bearings equipped with low-density silicon nitride balls offer the possibility of operating at higher speeds, coupled with less internal heat generation, which can significantly reduce weight.

The most common form of hybrid ceramic bearings is angular contact ball bearings equipped with silicon nitride balls, which can effectively operate at high speeds under both radial and axial loads. However, axial loads can only be applied from one direction. Therefore, these bearings are usually installed in pairs and preloaded to ensure the correct contact angle. Compared to deep groove ball bearings, angular contact ball bearings have a larger opening at one end, so reinforced phenolic resin cages are usually used. Some hybrid bearing products only convert steel balls into silicon nitride balls in terms of materials, but on the other hand, the geometric dimensions of the grooves have also been improved to optimize bearing performance. Other types of ceramic balls can be used in special occasions, such as instrument bearings and gyroscopic bearings.