Ceramic bearings are a kind of bearing that uses ceramic material for one or both races and rolling elements(such as balls or rollers). General ceramic materials include zirconium oxide(ZrO2), and silicon nitride(Si3N4). These ceramic bearings are widely applied on many occasions with special requirements, especially in extremely specific environments and conditions.
2. Ceramic bearings classification
(1) Classification by ceramic content Full ceramic bearings: This type of bearings refers to bearings whose rolling elements and inner and outer races are all made of ceramic materials. It is suitable for environments with extreme temperatures, strong corrosion, or high insulation requirements.
Hybrid ceramic bearings: This type of bearing is usually made of mixing ceramic and metal materials. This design combines the advantages of ceramics and metals. The price is lower in cost than full ceramic bearings.
(2) Classification by ceramic materials
Zirconium oxide ceramic bearings (ZrO2): This type of bearings has good toughness and corrosion resistance. It is suitable for use in harsh corrosive environments.
Silicon nitride ceramic bearings (Si3N4): This type of bearings has high strength, high-temperature resistance, impact resistance, etc., and it is suitable for high speed, high precision, and high-temperature environments.
Silicon carbide ceramic bearings (SiC): This type of bearings has extremely high hardness, excellent wear resistance, and excellent high temperature and corrosion resistance. It can work in extremely harsh environments and are suitable for high temperature, high pressure, and highly corrosive industrial fields, but the price is expensive.
Alumina ceramic bearings (Al2O3): This type of bearings has low density and high hardness, but they are rarely used and are usually suitable for occasions with less demanding requirements.
(3) Classification by rolling elements
Ceramic ball bearings: Such as ceramic deep groove ball bearings, ceramic miniature ball bearings, ceramic thin section bearings, ceramic angular contact ball bearings, ceramic self-aligning ball bearings, ceramic thrust ball bearings, etc.
Ceramic roller bearings: Such as ceramic tapered roller bearings, ceramic cylindrical roller bearings, etc.
(4) Classification by flange structure
Flangeless ceramic bearings: It is a standard, traditional design; it finds wide application in usual industrial usages.
Flange ceramic bearings: A flange structure is designed on the outer ring to mount and locate a bearing in special equipment.
3. Ceramic bearings characteristics
(1) Lightweight: The density of the ceramic material is always low, making it lighter compared with steel of the same size. Therefore, it can reduce the bearings' inertia and make them achieve higher rotation speed.
(2) High hardness: The hardness of the ceramic material is much higher than steel. Thus, they have better wear resistance. Moreover, under working conditions with high temperatures or chemical corrosion, their service life would be longer.
(3) High-temperature resistance: High temperature has little effect on the ceramics; they can bear large heat and thus work at extreme temperatures without deformation or performance degradation that happens to metal bearings.
(4) Corrosion resistance: Resistance against most chemicals; hence, it is suitable to work in corrosive environments.
(5) Insulation: Because of low electronic conduction in ceramics, they have good electrical insulation and anti-magnetic interference performance. They are suitably used in places where electrical insulation is needed, such as motors.
(6) Low thermal expansion: the thermal expansion coefficient of ceramic materials is low. In case there is a wide range of temperature variation in application environments, the amount of change in size is smaller and the stability will be higher.
(7) Low friction: due to the smoothness of ceramics, the friction is low, with reduced heat generation during application, hence reduced energy losses.
4. Ceramic bearings application
Ceramic bearings are widely used in a variety of high-demand industries, especially in environments with high speed, precision, corrosion resistance, high-temperature resistance, and high insulation requirements, showing superior performance. Ceramic bearings can be used in the following areas, but far more than that.
(1) Aerospace
(2) High-speed machinery and equipment
(3) Motors and generators
(4) Semiconductor manufacturing
(5) Medical field
(6) Food and beverage equipment
(7) Sports equipment
(8) Automotive industry
(9) Laboratory equipment and measuring instruments
(10) High and low temperature equipment
