Ceramic ball bearings
Ceramic materials are noted for better or particular characters, such as wearability, corrosion resistance, high temperature resistance, electrical insulation (except SiC), non-magnetic, high strength, high rigidity and low specific gravity. These properties qualify them for replacing steel to make bearings serve in conditions of higher speed, harsh environment and less lube, and decrease wear, noise, vibration and maintenance time of bearings, and eventually increase performance, reliability and life of bearings.
Ceramic materials used for bearings include mainly silicon nitride, zirconia, alumina (Al2O3) and silicon carbide . Si3N4 is the first choice because of its excellent characters. Silicon nitride bearing balls fail in the same manner as steel balls of spalling surface while ZrO2 , Al2O3 and SiC fail in form of crush, a catastrophic failure.
- Transmission of high temperature furnaces
Si3N4 retains strength and hardness at nearly up to 800℃, while steel hardness drops above 120℃.
- High-speed rotation field
High speed motor spindle bearings, main shaft bearings of machine tools, dental drill bearings, computer hard disk drive bearings and precise instrument bearings. At much lower specific gravity, ceramic rolling elements can effectively restrain the centrifugal force which appears in high speed rotation, and reduce the load of rolling elements. At the same time the effect of turning slide between rolling elements and raceway corresponding reduces.
- Aviation and airspace fields
The coefficient of thermal expiation of Si3N4 is 0.000006/K while that of bearing steel is 0.0001/K /K, therefore Si3N4 ceramic bearings are more stable and reliable in a temperature changeable condition.
- The main shaft of machine tools
Si3N4 has much higher hardness than bearing steel, and 1/3 modulus of elasticity larger than that of bearing steel. Elastic deformation of Si3N4 is small under an identical load. Therefore, a ceramic bearing has better machining precision.
- Chemical machinery, food industry and marine industry
Ceramic bearings can solve corrosion problems.
- High vacuum field
Ceramic bearings self-lubricate. This prevent vacuum pollution from lubrication contamination.
- Strong magnetic environment
In a strong magnetic environment, metal powder coming from steel components adheres to the surfaces of rolling element and raceway. Ceramic bearings are the solution to this problem.
- Roller skates, aeromodellings and motor-driven toys etc in hobby use
Because of price, all-ceramic bearings are used merely in very demanding applications. In addition, hybrid ceramic bearings - made of ceramic balls and Chrome or stainless steel rings - are widely used. Owing to new shaping technology (extreme net dimensions approaching) of ceramic balls, ceramic bearing can be applied not only in critical industrial spheres but also in civil fields such as roller skates, aeromodellings and motor-driven toys, etc.
Types of Ceramic Balls (General Applications)
Ceramic ball bearings