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Silicon nitride Ceramics(Si3N4), are the most suitable ceramic bearings for electric vehicles. Ceramic bearings, as a new material bearing, have excellent performance that metal bearings cannot match, such as resistance to high temperatures and super strength.

In practice, most ceramic bearings can be considered as hybrid bearings, which combine ceramic balls with steel raceways. Pure ceramic bearings are also possible, as the ceramics are very smooth and there will not be enough friction in the system.

In hybrid bearings, if not controlled, the smoothness of ceramics can also be problematic. If the balls are too smooth, they may become anti lubricating.

In high-speed precision bearings, hybrid ceramic ball bearings are the most commonly used. The rolling element uses hot pressed Si3N4 ceramic balls, and the bearing ring remains a steel ring. This type of bearing has a high degree of standardization, minimal structural changes to the machine tool, and is easy to maintain,

Especially suitable for high-speed operation situations. The high-speed electric spindle assembled by it has advantages such as high speed, high stiffness, high power, and long service life.

Time has proven that as a new material for bearings, it must have dimensional stability at different temperatures to ensure that bearings maintain precise dimensions and fit in temperature changing working environments. In special environments, it must also have corrosion resistance and decomposition resistance.

What are the advantages of ceramic bearings? When it comes to bearings, the lighter the better. Silicon nitride is lighter than steel, and ceramic bearing balls weigh less than half of steel. Electric vehicle engineers like to minimize weight, but this is not the only benefit.

Low friction coefficient

Oil lubricated ceramic bearings have a lubricating capacity that is not lower than traditional lubricants commonly used in steel bearings even when the lubricating oil becomes thinner or lacking; Ceramic bearing balls generate less friction within the bearing assembly, which means they need to

Require less lubricant, less wear, less raceway stress, and lower operating temperature.

Light weight and long service life

The density of ceramic rolling balls is lower than that of steel, and their weight is naturally lighter. Therefore, they can reduce the centrifugal friction of the outer ring during rotation, and the service life of natural ceramic bearings can be extended. The service life of all ceramic bearings can be longer than that of all steel bearings

10-50 times, the service life of hybrid ceramic bearings will be about 3-5 times longer than that of all steel bearings; In terms of service life, ceramic bearings are much longer than metal bearings.

Strong stability, not easily deformed

Ceramic bearings are not only lighter than steel, they are more sturdy and rarely deform due to stress. Ceramic bearings have greater rigidity than metal bearings, and ceramic materials have a higher elastic modulus. Their rigidity is 15-20% higher than ordinary steel bearings, and their hardness is twice that of steel,

The hardness is more than 60% higher than that of steel. Compared to metal bearings, ceramic bearings are more resistant to corrosion and wear. Due to the different materials themselves, ceramic bearings have better corrosion and wear resistance than metal bearings.

Low expansion coefficient and high temperature resistance

Because ceramic ball bearings are less affected by thermal expansion and contraction than steel bearings, they are allowed to work in environments with large temperature differences and drastic temperature changes. And ceramics also have the ability to withstand high temperatures,Ceramic bearing balls can operate at temperatures up to 1000 ℃, far exceeding the requirements for automotive operation.

● Electrical insulation

Ceramic ball bearings can operate at temperatures above 500 degrees Celsius and have advantages such as non conductivity and non magnetism. The use of ceramic balls in bearings can insulate the inner and outer rings of the bearings, as ceramic balls are insulators, 

By using ceramic balls between the inner and outer rings of bearings, insulation can be achieved. This enables the bearing to be used in a conductive environment.

For electric vehicles, one of the biggest benefits of ceramic bearing balls is that they have electrical resistance, and the bearings do not want current to pass through because current accelerates bearing failure.

Silicon nitride has electrical resistance, which is usually beneficial in almost all bearing applications. When using high-voltage traction motors in automobiles, electrical pitting corrosion can easily occur inside the bearings due to current leakage, ultimately leading to early failures.

If steel bearings are used, the only option is to coat the steel with insulation material, which increases the complexity of the manufacturing process and brings opportunities for quality pollution.