Conventional bearings are mostly made of metal, with oil as the lubricating medium. However, there are many disadvantages in use, such as not suitable for high temperature, high speed, chemical corrosion, oil lubrication, leakage and pollution of the environment. Bearings made of ceramic materials can make up for the shortage of metal bearings.
Si3 N4 has become the material of choice for the manufacture of ceramic rolling bearings with its excellent performance. It has been applied in many fields such as high-speed lathes, aerospace engines, chemical machinery and equipment. For example, Norton Corporation of the United States has applied Si3N4 ceramic bearings to the shuttle's hydraulic pumps. Pharmaceutical equipment as well as printing and dyeing, fishing equipment. It has been proven that ceramics are successful as a rolling bearing material. Ceramic materials used in the manufacture of plain bearings (water lubrication) are mainly oxide ceramics and non-oxide ceramics. Oxide ceramics mainly include alumina, zirconia, etc.; non-oxide ceramics mainly include carbides and nitrides. Tests have shown that non-oxide ceramics have better wear resistance, with Sialon and Si3N4 having the best overall performance. Mo2 FeB2
It is a newly developed ceramic sliding bearing material with good heat resistance, wear resistance, corrosion resistance and good weldability with steel. It can be widely used in all kinds of sliding bearings. Ceramic bearings have the following advantages: High speed: The weight of ceramics is only 40% of the weight of the same volume of steel, which can reduce the centrifugal load and slip, so that the ceramic bearings can increase the speed of the bearings by 20% ~ 40%. Long life: The hardness of ceramic materials is much higher than the hardness of steel, and the high hardness can reduce wear. In addition, ceramics have a high compressive strength, which is about 5 to 7 times that of steel depending on the specific material and test type. When there are impurities in the bearing, the ceramic bearing rarely causes spalling failure, so the ceramic bearing usually has a longer service life.
Low heat: The coefficient of friction of ceramics is about 30% of that of steel, so ceramic bearings generate less heat, which extends the life of the bearings.
Low thermal expansion: The thermal expansion of silicon nitride is about 20% of that of steel, which is beneficial for use in environments with large temperature variations. However, when selecting the steel for the shaft and housing, measures must be taken to suit the fit.
Corrosion resistance: The inactive chemical properties of ceramic materials give ceramic bearings excellent corrosion resistance.
Insulation: The ceramic material is not electrically conductive, which can protect the bearing and the bearing seat from arc damage.
High temperature resistance: The allowable operating temperature of ceramic bearings is 1 090 e. Ceramic materials do not reduce strength and hardness even at high temperatures, so this material is very advantageous for bearings used in high temperature environments.
Ceramic material for bearing
2019 11/11