Bearing ideal material: silicon nitride ceramics

Bearing the ideal material: 2021 - silicon nitride ceramics 01 - 23 silicon nitride ceramic bearing as an important basis of mechanical parts, since it has unmatched by other bearing excellent features, in the material world. Silicon nitride is not the most hard in industrial ceramics, toughness is not the highest, but the requirement of high performance bearing applications, the silicon nitride is thought to have the best comprehensive mechanical and physical properties. Five kinds of bearing material performance contrast heat-resistant steel bearing generally use the temperature over 120 ℃, the hardness will reduce, rolling life will decline. The silicon nitride has good temperature characteristic, especially suitable for high temperature environment. Centrifugal force density of silicon nitride is about 3. 24× The density of 103 kg/m3, and bearing steel is about 7. 8× 103 kg/m3, is only about 40% of the bearing steel density, so when using roller bearings, bearing rotates at high speed to inhibit the increase of the rolling element load caused by centrifugal force effect. The linear expansion coefficient of linear expansion coefficient of silicon nitride is about 1/4 of bearing steel, so the size of the change with temperature variation is small, it is used in the environment of the temperature change is big. Hardness, modulus of elasticity and poisson's ratio for the elastic coefficient of silicon nitride is about 1 of bearing steel. Five times, so the relative load the elastic deformation of small, relatively high rigidity of the payload. Corrosion resistance, nonmagnetic, insulation chemical machinery and equipment, food, Marine and other departments use the machine, using steel bearing, its corrosion is a problem. In strong magnetic environment, the use of steel bearings, powder itself from bearing wear down by adsorption between the roller and the rolling surface, this will be a bearing of the main causes of early spalling damage and increase noise. In recent years, the silicon nitride ceramic bearing in aerospace, navigation, nuclear industry, petroleum, chemical industry, textile industry, machinery, metallurgy, electric power, food, locomotive, subway, high speed machine tools and scientific research and national defense military technology in areas such as indispensable substitution effect is gradually known by people. （ Source: China association of shaft bearing industry), the