Silicon nitride bearing is made of a high-melting-point ceramic material that is extremely hard and relatively chemically inert. Silicon nitride Si3N4 ceramic is prepared by heating powdered silicon between 1300 °C and 1400 °C in an atmosphere of nitrogen. Then the powder of silicon nitride can be sintered to the designed shape. Si3N4 ceramic is an ideal material for bearings. Silicon nitride ceramic bearing has good wear and corrosion resistance, and great mechanical strength under high temperature. We can supply full ceramic and hybrid bearings products made of silicon nitride, zirconia as well as silicon carbide.
Si3N4 | ZrO2 | Steel | |
Working temperature | 800 C | 800 C | 180 C |
Density | 3.24 g/cm3 | 6 g/cm3 | 7.8 g/cm3 |
Thermal expansion coeff. | 3.4×10-6 | 10.5 | 12.5×10-6 |
Hardness, HV | 1500 | 1300 | About 750 |
Young’s Module | 320 GPa | 210 GPa | 208 GPa |
Corrosion resistance | Good | Good | Poor |
Thermal conductivity | Low | Low | High |
Magnetism | None | None | Yes |
Wear resistance | Excellent | Excellent | Good |
Silicon nitride ceramic is ideal for bearing parts. Silicon nitride bearing balls have already been applied in automobiles, rockets high-speed engines, equipment working in a corrosive environment, and some performance model cars. Compared with steel, high-performance ceramic balls have better mechanical properties under high temperatures and could survive most corrosive chemicals. As the price of ceramic materials decreased, they could have more applications.