Silicon Nitride Ceramics
Aluminum oxide ceramics, silicon nitride ceramics, zirconia ceramics
Silicon nitride ceramics have high fracture toughness, compressive strength close to corundum, self-lubricating and anti-wear. High temperature resistance, low coefficient of thermal expansion, and excellent thermal conductivity. The working environment of high temperature, high speed, and strong corrosion often encountered has unique product value. The most prominent features are: (1) High fracture toughness, strength close to that of corundum, and self-lubricating. (2) Good temperature resistance, small thermal expansion coefficient, and high-quality heat conduction characteristics, so it has good high temperature shock resistance, and it is not easy to crack when it is thermally damaged from room temperature to 1000 °C. Silicon nitride ceramics have excellent chemical stability and excellent mechanical properties, and can be used as parts of thermal equipment such as crucibles, burners, and aluminum electrolytic cell linings in the metallurgical industry.
However, the excellent performance of silicon nitride has special use value for the working environment of high temperature, high speed and strong corrosive medium often encountered in modern times.
1. High mechanical strength, harder than corundum, self-lubricating and wear-resistant. The bending strength at room temperature can be as high as 980MPa or more, which can be compared with alloy steel, and the strength can be maintained until 1200° without falling.
2. High thermal stability, small thermal expansion coefficient and good thermal conductivity, so the thermal shock resistance is very good, and the thermal shock from room temperature to 1000° will not crack.
3. The chemical performance is stable, and it can resist the corrosion of almost all inorganic acids (except HF) and caustic soda (NaOH) solution with a concentration below 30%, and can also resist the erosion of many organic substances. It is suitable for various non-ferrous metal melts (especially aluminum liquid ) is non-wetting and can withstand strong radiation.
4. Low density, small specific gravity, only 2/5 of steel, good electrical insulation.
The initial application of silicon nitride ceramics is mainly used in machinery, metallurgy, chemical industry, aviation, semiconductor and other industries, as parts of some equipment or products, and achieved good expected results. In recent years, with the development of manufacturing industry and testing and analysis technology, the reliability of silicon nitride ceramic products has been continuously improved, so the application area has been continuously expanded. What is particularly appreciated is that the silicon nitride ceramic engine is being developed, and great progress has been made, which has become a major event that has attracted worldwide attention in science and technology.