Silicon nitride is high-temperature and wear-resistant, used as mechanical parts, used as rotors and stators in engines, etc.; hot-pressed piston crowns, reaction sintered burners, spark plugs, cylinder liners and other precision parts; good thermal shock resistance, used as Thermocouple casing, casting mold, crucible, furnace, burner, heating body fixture, furnace lining, aluminum liquid conduit, valve, etc.; good corrosion resistance, used as ball valve, sealing ring, filter, heat exchanger parts in chemical industry, etc. ; Good wear resistance, used as bearing balls, rollers, seat rings, high-temperature bolts, plunger pumps, sealing materials, etc. in the mechanical industry; used as circuit substrates, film capacitors, and high-temperature insulators in electronics, military and nuclear industries , radome, gun barrel lining, nuclear reactor support, isolation parts, etc.

Reaction sintered silicon nitride is formed by molding silicon powder according to the shape of the product, and then nitriding it in a nitriding furnace. The product has a porosity of about 20%, low density, and low strength; reaction sintered silicon nitride can produce very Complex products that do not require expensive machining. The density of reaction sintered silicon nitride is not high, the density is 2-2.7g/cm ³ , and the performance index has a certain gap compared with normal pressure sintered silicon nitride and hot-pressed sintered silicon nitride, which is suitable for the application of silicon nitride in general occasions Components with intrinsic properties.

Hot-pressed sintered silicon nitride is sintered in a hot-pressed furnace with a temperature of 1700-1800°C, a protective atmosphere, and a pressure of 20-30MPa. The hot-pressed sintered silicon nitride has a high density, a density of 3.2g/cm 3 , and a low ^porosity . Compared with reaction sintered silicon nitride, the performance index has been greatly improved, but limited by the sintering mold, only products with simple shapes can be prepared, and parts with complex shapes need subsequent precision machining.

Atmospheric pressure sintered silicon nitride generally adopts liquid phase sintering, adding appropriate additives, and sintering under a nitrogen protective atmosphere. It has a higher density. Compared with hot-press sintering, it can form some complex shapes. It is a material commonly used in industrial production. , high density, density 3.2g/cm ³ , can produce precision parts with complex shapes in batches.

Re-sintered silicon nitride is to re-sinter the reaction-sintered silicon nitride containing additives under a certain nitrogen pressure and a higher temperature to make it densified. It is also called secondary reaction sintered silicon nitride. The sintered silicon nitride has improved a lot and can be close to hot-pressed sintered silicon nitride. The linear relationship between density and shrinkage is good, and the corresponding dimensional accuracy can be controlled.

Hot isostatic pressing sintered silicon nitride is uniform sintering of silicon nitride under high temperature and high pressure. It has the best performance and high density. Highly demanding precision parts.