Performance characteristics of silicon nitride materials

with the in-depth study of silicon nitride ceramic materials, its excellent properties in thermal conductivity and biocompatibility are gradually recognized by scientific researchers and developed and applied. This article elaborates on the preparation method of silicon nitride powder, and reviews the research progress of silicon nitride ceramics as structural ceramics in the mechanical and aerospace fields. In addition, it introduces the research and application status of silicon nitride ceramics as functional ceramics in the semiconductor field and biopharmaceutical field, and finally looks forward to its future development.

① Thermal properties: It is a high-temperature refractory material with no melting point. It decomposes at about 1900°C under normal pressure. It has strong resistance to high-pressure creep. The load softening point of reaction-sintered silicon nitride without binder can be as high as 1800°C.

② Good thermal conductivity;

③ Small thermal expansion coefficient;

④ Good electrical insulation performance, small dielectric constant and high breakdown voltage resistance.

① Anti-oxidation: Does not react with oxygen in dry atmosphere below 800℃;

② Resistance to molten metal corrosion: Silicon nitride is not wetted by single metal melts (except copper) and is not corroded;

③ Resistance to acid, alkali and salt corrosion: It is easily soluble in hydrofluoric acid and has no effect on dilute acid.

① High temperature strength is good. The high temperature strength at 1200℃ is not much reduced compared with the room temperature strength. In addition, its high temperature creep rate is very low. These are all determined by the nature of strong covalent bonds;

② High hardness, second only to a few superhard materials such as diamond, cubic BN, B4C, etc.;

③ Low friction coefficient, self-lubricating, similar to the metal surface with oil.