Silicon nitride ceramic is an inorganic material ceramic that does not shrink during sintering. Silicon nitride is very strong, especially hot pressed silicon nitride, which is one of the hardest substances in the world. Has high strength, low density, high temperature resistance and other properties. Simply put, it is a covalent bonding compound with the basic structural unit being a [SiN4] tetrahedron. The silicon atom is located at the center of the tetrahedron, surrounded by four nitrogen atoms located at the four vertices of the tetrahedron. Then, every three tetrahedrons share one atom, forming a continuous and solid network structure in three-dimensional space. Many characteristics of silicon nitride ceramics are attributed to this structure. Pure Si3N4 has two crystal structures, α and β, both of which are hexagonal. Its decomposition temperature is 1800 ℃ in air and 1850 ℃ in 110MPa nitrogen gas. Si3N4 has a low coefficient of thermal expansion and high thermal conductivity, therefore it has excellent thermal shock resistance.

Silicon nitride ceramics also have high strength and impact resistance during use, but they will be damaged with increasing use time at temperatures above 1200 ℃, resulting in a decrease in strength. Alternatively, they are more prone to fatigue damage at temperatures above 1450 ℃. Therefore, the working temperature of Si3N4 generally does not exceed 1300 ℃. Due to its low theoretical density, Si3N4 is much lighter than steel and engineering high-temperature alloy steel. So, what everyone must know is that in places where materials are required to have high strength, low density, and high temperature resistance, Si3N4 ceramics should be used instead. Silicon nitride ceramics, as excellent high-temperature engineering materials, can better leverage their advantages in high-temperature applications. In short, it has extremely strong high temperature resistance and can maintain its strength even at 1200 ℃. It does not melt into a molten state after heating and only decomposes at 1900 ℃. It has amazing chemical corrosion resistance and can resist almost all inorganic acids and less than 30% caustic soda solutions, as well as corrosion from many organic acids; Meanwhile, silicon nitride ceramics are also a high-performance electrical insulation material.