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. With high strength, low density, high temperature resistance and other properties.
Si3N4 ceramic is a covalent bond compound, the basic structural unit is [SiN4] tetrahedron, the silicon atom is located in the center of the tetrahedron, and there are four nitrogen atoms around it, which are located at the four vertices of the tetrahedron, and then every three Each tetrahedron shares the form of an atom, forming a continuous and solid network structure in three-dimensional space.
Si3N4 has low thermal expansion coefficient and high thermal conductivity, so it has excellent thermal shock resistance. The hot-pressed sintered silicon nitride will not break even when it is heated to 1000℃ and put into cold water. At not too high temperature, Si3N4 has high strength and impact resistance, but it will be damaged with the increase of use time above 1200℃, reducing its strength, and it is more prone to fatigue damage above 1450℃, so Si3N4 The operating temperature generally does not exceed 1300 ℃. Since Si3N4 has a low theoretical density and is much lighter than steel and engineering superalloy steel, it is more appropriate to use Si3N4 ceramics to replace alloy steel in those places where materials are required to have high strength, low density, high temperature resistance, etc.