Silicon Nitride(Si3N4)

Many of the properties of silicon nitride are attributed to this structure. Pure Si3N4 has two crystal structures, α and β, both hexagonal crystals, and its decomposition temperature is 1800 ° C in air and 1850 ° C in 110MPa nitrogen. Si3N4 has low thermal expansion coefficient and high thermal conductivity, so it has excellent heat shock resistance. The hot-pressed sintered silicon nitride will not break after being heated to l000℃ and put into cold water. At not too high temperatures, Si3N4 has high strength and impact resistance, but above 1200℃ will be damaged with the growth of use time, so that its strength is reduced, more prone to fatigue damage above 1450℃, so the use of Si3N4 temperature generally does not exceed 1300℃. Because the theoretical density of Si3N4 is low, it is much lighter than steel and engineering ultra-heat resistant alloy steel, so it is suitable to replace alloy steel with Si3N4 ceramics in those places where the material is required to have high strength, low density, high temperature resistance and other properties.