High strength silicon nitride, silicon nitride, especially hot, is the world''s one of the hardest substances. It is a very high temperature, the intensity has been able to maintain a high temperature to 1200 ℃ without drop, heat will not melt into the melt until 1900 ℃ to decompose, and have an amazing resistance to chemical corrosion, resistant to almost all inorganic acids and 30% or less of the caustic soda solution, but also the ability of many organic corrosion; but it is also a high-performance electrical insulation materials.