Material Properties Of Silicon Nitride

Silicon nitride has high strength, especially hot-pressed silicon nitride, which is one of the hardest substances in the world. It is extremely resistant to high temperatures, and its strength can be maintained up to 1200°C without decreasing. It does not turn into a molten body after heating and does not decompose to 1900°C. It has amazing chemical corrosion resistance and can withstand almost all inorganic acids and caustic soda solutions with a concentration of less than 30%, as well as withstand corrosion from many organic acids; It is also a high-performance electrical insulating material.

Silicon nitride properties Chemical formula Si3N4. White powdery crystals; melting point 1900°C, density 3.44 g/cm (20°C); There are two options: α-type - hexagonal structure with tight packing; β-type is a structure that resembles spar. Silicon nitride has a gray color in the presence of impurities or excess silicon.

Silicon nitride practically does not react with water, is slowly hydrolyzed in concentrated solutions of strong acids to form ammonium salts and silica, is easily soluble in hydrofluoric acid and has no effect on dilute acid. A concentrated solution of strong alkali can slowly corrode silicon nitride, and molten strong alkali can quickly convert silicon nitride into silicate and ammonia. Silicon nitride can reduce transition metal oxides (see transition elements), lead oxide, zinc oxide and tin dioxide at temperatures above 600°C, as well as release nitrogen oxide and nitrogen dioxide.