Silicon nitride ceramics is a kind of inorganic material without shrinkage when sintering.It is made of silicon powder as raw material, then make the powder required shape by usual method of forming and do the first nitrogen treatment in the nitrogen with the temperature 1200℃, silicon nitride will be created by the chemical reaction between some silicon powder and nitrogen, at this time green body has a certain degree of intensity. And do the second nitrogen treatment in the furnace by the temperature 1350℃～1450℃, finally get silicon nitride. Silicon nitride of 99% theoretical density can be made by the way of hot pressing.

 Silicon nitride ceramic can be used to make combustion chamber in gas turbine, mechanical sealing ring, pipes and valves of electromagnetic pump for transmitting molten aluminium, permanent mold and the separation ring for molten steel.It can be used as the parts in projects of high temperature, senior refractory of metallurgical industry, anticorrosion parts and sealing parts in chemical industry and cutters in mechanical process industry.