Reaction sintering refers to the process of obtaining a predetermined sintered body by chemically reacting the raw material molded body through the solid phase, liquid phase and gas phase at a certain temperature, densification and synthesis of prescribed components at the same time. The process is as follows: mixing high-purity silicon powder with a binder and molding, then placing it in a N2 atmosphere or immersing it in molten silicon, and reacting silicon or nitrogen or molten silicon in the green body to prepare silicon nitride products.

Reaction sintering is the earliest silicon nitride preparation process. The initial production of reaction sintered silicon nitride generally contains about 25% air pores, and the degree of densification is not high enough, so it is difficult to reflect the high strength and hardness of silicon nitride materials. performance. But even so, reaction-bonded silicon nitride still has high enough temperature resistance and corrosion resistance, so it is common in the field of refractory materials, mainly used to prepare thermocouple protection tubes, metal melting crucibles and rocket nozzles.