The way for making reaction bonded silicon carbide ceramic was first studied in the United States. The process of reaction bonded silicon carbide is as follows: first, the mixture of alpha SiC powder and graphite powder is mixed proportionally, and then the porous body is made by dry pressing, extrusion or slip casting.
In contact with liquid Si at high temperature, the C in the blank body reacts with the infiltrated Si to produce β SiC, which is combined with the alpha SiC, and the excess Si is filled in the pores, thus the No hole and dense reaction sintering body is obtained for rbsic. The reaction boned silicon carbide ceramic usually contains 8% free Si. Therefore, in order to ensure the complete infiltration of Si, the green body for sisic ceramic should have enough porosity. By adjusting the content of alpha SiC and C in the initial mixture, the granularity gradation of alpha SiC, the shape and granularity of C and the molding pressure, the proper density of green body of sisic is obtained.