Environment-Friendly Preparation of Reaction-Bonded Silicon Carbide by Addition of Boron in the Silicon Melt.

Reaction-bonded silicon carbide ceramics were sintered by infiltration of Si and B-Si alloy under an argon atmosphere at different temperatures. The element boron was added to the silicon melt to form a B-Si alloy first. The mechanical properties of samples were improved by infiltration of the B-Si melt. The samples infiltrated with the Si-only melt were found to be very sensitive to experimental temperature. The bending strengths of 58.6 and 317.0 MPa were achieved at 1530 and 1570 °C, respectively. The sample made by infiltration of B-Si alloy was successfully sintered at 1530 °C. The relative density of the sample was more than 90%. The infiltration of B-Si alloy reduced the sintering temperature and the bending strength reached 326.9 MPa. The infiltration mechanism of B-Si alloy is discussed herein.