Corrosion behavior of pressureless-sintered SiC in molten NaCl–KCl–MgCl2 salt at 700 °C

Abstract

The corrosion behavior of pressureless-sintered SiC in a molten NaCl–KCl–MgCl2 salt at 700 °C was investigated. Results indicate that it is prior for SiC and sintering aid B around grain boundaries to be corroded. MgCl2⋅xH2O(x=4,6) in the salt plays an important role in the corrosion of SiC. MgCl2⋅xH2O is hydrolyzed to HCl, H2O, and MgO, which react with SiC and B to form C, SiO2, SiCl4, B2O3, and Mg2SiO4. The corrosion depth of SiC and the concentrations of elements Si and B in the salt increase with the corrosion time, which are fitted well with Fick's law of diffusion.