Effects of molten Na2SO4 on wet oxidation behavior of SiCf/SiC composites above 1200 ℃

Abstract

For SiCf/SiC composites used in the hot section components of turbine engines, corrosion under high temperature oxidative environment has become potential threat to the service life of the materials. Here, the corrosion behaviors of SiCf/SiC composites exposed to wet-oxygen and Na2SO4-wet-oxygen environments were discussed respectively. In wet-oxygen environment, the oxide scale formed on SiCf/SiC surface is thin and porous, leading to slight oxygen infiltration into SiCf/SiC and thus slow weight gain. However, in Na2SO4-wet-oxygen environment, molten Na2SO4 can affect the phase transformation of SiO2. With the temperature rising to 1400 ℃, the weight gain rates of SiCf/SiC begin to decrease and Na2SO4 melt penetrates into the composites, which can bring more serious corrosion on SiCf/SiC. This work can offer important guidance to improve the corrosion resistance of SiCf/SiC composites.