Comparison of the Reaction Behavior of Hexagonal Silicon Carbide Powder in Different Atmospheres

The reaction behavior of hexagonal silicon carbide (h-SiC) powder under different atmospheres including dry air, air containing 20 vol pct water vapor, and Ar containing 20 vol pct water vapor at 1373 K to 1773 K (1100 A degrees C to 1500 A degrees C) for 10 hours has been investigated and compared. The SiC powder exhibits good oxidation resistance up to 1373 K (1100 A degrees C) and its reaction behavior depends on both the temperature and atmosphere. Below 1773 K (1500 A degrees C), water vapor can promote the formation of pores and enhance the oxidation of SiC powder. However, it tends to aggravate the surface sintering and intensify the volatilization reaction at 1773 K (1500 A degrees C). This phenomenon is further verified with the increasing water vapor content. Based on this, a gas-solid model is adopted to deal with the corresponding reaction kinetics, and especially both oxidation and volatilization reactions are considered when dealing with the reaction kinetics of SiC powder in water-containing atmospheres.