Effect of Ti combined with Si and C on mechanical performance and oxidation resistance of SiC castables for plasma gasifier

Abstract Gaseous products released during the oxidation of SiC at 1700 °C lead to serious degradation of SiC castables. Ti combined with Si and carbon black are added to improve the mechanical behavior and oxidation resistance of SiC castables in this study. The mechanical behavior, isothermal oxidation, microstructure, and thermodynamic analysis are used to evaluate the properties of SiC castables. The result shows that SiC castables with more Ti exhibit better degradation resistance at high temperature oxidation atmosphere. The preferential oxidation of metal Ti to TiO2 reduces the oxidizing gases and increases the content of SiO (g) in the matrix, which is beneficial for the generation of SiC fibers; in turn, this reinforces the mechanical behavior. In addition, a certain amount of TiO2 dissolves into SiO2 glass following the decrease in viscosity. TiO2 is not only more difficult to volatilize than SiO2, but also can decrease the viscosity of SiO2 glass to improve the mobility of the liquid, which is good for healing the pores on the surface and protecting the inner SiC from being oxidized; this improves the mechanical properties and oxidation resistance.