High-temperature oxidation response of Mo–Si–B composites with TiO2W/SiCW addition

Abstract

Abstract In this study, TiO2W addition improved the oxidation resistance of the Mo–Si–B composite at 1300 °C. The TiO2 partially dissolved in SiO2 modified the network structure of the SiO2 glass and improved its fluidity at the initial oxidation stage. This favored to a continuous scale cover on the surface of the Mo–Si–B composite rapidly. The residual TiO2W promoted the formation of a passivated multilayer borosilicate scale at current temperature, which could impede the MoO3 volatilisation and O diffusion at the stable oxidation stage. The SiCW addition, compared to the TiO2W, especially could ensure the Mo–Si–B–SiC composite withstand a higher temperature such as 1400 °C. Its oxidation and the more intermetallics in the composite could increase the number of active sites of the SiO2 glass, thereby supplying the borosilicate scale with a relatively sufficient Si element. Thus, the transient oxidation stage was minimised and the initial mass loss was reduced, which indicated a continuous borosilicate scale had formed quickly at the initial stage. Finally, the improved viscosity of the borosilicate due to a lower B/Si ratio, could obviously decreased the oxygen diffusion and enabled the formation of a protective borosilicate layer at or above 1400 °C.