The 10th International Conference on Energy, Resources, Environment and Sustainable Development (ERESD 2024)

The present study investigates the preparation of homogeneous and dense Mo(Al_xSi_1-x)₂(x=0,0.05,0.1,0.15,0.2) powders using the self-propagating high-temperature synthesis (SHS) technique, followed by the fabrication of Al-modified MoSi₂ ceramics using spark plasma sintering (SPS) technology. The microstructural evolution and high-temperature oxidation resistance of the ceramics are observed. The results indicate that after oxidation, MoSi₂ is mainly composed of MoSi₂ phase and SiO₂ phase. Upon addition of Al, Mo(Al_xSi_1-x)₂(x=0,0.05,0.1,0.15,0.2) is primarily composed of MoSi₂ phase, Al₂O₃ phase, and SiO₂ phase. The partial substitution of Si with Al enhances the oxidation resistance of MoSi₂. Because a protective alumina (Al₂O₃) film is formed through the substitution reaction at the original site. The SiO₂ material generated by MoSi₂ tends to evaporate and peel off in a reducing environment, whereas the alumina oxide skin formed by Mo(Al,Si)₂ is stable and adherent. And during the oxidation process at 1500°C, Mo(Al_0.05Si_0.95)₂ exhibits stable and slow mass gain. This is mainly attributed to the formation of a dense and intact Al₂O₃-SiO₂ oxide film on the surface of Mo(Al_0.05Si_0.95)₂ during oxidation, which suppresses the high-temperature diffusion of oxygen and effectively prevents further oxidation of the ceramic internally. Compared to the monolithic MoSi₂ ceramic, the modified Mo(Al_0.05Si_0.95)₂ ceramic exhibits less weight gain and a denser morphology, demonstrating relatively better high-temperature oxidation resistance.