Preparation of MoSi2@ZrO2 core-shell powders by hydrothermal-calcination and evaluation of low-temperature oxidation resistance

MoSi2 is a promising candidate for high-temperature, structural materials. However, their oxidation resistance is poor below 600 °C. To prevent MoSi2 from being oxidized at low temperatures, core-shell structured MoSi2@ZrO2 powder were prepared by hydrothermal-calcination approach. First, MoSi2@Zr(OH)4 core-shell composite powder with nano-sized Zr(OH)4 shell particles were synthesised using a hydrothermal method. Subsequently, the MoSi2@ZrO2 core-shell structured powder were obtained by calcination of the MoSi2@Zr(OH)4 powders at 900 °C for 2h. Finally, microstructure and oxidation behaviour of the MoSi2@ZrO2 powder at 400 °C–600 °C in air were investigated systematically. Microstructural analysis revealed that all samples had a distinct core-shell structure, and the ZrO2 shells coated the surface of the MoSi2 core. Oxidation behaviour studies showed that the dense ZrO2 shell layer could isolate the MoSi2 surface from oxygen, improving the low-temperature oxidation resistance and providing better low-temperature antioxidant properties than those of the MoSi2 and MoSi2@Zr(OH)4 core-shell structures.