Microstructure and oxidation resistance of Si-MoSi2 ceramic coating on TZM (Mo-0.5Ti-0.1Zr-0.02C) alloy at 1500 °C

The Si-MoSi2 ceramic coatings were prepared on TZM alloy through a hot dip silicon-plating (HDS) process. The hot dip experiments results showed that Si-MoSi2 ceramic coatings have a very dense surface morphology and low roughness (0.258 ± 0.009 to 0.347 ± 0.019 μm). The Si-MoSi2 ceramic coatings presents a typical layered structure with the outermost silicon-rich MoSi2 layer, the intermediate layer is the pure MoSi2 layer, and the Mo5Si3/Mo5Si3C diffusion layer between the MoSi2 layer and the TZM substrate. The oxidation tests showed that MoSi2 ceramic coating maintained a complete appearance after high temperature oxidation at 1500 °C for 4 h. The self-healing SiO2 protective film effectively inhibits the diffusion of oxygen and reduces the consumption rate of MoSi2 layer. HDS Si-MoSi2 ceramic coating presents a very excellent oxidation resistance at high temperature, which is mainly attributed to the uniform and dense coating structure and high surface silicon concentration.