Study on high temperature oxidation resistance of HfSi2 modified MoSi2 coating

MoSi 2 and MoSi 2 -20%HfSi 2 coatings were prepared on Nb-based alloy by spark plasma sintering (SPS). The addition of HfSi 2 significantly improved the antioxidant performance. After oxidation at 1250 °C, compared with MoSi 2 , the surface cracks of MoSi 2 -20%HfSi 2 were obviously reduced and the thickness of oxidation layer was thinner. After oxidation at 1550 °C, the growth rate constant of the MoSi 2 oxidation layer was 0.73 μm 2 /h, 1.82 times that of the MoSi 2 -20%HfSi 2 oxidation layer. The main reason is that the interaction between Hf 4+ and [SiO 4 ] tetrahedral units formed a network structure, which increases the viscosity of the oxidation layer.