Deposition and oxidation behaviour of molybdenum disilicide coating on Nb based alloys substrate by combined AIP/HAPC processes

A MoSi2 coating was prepared on Nb-10Hf-1Ti alloys by a two-step process. The first step was arc ion plating (AIP) of the Mo layer, and the second step was halide-activated pack cementation (HAPC) of Si. The coating is composed of an outer layer of MoSi2 and an inner bond layer. After oxidation testing at 1200 degrees C for 100 h in a static air atmosphere, the mass gain of the coated specimen was 0.64 mg/cm(2). The good oxidation resistance of the MoSi2 coating is attributed to the protective SiO2 scale generated by the oxidation process.