Abstract:Objective: To investigate the effects of different PS-PVD process conditions on the properties of MoSi2 coatings. Methods: Two types of MoSi2 powders were prepared using a centrifugal spray dryer and a two-fluid spray dryer. MoSi2 coatings with varying process conditions were deposited on TZM alloy surfaces via plasma spray-physical vapor deposition (PS-PVD). The cross-sectional morphology, elemental distribution, phase composition, and relative content of the coatings were analyzed using scanning electron microscopy and X-ray diffraction. The effects of process parameters and powder types on coating thickness, hardness, physical phases, and microstructure were investigated. The oxidation resistance of the coatings at 1600°C was tested, and the oxidation products were characterized and analyzed. Results: The PS-PVD-deposited coating on the molybdenum alloy surface exhibited a “dense columnar crystal” structure. Particle deposition occurred via gas-liquid co-deposition, with primary products comprising tetragonal MoSi2 (t-MoSi2), tetragonal Mo5Si3 (t-Mo5Si3), hexagonal MoSi2 (h-MoSi2), and cubic Si (c-Si). The original powder state and sputtering distance significantly influenced the deposition state and phase composition of MoSi2, consequently affecting the coating hardness and deposition efficiency. The PS-PVD-prepared Mo-Si coating exhibited four layers after oxidation: a surface SiO2 layer, a Mo-Si-O mixed layer, a Si diffusion layer, and a SiO2 reaction layer. Oxidation failure of the coating first occurred in the SiO2 reaction layer.