Microstructure and Oxidation Behavior of Molybdenum Disilicide Coating Prepared by Air Plasma Sprayed

Intermetallics molybdenum dislicied has a great potential as a protective coating in aircraft engines and gas turbines in the elevated temperature. The suit for plasma spraying MoSi2powders were prepared by spray drying process and vacuum sintered. The oxidation behaviors of the coating were determined at 1200 °C. The coatings as sprayed and oxidized were characterized by XRD, SEM and EDS. Results show that the flow ability and loose density of MoSi2powder by sintered treatment, were 17.1 s/50g and 2.1g/cm3, respectively, ideal for air plasma spraying. During the course of spraying, some of molybdenum disilicide with a tetragonal lattice was converted into molybdenum disilicide with a hexagonal lattice. Also, part of MoSi2 phase oxidized and transformed to Mo5Si3phase. A relative dense molybdenum disilicide coating was prepared by air plasma spraying. A protective SiO2layer, seems to be glassy, with a thickness about 10 μm was formed on the surface of MoSi2coating during MoSi2coating oxidized at 1200°C for 200 h. The results of the oxidation tests show that MoSi2coating prepared by air plasma spraying may be provide a protect layer for high temperature structure material.