Microstructure and oxidation behavior of Molybdenum disilicide coating prepared by air plasma sprayed

摘要

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 MoSi_2 powders were prepared by spray drying process and vacuum sintered. The oxidation behaviors of the coating were determined at 1200℃. The coatings as sprayed and oxidized were characterized by XRD, SEM and EDS. Results show that the flow ability and loose density of MoSi_2 powder by sintered treatment, were 17.1 s/50g and 2.1g/cm~3, 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 MoSi_2 phase oxidized and transformed to Mo_5Si_3 phase. A relative dense molybdenum disilicide coating was prepared by air plasma spraying. A protective SiO_2 layer, seems to be glassy, with a thickness about 10 μm was formed on the surface of MoSi_2 coating during MoSi_2 coating oxidized at 1200℃ for 200 h. The results of the oxidation tests show that MoSi_2 coating prepared by air plasma spraying may be provide a protect layer for high temperature structure material.