The invention relates to a method for preparing a LaB6 / Si-Mo gradient high-temperature anti-oxidation
coating. According to the method, a SiC internal
coating is prepared on the surface of a C / C
composite material to relieve the problem of concentrated thermal stress caused by
thermal expansion coefficient difference between a matrix and the
coating; the intermediate layer is a SiC-MoSi2 transition coating and serves as a
transition layer of internal and external coatings, cracks, pores and other defects of the external coating generated under a high-temperature condition can be effectively reduced, the excellent high-temperature
oxidation resistance of the coating can be achieved, and the resistance adaptability of the C / C
composite material under high-temperature aerobic relieving condition is further improved; the LaB6 / Si-Mo coating is prepared by utilizing a
plasma spraying method, so that the thickness of the coating can be accurately controlled, and the problem of uneven thickness of the coating is solved. Gradient is sequentially formed among the coatings, so that generation of thermal stress is reduced, and the
binding force among the coatings is improved. Advantages of the
plasma spraying method and an embedding method are combined, so that the high-temperature
oxidation resistance of the coating can be greatly improved.