One kind of SiC-TaC coating / substrate combined with modified C / C composite material and its preparation method

The invention discloses a SiC-TaC coating/matrix collaborative modified C/C composite material and its preparation method. The composite material provided by the invention comprises two parts. The portion below the surface of the C/C composite material is the matrix modified portion with the thickness being 0.1-10mm. In addition, carbide in the C/C composite material emerges in gradient distribution. The portion which is deposited on the surface of a carbon material is a coating portion with the thickness being 10-300 microns. The preparation method of the composite material comprises the following steps of: cutting a C/C green body at the density of 0.80g/cm -1.60g/cm into an annular shape or a plate shape, followed by ultrasonic cleaning and drying, placing into a multifunctional CVD furnace, depositing carbide on the surface layer and surface of the C/C green body by controlling deposition parameters, further densifying the green body by the use of pyrolytic carbon so as to obtain the high-density coating/matrix collaborative modified C/C composite material. The main advantages of the invention are as follows: by the penetration of carbide through the surface layer of the C/C composite material, the thermal expansion coefficient of the matrix is raised, the interfacial bonding state is improved, a continuous transition of carbide is formed between the coating and the matrix, and the metallurgical bonding is accomplished between the coating and the matrix.