c/sic composite material surface coating system and preparation method thereof

Abstract

The invention discloses a C / SiC composite material surface coating system and a preparation method thereof. The surface coating system is arranged on the surface of the C / SiC composite material substrate, including mullite coating and yttrium silicate coating arranged sequentially from bottom to top. The preparation method includes (1) preparation of Al2O3-SiO2 composite sol; (2) preparation of slurry raw material for yttrium silicate coating; (3) preparation of mullite coating; (4) preparation of yttrium silicate single-layer coating or silicic acid Yttrium multilayer coating. The surface coating system of the C / SiC composite material of the present invention has the characteristics of high density and high temperature resistance, and its preparation method has universal engineering application.

Description

technical field [0001] The invention belongs to the field of high-temperature-resistant fiber-reinforced ceramic-based composite materials, and relates to a C / SiC composite material surface coating system and a preparation method thereof, in particular to a novel double-layer high-temperature-resistant and Oxidized coatings and methods for their preparation. Background technique [0002] Carbon fiber reinforced silicon carbide (C / SiC) composites have excellent properties such as high specific strength and specific modulus, high temperature resistance, high damage tolerance, corrosion resistance, etc., and are considered as a strategic thermal structural material. , energy, chemical and other fields have broad application prospects. As a thermal structural material, C / SiC composites face the problem of high-temperature oxidation failure during application. The main reason is that carbon fibers will be severely oxidized above 400 °C and there are a large number of pores and c...

AI Technical Summary

Problems solved by technology

The shortcomings of these schemes are: (1) The density of the yttrium silicate coating itself is not enough, and the oxygen in the Y 2 o 3 and SiO 2 The diffusion coefficients in are very low, but if the coating itself is not dense enough, this advantage will be lost a lot

Blindly increasing the sintering temperature may not achieve the effect, but will cause damage to the composite substrate

Although the density can be improved by adding the outermost layer of the glass phase, the temperature resistance of the glass phase is limited, and the performance in a corrosive atmosphere is not ideal; (2) As time goes on, the SiC inner coating will gradually oxidize to SiO 2 , the generated gaseous by-products will cause the yttrium silicate coating to crack or fall off when it diffuses outward, thus affecting the long-term anti-oxidation effect of the coating; (3) Some preparation methods such as hot isostatic pressing, chemical vapor deposition, Electrophoretic deposition methods are difficult to apply to the preparation of surface coatings for components with complex shapes

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