C/SiC composite surface coating system and preparation method thereof

Abstract

The invention discloses a C / SiC composite surface coating system and a preparation method thereof. The surface coating system is arranged on the surface of a substrate of a C / SiC composite and comprises a mullite coating and an yttrium silicate coating which are sequentially distributed from bottom to top. The preparation method comprises steps as follows: (1), preparing Al2O3-SiO2 composite sol; (2), preparing raw mud materials of the yttrium silicate coating; (3), preparing the mullite coating; and (4), preparing the single-layer yttrium silicate coating or the multi-layered yttrium silicate coating. The C / SiC composite surface coating system has the characteristics of high densification and high temperature resistance, and the preparation method of the C / SiC composite surface coating system has engineering application universality.

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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