Surface coating system of fiber reinforced ceramic matrix composite material and preparation method therefor

Abstract

The present invention provides a surface coating system of fiber reinforced ceramic matrix composite material, wherein the surface coating system is arranged on the substrate surface of the fiber reinforced ceramic matrix composite material and comprises a Sic coating layer, a mullite coating layer and a yttrium silicate coating layer laid in order from bottom to top. The preparation method comprises the following steps of preparing sludge raw materials of the Sic coating layer, the mullite coating layer and the yttrium silicate coating layer respectively, and preparing the Sic coating layer, the mullite coating layer and the yttrium silicate coating layer. The present invention is used for the surface coating system of the fiber reinforced ceramic matrix composite material, has the advantages of high density, high temperature resistance and anti-oxidation.

Description

technical field [0001] The invention relates to the field of high temperature resistant fiber-reinforced ceramic matrix composite materials, relates to a surface coating system of fiber-reinforced ceramic matrix composite materials and a preparation method thereof, in particular to a new type of coating for protecting C / SiC, SiC / SiC, C A three-layer high-temperature-resistant and anti-oxidation coating for composite materials such as / C and a preparation method thereof. Background technique [0002] Fiber-reinforced ceramic matrix composite materials represented by carbon fiber-reinforced silicon carbide (C / SiC), silicon carbide fiber-reinforced silicon carbide (SiC / SiC), and carbon fiber-reinforced carbon (C / C) composite materials have high specific strength and specific modulus It is considered as a strategic thermal structural material and has broad application prospects in aerospace, transportation, energy, chemical and other fields. [0003] As thermal structural mater...

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

Although this solution can avoid the problem of cracking or peeling off of the yttrium silicate outer coating caused by the oxidation of the SiC inner coating, it also exposes some shortcomings: (1) Due to the limitation of the sol synthesis technology, it is currently impossible to directly synthesize Stone stoichiometric ratio (Al 2 o 3 / SiO 2 Al with a mass ratio of 2.13:1 to 3.55:1) 2 o 3 -SiO 2 Sol, currently available Al of sol 2 o 3 / SiO 2 The highest mass ratio is only 2:1, and the conversion is surplus SiO 2 of mullite, these surplus SiO 2 Above 1450°C, it will cause carbothermal reduction reaction with free carbon in the composite material and destroy the coating. In an environment with high temperature water vapor, there will be a surplus of SiO 2 It also reacts to form gaseous Si(OH) 4 And rapid loss; (2) affected by Al 2 o 3 -SiO 2 Due to the influence of sol film-forming properties, cohesiveness and solid content, the density and adhesion of mullite coating are not ideal enough, and the preparation efficiency is low

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