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

Abstract

The invention provides a surface coating system of a fiber-reinforced ceramic matrix composite material. The surface coating system is arranged on the substrate surface of the fiber-reinforced ceramic matrix composite material. The surface coating system includes SiC coating, Mo Stone coating and yttrium silicate coating. The preparation method includes preparation of mud raw material for SiC coating, preparation of mud raw material for mullite coating, preparation of mud raw material for yttrium silicate coating, preparation of SiC coating, preparation of mullite coating, preparation of yttrium silicate coating and other steps. The surface coating system used in the fiber-reinforced ceramic matrix composite material of the present invention has the advantages of high density, high temperature resistance, oxidation resistance and the like.

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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