Method for preparing microstructural interlayer interface Mullite/yttrium silicate complex coating

Abstract

The invention relates to a method for preparing a microstructural interlayer interface Mullite / yttrium silicate complex coating. The method comprises the steps that mullite fibers are ball-milled into powder, and the powder is dispersed into 1-methyl pyrrolidone to obtain an even suspension; a mixed adhesive is added to be mechanically stirred to be uniform, the mixture is injected to the surface of a C / SiC composite with a Si boding layer, and a mullite porous coating is obtained through sintering; yttrium nitrate hexahydrate and ethyl orthosilicate are taken to be dissolved in deionized water to obtain sol, the mullite porous coating is spin-coated with the sol after heat dipping, and repeated heat dipping-heat treatment is carried out to obtain the dense Mullite / yttrium silicate environmental barrier complex coating. Compared with the prior art, the method has the advantages that micropores are evenly distributed, interface binding is good, and crack growth is resisted.

Description

technical field [0001] The invention relates to a preparation method of a composite environmental barrier coating, in particular to a preparation method of a Mullite / yttrium silicate composite coating at the interface of a microstructure structure intermediate layer. Background technique [0002] Carbon fiber reinforced silicon carbide ceramic matrix composites (C / SiC, CMCs) is a new type of high-performance composite material. Since the 1970s, it has become a new hotspot in the field of structural materials research. C / SiC composite material has the following two advantages: on the one hand, the introduction of continuous carbon fiber improves the toughness of the composite material; Material. It has been more and more widely used in military and civil important fields, such as high-temperature parts of aero-engines, high-speed brake materials, rocket nozzles, thermal protection systems of space shuttles, first-wall materials of nuclear reactors, etc. However, the C / SiC c...

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Problems solved by technology

Although the preparation of C / SiC composite environmental barrier coatings by atmospheric plasma spraying technology can control and prepare lamellar structure, the coating has good adhesion, but there is a certain porosity in the coating, and the uniformity and composition of the coating are difficult. control, it is impossible to achieve multi-phase composite and densification of the coating; at the same time, due to the existence of thermal stress, vertical cracks appear in the coating, which will be detrimental to the later performance of the coating

The coating prepared by chemical vapor deposition needs to be carried out at a high temperature of 900-1200 ° C, and the deposition efficiency is low, the cost is high, the composition of the coating is difficult to control, and the exhaust gas is difficult to recycle.

The surface of the outer coating prepared by the sol-gel method is prone to cracking and the coating thickness is insufficient and the shortcomings of high temperature heat treatment in the later stage

However, the preparation of the coating by the slurry coating method still has the disadvantages of repeated spin coating and cannot be completed at one time, and requires post-heat treatment.

Similarly, although the magnetron sputtering method and the electron beam physical vapor deposition method have prepared environmental barrier coatings, the deposition efficiency of this process is low, requiring the preparation of the target material in the early stage, which requires high equipment and is difficult to control. Environmental barrier performance still needs to be further improved

There is also a method of preparing a coating using a polymer precursor ceramic method. This method directly prepares a coating that will cause volume shrinkage of the coating and at the same time, the deposition efficiency of the coating is low and the compactness is poor.

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