Preparing method for low-heat-conductivity SiCN-Y2SiO5 environment blocking composite coating

Abstract

The invention relates to a preparing method for a low-heat-conductivity SiCN-Y2SiO5 environment blocking composite coating. The preparing method comprises the steps that ceramic aggregate powder Y2SiO5 and SiCN are mixed and then dispersed into an isopropyl alcohol solvent to obtain a uniform suspension; then, a mixture binding agent is added, and it is ensured that the binding agent is fully dissolved and mixed in the suspension; finally, the electrospinning technique and supersonic speed plasma spraying are combined to prepare the SiCN-Y2SiO5 environment blocking composite coating. Compared with the prior art, the SiCN-Y2SiO5 environment blocking composite coating has advantages of high interface bonding performance and low heat conductivity, the uniform multi-phase SiCN-Y2SiO5 environment blocking composite coating is obtained, and heat treatment in a later stage is not needed.

Description

technical field [0001] The invention relates to a preparation method of a polymer precursor ceramic outer coating, in particular to a low thermal conductivity SiCN-Y 2 SiO 5 Preparation method of environmental barrier composite coating. 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 composite material will rapidl...

AI Technical Summary

Problems solved by technology

Although the preparation of C / SiC composite environmental barrier coatings by single atmospheric plasma spraying technology can control and prepare lamellar structure, there is a certain porosity in the coating, but the specific pore structure, uniform distribution and pore size are difficult to control. It is impossible to control the thermal conductivity and compactness 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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