Method for preparing SiC ceramic-based composite material from spongy silicon carbide nanofiber preform

Abstract

The invention discloses a method for preparing a SiC ceramic-based composite material from a spongy silicon carbide nanofiber preform. The method comprises: filling a glass tube with a spongy SiCnf material, and pre-compressing the spongy SiCnf material by external force to obtain a pre-compressed body; soaking the pre-compressed body in a low-concentration phenolic resin solution, taking out the pre-compressed body after soaking, drying the pre-compressed body to be half-dry, putting the pre-compressed body into a mold, carrying out pressing, drying, cracking, and repeating for multiple times; carrying out vacuum impregnation with a PCS solution, taking out the product, carrying out drying and cracking, and repeating for multiple times; after completely cooling, carrying out vacuum impregnation with a high-concentration phenolic resin solution, carrying out drying and cracking, and repeating for multiple times; and placing the above in a crucible, uniformly covering the surface with Si powder, and then firing. According to the invention, the characteristics of high strength, wear resistance, corrosion resistance and the like of SiC ceramic are retained, and the composite material also has the advantages of low density, high toughness and stable high-temperature performance, so that preparation of the SiCnf / SiC composite material with high volume fraction, high compact network structure, low porosity and low residual silicon is realized, and the composite material has excellent mechanical properties of a SiCnf reinforcement.

Description

technical field [0001] The invention relates to a method for preparing a silicon carbide composite material, in particular to a method for preparing a SiC ceramic matrix composite material from a spongy silicon carbide nanofiber prefabricated body. Background technique [0002] Compared with continuous SiC ceramic fibers, silicon carbide nanofibers (SiCnf) have a single crystal structure, high tensile strength and elastic modulus, and are an ideal reinforcement. At present, SiCnf is mainly introduced into the ceramic matrix as a second reinforcement, and is compounded by in-situ growth on the surface of SiCf / Cf or in the pores of the ceramic to strengthen and toughen the micro-region matrix and improve the matrix's ability to resist crack growth. [0003] The biggest disadvantage of SiC ceramics is its high brittleness and poor thermal shock resistance, which limit its application in the field of thermal structural materials. The defects of high brittleness of SiC ceramic m...

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Problems solved by technology

However, SiCnf / SiC ceramic matrix composites prepared by in-situ growth method have a small volume content of SiCnf, the interface between SiCnf and the matrix is ​​difficult to control, the growth of SiCnf is affected by the size and distribution of pores or gaps, and composite materials often have a "bridging" effect. , it is difficult to fully reflect the excellent mechanical properties of SiC

There are few reports on high volume fraction, high density single crystal SiCnf reinforced SiC ceramic composites

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