Preparation method of silicon carbide fiber reinforced silicon carbide composite material

Abstract

The invention discloses a preparation method of a silicon carbide fiber reinforced silicon carbide composite material. The preparation method comprises the following steps of preparing a SiC fiber knitted piece, placing the SiC fiber knitted piece into a vacuum furnace to carry out chemical vapor deposition through adopting methane or propylene as feed gas and a pressure difference method to deposit a carbon coating on the surface of the SiC fiber knitted piece, carrying out a vacuum impregnation process on the SiC fiber knitted piece deposited with the carbon coating through adopting a liquid SiC ceramic precursor as impregnation liquid, putting the impregnated SiC fiber knitted piece into a mold, carrying out thermal molding crosslinking in a dynamic nitrogen atmosphere, putting the crosslinked SiC fiber knitted piece into a cracking furnace to carry out high temperature cracking in a dynamic nitrogen atmosphere, repeating a vacuum impregnation-thermal molding crosslinking-high temperature cracking cycle so as to finish preparation until the weight increment of a sample obtained after the vacuum impregnation-thermal molding crosslinking-high temperature cracking cycle is less than 1% of the weight increment of the sample obtained after the previous cycle. The preparation method has the advantages of short period, low cost, low pollution and toxic effects, etc.

Description

technical field [0001] The invention relates to the field of silicon carbide-based composite materials, in particular to a method for preparing a silicon carbide fiber-reinforced silicon carbide composite material. Background technique [0002] With the development of human science and technology, how to further improve the performance of structural materials has gradually become an important breakthrough to accelerate scientific and technological progress. The fatal weakness of SiC ceramic material, such as high brittleness and poor reliability, seriously hinders its practical application as a structural material. Silicon carbide fiber reinforced silicon carbide (SiC f / SiC) composites are prepared by adding SiC fibers to SiC ceramic materials as the second phase, which can absorb energy through mechanisms such as crack deflection, fiber breakage and fiber pull-out during the fracture process, and enhance the strength and toughness of the material. SiC f / SiC composite m...

AI Technical Summary

Problems solved by technology

However, the ceramic yield of the current ceramic precursors is not satisfactory. A large number of small molecules overflow during the cracking process, resulting in high porosity of the material and easy formation of closed pores; Large changes in medium density and large volume shrinkage directly lead to internal stress inside the material, which in turn induces micro-cracks, which is not conducive to the improvement and stability of material properties

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