Method for preparing SiCf/SiC compound material by combination of chemical vapor carbon deposition process and gas phase siliconizing process

Abstract

The invention discloses a method for preparing SiCf / SiC compound material by combination of a chemical vapor carbon deposition process and a gas phase siliconizing process, comprising the following steps: taking SiC fiber as a raw material, adopting three dimensional weaving technology to prepare SiC fibre-woven pieces; taking trichloromethyl silane as a deposition material and carrying out a primary chemical vapor deposition on the SiC fibre-woven pieces with thickness of deposited SiC coating being 0.1-70 mum; then taking methane or propylene gas as a raw material and carrying out carbon deposition on SiC fibre-woven pieces by a secondary chemical vapor deposition, thus obtaining SiCf / C midbody; finally, taking simple substance silicon as a raw material and carrying out siliconizing on the SiCf / C midbody by the gas phase siliconizing process, thus obtaining the SiCf / SiC compound material. The method of the invention has the advantages of short preparation cycle and low cost, thus being capable of preparing SiCf / SiC composite material featuring high compactness, high mechanical property and thermal conduction.

Description

technical field [0001] The invention relates to a method for preparing SiC-based composite materials, in particular to a method for preparing SiC by combining chemical vapor deposition carbon and vapor phase siliconizing process f / SiC composite method. Background technique [0002] Due to the bonding characteristics of its molecular structure, SiC ceramics lack plastic deformation ability and are brittle, which seriously affects their application as structural materials. SiC ceramics are reinforced with SiC fibers. During the fracture process, the material absorbs energy through mechanisms such as crack deflection, fiber breakage, and fiber pull-out, which enhances the strength and toughness of the material. [0003] SiC f / SiC composite material is the most ideal new-generation high-temperature structural material in the fields of aerospace and atomic energy. It has high strength, high rigidity, high hardness, wear resistance, corrosion resistance, high temperature oxida...

AI Technical Summary

Problems solved by technology

SiC prepared by CVI process f The β-SiC / SiC composite material has high purity and crystallinity and good radiation resistance, but its main disadvantage is that the prepared composite material has a porosity of 10% to 15%, which reduces the mechanical properties and resistance of the composite material. Oxidation performance, at the same time, the densification speed of SiC matrix is ​​low, the preparation cycle is long, and the cost is high

Compared with the CVI process, the PIP process is simple, low in cost, and allows the preparation of large and complex-shaped components, but there are still disadvantages such as high porosity, low crystallinity of the SiC matrix, and poor radiation resistance.

The HP process can obtain high-density composite materials, but the high temperature and high pressure environment is easy to cause damage to SiC fibers, resulting in SiC f / SiC composite material performance is not high

SiC prepared by NITE process f Although the / SiC composite material can achieve high density and crystallinity, and has good chemical stability, the impurity content is high and the distribution is uneven. SiC fibers are prone to chemical reactions with the matrix, which leads to the inability of the material to be completely dense and reach the stoichiometric ratio. , affecting thermal conductivity and radiation performance

The RS process cycle is short, the equipment requirements are relatively low, and the cost is low. It can realize the preparation of completely dense, high thermal conductivity, near-net shape and complex shape components; however, the RS process mainly forms a carbon frame structure with certain pores first. Then by reacting with silicon at high temperature, the carbon is converted into SiC. The existing RS process almost all adopts the method of liquid phase siliconizing. Because the molten silicon enters the pores under capillary action, it is easy to block and cause defects, which makes the material performance Poor performance

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