Silicon carbide fibre-reinforced silicon carbide composite microwave-absorbing ceramic and preparation method thereof

Abstract

The invention discloses a silicon carbide fibre-reinforced silicon carbide composite microwave-absorbing ceramic. The microwave-absorbing ceramic consists of continuous silicon carbide fibre-reinforced silicon carbide composite material; wherein silicon carbide fibre cloth overlaid layer by layer is used as reinforcement; the silicon carbide fibre cloth is connected into a whole in a way of sewing with carbon fibres in Z direction; the band width, of which the reflectivity is lower than -8dB in frequency band of 8GHz to 18GHz, is 6.5 GHz to 10 GHz at normal temperature; and the density is lower than 2.1 / cm <3>. The method for preparing the microwave-absorbing ceramic comprises the following steps: weaving the continuous silicon carbide fibres into silicon carbide fibre plain cloth; sewing the plain cloth into a whole body in a Z direction by carbon fibres to prepare a preformed body; dipping, pyrolyzing and densifying the preformed body repeatedly by using precursor dipping and pyrolysis technology, thus obtaining the microwave-absorbing ceramic. The product provided by the invention has advantages of simple structure, wide absorbing frequency band, light weight, thin thickness, good mechanical property, etc.

Description

technical field [0001] The invention mainly relates to the field of radar wave-absorbing ceramics, in particular to a wave-absorbing ceramic made of single-layer structure silicon carbide composite material and a preparation method thereof. Background technique [0002] There are two main types of radar absorbing ceramic materials currently developed. One is a particle-reinforced ceramic material that uses ceramic particles as a radar absorber and is prepared by a hot-pressing process, such as Si / C / N ceramic particle-reinforced LAS glass, mullite, Si 3 N 4 and other ceramic materials, but these materials have the following disadvantages: 1) Dielectric properties are difficult to achieve gradient distribution, and the radar absorption frequency band is narrow; 2) Particle-reinforced ceramic materials have poor toughness and are prone to catastrophic failure; 3) Hot pressing process is difficult Preparation of large complex components. The other is SiC continuous fiber rein...

AI Technical Summary

Problems solved by technology

One is a particle-reinforced ceramic material that uses ceramic particles as a radar absorber and is prepared by a hot-pressing process, such as Si / C / N ceramic particle-reinforced LAS glass, mullite, Si 3 N 4 and other ceramic materials, but these materials have the following disadvantages: 1) Dielectric properties are difficult to achieve gradient distribution, and the radar absorption frequency band is narrow; 2) Particle-reinforced ceramic materials have poor toughness and are prone to catastrophic failure; 3) Hot pressing process is difficult Preparation of large complex components

[0004] The two radar absorbing ceramics disclosed above have excellent room temperature and high temperature broadband absorbing characteristics, but there are still the following deficiencies: 1) Before the preparation of the absorbing ceramics, it is necessary to optimize the design of the material structure parameters, and according to the optimized value The raw material silicon carbide fiber is modified, and the processing process is complicated; 2) The parameters of each functional layer of the wave-absorbing ceramics are many, and the parameters are difficult to control, and it is difficult to achieve the expected value

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