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Quick preparation method of wave-absorbing ceramic-based composite material with electromagnetic-impedance gradient matrix

A composite material and impedance gradual change technology, which is applied in the field of rapid preparation of wave-absorbing ceramic matrix composite materials, can solve the problems that limit the wide application of ceramic matrix composite materials, long process cycle, and increase the cost of material preparation, so as to achieve excellent oxidation resistance and improve The effect of microwave absorption performance and short preparation cycle

Active Publication Date: 2019-01-25
NORTHWESTERN POLYTECHNICAL UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

At the same time, in the densification process of ceramic matrix composites, the commonly used processes such as chemical vapor infiltration (CVI) and polymer impregnation pyrolysis (PIP) have a long cycle, which inevitably increases the cost of material preparation and limits the development of ceramic matrix composites. wider application of

Method used

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  • Quick preparation method of wave-absorbing ceramic-based composite material with electromagnetic-impedance gradient matrix
  • Quick preparation method of wave-absorbing ceramic-based composite material with electromagnetic-impedance gradient matrix

Examples

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Effect test

Embodiment 1

[0024] Example 1: Using two-dimensional laminated high-resistance SiC fibers with a fiber volume fraction of 35% as a preform, a uniform BN interface layer (with a thickness of 500 nm) was prepared on the inside / surface of the preform by the CVI method. Using propylene as the precursor gas, pyrolytic carbon was deposited on the prefabricated body with the interface layer by CVI method. The deposition temperature was 1000 °C and the deposition time was 500 h. Porous SiC with an open porosity of about 30% was prepared. f / C Composite. In the resulting SiC f The surface of the / C composite material is coated with industrial silicon powder with a particle size of 10 μm, placed in a vacuum furnace with an absolute pressure of 1000 Pa, and the temperature is raised to 1500 °C at a rate of 30 °C / min, and kept for 1 hour, so that the silicon is melted and infiltrated into the pores. SiC f / C composite material preform, and react with C matrix to form SiC, and then cool down to room ...

Embodiment 2

[0025] Example 2: Two-dimensional semi-transparent wave-type Si with a fiber volume fraction of 30% using the CVI process 3 N 4 A uniform BN interface layer (500nm in thickness) was prepared inside / on the surface of the fiber preform. Using phenolic resin as the organic precursor of C, the C matrix was prepared inside the prefabricated body with the interface layer prepared by the PIP process, and a porous Si with an open porosity of about 30% was obtained. 3 N 4f / C Composite. In the resulting Si 3 N 4f The surface of the / C composite material prefabricated body is coated with industrial silicon powder with a particle size of 10 μm, placed in a vacuum furnace with an absolute pressure of 1000 Pa, and the temperature is raised to 1500 °C at a heating rate of 30 °C / min, and kept for 1 hour to melt and infiltrate the silicon to porous Si 3 N 4f / C composite material preform, and react with C matrix to form SiC, and then cool down to room temperature at a rate of 10°C / min....

Embodiment 3

[0026] Example 3: Two-dimensional laminated wave-transparent Al with a fiber volume fraction of 45% using the CVI process 2 o 3 A uniform BN interface layer (500nm in thickness) was prepared inside / on the surface of the fiber preform. The preform with the BN interface layer was placed in a pyrolytic carbon deposition furnace, and the pyrolytic carbon matrix was prepared by the CVI method at 1000 °C with methane as the precursor gas to obtain porous two-dimensional Al 2 o 3f The prefabricated body of / C composite material has a porosity of about 35vol.%, which is ultrasonically cleaned and dried for use. In the resulting SiC f The surface of the / PyC composite preform is coated with industrial silicon powder with a particle size of 20 μm, placed in a vacuum furnace with an absolute pressure of 1000 Pa, and the temperature is raised to 1500 °C at a heating rate of 30 °C / min, and the temperature is kept for 0.5 h to melt the silicon. Infiltrated into porous Al 2 o 3f / C pre...

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Abstract

The invention relates to a quick preparation method of a wave-absorbing ceramic-based composite material with an electromagnetic-impedance gradient matrix. The quick preparation method comprises the following steps of firstly adopting a CVI (Chemical Vapor Infiltration) or PIP (Polymer Infiltration and Pyrolysis) process to prepare a porous carbon-based composite material, then adopting an RMI (Reactive Melt infiltration) process to obtain a C-SiC-based composite material, finally adopting a nitriding process to transform residual Si in the composite material into Si3N4, and obtaining the wave-absorbing ceramic-based composite material, wherein the phase composition of the matrix is C, SiC and Si3N4 from inside to outside, and the matching property with electromagnetic impedance of a freespace is gradually improved; the phase composition of the matrix is Si3N4, SiC and C from outside to inside, and the loss capability to electromagnetic waves is gradually enhanced. The quick preparation method has the beneficial effects that the process controllability is strong, and compared with the CVI and PIP methods, the quick preparation method is short in preparation period and low in production cost. In the aspect of electromagnetic property of the composite material, the matching property of the matrix material with the impedance of the free space is gradually improved, the loss capability to the electromagnetic waves from outside to inside is gradually enhanced, so that the benefit to improving the wave-absorbing property of the composite material is achieved.

Description

technical field [0001] The invention belongs to a method for preparing a ceramic-based composite material, and relates to a rapid preparation method for a wave-absorbing ceramic-based composite material with an electromagnetic impedance gradient matrix. Background technique [0002] Ceramic matrix composites are widely used as high-temperature structural materials for advanced equipment due to their good mechanical properties, thermophysical properties, and environmental performance. With the development of aerospace and military technology, radar stealth technology has become the key to improving the overall performance of equipment, and it is imperative to develop microwave-absorbing ceramic matrix composites. [0003] The two principles for ceramic matrix composites to have excellent wave-absorbing performance are: (1) matching the electromagnetic impedance of free space; (2) strong electromagnetic wave attenuation ability. That is, when the wave impedance of the materia...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/80C04B35/84C04B41/87
CPCC04B35/806C04B41/009C04B41/5066C04B41/87C04B2235/3826C04B2235/422C04B2235/5224C04B2235/524C04B2235/5244C04B41/4529
Inventor 叶昉殷小玮李明星莫然成来飞张立同
Owner NORTHWESTERN POLYTECHNICAL UNIV
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