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Method for preparing wave-transparent bn fiber-reinforced si-b-n ceramic matrix composites by cvd/cvi method

A fiber toughening and composite material technology is applied in the field of wave-transmitting BN fiber toughening Si-B-N ceramic matrix composite materials prepared by CVD/CVI method, which can solve the problem of fiber and matrix modulus and thermophysical properties mismatch, wave transmission Type CFCC lacks interface control, and the cracks and pores are not continuous and dense enough to achieve the effects of regulation and optimization, wave transmission properties and mechanical properties, and improvement of thermophysical properties mismatch.

Active Publication Date: 2021-04-02
NORTHWESTERN POLYTECHNICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In order to avoid the deficiencies of the prior art, the present invention proposes a CVD / CVI method for preparing wave-transparent BN fiber-reinforced Si-B-N ceramic matrix composites, which solves the problem of cracks and cracks in the wave-transparent CFCC matrix prepared by the current PIP method. Pores are not continuous and compact enough, material performance is limited, wave-transparent CFCC prepared by CVD / CVI method lacks interface control, fiber and matrix modulus and thermophysical properties mismatch, and material properties need to be improved urgently, etc.

Method used

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  • Method for preparing wave-transparent bn fiber-reinforced si-b-n ceramic matrix composites by cvd/cvi method
  • Method for preparing wave-transparent bn fiber-reinforced si-b-n ceramic matrix composites by cvd/cvi method
  • Method for preparing wave-transparent bn fiber-reinforced si-b-n ceramic matrix composites by cvd/cvi method

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Experimental program
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Effect test

Embodiment 1

[0034] Step 1. Pretreatment of BN fiber preform. Divide 20 flat sheets into 10×10cm 2 The BN fiber cloth is soaked in xylene for 48 hours, then washed three times with xylene and three times with alcohol, and finally dried at 80°C to remove the adhesive layer.

[0035] Step 2. Preparation of BN interface. Lay the degummed BN fiber cloth in a graphite fixture to form a two-dimensional prefabricated body, and hang the prefabricated body in the isothermal zone of the deposition furnace. The deposition process parameters of the BN interface are: BCl 3 The flow rate is 100ml / min, NH 3 The flow rate is 300ml / min, H 2 The flow rate is 500ml / min, the Ar flow rate is 500ml / min, the furnace pressure is 1kPa, the deposition temperature is 650°C, the deposition time is 50h, and the thickness of the BN interface is 1500nm. Then, the BN fiber preform containing the BN interface was placed in a high temperature furnace for heat treatment, the treatment temperature was 1300°C, and the tr...

Embodiment 2

[0039] Step 1. Pretreatment of BN fiber preform. Entrust the fiber weaving unit to weave BN fiber bundles into a fiber prefabricated body with a two-dimensional and a half structure. Soak the two-dimensional semi-BN fiber prefabricated body in xylene for 48 hours, wash it three times with xylene and three times with alcohol, and finally dry it at 80°C to remove the glue layer.

[0040] Step 2. Preparation of BN interface. Hang the degummed two-dimensional semi-BN fiber preform in the isothermal zone of the deposition furnace. The deposition process parameters of the BN interface are: BCl 3 The flow rate is 100ml / min, NH 3 Flow rate is 300ml / min, Ar flow rate is 500ml / min, H 2 The flow rate is 500ml / min, the pressure in the furnace is 1kPa, the deposition temperature is 650°C, the deposition time is 40h, and the interface thickness of the prepared BN is 1000nm. Then, the BN fiber preform containing the BN interface was placed in a high temperature furnace for heat treatmen...

Embodiment 3

[0044] Step 1. Pretreatment of BN fiber preform. Entrust the fiber weaving unit to weave BN fiber bundles into a fiber prefabricated body with a three-dimensional four-way structure. Soak the three-dimensional four-way BN fiber prefabricated body in xylene for 48 hours, then wash it three times with xylene and three times with alcohol, and finally dry it at 80°C to remove the glue layer.

[0045] Step 2. Preparation of BN interface. Hang the three-dimensional four-directional BN fiber preform after degumming in the isothermal zone of the deposition furnace. The deposition process parameters of the BN interface are: BCl 3 The flow rate is 100ml / min, NH 3 Flow rate is 300ml / min, Ar flow rate is 500ml / min, H 2 The flow rate is 500ml / min, the pressure in the furnace is 1kPa, the deposition temperature is 750°C, the deposition time is 15h, and the interface thickness of the prepared BN is 800nm. Then, the BN fiber preform containing the BN interface was placed in a high temper...

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Abstract

The invention relates to a method for preparing a wave-transmitting BN fiber toughened Si-B-N ceramic-based composite material through CVD / CVI method. First, a uniform, continuous BN interface with aspecific thickness is prepared in a pretreated BN fiber preform through CVD / CVI method; then, a reaction gas proportion of an Si source, a B source and an N source in a precursor system is controlledin a proper temperature arrange so as to prepare an Si-B-N substrate with a multi-layer component gradient structure in the BN fiber preform with the BN interface through CVD / CVI method, components ofeach layer of substrate are in gradient distribution, the content of Si increases gradually and the content of B decreases gradually from the BN interface to a composite material surface; and finally, a uniform, continuous Si3N4 coating with a specific thickness is prepared on the composite material surface through CVD / CVI method. The method prepares the wave-transmitting BNf / Si-B-N composite material with controllable dielectric and mechanical properties.

Description

technical field [0001] The invention relates to a method for preparing a wave-transparent BN fiber toughened Si-B-N ceramic matrix composite material by a CVD / CVI method, in particular to a method for preparing a wave-transparent continuous BN fiber by chemical vapor deposition / infiltration (CVD / CVI) A method for toughening multilayer compositionally graded Si-B-N ceramic matrix composites. Background technique [0002] The high-speed aircraft head radome is a high-temperature wave-transmitting component, which faces harsh thermal environments such as high temperature, high pressure, vibration and shock, so high requirements are placed on the radome material. In order to meet the dual requirements of high-speed flight and precise guidance at the same time, the radome material generally needs to meet the following conditions: low dielectric constant (generally should be less than 10), low thermal expansion coefficient, good mechanical properties, thermal shock resistance, par...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/80C04B35/591C04B41/87
CPCC04B35/803C04B35/591C04B41/5066C04B41/87C04B2235/386C04B2235/75C04B41/4531C04B41/4529
Inventor 叶昉刘永胜李建平程赞粼李明星成来飞张立同
Owner NORTHWESTERN POLYTECHNICAL UNIV
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