Vortex auxiliary system and method for preparing fiber reinforced composite material by chemical vapor infiltration method

A chemical vapor infiltration and composite material technology, applied in the field of eddy current auxiliary system and preparation, can solve the problems of increasing sample thickness, destroying the integrity of mechanical properties, and unable to deposit cylindrical samples with higher thickness, so as to achieve increased compactness and uniform density properties, increased gas diffusion kinetic energy, and increased material density

Pending Publication Date: 2022-03-04
NORTHWESTERN POLYTECHNICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Cylindrical samples with higher thickness cannot be deposited by traditional laminar flow uniform hole mold rectification method, premature sealing time, difficult to adjust process parameters, etc. will have a negative impact on the CVI process
As a result, this method can only reach a penetration depth of 2-5mm
[0004] Chinese patent application CN 105367105A discloses a method for preparing thick-walled ceramic matrix composites with mechanical processing assisted CVI. The method drills holes in the thickness direction of the sample and expands the diffusion and mass transfer channels of the airflow to increase the thickness of the sample (greater than 5mm), but this method damages the integrity of ceramic matrix composites and cannot meet the requirements for the preparation of large components.
Although the subsequent diversion holes will be filled and densified by fibers, the drilling will still destroy the integrity of the original prefabricated mechanical properties

Method used

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  • Vortex auxiliary system and method for preparing fiber reinforced composite material by chemical vapor infiltration method
  • Vortex auxiliary system and method for preparing fiber reinforced composite material by chemical vapor infiltration method
  • Vortex auxiliary system and method for preparing fiber reinforced composite material by chemical vapor infiltration method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0068] Example 1. Eddy-current-assisted CVI co-deposition of carbon-rich C / Cx-SiCy composites for densification.

[0069] Step 1: Prepare a 2.5D needle-punched carbon felt (density 0.41g / cm3) preform into a hollow cylinder with an outer diameter of 42mm, an inner diameter of 18mm, and a height of 70mm.

[0070] Step 2: Assemble the mold according to the order of gas inlet, auxiliary vortex platform, deposition chamber, and gas outlet, put the preform into it, and place it in a high-temperature vacuum furnace. Deposit the preform according to the following process parameters: deposition temperature 1100°C, atmospheric pressure 5000Pa, methane: 20ml / min, hydrogen 200ml / min, carrier gas hydrogen 16ml / min, argon 600ml / min, the molar mass ratio of hydrogen to MTS is 10:1. Deposit for 50h, then cool down naturally, repeat 2 times. The preform was removed from the graphite mold to obtain 0.58 g / cm 3 C / Cx-SiCy composites.

[0071] Step 3: Grind the outer surface of the composite ...

Embodiment 2

[0075] Example 2. Eddy-current-assisted CVI co-deposition of silicon-rich C / Cx-SiCy composites for densification.

[0076] Step 1: Prepare a 2.5D needle-punched carbon felt (density 0.41g / cm3) preform into a hollow cylinder with an outer diameter of 45mm, an inner diameter of 6mm, and a height of 70mm.

[0077] Step 2: Assemble the mold according to the order of gas inlet, auxiliary vortex platform, deposition chamber, and gas outlet, put the preform into it, and place it in a high-temperature vacuum furnace. Deposit the preform according to the following process parameters: deposition temperature 1150°C, atmospheric pressure 3500Pa, methane: 20ml / min, hydrogen 300ml / min, carrier gas hydrogen 10ml / min, argon 450ml / min, the molar mass ratio of hydrogen to MTS is 10:1. Deposit for 60h, then cool down naturally, repeat 2 times. The preform was removed from the graphite mold to obtain a 0.45 g / cm3 C / Cx-SiCy composite.

[0078] Step 3: Grinding the outer surface of the composit...

Embodiment 3

[0082] Example 3. Cylindrical co-deposited carbon-rich C / Cx-SiCy composites were prepared by traditional CVI method.

[0083] Step 1: Prepare the 2.5D needle-punched carbon felt (density 0.41g / cm3) preform into a hollow cylinder with an outer diameter of 40mm, an inner diameter of 18mm, and a height of 70mm.

[0084] Step 2: Assemble the mold according to the order of gas inlet, traditional CVI rectification hole deposition platform, deposition chamber, and gas outlet, put the preform into it, and place it in a high-temperature vacuum furnace. Deposit the preform according to the following process parameters: deposition temperature 1100°C, atmospheric pressure 5000Pa, methane: 20ml / min, hydrogen 200ml / min, carrier gas hydrogen 16ml / min, argon 600ml / min, the molar mass ratio of hydrogen to MTS is 10:1. Deposit for 52h, then cool down naturally, repeat 2 times. The preform was removed from the graphite mold to obtain 0.49 g / cm 3 C / Cx-SiCy composites.

[0085] Step 3: Grind ...

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Abstract

The invention relates to a vortex auxiliary system for preparing a fiber reinforced composite material by a chemical vapor infiltration method and a preparation method, when a ceramic matrix composite material is prepared by using a conventional CVI (Chemical Vapor Infiltration) mode, an inner layer vortex and an outer layer vortex are constructed through the vortex auxiliary system, so that gas has an initial velocity of moving towards the inside of a fiber preform when passing through the surface of the fiber preform. Therefore, in the densification process, gas diffusion power has vortex flow diffusion power. Meanwhile, a vortex-assisted deposition mode is used, and a mode of removing an outer side hole sealing layer by mechanical processing is also used, so that the compactness and density uniformity of the composite material prepared by the CVI are improved, the diffusion depth of about 10mm can be realized, the preparation of the large-size ceramic matrix composite material is realized, and the relative density reaches more than 90%.

Description

technical field [0001] The invention belongs to the field of chemical vapor infiltration (CVI) preparation in the field of ceramic matrix composite materials, and relates to an eddy current auxiliary system and a preparation method for preparing fiber reinforced composite materials by chemical vapor infiltration. When using the conventional CVI method to prepare ceramic matrix composites, the reaction gas is introduced into the deposition chamber by constructing two layers of eddy currents inside and outside, so that the gas has an initial velocity when passing through the surface of the fiber preform. Therefore, in addition to the conventional "concentration diffusion", the gas diffusion dynamics in the densification process also have the "flow diffusion" dynamics of eddy currents. This method not only increases the compactness and density uniformity of the composite material prepared by CVI, but also realizes a diffusion depth of about 10mm, and realizes the preparation of l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C16/455C23C16/32C04B35/52C04B35/622C04B35/80
CPCC23C16/325C23C16/455C04B35/80C04B35/52C04B35/622C04B2235/5244C04B2235/77C04B2235/6567
Inventor 郭领军刘宁坤李贺军黎云玉钟磊王建成李凯娇
Owner NORTHWESTERN POLYTECHNICAL UNIV
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