Method for in-situ synthesis of SiC nanowires modified carbon/carbon composite preform by sol-gel method

A technology of sol-gel method and carbon composite materials, which is applied in the field of in-situ synthesis of SiC nanowire modified carbon/carbon composite material preforms by sol-gel method, which can solve the problems of carbon fiber damage and other problems, and achieve low cost and low decomposition temperature , Improve the effect of densification efficiency

Active Publication Date: 2014-09-10
NORTHWESTERN POLYTECHNICAL UNIV
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  • Abstract
  • Description
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Problems solved by technology

This method has an obvious disadvantage, that is, the preform needs to be repeatedly impregnated in the precursor solution and carbonized under high pressure in an inert atmosphe

Method used

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  • Method for in-situ synthesis of SiC nanowires modified carbon/carbon composite preform by sol-gel method
  • Method for in-situ synthesis of SiC nanowires modified carbon/carbon composite preform by sol-gel method
  • Method for in-situ synthesis of SiC nanowires modified carbon/carbon composite preform by sol-gel method

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Experimental program
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specific Embodiment

[0051] figure 1 As shown, the schematic diagram of the CVI deposition SiC nanowire modified carbon / carbon composite material prefabricated device, the position and connection relationship of each part are correct, the ratio is according to the amount, and the operation is performed in sequence.

[0052] In the furnace body 1, there are graphite gas pipes 2 and graphite molds 3 for deposition, carbon felt-silica gel 4 in the graphite mold, sealing rings 5 ​​and circulating water 6 for cooling at the upper and lower ends of the furnace body, and the furnace body The upper cover 7 and the lower cover 8 of the furnace body are hermetically connected with the furnace body through sealing bolts 10 . There is a thermocouple 9 in the constant temperature zone where the sample is placed in the middle of the furnace body to test the reaction temperature of the furnace body. The gas outlet of the furnace body is connected to the gas pipe 11, the vacuum gauge 18, and the vacuum pipe 12 t...

Embodiment 1

[0057] (1) 2D carbon felt (density about 0.3-0.4g / cm 3 ) cutting, shearing and grinding into regular and flat samples of 70×50×10 mm in size, and then placed in an oven and dried at 60°C for 10 hours for later use.

[0058] (2) Weigh 41.6 g of tetraethyl orthosilicate (TEOS) and place it in a beaker, add 19.2 g of absolute ethanol (ETOH) into the beaker, add a magnetic rotor and stir on a magnetic stirrer for 30 minutes, then add 7.2 g of deionized water g, continue magnetic stirring for 30 min. While stirring continuously, add hydrochloric acid solution dropwise to adjust the pH value to between 2.5-3.

[0059] (3) Cover the beaker with a plastic wrap, then place the solution in an oil bath stirring device and stir at 70° C. for 2 h. Then put it in an oven at 60°C to dry and gel for 24 hours, and use it as a sol impregnation solution for later use.

[0060] (4) Place the prepared carbon felt sample in the above-mentioned sol impregnation solution, and impregnate for 72 hou...

Embodiment 2

[0067] (1) 2D carbon felt (density about 0.3-0.4g / cm 3 ) cutting, shearing and grinding into regular and flat samples of 70×50×10 mm in size, and then placed in an oven and dried at 60°C for 10 hours for later use.

[0068] (2) Weigh 41.6g of tetraethyl orthosilicate (TEOS) and place it in a beaker, then add 19.2g of absolute ethanol (ETOH) into the beaker, add a magnetic rotor and stir on a magnetic stirrer for 30min, then add deionized water 7.2g, continue magnetic stirring for 30min. While stirring continuously, add hydrochloric acid solution dropwise to adjust the pH value to between 2.5-3.

[0069] (3) Cover the beaker with a plastic wrap, then place the solution in an oil bath stirring device and stir at 70° C. for 2 h. Then put it in an oven at 60°C to dry and gel for 24 hours, and use it as a sol impregnation solution for later use.

[0070] (4) Place the prepared carbon felt sample in the above-mentioned sol impregnation solution, and impregnate for 72 hours by soa...

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Abstract

The invention relates to a method for in-situ synthesis of a SiC nanowires modified carbon/carbon composite preform by a sol-gel method. Since a silica sol-gel system with a porous microstructure is firstly obtained by the sol-gel method, the contact area of the reaction is increased to a greater extent, and the grown nanowires have certain directionality, which is conductive to improving the mechanical properties of materials. The nanowires are immersed in a 2D carbon felt, the obtained silicon source capable of generating SiC nanowires is uniformly dispersed and has low decomposition temperature, the grown nanowires can be stably and uniformly dispersed in the carbon felt, and the efficiency of the densification can be greatly improved. The carbon sources provided by isothermal CVI process deposition natural gas and capable of generating SiC nanowires are reacted with silicon source to generate nanowires and a part of carbon sources are formed into pyrolytic carbon and coated on the surface of nanowires, and the phenomena of the falling, growing and breakage of nanowires occurring in the course of obtaining high-density C/C composite material by the subsequent densification are effectively avoided.

Description

technical field [0001] The invention belongs to the technical field of preparation of carbon / carbon composite material prefabricated body and application of sol-gel method for synthesizing nanowires, and relates to a method for in-situ synthesis of SiC nanowire modified carbon / carbon composite material prefabricated body by sol-gel method. Background technique [0002] As an advanced composite material, C / C composite material has dual characteristics of structural material and functional material. It has a series of excellent properties such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance, fatigue resistance, creep resistance, low density, electrical conductivity, heat transfer and small expansion coefficient. Fang attaches great importance to it and first applies it to the military and aerospace fields. At present, the liquid phase impregnation method is one of the only methods for preparing C / C composites. The principle...

Claims

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Application Information

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IPC IPC(8): C04B35/83
Inventor 李贺军林红娇瞿怀远霍俊豪郭领军史小红
Owner NORTHWESTERN POLYTECHNICAL UNIV
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