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Method for in-situ growth of silicon carbide nanowires by adopting non-catalytic precursor impregnation and pyrolysis method

A silicon carbide nanowire, dipping and cracking technology, applied in the direction of additive processing, etc., can solve the problems that have not been reported, it is difficult to grow SiCNWs, reduce the supersaturation of necessary gas phase substances, etc., achieve strong controllability, and achieve uniform growth , Improve the effect of gas phase supersaturation

Active Publication Date: 2020-05-29
NORTHWESTERN POLYTECHNICAL UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The "one-step" reaction process not only generates the necessary gas-phase substances required for the growth of SiCNWs, but also generates a large amount of unnecessary gas-phase substances. The existence of these unnecessary gas-phase substances greatly reduces the supersaturation of the necessary gas-phase substances, so the "one-step method" "It is difficult to realize the growth of SiCNWs without catalytic PIP
At the same time, the team also noticed that the pore structure of the substrate has a great influence on the supersaturation of the gas phase. We previously developed a spray granulation combined with 3D printing to prepare SiC with two-stage pore structure. W The method of preform (CN108706978A), on this basis, it is found through research that this SiC W The two-stage pore structure of the preform is beneficial to increase the supersaturation of the gas phase, and the relevant knowledge has not been reported so far

Method used

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  • Method for in-situ growth of silicon carbide nanowires by adopting non-catalytic precursor impregnation and pyrolysis method
  • Method for in-situ growth of silicon carbide nanowires by adopting non-catalytic precursor impregnation and pyrolysis method
  • Method for in-situ growth of silicon carbide nanowires by adopting non-catalytic precursor impregnation and pyrolysis method

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Experimental program
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Effect test

preparation example Construction

[0037] Step 1. Two-stage Porosity SiC W Preform preparation:

[0038] Mix deionized water and dextrin according to 9:1 and magnetically stir for 0.5~1h to obtain a deionized aqueous solution of dextrin, and SiC W 40-70wt.% by mass fraction, 0-2wt.% by mass fraction of polyethylene glycol-400 (PEG-400), 0-3.5wt.% by mass fraction of tetramethylammonium hydroxide (TMAH) and dextrin The deionized aqueous solution is mixed and put into a ball milling tank, and the ball milling tank is put into a roller ball mill and ball milled at a speed of 20-70r / min for 2-30h. The uniformly mixed slurry obtained is used for spray granulation. The air inlet temperature of the spray dryer is between 200-300°C, the outlet temperature is between 60-100°C, and the atomizer speed is between 300Hz-400Hz. The feed rate is 0.1 ~ 1ml / s, thus SiC can be prepared W spherical particles. Then the SiC W The spherical particles are fed into the 3D printing equipment for printing, the layer thickness is se...

Embodiment 1

[0046] Step 1: Two-stage porosity SiC W Preparation of preforms. Mix 92g deionized water and 10.2g dextrin with magnetic stirring for 0.5h, then mix 180g SiC W , 5.7g PEG-400, 6.5g TMAH and the deionized aqueous solution of dextrin are mixed and put into a ball mill jar, and then the ball mill jar is put into a drum-type ball mill and ball milled at a speed of 50r / min for 36h to obtain a uniformly mixed slurry, and then The slurry is introduced into the spray dryer, the inlet temperature is 200°C, the outlet temperature is 70°C, and the atomizer speed is 400Hz, thus SiC can be prepared W Spherical particles 140g. 140g SiC W Put the spherical particles into the 3DP molding equipment, set the printing layer thickness to 0.1mm, and the binder saturation to 100% / 200%. After the printing is completed, place the SiC W The preform was taken out after drying in situ for 10 hours.

[0047] Step 2: Impregnation, curing and cracking of the precursor. 35g PCS and 70g xylene were mix...

Embodiment 2

[0050] Step 1: Two-stage porosity SiC W Preparation of preforms. Mix 99g deionized water and 11g dextrin with magnetic stirring for 0.5h, then mix 154g SiC W , 5.4g PEG-400, 6.5g TMAH and the deionized aqueous solution of dextrin are mixed and put into a ball mill jar, and then the ball mill jar is put into a drum type ball mill and ball milled at a speed of 50r / min for 30h to obtain a uniformly mixed slurry, and then The slurry is introduced into the spray dryer, the inlet temperature is 200°C, the outlet temperature is 70°C, and the atomizer speed is 400Hz, thus SiC can be prepared W Spherical particles 120g. 120g SiC WPut the spherical particles into the 3DP molding equipment, set the printing layer thickness to 0.1mm, and the binder saturation to 100% / 200%. After the printing is completed, place the SiC W The preform was taken out after drying in situ for 10 hours.

[0051] Step 2: Impregnation, curing and cracking of the precursor. 35g PCS and 70g xylene were mixed ...

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Abstract

The invention relates to a method for in-situ growth of silicon carbide nanowires by adopting a non-catalytic precursor impregnation and pyrolysis method. The method comprises the following steps: impregnating a PCS and xylene mixed solution into a SiCW preform, performing curing at 200 DEG C for 1 hour, and performing pyrolyzing at 900-1100 DEG C for 2 hours to obtain porous SiCW / SiC; and 3, performing heat treatment of porous SiCW / SiC: carrying out heat treatment on the porous SiCW / SiC at 1300-1500 DEG C for 2 hours, wherein the 'two-step method' refers to impregnation curing cracking and heat treatment. According to the method, unnecessary gas phases for growing the SiCNWs are removed by utilizing solidification and cracking; then a gas phase necessary for growing SiCNWs is released through heat treatment, the supersaturation degree of the necessary gas phase is greatly improved through the two-stage pore structure of the SiCNWs prefabricated body, and therefore PIP non-catalytic in-situ growth of the SiCNWs is achieved.

Description

technical field [0001] The invention belongs to the field of nanomaterial preparation, and relates to a method for growing silicon carbide nanowires in situ by a non-catalyzed precursor dipping and cracking method. Background technique [0002] Silicon carbide ceramic matrix composites (SiC-CMC) have broad application prospects in the aerospace field due to their excellent properties such as high strength, high modulus, good toughness, low density, high temperature resistance, wear resistance and corrosion resistance. SiC-CMC usually includes three structural units: reinforcement, interface, and matrix. The role of the reinforcement is to strengthen and toughen the ceramic matrix. At present, the reinforcements of SiC-CMC mainly include continuous fibers, chopped fibers, whiskers and particles. The reinforcements of SiC-CMC developed in the early stage are usually single-phase reinforcements, that is, one of the above-mentioned reinforcements is used. Along with the first s...

Claims

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Application Information

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IPC IPC(8): C04B35/80C04B35/573C04B35/571B33Y70/00B33Y80/00
CPCC04B35/573C04B35/571B33Y70/00B33Y80/00C04B2235/6026C04B2235/656C04B2235/6567C04B2235/6562C04B2235/6565C04B2235/526C04B2235/5264
Inventor 成来飞吕鑫元叶昉张立同
Owner NORTHWESTERN POLYTECHNICAL UNIV
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