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Method for in situ growth of silicon carbide nanowires by immersion cracking method without catalytic precursors

A silicon carbide nanowire, dipping and cracking technology, applied in the direction of additive processing, 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 large pore space, improve gas phase process The effect of saturation and high aspect ratio

Active Publication Date: 2022-06-07
NORTHWESTERN POLYTECHNICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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 immersion cracking method without catalytic precursors
  • Method for in situ growth of silicon carbide nanowires by immersion cracking method without catalytic precursors
  • Method for in situ growth of silicon carbide nanowires by immersion cracking method without catalytic precursors

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Experimental program
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Effect test

preparation example Construction

[0037] Step 1. Two-stage Porous SiC W Preparation of preforms:

[0038] The deionized water and dextrin were mixed magnetically at a ratio of 9:1 for 0.5 to 1 h to obtain a deionized aqueous solution of dextrin. W By mass fraction 40~70wt.%, polyethylene glycol-400 (PEG-400) by mass fraction 0~2wt.%, tetramethylammonium hydroxide (TMAH) by mass fraction 0~3.5wt.% and dextrin The deionized aqueous solution is mixed and put into a ball mill tank, and the ball mill tank is put into a drum ball mill for ball milling at a speed of 20 to 70 r / min for 2 to 30 hours. The obtained uniformly mixed slurry is used for spray granulation. The inlet air temperature of the spray dryer is between 200 and 300°C, the outlet temperature is between 60 and 100°C, and the rotational speed of the atomizer is between 300Hz and 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 sent to the 3D printing equipment for printin...

Embodiment 1

[0045] Step 1: Two-stage Porous SiC W Preparation of preforms. Mix 92g deionized water and 10.2g dextrin with magnetic stirring for 0.5h, and then mix 180g SiC W , 5.7g PEG-400, 6.5g TMAH and the deionized aqueous solution of dextrin were mixed and put into the ball mill, and then the ball mill was put into the drum ball mill at a speed of 50r / min for 36h to obtain a uniformly mixed slurry. The slurry is introduced into the spray dryer, the inlet temperature is 200 °C, the outlet temperature is 70 °C, and the speed of the atomizer is 400 Hz, so that SiC can be prepared. W Spherical particles 140g. 140g SiC W The spherical particles are put into the 3DP molding equipment, the printing layer thickness is set to 0.1mm, and the binder saturation is 100% / 200%. W The preform was dried in situ for 10 h and taken out.

[0046] Step 2: Impregnation, solidification and cracking of precursors. Mix 35g PCS and 70g xylene and stir magnetically for 30min to obtain a xylene solution of...

Embodiment 2

[0049] Step 1: Two-stage Porous SiC W Preparation of preforms. Mix 99g deionized water and 11g dextrin with magnetic stirring for 0.5h, and then mix 154g SiC W , 5.4g PEG-400, 6.5g TMAH and the deionized aqueous solution of dextrin were mixed and put into the ball mill tank, and then the ball mill tank was put into the drum ball mill and ball milled at a speed of 50r / min for 30h to obtain a uniformly mixed slurry. The slurry is introduced into the spray dryer, the inlet temperature is 200 °C, the outlet temperature is 70 °C, and the speed of the atomizer is 400 Hz, so that SiC can be prepared. W Spherical particles 120g. 120g SiC WThe spherical particles are put into the 3DP molding equipment, the printing layer thickness is set to 0.1mm, and the binder saturation is 100% / 200%. W The preform was dried in situ for 10 h and taken out.

[0050] Step 2: Impregnation, solidification and cracking of precursors. Mix 35g PCS and 70g xylene and stir magnetically for 30min to obta...

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Abstract

The invention relates to a method for in-situ growth of silicon carbide nanowires by impregnating and cracking method of non-catalyzed precursors, in which PCS and xylene mixed solution is impregnated into SiC W In the preform, cure at 200°C for 1 hour, and crack porous SiC at 900-1100°C for 2 hours W / SiC; 3. Porous SiC W / SiC heat treatment: the porous SiC W / SiC is heat treated at 1300-1500°C for 2 hours, and the "two-step method" refers to immersion, curing, cracking and heat treatment. The present invention uses solidification and cracking to first remove the unnecessary gas phase for growing SiCNWs, and then uses heat treatment to release the necessary gas phase for growing SiCNWs, and at the same time utilizes SiC W The two-stage pore structure of the preform greatly increases the supersaturation of the necessary gas phase, thereby realizing the PIP non-catalytic in situ growth of SiCNWs.

Description

technical field [0001] The invention belongs to the field of nanomaterial preparation, and relates to a method for in-situ growth of silicon carbide nanowires by impregnation and cracking method without catalytic precursor. 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 function of 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 reinforcements is used. Following the first synt...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/80C04B35/573C04B35/571B33Y70/10B33Y80/00
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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