Preparation method of self-setting silicon nitride foamed ceramic

A technology of foam ceramics and silicon nitride, which is applied in the field of preparation of self-setting silicon nitride foam ceramics, can solve problems such as difficult to precisely control the shape and microstructure, destroy the uniformity of the foam ceramic structure, and complex foam ceramic technology, and achieve improvement High temperature performance and stability, low sintering shrinkage, good structural stability

Active Publication Date: 2021-08-10
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The template needs to be removed in the process of preparing foamed ceramics by using the organic template method. During this process, the decomposition of organic matter and the gas discharge process will leave holes and cracks on the ceramic skeleton, thereby destroying the structural uniformity of the foamed ceramics and reducing the mechanical properties; The process of preparing silicon nitride foam ceramics by foaming method is complicated, and it is difficult to accurately control the shape and microstructure of the final product, resulting in poor mechanical properties

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] (1) Prepare 3K carbon fiber T300 as chopped fibers, and then use felting equipment to obtain carbon fiber felt A with a thickness of 5mm and a fiber volume fraction of 8%;

[0029] (2) Put high-purity silicon powder (99.99%) with an average particle size of 1.5 μm into alcohol according to the proportion of solid content of 20wt.%, and add 1wt.% PEI and 2wt.% PVB to the solvent, after high-energy ball milling After 2h, silicon slurry B was obtained;

[0030] (3) Place the carbon fiber felt A in the silicon slurry B, make the silicon slurry B fully impregnate the carbon fiber felt A under the action of 3MPa pressure, then take the carbon fiber felt A with the slurry out of the silicon slurry B, and then Dry at 60°C for 10 hours to obtain slurry product C;

[0031] (4) Place the slurry product C in 96% N 2 -4%H 2 In a flowing nitrogen-hydrogen mixed atmosphere, the gas flow rate is 1L / min, and the temperature rises to 1360°C at a rate of 2°C / min, and then is kept for 2...

Embodiment 2

[0034] (1) with step (1) in embodiment 1;

[0035] (2) Put high-purity silicon powder (99.99%) with an average particle size of 1.5 μm into alcohol according to the ratio of solid content of 35wt.%, and add 1wt.% PEI and 3wt.% PVB to the solvent, and perform high-energy ball milling After 2h, silicon slurry B was obtained;

[0036](3) with step (3) in embodiment 1;

[0037] (4) with step (4) in embodiment 1;

[0038] The test shows that the average nitriding rate of the sample is 97.8%, the obtained carbon fiber reinforced silicon nitride foam ceramics has a porosity of 63.5%, an average pore size of 450 μm, a flexural strength of 38.7 MPa, and a compressive strength of 9.4 MPa.

Embodiment 3

[0040] (1) with step (1) in embodiment 2;

[0041] (2) with step (2) in embodiment 2;

[0042] (3) with step (3) in embodiment 2;

[0043] (4) with step (4) in embodiment 2;

[0044] (5) Place D in B, repeat step (3) to step (4), the number of repetitions is 1, and obtain silicon nitride foam ceramic E;

[0045] Tests show that the average nitriding rate of the sample is 96.5%, the obtained carbon fiber reinforced silicon nitride foam ceramics has a porosity of 57.5%, an average pore size of 380 μm, a flexural strength of 43.8 MPa, and a compressive strength of 11.3 MPa.

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Abstract

The invention discloses a preparation method of self-setting silicon nitride foamed ceramic, and belongs to the technical field of advanced ceramics. The method comprises the following steps: 1) preparing inorganic continuous long fibers into chopped fibers, and obtaining a fibrofelt with a certain shape, thickness and fiber volume fraction by using felt making equipment; 2) putting the mixed micro powder of silicon powder and silicon nitride into a solvent, adding a surfactant and a binder, and carrying out ball milling to obtain silicon-containing slurry; 3) placing the fiber felt in the silicon-containing slurry, fully impregnating the fiber felt with the silicon-containing slurry under the action of pressure, taking out the fiber felt, and drying the fiber felt to obtain a slurry hanging product; 4) placing the slurry hanging product in nitrogen or nitrogen-hydrogen mixed atmosphere, nitriding the silicon powder at high temperature to generate silicon nitride, and realizing reactive sintering in the continuous conversion process of the silicon nitride to obtain fiber-reinforced silicon nitride foamed ceramic; and 5) placing the silicon nitride foamed ceramics in the silicon-containing slurry, and repeating the steps 3) and 4) to obtain the self-setting silicon nitride foamed ceramics with different pore sizes and porosities. Micropores and microcracks are few, the junction temperature is low, and the shrinkage rate is small.

Description

technical field [0001] The invention belongs to the technical field of advanced ceramics, in particular to a preparation method of self-setting silicon nitride foam ceramics. Background technique [0002] Silicon nitride foam ceramics is a porous ceramic material with low density, low thermal conductivity, low thermal expansion coefficient, good high temperature stability, good thermal shock resistance, etc. It is mainly used in thermal protection, molten metal filtration, separation membrane and Catalyst carrier and other fields. At present, the preparation methods of silicon nitride foam ceramics include organic template method, foaming method and so on. The organic template method is to use porous organic materials (mostly polyurethane sponge) as a template to make silicon nitride ceramic slurry adhere to the organic porous membrane plate, and then remove the template by heat treatment. After the ceramic slurry is solidified and sintered, the shape of the template is ret...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/591C04B35/80C04B35/622C04B38/00
CPCC04B35/591C04B35/622C04B38/00C04B2235/46C04B2235/6582C04B2235/428C04B2235/5445C04B2235/5436C04B2235/5248C04B2235/616C04B2235/6562C04B2235/6567C04B2235/96C04B35/806C04B38/0051C04B38/0074
Inventor 李思维肖礼成汤明兰琳陈立富
Owner XIAMEN UNIV
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