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Method for preparing silicon nitride crystal whisker

A technology for silicon nitride whiskers and silicon nitride powder is applied in the field of preparation of ultra-fine silicon nitride powder, and can solve the problems of the type, method and process limitation of preparing whiskers, and that the whiskers are not very perfect and accurate. Achieving the effect of high conversion rate and high product purity

Inactive Publication Date: 2015-04-08
青岛桥海陶瓷新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In short, the current growth theory of whiskers is not very perfect and accurate, and is limited by the type, method, and process of preparing whiskers.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Silicon nitride powder and silicon powder are dried in a drying system, the drying temperature is 80°C, and the drying time is 8 hours to remove the adsorbed water in the powder; according to the quality of silicon nitride powder: silicon powder = 10:90 Ratio and add 10% ammonium chloride as an additive, the fineness of silicon nitride powder and silicon powder is 1-10 microns; fully mix in the raw material mixing system to make the raw materials evenly distributed; send the mixed materials into the nitriding furnace, Add dehydrated and deoxidized nitrogen / hydrogen, the volume ratio of nitrogen and hydrogen is: 3:1, nitriding at 0MPa, 1500°C for 30 hours, and then cooling to obtain silicon nitride whiskers.

[0027] 36% are β-Si3N4 whiskers, 64% α-Si3N4 whiskers, α-Si3N4 whiskers have smooth surfaces, some are defective, and have bifurcated whiskers; rare.

Embodiment 2

[0029] Dry silicon nitride powder and silicon powder in a drying system, the drying temperature is 90°C, and the drying time is 8 hours to remove the adsorbed water in the powder; according to the quality of silicon nitride powder: silicon powder = 30:70 Ratio and add 6% ammonium chloride as an additive, the fineness of silicon nitride powder and silicon powder is 1-10 microns; fully mix in the raw material mixing system to make the raw materials evenly distributed; send the mixed materials into the nitriding furnace, Add dehydrated and deoxidized nitrogen / hydrogen, the volume ratio of nitrogen and hydrogen is: 3:1, nitriding at 0.1MPa, 1500°C for 30 hours, and then cooling to obtain silicon nitride whiskers.

[0030] 75% α-Si3N4 whiskers, 25% β-Si3N4 whiskers, the surface of the whisker structure is smooth, a small amount of defects

Embodiment 3

[0032] Dry silicon nitride powder and silicon powder in a drying system at a drying temperature of 80-100°C and a drying time of 8 hours to remove the adsorbed water in the powder; according to silicon nitride powder: silicon powder = 50:50 The mass ratio of 15% ammonium chloride is added as an additive, and the fineness of silicon nitride powder and silicon powder is 1-10 microns; it is fully mixed in the raw material mixing system to make the raw materials evenly distributed; the mixed material is sent to the nitriding furnace , add dehydrated and deoxidized nitrogen / hydrogen, the volume ratio of nitrogen and hydrogen is: 3:1, nitriding at 0.1MPa, 1450°C for 30 hours, and then cooling to obtain silicon nitride whiskers.

[0033] It is mainly α-Si3N4 whiskers with a diameter of 100-200nm and no obvious defects.

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Abstract

The invention relates to a method for preparing silicon nitride crystal whisker. The method comprises the following step of nitriding silicon nitride powder and silicon powder in a nitrogen furnace filled with nitrogen and hydrogen at high temperature. On the basis of the scheme, before high-temperature nitridation, thesilicon nitride powder and the silicon powder are mixed in a weight ratio of (10-50):(90-50). The method has the beneficial effects that ammonium chloride and hydrogen are added, the nitride crystal whisker is prepared by virtue of the direct nitridation process of silicon powder, the content of silicon in a product is very low, and the conversion rate is high. As silicon nitride powder is adopted as a diluent, the nitridation process of silicon powder is effectively controlled, and the method has the advantages of high conversion rate, in-batch production and high product purity, and is particularly applicable to in-batch production of silicon nitride crystal whisker.

Description

technical field [0001] The invention relates to the technical field of preparation of ultrafine silicon nitride powder, in particular to a method for producing silicon nitride whiskers by direct nitriding of silicon powder. Background technique [0002] Whisker is a high-strength whisker-like single crystal synthesized under artificial control conditions. Its crystal structure is relatively complete, with few internal defects, and its strength and modulus are close to ideal crystals. Therefore, whiskers are often added as reinforcing components to metal matrix, ceramic matrix and polymer matrix to strengthen and toughen them. [0003] There have been many studies on SiC whiskers in the past. The strength and modulus of silicon carbide whiskers are indeed better than those of silicon nitride whiskers, but Si 3 N 4 Whiskers have better high temperature resistance, high strength, high modulus, low expansion and good chemical stability than SiC, and are considered to be idea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B29/38C30B29/62C30B1/10
CPCC30B29/38C30B1/10C30B29/62
Inventor 刘在翔邸庆法
Owner 青岛桥海陶瓷新材料科技有限公司
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