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Preparation method of alpha-silicon nitride

A technology of phase silicon nitride and silicon nitride powder, which is applied in the field of preparation of ultrafine silicon nitride powder, can solve the problems of slow phase transformation process, complicated operation, equipment corrosion, etc., and achieve stable product quality, simple equipment, and reaction stable effect

Inactive Publication Date: 2015-04-22
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

[0006] Gao Liwen and others invented the "high α-Si 3 N 4 Phase Silicon Nitride Preparation Method" (Chinese Patent Publication No. CN101269803A), in which silicon powder and silicon nitride powder are mixed and pressed into a furnace for nitriding, although high-α-phase silicon nitride powder can be produced in large quantities, but Due to the need for segmented heating and pressure control, the operation is complicated and difficult to control
[0007] "A preparation of high α-Si" invented by Russia Merzhanov et al. 3 N 4 "method" (US Patent US5032370), it is necessary to complete the synthesis reaction under relatively high nitrogen pressure (4 ~ 30Mpa), the requirements for equipment are more stringent, the probability of accidents increases, and a large amount of ammonia salt containing Cl and F needs to be added at the same time. Severe corrosion of equipment and increased costs, these reasons are not conducive to large-scale production
[0008] Qi Longhao of Tsinghua University and others invented the "Plasma Chemical Vapor Phase Process for Batch Production of Silicon Nitride Powder Phase Inversion Process and System" (Chinese Patent Publication No. CN1397487). Silicon batch crystallization process to obtain high α-phase silicon nitride, but due to the slow phase transformation process, the efficiency is low and the cost is still high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] The silicon nitride powder and the silicon powder are dried, the drying temperature is 80°C, and the drying time is 8 hours to remove the water adsorbed in the powder; fully mix according to the mass ratio of silicon nitride powder: silicon powder = 30:70; Send the mixed material into the nitriding furnace, fill it with dehydrated and deoxidized nitrogen, then nitriding at 1300°C for 30 hours, and then cool.

[0027] The conversion rate is 97.6%, and the α-phase content can reach 93.2%, with high economic benefit and large output.

Embodiment 2

[0029] The silicon nitride powder and the silicon powder are dried, the drying temperature is 90° C., and the drying time is 8 hours, and the water adsorbed in the powder is removed; fully mixed according to the mass ratio of silicon nitride powder: silicon powder = 50:50; Send the mixed material into the nitriding furnace, fill it with dehydrated and deoxidized nitrogen, then nitriding at 1300°C for 30 hours, and then cool.

[0030] The conversion rate can reach 99.1%, and the alpha phase content can reach 96.1%.

Embodiment 3

[0032] The silicon nitride powder and the silicon powder are dried, the drying temperature is 100° C., and the drying time is 8 hours to remove the adsorbed water in the powder; fully mix according to the mass ratio of silicon nitride powder: silicon powder = 70: 30; Send the mixed material into the nitriding furnace, fill it with dehydrated and deoxidized nitrogen, then nitriding at 1300°C for 30 hours, and then cool.

[0033] The conversion rate can reach 99.9%, the α phase content can reach 98.1%, the nitriding rate is high, and the α phase purity is high, but the benefit is a bit lower than the previous two schemes.

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Abstract

The invention relates to a preparation method of alpha-silicon nitride. The alpha-silicon nitride is prepared by the following steps: carrying out high-temperature nitridation on silicon nitride powder and silicon powder in a nitrogen furnace filled with nitrogen; and mixing the silicon nitride powder with the silicon powder at the weight ratio of (30-70): (70-30). According to the method, reaction is carried out in a low-pressure condition, so that compared with other methods, the method is relatively good in safety; raw materials are subjected to pretreatment, so that the product purity is ensured; an intelligent temperature control system is adopted, so that the method is simple and convenient to operate, and stable in reaction; and the alpha-silicon nitride is stable in quality, simple in equipment, low in cost and high in yield.

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 powder by direct nitriding of silicon powder. Background technique [0002] Among various ceramic materials, silicon nitride (Si 3 N 4 ) Ceramics are new engineering materials with the most development potential and application market. Because of its advantages such as high specific strength, high specific modulus, high temperature resistance, oxidation resistance and wear resistance, and high thermal shock resistance, silicon nitride ceramics have special applications in working environments with high temperature, high speed, and strong corrosive media. value. [0003] High quality Si 3 N 4 The preparation of ceramic products requires the use of high-quality Si 3 N 4 Powder. There are many known preparation methods of silicon nitride powder, the most researched are the following: silicon powde...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B21/068
Inventor 刘在翔邸庆法
Owner 青岛桥海陶瓷新材料科技有限公司