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Nitriding sintering method for silicon nitride and silicon carbide combined refractory product

A technology of nitriding firing and refractory products, which is applied in the field of nitriding firing of silicon nitride combined with silicon carbide refractory products, which can solve the problems of incomplete nitriding, low conversion rate, slow nitriding reaction speed, and inability of nitriding reaction Continue to wait for the problem to achieve the effect of solving the incomplete response

Active Publication Date: 2018-03-06
中钢宁夏耐研滨河新材料有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition to continuously improving the heat preservation of the nitriding furnace and the distribution structure of the heating body, the common solution is to increase the overall temperature of the nitriding furnace to ensure that the low temperature zone of the nitriding furnace is also in the temperature range where the nitriding reaction occurs, which increases energy consumption and also The risk of incomplete nitriding and low conversion rate of products in the low temperature zone of the nitriding furnace cannot be completely avoided
[0005] The influence of the exothermic effect of metal silicon powder nitriding: when the particle size of silicon powder is finer, due to the large specific surface area, its nitriding power is stronger, and the heat release of nitriding sintering reaction is faster, which will cause the furnace temperature to rise spontaneously and cannot be controlled
Once the temperature exceeds the melting point of silicon in the early stage of reaction sintering, silicon melting will occur, blocking the nitriding channel inside the green body, resulting in the inability to continue the nitriding reaction; when the particle size of silicon powder is relatively coarse, the temperature of the nitriding furnace is easy to control, but the nitrogen The nitriding reaction speed is slow, the final conversion rate of silicon powder is low, and a higher firing temperature or longer holding time is required, which increases energy consumption and the risk of incomplete nitriding
[0006] The above two problems are the main reasons for the high cost, performance and quality fluctuations of silicon nitride bonded silicon carbide refractory products

Method used

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Embodiment 1

[0035] Industrial black silicon carbide, fine silicon powder and coarse silicon powder with a purity of more than 98% are selected as raw materials, and the particle size of fine silicon powder is D 50 15-20μm, fine silicon powder and industrial black silicon carbide are mixed, formed, and dried to obtain a 70mm thick low-temperature zone brick, and the particle size of coarse silicon powder is D 50 It is 65-76μm, and then coarse silicon powder and industrial black silicon carbide are mixed, formed, and dried to obtain 70mm thick bricks in the normal temperature zone to be fired with the bricks in the low temperature zone, and the bricks in the low temperature zone and normal temperature zone The volume ratio is 1:5, the highest nitriding firing temperature is monitored at 1400°C, the gas outlet is closed after the normal program keeps warm for 4 hours, and the N 2 Flow rate, until the nitriding furnace is at normal pressure, continue to keep warm for 6h, and then stop passing...

Embodiment 2

[0037] Industrial black silicon carbide, fine silicon powder and coarse silicon powder with a purity of more than 98% are selected as raw materials, and the particle size of fine silicon powder is D 50 10-15μm, fine silicon powder and industrial black silicon carbide are mixed, formed, and dried to obtain a 50mm thick low-temperature zone brick, and the particle size of coarse silicon powder is D 50 It is 48-65μm, and then coarse silicon powder and industrial black silicon carbide are mixed, formed, and dried to obtain 50mm thick bricks in the normal temperature zone to be fired with the bricks in the low temperature zone, and the bricks in the low temperature zone and normal temperature zone The volume ratio is 1:7, the maximum nitriding firing temperature is monitored at 1380°C, the gas outlet is closed after the normal program keeps warm for 6 hours, and the N 2 Flow rate, until the nitriding furnace is at normal pressure, continue to keep warm for 5h, and then stop passing...

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Abstract

The invention provides a nitriding sintering method for a silicon nitride and silicon carbide combined refractory product. The nitriding sintering method comprises the steps of pressing a low temperature zone green body, pressing a normal temperature zone green body, sending into a furnace, warming and sintering and cooling and discharging out of the furnace. In the step of pressing the low temperature zone green body, silicon carbide and fine silicon powder with a granularity not higher than 20mu m are weighed according to a proportion and utilized as raw materials to prepare the low temperature zone green body; in the step of pressing the normal temperature zone green body, silicon carbide and coarse silicon powder with a granularity larger than 20mu m and smaller than 40mu m are weighedaccording to a proportion to be prepared into the normal temperature zone green body; in the operation of sending into the furnace, the low temperature zone green body is sent into a low temperaturezone of a shuttle-type nitriding furnace, and the normal temperature zone green body is sent into a normal temperature zone of the shuttle-type nitriding furnace. According to the method disclosed bythe invention, traditional manure silicon nitride and silicon carbide combined production equipment is utilized; by reasonably analyzing a temperature field distribution situation in the furnace, silicon powder with different granularities is correspondingly set to be utilized as a raw material to respectively form the green bodies corresponding to the different zones; furthermore, temperature cancorrespond to the green bodies; thus, the problem that silicon fusing and nitriding reaction are not complete is solved, and dual purposes are achieved.

Description

technical field [0001] The invention relates to the technical field of preparation of refractory materials, in particular to a method for nitriding and firing silicon nitride-bonded silicon carbide refractory products. Background technique [0002] Silicon nitride combined with silicon carbide refractory products have many excellent properties such as strong slag resistance, good thermal shock stability, high temperature strength, etc., and are widely used in large-scale ironmaking blast furnaces, aluminum electrolytic cells, ceramic kiln furniture and other industries. However, with the advancement of industrial technology in metallurgy, ceramics and other industries and the continuous emergence of emerging industries, higher requirements are placed on the performance of the required refractory materials. For this reason, the present invention proposes a method based on the existing production line The high-efficiency nitriding and firing method of silicon nitride combined ...

Claims

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Application Information

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IPC IPC(8): C04B35/66C04B35/573C04B35/565
CPCC04B35/565C04B35/573C04B35/66C04B2235/428C04B2235/46C04B2235/606C04B2235/656C04B2235/6567C04B2235/658C04B2235/66C04B2235/95
Inventor 吕春江张海涛王波杨奎龚剑锋
Owner 中钢宁夏耐研滨河新材料有限公司
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