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Method for removing silicon nodules on surface of reactive sintering silicon carbide ceramic by using molten salt

A technology of silicon carbide ceramics and sintered silicon carbide, which is applied in the field of removal of residual silicon tumors on the surface of reaction sintered silicon carbide ceramics, can solve the problems of easy contact with human body, heavy environmental load, strong corrosion, etc. Difficulty, the effect of simple processing

Active Publication Date: 2021-07-13
浙江东新新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] However, sodium hydroxide is highly corrosive. When in use, it often causes certain harm due to its easy contact with the human body or entering the environment.
In addition, in order to completely remove silicon tumors on the surface of silicon carbide ceramics and speed up the processing efficiency, excessive sodium hydroxide is often used. After the treatment is completed, a large amount of strong alkali residue will be produced, which is highly corrosive.
Therefore, before the residue is discharged, it needs to be neutralized with sulfuric acid, which has a large environmental load

Method used

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  • Method for removing silicon nodules on surface of reactive sintering silicon carbide ceramic by using molten salt
  • Method for removing silicon nodules on surface of reactive sintering silicon carbide ceramic by using molten salt
  • Method for removing silicon nodules on surface of reactive sintering silicon carbide ceramic by using molten salt

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Embodiment 1

[0044] Embodiment 1, a kind of method that reaction sintered silicon carbide ceramic surface silicon is processed on the basis of solid inorganic salt composition mixed molten salt, comprises the following steps:

[0045] 1), weigh 5g sodium hydroxide, 20g sodium carbonate, 20g sodium chloride, 10g sodium nitrate, 10g sodium sulfate, 10g sodium bromide, 15g potassium chloride, 10g potassium carbonate, and grind the above ingredients until 30-50 Purpose sieve, stir and mix evenly to make 100g mixed salt and then join in the reactor. The reaction kettle was heated to 550°C and kept for 1 hour. At this time, the mixed salt melted under the action of high temperature to generate a white molten salt.

[0046] 2) Take silicon carbide ceramics with silicon nodules on the surface as the object to be treated, immerse the ceramics in the molten salt obtained in step 1), and stir so that the ceramic samples can fully react in the molten salt, and the reaction temperature is controlled at...

Embodiment 2

[0053] Embodiment 2, a kind of method that the surface silicon of reaction sintered silicon carbide ceramics is processed on the basis of solid inorganic salt mixed molten salt:

[0054] The formula of mixed salt is changed into 10g sodium hydroxide, 30g sodium carbonate, 20g sodium chloride, 5g sodium nitrate, 5g sodium sulfate, 5g sodium bromide, 20g potassium chloride, 5g potassium carbonate; All the other are equal to embodiment 1.

[0055] The resulting effect is as figure 2 ; Compared with Example 1, the silicon element layer on the surface of the spline is also completely removed, and the whole turns into dark green. In addition, the fine silicon tumor area on the surface of the silicon carbide ceramic is removed, and the large silver-gray silicon element agglomerates are also removed. It was removed, but there were still a few black silicon tumor spots that did not fall off completely.

[0056] After changing the ratio of inorganic salts and increasing the content of...

Embodiment 3

[0057] Embodiment 3: A method for treating silicon on the surface of reaction sintered silicon carbide ceramics based on solid inorganic salt mixed molten salt:

[0058] The formula of mixed salt is changed to 20g sodium hydroxide, 20g sodium carbonate, 10g sodium chloride, 10g sodium nitrate, 10g sodium sulfate, 10g sodium bromide, 10 potassium chloride, 10g potassium carbonate. The melting temperature is 600°C.

[0059] The reaction temperature was controlled at 650° C., the holding time was 8 hours, and the stirring speed was 40 r / min.

[0060] The resulting effect is as image 3 . Compared with Examples 1 and 2, the silicon on the surface of silicon carbide ceramics, including the surface silicon element layer, the black fine silicon tumor area, and the silver-gray silicon element agglomerates, are all removed without residue, and the whole is dark green, reaching the Best removal effect.

[0061] Since the fine silicon nodule aggregates on the surface of silicon carbi...

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Abstract

The invention discloses a method for removing silicon nodules on the surface of reactive sintering silicon carbide ceramic by using molten salt. Silicon carbide ceramic which is prepared by reactive sintering and has silicon nodule points on the surface is used as a to-be-treated object, and the method comprises the following steps: heating mixed salt consisting of sodium hydroxide and solid inorganic salt until the mixed salt is molten to obtain molten salt; putting the to-be-treated object into molten salt, and carrying out heat preservation reaction, so as to remove silicon nodules on the surface of the silicon carbide ceramic; and taking out the silicon carbide ceramic, cooling, removing the solid salt on the surface of the silicon carbide ceramic, and drying at room temperature to finally obtain the silicon carbide ceramic with silicon nodule removed.

Description

technical field [0001] The invention relates to the surface treatment of silicon carbide ceramics, in particular to the removal of residual silicon nodules on the surface of reaction sintered silicon carbide ceramics. Background technique [0002] As a synthetic material, silicon carbide ceramics have good chemical stability, are not easy to be corroded and oxidized by acid and alkali, and have good structural properties. They are widely used in many fields, such as petroleum, chemical industry, machinery, electronics, aerospace aviation etc. At present, the industrial production methods of silicon carbide ceramics mainly include pressureless sintering, hot pressing sintering, hot isostatic pressing sintering and reaction sintering. Among them, reaction sintering is a common method for industrial production of silicon carbide. The process is mainly to let silicon infiltrate the α-SiC embryo body containing carbon powder at high temperature, and react between silicon and car...

Claims

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Application Information

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IPC IPC(8): C04B41/91
CPCC04B41/91C04B41/5361C04B41/009C04B35/573
Inventor 郭兴忠邹畅郑浦李志强周渭良阮万兴杨辉
Owner 浙江东新新材料科技有限公司
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