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Preparation method of coating for melting crucible

A melting crucible and coating technology, applied in the field of coating preparation, can solve the problems of small adhesion between coating and melting crucible, unable to achieve the effect of coating, complicated process, etc. Adhesion-friendly effect

Inactive Publication Date: 2011-10-19
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

There are many methods for preparing silicon nitride coatings, but usually the process is complicated and the cost is high
The invention patent with application number 200810243655.6 uses silicon nitride particles and deionized water to form a milky melt, which is sprayed under low pressure and then sintered to form a silicon nitride coating. However, in this method, deionized water is used to form a latex-like melt. Melt, after sintering, the adhesion between the coating and the melting crucible is small, and it is easy to fall off during the casting process, so that the effect of the coating cannot be achieved

Method used

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  • Preparation method of coating for melting crucible
  • Preparation method of coating for melting crucible

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Experimental program
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Effect test

Embodiment 1

[0021] The first step of baking pretreatment: the "three high" graphite crucible is selected as the melt carrier. Due to the long-term placement and the influence of the processing process, the crucible needs to be baked. The baking process is carried out in a directional solidification furnace. Insulate at 800°C for 1 hour at a vacuum of 5 Pa, take out the crucible after the furnace is cooled, and wash with acetone to remove the organic solvent on the inner wall;

[0022] The second step configures the suspension of silicon nitride coating: in the dehydrated ethanol solution of 20g 8wt%PVP, add 30g particle size and be the Si of 100 microns 3 N 4 powder, stir for about 2 hours to disperse the powder as evenly as possible, and let it stand for use;

[0023] The third step is to spray the coating: connect the cleaned spray gun to the air outlet of the air compressor, adjust the air pressure to 500Pa, first use anhydrous ethanol to test spray, and after the whole channel is smo...

Embodiment 2

[0026] The first step of baking pretreatment: choose Al 2 o 3 The crucible is used as the carrier of the melting material. Due to the long-term placement and the influence of the processing process, the crucible needs to be baked. The baking process is carried out in a directional solidification furnace. After cooling, take out the crucible and wash it with acetone to remove the organic solvent on the inner wall;

[0027] The second step configures the suspension of silicon nitride coating: in the dehydrated ethanol solution of 10g 6wt%PVP, add 20g particle size and be the Si of 130 microns 3 N 4 powder, stir for about 2 hours to disperse the powder as evenly as possible, and let it stand for use;

[0028] The third step is to spray the coating: connect the cleaned spray gun to the air outlet of the air compressor, adjust the air pressure to 300Pa, first use anhydrous ethanol to test spray, and after the whole channel is smooth, put the static Si 3 N 4 The supernatant of ...

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Abstract

The invention belongs to the technical field of coating preparation. A preparation method of a coating for a melting crucible comprises the following steps of: pre-drying the melting crucible; preparing a suspension by adopting a PVP (Polyvinyl Pyrrolidone) absolute ethanol solution and silicon nitride; uniformly spraying the suspension on the inner wall of the melting crucible; and pre-burning the melting crucible with sprayed coating to form a silicon nitride coating with uniform thickness and compact structure on the inner wall of the melting crucible. The method has the advantages that: the melting crucible is pre-dried and cleaned before being sprayed to contribute to adhesion of the coating; the PVP absolute ethanol solution is added to the suspension of the coating, the absolute ethanol is evaporated after the crucible is dried, the adhesive PVP leads the coating to be adhered on the inner wall of the crucible, and the coating has higher adhesive force, so that the crucible is prevented from reacting with and adhering melt, smooth demolding of ingots is realized, impurities are prevented from entering melt, the purification effect of the melt is realized, and the using requirement for the coating in a casting process is fulfilled.

Description

technical field [0001] The invention belongs to the technical field of coating preparation, in particular to a method for spraying a silicon nitride coating on the inner wall of a melting crucible. Background technique [0002] In the process of metallurgical smelting, impurity removal and ingot preparation, smelting crucibles are required. The smelting crucibles commonly used in industry are quartz or graphite crucibles. When the molten metal contacts the crucible, reaction adhesion will inevitably occur, and the impurities in the crucible will also will enter the silicon melt. Reactive sticking, infiltration and diffusion between the crucible and the metal can cause problems during ingot demolding, putting the polysilicon ingot at risk of cracking or cracking. High concentrations of impurities, such as C, O, etc., will have adverse effects on various properties of the ingot. Usually, a coating is applied on the crucible to isolate the melt from the melting crucible wall,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F27B14/10C03C17/22B05D7/24B05D3/00B05D3/02
Inventor 谭毅张磊许富民
Owner DALIAN UNIV OF TECH
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