Large polycrystalline silicon crucible, coating slurry thereof and preparation method of coating

Abstract

The invention discloses a large polycrystalline silicon crucible which comprises a crucible body and a crucible coating adhered to the crucible body, and slurry sprayed on the crucible coating is prepared from 15 to 23 percent of silicon nitride, 60 to 70 percent of water and 15 to 18 percent of silica sol by weight. The firmness and the high temperature resistance of the crucible coating are remarkably improved, and the requirement of a large crucible ingot on the coating quality can be met. The invention further discloses a coating of the large polycrystalline silicon crucible and the preparation method of the coating of the large polycrystalline silicon crucible.

Description

technical field [0001] The invention relates to the technical field of polysilicon production equipment, in particular to a large crucible for manufacturing polysilicon ingots. The invention also relates to the coating slurry and coating preparation method of the large crucible. Background technique [0002] In the preparation process of polysilicon ingot, ceramic crucible is an essential container, in which silicon material is melted, crystal grows, annealed and cooled, and cast into polysilicon ingot. Cutting silicon ingots into silicon wafers according to technical requirements becomes the base material for the production of solar cells. [0003] The material matrix of the ceramic crucible is ceramic, and its crystal phase is crystal and glass body. When preparing cast polysilicon, during the melting of raw materials and the process of crystal growth, the silicon melt and the crucible are in contact for a long time, which will cause sticking effect. Due to the different...

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Problems solved by technology

[0005] Crucible coating technology came with the development of polycrystalline casting technology. At first, people used silicon nitride and methyl cellulose to spray, but it needed to be sprayed twice, which was labor-intensive. Later, it was directly sprayed with silicon nitride. Baking process is required

[0006] In addition, with the development of ingot casting technology, silicon ingots are getting bigger and bigger. After upgrading to G6 silicon ingots, large crucibles (above 1m×1m) have a large amount of filler, high temperature melting time is long, and the requirements for the quality of the protective coating are relatively small. High, ordinary spraying ratio and method cannot meet the harsh requirements of large crucible ingots on coating quality, often causing quality problems such as sticking to the pot, resulting in a high level of production costs

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