Method for preparing crucible coating for polycrystalline silicon ingot casting and crucible

Abstract

The invention discloses a method for preparing a crucible coating for polycrystalline silicon ingot casting. The method includes the following steps that hexagonal boron nitride is weighed and slowly added into a mixed solution of silica sol and high-purity water to be evenly stirred, and needed slurry is prepared, wherein the slurry is prepared from, by weight, 20-23% of hexagonal boron nitride, 53-55% of high-purity water and 23-25% of silica sol; before spraying, the slurry is continuously stirred and kept at the room temperature of 24-28 DEG C, the temperature of a crucible to be sprayed is kept at 60-80 DEG C, the slurry is sprayed on the bottom face of the crucible, and silicon nitride is sprayed on the side face of the crucible; the sprayed crucible is roasted, and the crucible coating for polycrystalline silicon ingot casting is formed on the bottom face of the crucible after roasting. The process is simple, operation is convenient, impurity elements are not introduced, and high compactness of the crucible coating is effectively guaranteed, so that the prepared crucible coating is high in purity, accordingly crucible pollution caused by impurities is effectively inhibited, the coating at the bottom of the roasted crucible is good in stability and high in bonding strength, and the service life of a spoon at the bottom is prolonged.

Description

[0001] 【Technical field】 [0002] The invention belongs to the technical equipment field of polycrystalline silicon ingot production, and in particular relates to a method for preparing a crucible coating for polycrystalline silicon ingot and the crucible. [0003] 【Background technique】 [0004] At present, the absolute advantage in the cost of polycrystalline silicon cells makes it gradually replace the dominant position of monocrystalline silicon cells in the market. In the silicon material solar cell industry, polysilicon ingot casting has become the main ingot casting technology. In the process of polysilicon ingot casting, in order to make the silicon ingot be released from the mold and prevent the reaction between liquid silicon and the crucible made of quartz ceramics at high temperature, it is necessary to make a coating on the inner surface of the crucible, and the coating is required to be of high purity and properties. It is stable and has suitable bonding strength...

AI Technical Summary

Problems solved by technology

For example, silica sol contains nano-scale silica particles, which will react with silicon melt during ingot casting to form silicon monoxide; while organic substances will decompose or volatilize at high temperatures, which will reduce the overall density of the coating. It is easy to cause a certain degree of impurity pollution to the silicon ingot, thus affecting the quality of the silicon ingot

In addition, no sintering after spraying means that the crystallinity of the coating is low, and it is unstable compared with the ingot heating process, which will affect the growth of crystals, especially in the initial nucleation stage of crystal growth.

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