Silicon nitride coating of crucible for polycrystalline silicon ingot and preparation method thereof

Abstract

The invention relates to a silicon nitride coating of a crucible for polysilicon ingots and a preparation method thereof, belonging to the technical field of silicon nitride coating preparation. The mass percentage of each component of the silicon nitride coating is: silicon nitride powder Material 35%-50%, microcrystalline cellulose 20%-30%, silica sol 5%-10%, ceramic binder 0.5%-1%, and the rest is water 20%-40%. Its production steps are as follows: ( 1) Preparation of wet material: Mix silicon nitride powder, water, microcrystalline cellulose, silica sol and ceramic binder according to the proportion and stir it with a mixer to form material A; (2) Preparation of granulation: extrude material A extruded into cylindrical strips, and then rolled into spherical particles by a spheronizer as material B, which is stored in a particle storage tank; (3) high-pressure cold spraying, without heating the crucible, using high-pressure cold spraying technology The silicon nitride particles are flattened and plastically deformed on the surface of the crucible and firmly attached, the porosity is low and the compactness is good, the qualified rate of the product is high, and the production cost is reduced.

Description

technical field [0001] The invention relates to a silicon nitride coating of a crucible for polycrystalline silicon ingots and a preparation method thereof, belonging to the technical field of silicon nitride coating preparation. Background technique [0002] Ceramic crucible is an essential container in the process of preparing polysilicon ingots. Silicon materials are cast into polysilicon ingots after melting, crystal growth and return cooling in the crucible, and the silicon ingots are cut into silicon wafers according to technical requirements, which are used for the production of solar cells. Matrix material; the material matrix of the ceramic crucible is ceramic, and its crystal phase is crystal and glass body. When preparing cast polysilicon, in the process of raw material melting and crystal growth, the long-term contact between the silicon melt and the crucible will cause stickiness. The thermal expansion coefficients of the body and the crucible are different. If ...

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Problems solved by technology

[0003] The traditional spraying process of silicon nitride coating needs to heat up and bake the crucible multiple times. The thickness and uniformity of the silicon nitride coating cannot be controlled. It requires high temperature and high energy consumption and takes a long time, resulting in excessive energy consumption and production costs. high and low production efficiency; the non-baking coating technology in the prior art refers to spraying the silicon nitride slurry onto the crucible when the temperature rises to a certain temperature. It still needs to be sprayed multiple times, and the ambient temperature is uncontrollable under natural conditions. The ambient temperature will also change with the change of seasons, which will affect the quality of natural drying of the crucible coating, and will easily cause a large number of unqualified crucibles to stick together, resulting in an increase in the failure rate. High, production quality is difficult to guarantee

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