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 a polycrystalline silicon ingot and a preparation method thereof, and belongs to the technical field of silicon nitride coating preparation. The silicon nitride coating is prepared from the following components in percentage by mass: 35 to 50 percent of silicon nitride powder, 20 to 30 percent of microcrystalline cellulose, 5 to10 percent of silica sol, 0.5 to 1 percent of aceramic bonding agent and 20 to 40 percent of water. The preparation method comprises the following steps: (1) wet material preparation: mixing the silicon nitride powder, water, microcrystalline cellulose, silica sol and theceramic bonding agent according to a certain proportion, and stirring the mixture with a stirrer to obtain a material A; (2) granulation: extruding the material A with an extruder to form a cylindrical stripped extrudate, then rounding the extrudate with a rounder to form spherical particles serving as a material B, and storing the material B in a particle storage tank; (3) high-pressure cold spraying: flattening silicon nitride particles on the surface of the crucible by using a high-pressure cold spraying technology without heating the crucible in order that the silicon nitride particles are subjected to plastic deformation and adhere firmly. The silicon nitride coating has the advantages of low porosity, high density and high product yield, and the production cost is lowered.

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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