Production method of large polycrystalline ingot

Abstract

The invention relates to the technical field of ingot casting of solar energy batteries, in particular to a production method of a large polycrystalline ingot. Silicon nitride and water are mixed uniformly through electric mixing for 15-30 minutes, and the mixture is used as a coating liquid, the coating liquid is uniformly coated on the inner surface of a crucible after the crucible is preheated, and then high-temperature baking is carried out on the crucible, a silicon material is loaded in the baked crucible, and then charging is carried out on the crucible loaded with the silicon material, shielding gas-argon passes through a polycrystalline furnace after vacuumizing is carried out on the polycrystalline furnace, the polycrystalline furnace is heated to melt the silicon material, and then, the melted silicon material is gradually crystallized from the bottom part to the top part through directional solidification, and then discharging is carried out after gradual cooling is carried out through high-temperature annealing, the crucible is disassembled after the discharged polycrystalline ingot is cooled at room temperature, so as to obtain the polycrystalline silicon ingot whichis sliced to prepare the battery. The large charging amount is realized, the capacity of the casting ingot is improved, the utilization rate of the polycrystalline ingot is improved, the cost is reduced, the requirements of a high-load slicer are met, and the crystal quality is kept to be unchanged.

Description

technical field [0001] The invention relates to the technical field of solar cell ingot casting, in particular to a production method of a large polycrystalline ingot. Background technique [0002] Polycrystalline ingot uses quartz crucible as the container for polycrystalline silicon ingot. Through the control of dual temperature zones or three temperature zones, the temperature gradient between the upper and lower sides of the ingot is used to achieve directional solidification. Silicon nitride powder coating is used as the crucible release agent to obtain different This method is widely used in the solar cell ingot casting industry. At present, the 450kg polycrystalline ingot furnace type is generally used in the industry. Due to the production capacity or the load of the slicer, the actual feeding amount is generally 390-420kg. With the development of the industry, the competition is becoming more and more fierce, and solar cell manufacturers are paying more and more at...

AI Technical Summary

Problems solved by technology

The current large furnace models are developing horizontally, that is, the original 400kg ingot can cut 25 small pieces of 156mm×156mm×250mm, and the 600kg ingot can cut 36 such small pieces. Part, the length that can be used for slicing is about 200mm. It can be seen from this that although the 600kg large furnace improves the production capacity of ingots, it is far from meeting the maximum production capacity of slicing. For a slicing machine that can cut 250mm long ingots, Its capacity does not match