Method for molding high-purity alumina for LED sapphire single crystal

Abstract

The invention relates to a method for molding high-purity alumina for an LED sapphire single crystal. The method comprises the following steps: (1) carrying out high-temperature and heat-preservation calcination of high-purity aluminum ammonium sulfate, cooling with circulating water after discharging from a furnace, and allowing a sintered alumina coarse powder to have the alpha-Al2O3 phase content of 60-65% and the gamma-Al2O3 phase content of 35-40%; (2) crushing the sintered alumina coarse powder with an airflow crushing device to obtain an alumina ultrafine powder; and (3) directly carrying out one-time stamping molding on the alumina powder, to obtain a high-purity alumina round cake green body. The method has no addition of any adhesion agent, adopts direct dry pressing molding, ensures the purity of the molded-shaped alumina is not polluted, and ensures the single crystal quality of the produced LED sapphire single crystal; and the molded-shaped alumina is an ideal raw material for replacing high-purity alumina imported from abroad in the LED sapphire single crystal growth field.

Description

technical field [0001] The invention relates to a method for molding LED sapphire single crystal with high-purity alumina, in particular to a method for pressing and molding high-purity alumina without adding any binder. Background technique [0002] With the development of high technology, in the field of LED sapphire single crystal growth, the requirements for high-purity alumina are very high. The purity of high-purity alumina must reach 99.999% or more. Because the volume of single crystal growth furnaces is generally small, powder cannot be used. For crystal growth, transparent polycrystalline blocks or alumina blocks are mostly used. Most of the block high-purity alumina produced by traditional processes uses binders in the production process, because any binders have trace impurity elements after calcination. As a result, the purity of the bulk alumina decreases, which directly affects the quality of the subsequent LED sapphire single crystal, causing lattice defects ...

AI Technical Summary

Problems solved by technology

[0002] With the development of high technology, in the field of LED sapphire single crystal growth, the requirements for high-purity alumina are very high. The purity of high-purity alumina must reach 99.999% or more. Because the volume of single crystal growth furnaces is generally small, powder cannot be used. For crystal growth, transparent polycrystalline blocks or alumina blocks are mostly used. Most of the block high-purity alumina produced by traditional processes uses binders in the production process, because any binders have trace impurity elements after calcination. As a result, the purity of the bulk alumina decreases, which directly affects the quality of the subsequent LED sapphire single crystal, and causes lattice defects in the single crystal, making it impossible to subsequently process LED sapphire substrates.

[0003] Because the high-purity alumina powder produced in general industry is to calcine the high-purity alumina semi-finished product at a kiln temperature of 1300 degrees, the α content of the powder is more than 98%, and the γ phase is extremely low, resulting in the lack of activity of alumina.

In addition, most of the bulk high-purity alumina produced by the traditional process uses binders in the production process, because any binder will have trace impurity elements after calcination, resulting in a decrease in the purity of the bulk alumina, which cannot be used for LED sapphire single crystal field