Preparation method for alpha-aluminium oxide monocrystal

Abstract

The invention belongs to the techncial field of preparation methods for synthetic sapphire crystals, and especially realtes to a preparation method for an alpha-aluminium oxide monocrystal, aiming to solve the technical problems on providing the preparation method for the alpha-aluminium oxide monocrystal with the characteristics of environment protection and stable product quality. The preparation method of the alpha-Al2O3 monocrystal comprises the steps of adding raw materials; inserting a seed crystal; sintering the crystal; crystallizing the chemical materials; expanding the center and the crystal; and carrying out isodiametric growth and the like, wherein the raw materials are delta-Al2O3 and the crystal for inserting is a seed crystal with the crystal orientation of 75-degree axis A. The invention can ensure that the qualification rate of the alpha-Al2O3 monocrystal is enhanced; the rejection rate is reduced; and the production cost is saved.

Description

technical field [0001] The invention belongs to the technical field of preparation methods of artificial sapphire crystals, in particular to α-Al 2 o 3 Method for the preparation of single crystals. Background technique [0002] With α-Al 2 o 3 The application of single crystal is more and more extensive, and the production scale is also increasing. Currently producing α-Al 2 o 3 The single crystal method is mainly to use ammonium aluminum sulfate to desulfurize and deammonize to obtain γ-Al 2 o 3 Powder, γ-Al 2 o 3 The powder is further prepared to obtain α-Al 2 o 3 single crystal. by γ-Al 2 o 3 Powder preparation of α-Al 2 o 3 The process flow of single crystal is: add raw material→ignite hydrogen-oxygen flame→chemical material crystallization→crystal expansion→normal equal-diameter growth→turn off hydrogen-oxygen flame and stop furnace→take out single crystal, which specifically includes the following steps: [0003] 1. Raw material addition: due to γ-Al ...

AI Technical Summary

Problems solved by technology

[0014] 1. γ-Al 2 o 3 The shape of the powder is flake or hemispherical, and the dispersibility is not good, which will cause agglomeration, resulting in poor sliding performance, and prone to air leakage of empty powder;

[0015] 2. γ-Al 2 o 3 The average particle size of the powder particles is 4.4 μm, and the specific gravity of the particles is relatively light. Therefore, when growing crystals, it is necessary to use oxygen to carry the powder material, which leads to large temperature field changes during growth due to dispersion, which is not conducive to operation control, and is prone to deformation or over-melting. Non-conforming products such as internal non-melting layer and bubbles, α-Al 2 o 3 The internal quality of single crystals is not guaranteed

[0016] 3. γ-Al 2 o 3 The powder is purified by ammonium aluminum sulfate, if the sulfur is not completely removed, it will directly affect its quality

[0017] 4. The production utilization rate is low, 70% in theory, but less than 65% in practice (due to its small proportion, it is easy to fly and not concentrate and other factors cause waste)

[0018] 5. γ-Al 2 o 3 When the powder is purified, a large amount of harmful gases containing sulfuric acid and ammonium will be produced, which will have a great impact on the environment

There were also several companies in China who wanted to change the α-Al 2 o 3 Raw materials for the production of single crystals, but in practice, they were not successful or did not achieve the desired effect