Patent ID: 7959894

Claim:
A method for preparing a flaky α-alumina crystal comprising: 1) preparing a metal precursor solution containing 0.04-5 parts by weight of a zinc precursor per 100 parts by weight of aluminum precursor; 2) titrating the metal precursor solution with a sodium salt solution to pH 6.0-7.5 and hydrolyzing it to prepare a gel mixture; 3) pre-treating said gel mixture by aging it at 60-100° C. for 5-30 hrs followed by drying; 4) calcining said pre-treated gel mixture at 300-700° C. for 1-5 hrs; 5) crystallizing said calcined gel mixture at 1,000-1,200° C. for 1-7 hrs to prepare a crystallized cake; and 6) cooling said crystallized cake to room temperature, dissolving said crystallized cake in 20-90° C. of water and filtering the dissolved crystallized cake to remove the flux and obtain a filtrate, dispersing the filtrate at 20-90° C. in a 0.1-10% sulfuric acid solution and filtering, washing and drying the filtrate to obtain an α-alumina crystal.