Study on ultrasound-assisted preparation of sphere-like high-purity alumina
Wenqi Tang, Jiyi Zhu, Hui Sun, Shusheng Lu, Guangmin Hu, Chaopeng Fu, Jiao Zhang
Abstract
Spherical alumina with a purity greater than 99.999% is calcined by the precursor obtained from the reaction of high-purity aluminum with ultrapure water, which is of great interest for grinding in semiconductor processing and other fields. In this study, tetramethylammonium hydroxide is introduced to the aluminum-water (Al-H 2 O) reaction, and the crystal growth of the HPA precursor is adjusted by ultrasonication. The ultrasound can break the gas barrier film at the early stage of the reaction, then increase the reaction potential energy on the aluminum surface, accelerate the reaction rate, and inhibit the preferential growth of Al(OH) 3 crystals along (110), (111), (131), and (202) faces. It increases the dissociation rate of crystals in the corresponding crystal faces and promotes the formation of the Al-O bond in Al(OH) 3 and Al 2 O 3 to obtain fine HPA precursors with uniform size distribution. Then, the ultrafine and sphere-like α-Al 2 O 3 powders with a particle size D 50 of 370 nm are prepared after calcination at 1250 °C.