Formation of High-Purity Zircon Powder from Amorphous ZrO_2 and Amorphous SiO_2

摘要

The preparation of high-purity zircon powder from an equimolar mixture of amorphous silica and amorphous zirconia was studied using ZrOCl_2 and S_i(OC_2H_5)_4 by the sol-gel pocess. Zircon is formed at temperature as low as 1200 deg C without any additives, predominantly from amorphous silica and tetragonal zirconia. When zircon seeds are added, formation temperature can be dropped more than 150 deg C. It is inferred fro mthe analysis of the evolution of crystal phase and the calculationof activation energies that the formation mechanism of zircon varies over different temperature range. At low temperature, zircon formation is controlled by the nucleation process, while at higher temperature, is controlled by the diffusion of SiO_2(or Si~4+) through the thin film formed between SiO_2 and ZrO_2.