Abstract
ZrSiO4 powders were prepared from partially hydrolyzed solutions of Si(OC2H5)4(TEOS) and ZrOCl2 aqueous solutions by the sol-gel processing, and the influence of amount of water for partial hydrolysis of TEOS, pH of the ZrOCl2 aqueous solution and mixing time on the formation rate of ZrSiO4 was investigated. The preparation conditions were evaluated by the formation rate of ZrSiO4 after 1.5wt% ZrSiO4 seed crystals were added to the precursor powders and then the powder mixtures were heated at 1200° to 1500°C for 2h. In the preparation of ZrSiO4 composition precursor gels from TEOS-ZrO2 sol and SiO2 sol-ZrOCl2, the H2O/TEOS molar ratio of about 2 and the pH of the ZrOCl2 aqueous solution of about 3 were appropriate. About 2h were necessary for mixing of partially hydrolyzed solution of TEOS and ZrOCl2 aqueous solution to improve the homogeneity of precursor sols, and more than 10h was required for the mechanical mixing of precursor sols. The formation of ZrSiO4 produced by firing the precursor sols obtained from the partially hydrolyzed solution of TEOS and ZrOCl2 aqueous solution at 1300° to 1400°C showed an accelerative increase through the Hedvall effect by silica.
