China's Refractories

Abstract: CaZrO3 powder was prepared using CaO, CaCO3 and Ca(OH)2 as calcium source, nano m-ZrO2 powder, micron m-ZrO2 powder, micron CaO partially stabilized ZrO2 (Ca-PSZ) powder as zircon source, through high temperature solid reaction. Effect of the calcination temperature (800, 900, 1 000, 1 100, 1 200, 1 300, 1 400, 1 500, and 1 600 ℃) and the holding time (3, 4, and 5 h) on the phase composition change was studied to research the synthesis mechanism. The synthesized CaZrO3 powder was mixed with CaO, MgO, Al2O3, Cr2O3, SiO2, and ZrO2 powder separately and fired at 1 500 ℃ for 3 h to prepare specimens to research the high temperature chemical stability of CaZrO3 with different reaction mediums. The results show that during the synthesis process, the CaZrO3 content does not always increase with the increasing calcination temperature or the prolonging holding time, CaZrO3 decomposes resulting from the diffusion of Ca2+ and O2- in CaZrO3 to m-ZrO2 or c-ZrO2. At high temperatures, when CaZrO3 is in alkaline environment (such as environment containing CaO or MgO), the high temperature chemical stability is high, but when CaZrO3 is not in alkaline environment (such as environment containing Al2O3, Cr2O3, SiO2 or ZrO2), the high temperature chemical stability is low.