Abstract
CaCO3-Ca(OH)2 mixed powders, coated with a chelate compound of aluminum corresponding to 0-0.5mass% Al2O3, were sintered at 1500°C for 2h in order to obtain CaO ceramics. The relative density was 95% for Al2O3-free CaO ceramics obtained from the 29mol% CaCO3-71mol% Ca(OH)2 mixed powder. On the other hand, a low density of 86% was found in the CaO ceramics prepared from 100% CaCO3 powder. The mass gain of Al2O3-free CaO ceramics and 100% CaCO3 powder was about 40% and 80%, respectively, according to a slaking-resistance test of 360h under 95% relative humidity at 50°C. The sinterability and slaking resistance of CaO ceramics prepared from CaCO3-Ca(OH)2 mixed powder were remarkably increased compared with those prepared from CaCO3 powder. The relative density and mass gain after slaking-resistance test were 97 and 12%, respectively, for the CaO ceramics prepared from the 29mol% CaCO3-71mol% Ca(OH)2 mixed powder coated with 0.01mass% Al2O3. The trace amount of Al2O3 coating on the starting powder led to an improvement of slaking resistance of CaO ceramics prepared from CaCO3-Ca(OH)2 mixed powder. The slaking-resistance of CaO ceramics prepared by Al2O3 coating method was higher than that obtained by conventional mixing of Al2O3 powder.
