Abstract
Natural lime containing 1.45wt% impurities produced from limestone and high-purity lime (99.9%) produced from calcium carbonate were used as the raw materials for the present study. These limes were molded into a circular disk or a plate by cold isostatic pressing (CIP) or uni-axial dust pressing, and then fired at 1800°C. Strength measurements by three-point bending test, estimation of the Weibull parameter and hydration test were carried out on the fired bodies. The following results were obtained:
(1) The mean bending strength for the bodies made of natural lime was from 74 to 86MPa, while for the bodies made of high-purity lime the mean strength was 135MPa.
(2) The Weibull parameter evaluated for the natural lime bodies was from 11 to 13, while for the high-purity lime bodies the parameter was 17. It was found that the high-purity lime body was more uniform in microstructure than the natural lime body. As for the natural lime bodies, the Weibull parameter of the samples obtained from the CIP-molded green body was higher than that of the samples from the uni-axially pressed green body.
(3) The weight gain of the high-purity lime body under a saturated water vapor pressure at 8°C was less than 3wt% after two months, while the natural lime body showed as much as 3wt% of gain only after two weeks under the same testing condition. This result showed clearly that hydration resistance of the high-purity lime body was much higher than that of the natural lime body.
