Properties of Alumina Powder Prepared by Precipitation Method(II) : Properties of Alumina Powder on Heat-Treatment

,; ,; ,; ,

J. Korean Ceram. Soc. > Volume 25(3); 1988 > Article

Journal of the Korean Ceramic Society 1988;25(3): 193.

침전법으로 제조한 Alumina 분말의 특성(II) : 열처리에 따른 Alumina 분말의 특성

홍기곤, 이홍림

연세대학교 공과대학 요업공학과

Properties of Alumina Powder Prepared by Precipitation Method(II) : Properties of Alumina Powder on Heat-Treatment

ABSTRACT

The starting materials were aluminum hydroxide prepared by precipitation method at the conditions of pH values; 7, 9, 10 and 11. The properties of alumina powder on heat-treatment were studied. After dehydrating structural water from amorphous aluminum hydroxide, the first formed phase was amorphous alumina and its specific surface are was decreased. The specific surface area was increased by dehydration of structural water from aluminum hydroxides except amorphous aluminum hydroxide. The specific surface area was increased with increase of the ratio of A1OOH to $A1(OH)_3$ in the region of transition aluminas. The rate of transition from aluminum hydroxide to alpha alumina occurred in the order of 7, 10, 9 and 11 of pH values. The morphology of alpha alumina powders was skeleton particles remaining outer shape of aluminum hydroxide. Both the elevation of heat-treatment temperature and the transition toalpha alumina decreased specific surface area and brought about the growth of particles.