抄録
Controlling the size of anisotropic alumina grains such as platelike grains in the sintered body has been considered to be important for improving toughness of alumina ceramics. In this study, the relationship between particle size of powders and platelike grain size in sintered bodies were mainly studied in four kinds of fine-ground alumina powders with different average particle sizes and same amounts of impurities by wet rotation ball-milling. Platelike grain sizes were governed by the number of nuclei for growing into platelike grain in sintered bodies and the growth rate of those grains. The number of nuclei decreased and the growth rate of platelike grain increased with increasing particle sizes of powders. These results were attributed to the width of particle size distributions of powders. As a result, platelike grain sizes increased as particle sizes of powders increased. Therefore, it was possible to control the size of platelike grain by the particle size of the powder. All the slopes of growth isotherms of platelike grains in logarithmic plot were nearly equivalent, that is, the mechanism of platelike grain growth of all powders can be considered to be the same.
