Reduction in specific surface area of an alumina powder at a relatively low temperature

A highly sinterable Al2O3 powder and its powder compact are simultaneously fired up to a given temperature at a constant rate of heating. The specific surface areas, S-p, of them decrease appreciably from 700 degrees C, but t here is a slight difference in the S-p value between them in the low temper ature region from 700 to 950 degrees C. This similarity suggests both sligh t neck growth and reduction of the S-p values through not only smoothing of rough surfaces but also disappearance of peculiarly small particles. Above 950 degrees C, on the other hand, appreciable neck growth results in more rapid decrease of the S-p value for the powder compact than for the powder. These explanations are well consistent with other empirical data, both var iations of shrinkage curves and the particle size distributions by prelimin ary firing. (C) 1999 Elsevier Science Limited and Techna S.r.l. All rights reserved.