PREPARATION OF FINE ALN POWDERS BY WET BALL-MILLING AND THEIR CHARACTERIZATION

Aluminum nitride (AIN) raw powder prepared by direct nitridation of me tallic aluminum powder was ground by wet ball-milling in order to obta in submicron fine powder for low-temperature sintering. The effects on the properties of the milled powders of milling conditions such as ba ll size, ball material, chemical species of the grinding fluid and wat er content of the grinding fluids were investigated. A larger grinding rate was observed using medium balls with diameters of less than 5 mm phi and grinding fluids with higher dipole moments such as 2-propanol and acetone. It was also indicated that SiAlON balls showed the least grinding wear, and that an increase in the water content of the grind ing fluid increased the oxygen content of the milled powder. Fine AIN powder with submicron size and sharp particle size distribution was ob tained by adjusting the milling conditions. This powder showed better sinterability and higher thermal conductivity than that obtained by th e usual dry grinding method.