Preparation of fine AIN powders by wet ball-milling and their characterization

Abstract

Aluminum nitride (AlN) raw powder prepared by direct nitridation of metallic aluminum powder was ground by wet ball-milling in order to obtain submicron fine powder for low-temperature sintering. The effects on the properties of the milled powders of milling conditions such as ball size, ball material, chemical species of the grinding fluid and water content of the grinding fluids were investigated. A larger grinding rate was observed using medium balls with diameters of less than 5 mmΦ 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 grinding fluid increased the oxygen content of the milled powder. Fine AlN powder with submicron size and sharp particle size distribution was obtained by adjusting the milling conditions. This powder showed better sinterability and higher thermal conductivity than that obtained by the usual dry grinding method.