Low Temperature Sintering of Fine AlN Powder Synthesized by Floating-Type Rapid Nitridation of Al Powder

Abstract

Fine and ultra-pure AlN powders were synthesized by floating-type direct nitridation of ultra-pure Al powder at 1350 to 1550 °C for 0.8 to 6.0 seconds. The AlN powders in perfect nitridation were produced by the nitridation at above 1450 °C for 3.5 seconds. Those AlN powders obtained were primary particle size of about 0.1 to 0.2 μm, and had metal impurities of less than 20 ppm and oxygen content of 0.6 wt %. High thermal conductive AlN ceramic of 170 W/mK, which was sintered at 1700 °C for 120 min in nitrogen atmosphere, could be obtained by sintering aid of 7 wt %YF₃. Neither pore nor precipitates of the second phase are observed at the grain boundary, and then the extensive grain growth is observed.