High Thermal Conductivity AlN from Combustion Synthesized AlN Powder

A combustion synthesis method has been developed for synthesis of AlN powder. The AlN products thus obtained were ground to have an average particle size of 2 mu m for sintering. Yttrium oxide was added to the AlN powder as sintering aid. The sintering was carried out in a microwave field at 2.45 GHz with a single-mode cavity. The specimens were sintered at temperature ranging from 1800 to 1900 degrees C with soaking times of 30 min to 3 hrs. The highest thermal conductivity of the as-sintered specimen achieved 195 W/mK. The as-sintered specimen was then placed in the microwave cavity again and was reheated at 1800 degrees C under reducing atmosphere for a time ranging from 30 min to 3 h. The thermal conductivity of the specimen could achieve 235 W/mK.