Synthesis of AlN Powder by Carbothermal Reduction-nitridation of Alumina/Carbon Black Foam

Alumina/carbon black foam was prepared by mechanical foaming and aqueous gelcasting and used as precursor for the production of AlN powder. The foam with large open pores ensures homogeneous solid-gas reaction during carbothermal reduction-nitridation (CRN) process. Further, the solid-gas contact is enlarged by oppositely feeding the foam and nitrogen in a vertical furnace. Solid-gas reaction efficiency of the CRN process was greatly enhanced when total porosity of the foam was >= 80%. XRD results revealed that gamma-Al2O3 transformed to alpha-Al2O3 and then was carbothermal reduction-nitridationed to be AlN phase. AlN powder with an average particle size of less than 1 mu m was synthesized at 1650 degrees C and contained 32.9wt% nitrogen.