Combustion synthesis of AlN with melamine as an additive

Melamine (C₃H₆N₆) was used as an additive for synthesizing aluminum nitride by combustion synthesis. It was found that at least 0.1 M of melamine addition to 1 M of aluminum and 0.8 MPa of nitrogen pressure were necessary to initiate a stable reaction. In addition to melamine, however, use of aluminum nitride as a diluent and application of forced nitrogen flow yielded better results. Analyzing the reaction temperatures, reaction rates, nitrogen contents, x-ray diffraction patterns, and scanning electron microscopy photographs, the optimum conditions for synthesizing AlN were established: (i) reactants were 90 wt% (1 M Al + 0.1 M melamine) + 10 wt% AlN diluent, (ii) chamber pressure was 0.9 MPa, and (iii) nitrogen flow rate was 15 l/min. Under these conditions, aluminum nitride with the stoichiometric nitrogen content of 34 wt% could be obtained.