Combustion synthesis of aluminum nitride particles and whiskers

Aluminum nitride (AlN) was produced via the combustion synthesis of loosely packed aluminum powder (pore fraction of similar to 0.8) in a graphite reactor that was lined with permeable carbon felt. Almost-complete conversion was achieved with a forced flow of nitrogen for beds 50-150 mm deep (mass of 200-650 g), The product was in the form of a loosely aggregated bed, with regions of distinct morphology, and had a predominantly whisker morphology, Some control over the microstructure was possible by changing the processing parameters. The addition of 5% of ammonia to the nitrogen resulted in a uniform production of whiskers, whereas a 50% solid-phase dilution with AlN favored the production of particles.