Combustion synthesis of fine AlN powder and its reaction control

Aluminum nitride powder produced by the combustion synthesis (SHS) usually contains coarse particles because of its high reaction temperature. These particles make it difficult to achieve sintering. To improve sinterability, the reaction temperature was controlled by adding hydrogen gas up to 20 vol.% to the reactant gas (nitrogen), and NH4F up to 1.5 mass% to the reactant mixture. The reaction temperature was lowered by 400 K when 10 vol.% of H2 and 1.0 mass% of NH4F were added. As a result, the specific surface area of the final powder increased by 80% compared to the powder obtained without addition. The addition of NH4F reduced the residual aluminum and oxygen content in the AlN products.