Synthesis of AlNSiC composites and solid solutions by field-activated self-propagating combustion

Abstract

The synthesis of AlN-SiC composites and solid solutions was achieved through the imposition of an electric field in self-propagating high-temperature reactions. Despite its highly exothermic nature, the reaction Si 3N 4 + 4Al + 3C = 4AlN + 3 SiC is not self-sustaining without the imposition of a threshold field (E) of 8 Vcm − 1. At higher fields, the nature of the product depended on the value of the field. At E = 8 and 16.5 V cm − 1, the product is a composite of AlN-rich and SiC-rich phases. The extent of solubility of each phase into the other increased with increasing field. When E = 25.0 V cm − 1, the product is a solid solution with the 2H structure. The degree of randomness of the solution increased with a further increase in the value of the imposed field. Compositional analyses of the product phases are in reasonable agreement with the reported tentative phase diagram for AlN and SiC. The work demonstrates the use of an electric field as a processing parameter in self-sustaining combustion synthesis of nitride composites and solid solutions.