Reactive Synthesis and Phase Stability Investigations in the Aluminum Nitride–Silicon Carbide System

Abstract

The effect of AlN on the structure formation of SiC was investigated. SiC was synthesized in the presence of AlN under vacuum at 1500°C, and the result was cubic SiC. The synthesis of AlN–SiC composites through the reaction Si3N4+ 4Al + 3C = 3SiC + 4AlN was also investigated and compared with synthesis via field‐activated self‐propagating combustion (FASHS). Reactants were heated in a vacuum furnace at temperatures ranging from 1130° to 1650°C. Below 1650°C, the reaction is not complete and at this temperature the product phases are AlN and cubic SiC. At 1650°C, the product contained an outer layer which contained β‐SiC only and an inner region which contained AlN and cubic SiC. 2H‐SiC and AlN composites synthesized via field‐activated self‐propagating combustion were annealed at 1700°C under vacuum. The AlN dissociated and evaporated and the 2H‐SiC transformed to the cubic β phase. Reasons for the differences in products of furnace heating and FASHS are discussed.