Sintering of silicon carbide obtained by combustion synthesis

An activated combustion synthesis method was utilized to synthesize silicon carbide from the elementary mixture in the presence of polytetrafluoroethylene (PTFE) as a thermochemical promoter and product's morphology modifier. Thermodynamic calculations in the initial Si-C-(C2F4)n mixture revealed the influence of PTFE amount and external gas pressure on the adiabatic temperature and equilibrium composition of the products. Combustion parameters and phase composition of the product were sensitive to silicon particle size, PTFE amount, sample diameter and gas pressure. Optimum conditions for the preparation of a mixture of alpha and beta SiC with up to 200 nm in particle size were determined. After consolidation by the spark plasma sintering technique some physicomechanical characteristics of the bulk specimens were measured.