Influence of an electric field on combustion synthesis process and microstructures of TiC–Al2O3–Al composites

In order to achieve combustion synthesis (CS) of high-density and fine-structured TiC–Al2O3–Al composites, the activation of combustion reactions of 3TiO2–3C–(4 + x) Al system with x ≥ 10 mol was conducted by means of external electric field. During the field-activated combustion synthesis (FACS), liquid Al in excess stoichiometric amount was generated and it infiltrated into the synthesized TiC–Al2O3 ceramic matrix with porosities, which directly results in a dense TiC–Al2O3–Al composites. The influence of electric field on CS process of the reactive system and the resulting microstructures of TiC–Al2O3–Al composites was investigated. The results show that an external electric field can effectively improve the adiabatic combustion temperature of the reactive system. Therefore a self-sustaining combustion of the system can be induced thermodynamically. In the experiments, both practical combustion temperature and propagation velocity of combustion wave were obviously enhanced with increasing field strength, whereas sizes of the synthesized TiC and Al2O3 particles were significantly decreased at the same time. Under an electric field of 25 V cm−1, TiC–Al2O3–Al composites with a relative density of 92.5% was successfully fabricated through the combustion reaction in the system with x = 14 mol, in which TiC and Al2O3 particles possess fine-structured sizes of 0.2–1.0 μm, with uniform distribution in metal Al.