WC‒TiC‒Al2O3 composite powder preparation by self-propagating high-temperature synthesis route

Abstract

Abstract WC‒TiC‒Al2O3 composite powder was prepared in a one-step self-propagating high-temperature synthesis process using WO3, TiO2, Al and C as starting materials in a prototype ignition apparatus. The effect of TiO2/WO3 molar ratio and the addition of extra carbon exceeding the stoichiometric value were studied as the main synthesis parameters. The results showed that the combustion front velocity decreased with increasing TiO2/WO3 molar ratio. X-ray diffraction analysis results showed that the WC‒W2C‒Al2O3 composite was developed in a WO3‒Al‒C system containing 2.5 times as much extra carbon as the stoichiometric value. Moreover, replacement of WO3 with TiO2 led to the formation of TiC, while tungsten carbide phases were eliminated completely to obtain the W‒TiC‒Al2O3 composite. Finally, the WC‒TiC‒Al2O3 composite was synthesized through the addition of 2.5 times as much extra carbon as the stoichiometric value to the 1.2WO3‒1.2TiO2‒4Al‒2.4C system in a one-step process. Thermal analysis data showed that the SHS reaction was initiated by the aluminothermic reduction of WO3. Also, microstructural characterization revealed that the formation of Al‒W melt had a key role for the synthesis of WC in the final product.