In-situ production of cobalt-vanadium carbide composite powder from Co3O4-V2O5-C-Mg via MASHS through magnesium-thermic reaction

The objective of the present study was production of cobalt-vanadium carbide composite powder via mechanically-activated self-propagating high-temperature (MASHS) combustion synthesis from oxide materials with magnesium as the activating agent. Initially, thermodynamic behavior of the reaction was studied according to the stoichiometric equation with the molar ratio of (1:1:9:2) for vanadium oxide, cobaltoxide, magnesium, and graphite, respectively. Based on the enthalpy (3155047 j/mol) and the reaction adiabatic temperature (Tad~3932.014), the reaction is in the MSR mode. In order to activate the starting powder, high energy planetary ball mill under argon atmosphere was used for 5 min with powder-to-ball weight ratio of 1:20. Thermal behavior of the activated powder was investigated by differential thermal analysis (DTA). For the combustion synthesis reaction, the pills made from the milled powder mixture were placed in a tube furnace under argon atmosphere at 700°C for 10 min. The XRD results indicated that at this temperature, the powder mixture of the precursors is combusted and cobalt-vanadium carbide composite powder with the twophases of magnesium oxide/ (VC, V8C7) is formed.