Production and characterization of cobalt/vanadium boride nanocomposite powder by mechanochemical method

In this research, cobalt-vanadium boride (Co-VB) nanocomposite was synthesized from powder mixture of cobalt oxide (Co3O4), vanadium oxide (V2O5), boron oxide (B2O3) and magnesium (Mg), via high energy ball milling. Regarding the value of adiabatic temperature, Co-VB nanocomposite has a potential to be the result of an induced self-sustaining reaction. The produced composite powder at various milling times was evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After milling for 15 min, an ignition occurred in the milling vial and, according to XRD, Co, VB, MgO, VO2 and Mg3(BO3)2 phases were generated. Findings showed that with increasing the time of milling to 30 min, the Mg3(BO3)2 unwanted phase was decomposed, the remaining vanadium oxide was reduced and the final reaction fully occurred. Regarding to XRD results and the X-ray mapping analysis, MgO which was the byproduct of the system, was completely removed from the produced powder by dissolving in hydrochloric acid 9%. Finally, TEM image also confirmed that the composite powder had a grain size of 30 nm after the leaching process.