The preparation of ultrafine V8C7 powder and its phase reactions

Abstract The conventional carbothermal synthesis of V8C7 powder has weak points such as high reaction temperature and large particle size. This paper discusses the preparation of ultrafine V8C7 powder by reducing and carburizing the vanadium oxides using the carbon which is pyrolyzed from the organic compounds and the phase reactions during the preparation of ultrafine V8C7 powder. V2O5 dissolves in a solution of organic acid in water, the amorphous powder precursor that contains vanadium is obtained by spray drying, then the powder precursor is heated in the vacuum furnace to prepare the ultrafine V8C7 powder. Because carbon and vanadium oxides are intimately mixed, the diffusion distance is shortened and the carburizing temperature decreased to inhibit the grain growth. It is beneficial for the observation of the phase reactions and the preparation of ultrafine V8C7 powder.