CHEMICAL VAPOR TRANSPORT PROCESS IN HYDROGEN REDUCTION OF BALL-MILLED MOLYBDENUM AND TUNGSTEN OXIDE POWDERS

Abstract

Chemical vapor transport of ball-milled MoO3 and WO3 powders in a non-isothermal hydrogen reduction process was discussed in terms of the sizes and specific surface area of oxide particles. Although all reduction processes were completed at nearly the same temperature, they became stepwise with lower starting temperatures and peak points of each sequence due to the refinement of the oxide particles. In particular, the chemical vapor transport process in the reduction of MoO3 (MoO3 -> MoO2) was strongly affected by the initial states of the oxide powders.