Effects of mechanical activation of MoO3/C powder mixture in the processing of nano-crystalline molybdenum

Nano-crystalline molybdenum with a mean crystallite size of 45 nm was synthesized through reduction of MoO3 by carbon using high energy ball milling and subsequent heat treatment. XRD, DTA/TG and SEM techniques were employed to evaluate the powder particle characteristics. It was found that initial mechanical activation at an ambient temperature did not result in the reduction of MoO3 to molybdenum. DTA/TG results showed that in a sample milled for 25 h, MoO2 and Mo2C were formed at 485 and 925 °C, respectively during carbo-thermal reduction of MoO3. At the final stage, Mo2C reacts with the remaining MoO2 at 1030 °C to produce nano-crystalline molybdenum.

Research Highlights► The mechano-chemical reduction of MoO3 to molybdenum does not occur during milling with carbon at ambient temperatures. ► MoO3 started to reduce with carbon and transform to MoO2 when milling was continued up to 50 h. ► Particles of the molybdenum product indicated to have a mean crystallite size of 45 nm and uniform size.