Study on regulation mechanism of morphology and particle size of molybdenum powder in hydrogen reduction process

This study applied a novel process for manufacturing molybdenum powder to regulate the morphology and particle size. The effects of water vapor pressure, temperature, and holding time on the morphology and particle size of molybdenum powder were studied, in which bottom-blowing hydrogen was configured with a consistent flow direction of water vapor generated by hydrogen reduction. The results showed that polyhedral molybdenum powders with uniform sizes were prepared at different positions in the crucible via a single nucleation mechanism, and the water vapor pressure was identified as a key factor for controlling the particle size. By adjusting the water vapor pressure, reaction time, and temperature, the molybdenum powders with a particle size between 1 & mu;m and 10 & mu;m was obtained. When the hydrogen reduction temperature increased from 950 degrees C to 1150 degrees C, the average particle size increased from 1.8 & mu;m to 3.4 & mu;m, and particle aggregation was exacerbated. Upon extending the holding time from 60 min to 180 min, the average particle size increased marginally from 3.4 & mu;m to 4 & mu;m. This study provides a new method and important theoretical guidance for manufacturing molybdenum powders with a uniform morphology and particle size.