Changes of Particle Size and Morphology of Prepared W/Mo Powders during Hydrogen Reduction Process with the Addition of ROH (R = Li, Na, K)

Abstract

In this paper, the influences of ROH (R = Li, Na, K) additions on the preparations of Tungsten (W)/Molybdenum (Mo) powders by hydrogen reduction of WO₃/MoO₂ in the temperature range of 800°C to 1100°C were studied in detail. In the absence of ROH addition, the prepared W/Mo powders basically maintained the morphology of raw oxide. However, with the assistance of ROH, the morphology and particle size of the products had been greatly changed. The grains of W and Mo were obviously coarsened, and micron-sized Mo powder and W powder with good dispersion can be prepared. In addition, the addition of ROH can promote the reduction rate of WO₃ but inhibit the reduction of MoO₂. Moreover, the effect of LiOH on grain growth is more significant than that of NaOH and KOH.

Fig. 8 SEM images of W prepared by reducing WO₃ with the assistance of 0.1% ROH at 900°C: (a) LiOH, α = 0.58; (b) NaOH, α = 0.60; (c) KOH, α = 0.64, (α is reaction extent).