| Abstrakt: |
In this study, the hydrogen reduction mechanism of MoO3was analyzed in detail using Ti-Mo core–shell powder manufactured through a milling and reduction process. MoO3and Ti powders were ball-milled to refine the MoO3powder and coat it onto the Ti powder to fabricated core-shell structure. Subsequently, the milled powder was reduced at 600°C in a hydrogen atmosphere. Phase analysis was conducted using X-ray diffraction, and oxidation state analysis was conducted using X-ray photoelectron spectroscopy. In addition, morphology analysis was performed using scanning electron microscopy, and elemental analysis was conducted using electron probe micro-analysis. It was confirmed that Mo9O26and Mo4O11intermediate phases are formed sequentially as MoO3is reduced to MoO2, and Mo9O26has a plate shape with a thickness of sub-70 nm, and Mo4O11exhibits a thickness of sub-300 nm. Especially, the Mo2O3intermediate phase, previously studied only theoretically, was experimentally confirmed for the first time in the reduction process from MoO2to Mo. Furthermore, the analysis of Mo-oxide intermediate phases was explained by the structural characteristics of the core–shell. The shell of Mo oxide is thick and dense, making it difficult for the vapor phase necessary for CVT reduction to penetrate and diffuse into the shell. As a result, rapid CVT reduction occurs outside the shell, while relatively slower reduction occurs inside the shell where intermediate phases are observed. |
