Mechanism and kinetics of silicothermic reduction of MoS2 for preparing ultra-fine grain MoSi2 powder

Abstract

In this work, ultra-fine grain MoSi 2 powders were prepared via silicothermic reduction of MoS 2 using CaO as a desulfurizer, and the mechanism and kinetics were studied in detail. The FE-SEM images demonstrated that the as-prepared MoSi 2 particles inherited the macro morphology and size of molybdenum sulfide and were almost not affected by the particle size of Si powder. Additionally, it was found that desulfurization reaction between CaO and gaseous SiS was a strong exothermic reaction, resulting in growth of MoSi 2 grains and difficult separation of the target product MoSi 2 from desulfurization product in the scale-up experiment. To solve this problem, graphite powder or carbon felt was introduced between the sample and CaO, and the residual S content of the prepared MoSi 2 powder was about 0.14% and 0.16%, respectively. This work provides new insights into the preparation of ultra-fine grain MoSi 2 powder by silicothermic reduction of MoS 2 -based molybdenum source. • Ultra-fine grain (about 300 nm) MoSi 2 powders were prepared via silicothermic reduction of MoS 2 . • Reaction mechanism and kinetics were studied in detail. • The as-prepared MoSi 2 inherits the macro morphology and particle size of molybdenum source.