Study on the thermal decomposition reaction process and kinetics of SF6 and tungsten

The thermal reaction of SF6 with tungsten powder was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC), combined with the characterization of solid decomposition products of SF6 and tungsten by SEM, EDS, XPS and Raman. Based on above experiments, a two-stage decomposition process of SF6 with tungsten was proposed: the first stage is the surface vulcanization reaction W+SF6→S2, mainly taken place at 600 °C, with the activation energy valued at 152.8 kJ·mol-1, according to Avrami-Erofeev equation; the second stage is the endothermic fluorination reaction WS2+SF6 →WF6, mainly taken place at 750 °C,, with the activation energy valued at 126.0 kJ·mol-1 according to the Avrami-Erofeev equation.