Study of the decomposition of SF6 in the presence of water, subjected to gamma irradiation or corona discharges

The influence of water on the degradation of SF₆ was studied by subjecting mixtures of SF₆ and H₂O either to irradiation by ⁶⁰Co γ-rays or to corona discharges (point-plane electrodes; voltage: DC negative or positive polarity). The stable-reaction products formed were analyzed and assayed with various analytical techniques including gas-phase chromatography, gas chromatography-mass spectrometry, specific electrode, colorimetry, atomic absorption, and EDAX (energy-dispersive analysis by X-rays). The influence of the energy input, the water content, the pressure of SF₆ and, for the corona discharges, the value of the discharge current and the polarity of the applied voltage on the formation of SOF₂ and SO₂F₂ which were the only two stable gaseous compounds detected, were all studied. The results obtained were compared with data from the literature and with the reaction schemes proposed to date, to explain the decomposition of SF₆ under the effect of similar or different input energies