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.