Surface reactions of SF6 decomposition products

This paper reports investigations on decay reactions of several SF6 decomposition products on technical surfaces at room temperature. processes were measured, with and without addition of water, with SF6 or argon as background gases. The surfaces were stainless steel, aluminium (GIS enclosure), and glass. The stainless steel surface was pretreated in different ways to investigate the role of the surface state. The SF6 decomposition products studied were S2F10, S2O2F10, SOF2, SOF4, and SF4. Their decay was measured by detecting the temporal development of their gas phase concentrations and of the concentrations of some of their gaseous reaction products by means of a FT-IR spectrometer. From the data obtained it can be inferred that surface decay is dominant at room temperature. Simple stoichiometric and kinetic models for these processes are proposed which provide a basis for the quantification on the life times and decay rates of toxic and corrosive decomposition products in SF6 insulated power equipment. They also provide some information on the limitations of gas sample storage.