Thermal Compatibility between Perfluoroisobutyronitrile-CO2 Gas Mixture with Copper and Aluminum Switchgear

Abstract

Perfluoroisobutyronitrile (C4F7N) has received extensive attention over the past three years as an environmental friendly gas insulating medium. At present, there are few studies on the compatibility of C4F7N with metal materials used in the electrical equipment. In this paper, we constructed a gas-solid interfacial reaction platform and carried out aging tests for C4F7N-CO2 gas mixture at different temperatures. The composition of the gas mixture and the surface morphology and the elemental composition of copper, aluminum were explored. The interaction mechanism between C4F7N-CO2 gas mixture and metal surface was also analyzed. It was found that C4F7N-CO2 gas mixture has better compatibility with aluminum than copper. The reaction between C4F7N-CO2 gas mixture and heated copper at 220 °C produces the gaseous by-product C3F6. The surface color of copper deepens and the corrosive degree increases with temperature, while the interaction between C4F7N and heated aluminum does not cause gas decomposition and metal corrosion. In general, the thermal stability of C4F7N-CO2 gas mixture associated with heated copper and aluminum is inferior to that of SF6