Thermal Compatibility Between Perfluoroisobutyronitrile-CO2 Gas Mixture With Copper and Aluminum Switchgear

Perfluoroisobutyronitrile (C
₄
F
₇
N) 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 C
₄
F
₇
N 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 C
₄
F
₇
N-CO
₂
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 C
₄
F
₇
N-CO
₂
gas mixture and metal surface was also analyzed. It was found that C
₄
F
₇
N-CO
₂
gas mixture has better compatibility with aluminum than copper. The reaction between C
₄
F
₇
N-CO
₂
gas mixture and heated copper at 220 °C produces the gaseous by-product C
₃
F
₆
. The surface color of copper deepens and the corrosive degree increases with temperature, while the interaction between C
₄
F
₇
N and heated aluminum does not cause gas decomposition and metal corrosion. In general, the thermal stability of C
₄
F
₇
N-CO
₂
gas mixture associated with heated copper and aluminum is inferior to that of SF
₆
.