Decomposition Properties of C4F7N/N2 Gas Mixture: An Environmentally Friendly Gas to Replace SF6

The insulation characteristics and decomposition components of C₄F₇N/N₂ gas mixture, a potential substitute for SF₆, were first explored by breakdown experiments/gas chromatography–mass spectrometer. The structural properties of C₄F₇N molecule and the decomposition mechanism of C₄F₇N/N₂ gas mixture were analyzed based on the density functional theory calculation and ReaxFF molecular dynamics simulation. We found that C₄F₇N/N₂ mixture has great self-recovery performance. The decomposition of C₄F₇N in a discharge mainly produces CF₄, C₂F₆, C₃F₈, CF₃CN, C₂F₄, C₃F₆, and C₂F₅CN, among which the relative content of C₂F₆, CF₄, and CF₃CN is higher. ReaxFF-MD simulations show that CF₃, CN, F, and C₃F₇ are the four main free radicals produced by C₄F₇N. The decomposition characteristics of N₂ are better than that of C₄F₇N. The addition of N₂ has a certain buffering effect to avoid the massive decomposition of C₄F₇N. The global warming potential value of a gas mixture containing 20% C₄F₇N decreased by 94.32% compared with SF₆. Relevant results not only reveal the decomposition characteristics of C₄F₇N/N₂ mixture in a discharge comprehensively, but also provide a reference for engineering application and emission of a C₄F₇N/N₂ gas mixture.