Compatibility and Interaction Mechanism between the C(4)F(7)N/CO(2)/O(2) Gas Mixture and FKM and NBR

[Image: see text] The C(4)F(7)N/CO(2)/O(2) gas mixture received a great deal of attention for its potential use in eco-friendly gas-insulated equipment (GIE). The evaluation of the compatibility between C(4)F(7)N/CO(2)/O(2) and sealing rubber is necessary and significant considering the high working pressure (0.14–0.6 MPa) of GIE. Herein, we explored the compatibility between C(4)F(7)N/CO(2)/O(2) and fluororubber (FKM) and nitrile butadiene rubber (NBR) for the first time by analyzing the gas components, rubber morphology, elemental composition, and mechanical properties. The interaction mechanism of the gas–rubber interface was further investigated based on the density functional theory. We found that C(4)F(7)N/CO(2)/O(2) is compatible with FKM and NBR at 85 °C, while the surface morphology changed at 100 °C, with white granular and agglomerated lumps appearing on FKM and multi-layer flakes being generated on NBR. The accumulation of the fluorine element occurred, and the compressive mechanical properties of NBR deteriorated after the gas–solid rubber interaction. Overall, the compatibility between FKM and C(4)F(7)N/CO(2)/O(2) is superior, which could be employed as the sealing material for C(4)F(7)N-based GIE.