Poor contact is one of the main causes of the internal fault of SF ₆ gas insulated equipment. Taking the most common over-thermal decomposition process of SF ₆ caused by poor silver-plated copper contacts as an example, this article combines with density functional theory (DFT) and establishes the gas–solid contact interface adsorption model of SF ₆ and its main decomposition characteristic products (SO ₂ F ₂ , SO ₂ , SOF ₂ , HF, and H ₂ S) with solid silver. Adsorption energy, charge transfer, and density of electronic state were used to analyze the reaction activity of SF ₆ and its main decomposition products with the Ag surface. It is found that SF ₆ and SO ₂ are chemically adsorbed on the Ag surface, and the reaction activity is relatively strong. When chemical adsorption occurs, SF ₆ bonds with the metal surface by the 2p orbitals of F atoms, and SO ₂ is bonded to the metal surface by the 2p orbitals of O atoms. There is also a strong reaction trend between HF and Ag (1 1 1), while SO ₂ F ₂ , SOF ₂ , and H ₂ S only physically absorbed with the Ag (1 1 1) surface. This indicates that under the local overheating failure caused by metal contacts, SF ₆ will first undergo chemical adsorption in the SF ₆ /Ag (1 1 1) system and then undergo a decomposition reaction near the metal surface rather than in free space. The participation of Ag reduces the difficulty of the decomposition reaction to some extent. The results lay a foundation for finally revealing the interfacial reaction process of SF ₆ -Ag.

#	Concept	H-Index	Publications	Citations
1	Engineering	1	1	14
2	Natural Sciences	1	1	14
3	Applied Physics	1	1	14
4	Chemistry	1	1	14
5	Materials Science	1	1	14

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