Interaction Mechanism between the C4F7N-CO2 Gas Mixture and the EPDM Seal Ring

Yi Li; Xiaoxing Zhang; Yalong Li; Dachang Chen; Zhaolun Cui; Wei Liu; Ju Tang

doi:10.1021/acsomega.9b04183

Interaction Mechanism between the C₄F₇N-CO₂ Gas Mixture and the EPDM Seal Ring

ACS Omega. 2020 Mar 11;5(11):5911-5920. doi: 10.1021/acsomega.9b04183. eCollection 2020 Mar 24.

Authors

Yi Li^{1

2}, Xiaoxing Zhang^{2

1}, Yalong Li², Dachang Chen², Zhaolun Cui², Wei Liu³, Ju Tang²

Affiliations

¹ School of Electrical and Electronic Engineering, Hubei University of Technology, Wuhan 430068, China.
² School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China.
³ Electric Power Research Institute of State Grid Anhui Electric Power Company Ltd., Hefei 230000, China.

Abstract

C₄F₇N (fluorinated nitrile) has been introduced as a remarkable substitute gas for the greenhouse gas SF₆ (sulfur hexafluoride) which is used in gas-insulated equipment (GIE). Intensive investigations about the compatibility between C₄F₇N and materials used in GIE are required to decide their long-term behavior. In this paper, the interaction mechanism between EPDM, used as a sealing ring in GIE, and C₄F₇N-CO₂ was explored. The composition and morphology properties of EPDM were first revealed based on scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that EPDM rubber is incompatible with the C₄F₇N-CO₂ gas mixture at temperatures higher than 70 °C. There exist chemical reactions between EPDM and C₄F₇N, resulting in the generation of gaseous byproducts including C₃F₆, CF₃H, and C₂F₅H and corrosion of EPDM. DFT calculation also shows that the interaction between C₄F₇N and EPDM could cause the dissociation of C₄F₇N. Relevant results provide important guidance for the engineering application of the C₄F₇N gas mixture.