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<p>With increasingly stringent environmental regulations, perfluoroisobutyronitrile (C<sub>4</sub>F<sub>7</sub>N/CO<sub>2</sub>) mixed gas has gained considerable attention as a substitute for sulfur hexafluoride (SF<sub>6</sub>) in gas circuit breakers. However, the mechanisms underlying its influence on the corrosion behavior of copper–tungsten (CuW) contact materials remain unclear. The corrosion behavior and interfacial reaction mechanisms of CuW contacts in SF<sub>6</sub> and 9%C<sub>4</sub>F<sub>7</sub>N/91%CO<sub>2</sub> environments&#xa0;are&#xa0;systematically compared. Corrosion morphology analysis revealed that, compared to SF<sub>6</sub>, contacts exposed to the mixed gas exhibited significantly increased surface defects including micro-pores and cracks, enlarged cross-sectional voids, and increased remelted tungsten layer thickness from approximately 69&#xa0;to&#xa0;94.6&#xa0;μm. Interfacial reaction analysis indicated that complex chemical reactions occurred between the decomposition products of the mixed gas and the contact materials, generating multiple corrosion products including CuO, Cu<sub>2</sub>O, CuF<sub>2</sub>, and WO<sub>3</sub>. To elucidate the physical nature of enhanced corrosion, a temperature field simulation model was established to simulate the phase transformation behaviors of the contact materials, including melting and vaporization processes. Simulation results demonstrated that the mixed gas environment resulted in higher peak surface temperatures and broader high-temperature regions on the contacts, leading to intensified phase transformations, which corroborated the experimentally observed enhanced corrosion phenomena. The coupled mechanisms of enhanced corrosion of CuW contacts in C<sub>4</sub>F<sub>7</sub>N/CO<sub>2</sub> mixed gas&#xa0;were&#xa0;elucidated, providing theoretical foundation and data support for the optimized design of contact materials, development of surface protection technologies, and reliability assessment in next-generation environmentally friendly gas circuit breakers.</p>

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Corrosion behavior and mechanism of CuW contact in C4F7N/CO2 under arc discharge

  • 期刊论文

  • 发表日期：

    2026年7月22日

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  • Xue-Ying Gao,
  • Xin Lin,
  • Yi Ding,
  • Jian-Wei Wei,
  • Ren-Hu Song

摘要

With increasingly stringent environmental regulations, perfluoroisobutyronitrile (C4F7N/CO2) mixed gas has gained considerable attention as a substitute for sulfur hexafluoride (SF6) in gas circuit breakers. However, the mechanisms underlying its influence on the corrosion behavior of copper–tungsten (CuW) contact materials remain unclear. The corrosion behavior and interfacial reaction mechanisms of CuW contacts in SF6 and 9%C4F7N/91%CO2 environments are systematically compared. Corrosion morphology analysis revealed that, compared to SF6, contacts exposed to the mixed gas exhibited significantly increased surface defects including micro-pores and cracks, enlarged cross-sectional voids, and increased remelted tungsten layer thickness from approximately 69 to 94.6 μm. Interfacial reaction analysis indicated that complex chemical reactions occurred between the decomposition products of the mixed gas and the contact materials, generating multiple corrosion products including CuO, Cu2O, CuF2, and WO3. To elucidate the physical nature of enhanced corrosion, a temperature field simulation model was established to simulate the phase transformation behaviors of the contact materials, including melting and vaporization processes. Simulation results demonstrated that the mixed gas environment resulted in higher peak surface temperatures and broader high-temperature regions on the contacts, leading to intensified phase transformations, which corroborated the experimentally observed enhanced corrosion phenomena. The coupled mechanisms of enhanced corrosion of CuW contacts in C4F7N/CO2 mixed gas were elucidated, providing theoretical foundation and data support for the optimized design of contact materials, development of surface protection technologies, and reliability assessment in next-generation environmentally friendly gas circuit breakers.