Theoretical Study on the Compatibility Between C4F7N Decomposition Products and Metals:a First-principles
The compatibility between gases and solid materials within gas chambers is crucial for the safe operation of equipment.Existing research focuses on the interactions between the main insulating gases and solids,while the decomposition products under electrical and thermal faults may also affect the performance of solid materials.Therefore,an interaction model between the main decomposition products of the eco-friendly insulating gas C4F7N(CO,CF4,and C3F6)and metal materials(Cu,Al)was established for study.Based on the first principle,microscopic parameters such as interaction energy,charge transfer,and differential charge density were calculated,the interaction mechanisms between the decomposition products and metals were explored from the perspectives of energy and electronic structure,and their compatibility was analyzed in depth.The results show that the interaction energies between CO,CF4,C3F6,and Cu(1 1 1)are-0.552 eV,0.317 eV,and 0.132 eV,and charge transfer amounts between CO,CF4,C3F6,and Cu(1 1 1)are 0.231e,0.006e and 0.156e respectively.The bonding effects are all relatively weak,indicating physical interactions,which in turn demonstrate great compatibility.CO and CF4 also exhibit good compatibility with Al(1 1 1),while C3 F6 shows poor compatibility at the Al(1 1 1)interface.Therefore,from the perspective of gas stability,Cu can be used as a conductive material in the gas chamber of eco-friendly C4F7N-CO2 insulated equipment,while avoiding the decomposition of C4F7N,thereby ensuring better operational safety of the equipment.
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