Thermal decomposition properties of fluoronitriles-N2 gas mixture as alternative gas for SF6

We explored the thermal decomposition properties of Fluoronitriles-N-2 (C4F7N-N-2) gas mixture using as SF6 substitute gas in GIE. The yield of main decomposition products of 10 %C4F7N-90 %N-2 gas mixture under different overheating temperature and gas pressure conditions were detected and analyzed. We found that thermal decomposition of C4F7N-N-2 mainly produces C3F6, C3F8, CF4, CF3CN, (CN)(2) and COF2. C3F6 is the first detected by-product at 350 degrees C, while CF4 and C3F8 were generated at temperatures higher than 500 degrees C. The yield and formation rate of C3F6, (CN)(2) increases with temperatures lower than 450 degrees C then decreases at higher temperatures, while the generation of C3F8, CF4, CF3CN and COF2 has positive correlation with temperature. C4F7N-N-2 gas mixture has great thermal stability at high pressure. The increase of gas pressure could effectively reduce the decomposition of C4F7N, which ensures the insulation strength of gas mixture.