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

• Thermal decomposition of C 4 F 7 N-N 2 generated C 3 F 6 firstly at 350℃. • CF 4 and C 3 F 8 were generated at temperatures higher than 450℃. • C 3 F 6 , C 3 F 8 , CF 4 , CF 3 CN, (CN) 2 and COF 2 are the main decomposition products. • Thermal stability of C 4 F 7 N-N 2 gas mixture at high gas pressure conditions is great. We explored the thermal decomposition properties of Fluoronitriles-N 2 (C 4 F 7 N-N 2) gas mixture using as SF 6 substitute gas in GIE. The yield of main decomposition products of 10 %C 4 F 7 N-90 %N 2 gas mixture under different overheating temperature and gas pressure conditions were detected and analyzed. We found that thermal decomposition of C 4 F 7 N-N 2 mainly produces C 3 F 6 , C 3 F 8 , CF 4 , CF 3 CN, (CN) 2 and COF 2. C 3 F 6 is the first detected by-product at 350℃, while CF 4 and C 3 F 8 were generated at temperatures higher than 500℃. The yield and formation rate of C 3 F 6 , (CN) 2 increases with temperatures lower than 450℃ then decreases at higher temperatures, while the generation of C 3 F 8 , CF 4 , CF 3 CN and COF 2 has positive correlation with temperature. C 4 F 7 N-N 2 gas mixture has great thermal stability at high pressure. The increase of gas pressure could effectively reduce the decomposition of C 4 F 7 N, which ensures the insulation strength of gas mixture. [ABSTRACT FROM AUTHOR]