Abstract:
To study the discharge decomposition characteristics of eco-friendly C
4F
7N/CO
2/O
2 ternary gas mixture, the decomposition experiments of C
4F
7N/CO
2/O
2 ternary gas mixture under corona discharge were carried out with different O
2 volume fractions. The main decomposition products include CF
4, C
2F
6, C
3F
6, C
3F
8, C
6F
14, CNCN and CF
3CN, in which the production of saturated fluorocarbon gases such as CF
4, C
2F
6 and C
3F
8 is high, while the production of unsaturated fluorocarbon gases C
3F
6 is low. The addition of O
2 can significantly inhibit the gas decomposition, after 60 h corona discharge of the gas mixture with 4% O
2 volume fraction, the production of CNCN is only 22.1% of that in the absence of O
2. With the increase of O
2 volume fraction, the formation rate of CNCN and other decomposition products decreases rapidly at first and then tends to be stable, and 2% to 8% volume fraction of O
2 has good inhibitory effect on the decomposition of the gas mixture. Based on the density functional theory, the simulation analysis of the decomposition process was carried out. It is found that O
2 will consume a large amount of free radicals by reacting with CF
3, CN, CF
3CFCN and other radicals, resulting in the inhibition of the formation of the main decomposition products with these free radicals as reactants.Under the action of O
2, the formation rate of main decomposition products shows a nonlinear variation with the increase of O
2 volume fraction. The ratio of C
2F
6/CF
4 is relatively stable, and it has a potential to be used as an indicator for corona discharge identification of C
4F
7N/CO
2/O
2 ternary gas mixture.