The purpose of this paper is to obtain the thermal decomposition mechanism of epoxy resin in SF

6

/N

2

mixed gas and the criterion for determining the characteristic decomposition component of the main weight loss interval.Therefore

the thermal decomposition characteristics of epoxy resin in SF

6

/N

2

atmosphere were studied by means of synchronous thermal analyzer and gas chromatography mass spectrometer.The concentration of the characteristic decomposition component was detected and a method for judging the local overheating failure of the epoxy resin surface was propose

d.The TG curve indicates that the main weight loss interval of the epoxy resin is not affected by the type of experimental gas

and the decomposition interval is 330℃～470℃.The DSC curve indicates that the decomposition of epoxy resin in SF

6

/N

2

atmosphere is a complex chemical process.As the proportion of N

2

in the mixed gas increases

the thermal stability of the system decreases

and the decomposition of SF

6

is intensified.CO

2

SO

2

H

2

S

SOF

2

and CF

4

were selected as characteristic components for detection.Under the condition of epoxy resin

the gas production rate and initial concentration of the characteristic components of different SF

6

ratio mixed gases are different

and the gas production temperature is the same.H

2

S and CF

4

were selected as the characteristic components for determining the POF temperature of epoxy resin surface

and a mathematical model was established.