Results and discussion

3.1. Experimental measurement of thermal decomposition products

To evaluate thermal stability and possible fire-extinguishing performance, the thermal decomposition products of CF3I are firstly analyzed. In the high-temperature condition, the CF3I should be thermally degraded into some products that may react with the OH· and H· radicals in the flame and thus restrain the chain reaction of combustion to a certain degree.
According to the thermal decomposition study of HFO-1336mzz(E) by Zhang16, considering the convergence of decomposition rate at 10s and the short time of fire extinguish process, the residence time of 10s is selected for thermal decomposition analysis. Considering the low molecular weight of CF3I, its decomposition into organic products is difficult, and the decomposition temperature should be relatively high. Therefore, the initial temperature of this experiment was set at 200oC. The upper limit of thermal decomposition was set at 800oC.
Fig.1 shows that the decomposition of CF3I started at 300oC. When the temperature reaches 400oC, silver particles are produced. Purple gas first appeared at the tube outlet at 500oC, and a large quantity of silver particles accumulated. The decomposition process stopped at around 700oC, producing large amounts of solids. The solid silver particles were characterized by XRD (Fig.S3 ) and proved to be iodine. GC/MS analysis of the exhaust gas (Fig.S4 ) shows that organic products were observed.