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.