Heat conduction and deflagration behavior of Al/PTFE induced by thermal shock wave under temperature gradient

Abstract

In order to reveal the influence of sintered and unsintered aluminum/polytetrafluoroethylene (Al/PTFE) reactive material on heat conduction, ignition and deflagration characteristics under the condition of thermal loading, the sintered and unsintered samples prepared by molding process are heated by acetylene flame as heat source. The heat conduction and deflagration behaviors of samples are measured synchronously by infrared thermal imager and high-speed camera before and after ignition. Meanwhile, combining with the three-dimensional differential equation of heat conduction in cylindrical coordinate system, the temperature gradient, heat flux and ignition moments during the process of heat conduction are solved by numerical simulation. The results show that the two kinds of samples both undergo the evolutions of temperature gradient and thermal shock wave induced by temperature gradient. The instantaneous energy accumulation caused by thermal shock wave promotes the samples to deflagrate, and the heat conduction durations before ignition, ignition temperature of sintered sample are both smaller than that of unsintered sample. The micro-morphologies before ignition indicate that the unsintered sample needs to accumulate more energy to achieve deflagration. The deflagration reaction extent of unsintered sample is more intense than that of sintered sample, however, the deflagration durations of sintered sample lasts longer. The maximum flame area of unsintered sample is 30.6% larger than that of the sintered sample, and the maximum temperatures of the flame core of sintered and unsintered sample are 1284 K and 1425 K, respectively.