Thermal Decomposition and Thermal Reaction Process of PTFE/Al/MnO₂ Fluorinated Thermite.

Jun Zhang,Jiaxiang Wu,Jiaying Kui,Shuangzhang Wu,Yuchun Li,Li Yang,Xiang Fang,Junyi Huang,Zhenru Gao,Zhongshen Yu

doi:10.3390/ma11122451

Abstract

To better understand the thermal decomposition and reaction process of a fluorine-containing powdery thermite, PTFE/Al/MnO2, reactions at different temperatures were investigated by the TG/DSC-MS technique. The corresponding reaction products were characterized with XRD phase analysis. Another three thermite materials, i.e., PTFE/Al, Al/MnO2, and PTFE/MnO2, were also prepared for comparison. Results showed that PTFE behaved as both oxidizer and reducer in PTFE/Al/MnO2 fluorinated thermite. The thermal decomposition and reaction process of as-fabricated ternary thermite could be divided into two stages—the mutual reaction between each of PTFE, Al, and MnO2 and the subsequent reaction produced between Al and Mn2O3/Mn3O4/MnF2. Compared with the three control systems, the specially designed ternary system possessed a shorter reaction time, a faster energy release rate, and a better heat release performance.

Highlights

Reactive materials can explode, deflagrate, and release a huge amount of chemical energy under impact
The limited extent of a combination between an oxidant and a reductant can result in a low reaction rate, a smaller amount of actual heat release, an unconcentrated reaction process, a high initial temperature (>900 ◦ C), a low energy release rate, and a compromised mechanical strength [2]
This study aims at providing practical guidance for the fluorination treatment of traditional thermites

Summary

Introduction

Deflagrate, and release a huge amount of chemical energy under impact. A typical representative of reactive materials [1], thermite features high energy, high density, flexible formulation, and a high adiabatic temperature. Conventional aluminothermic agents commonly comprise Al as the fuel and metal oxides (Fe2 O3 , MoO3 , CuO, Bi2 O3 , MnO2 , etc.). The limited extent of a combination between an oxidant and a reductant can result in a low reaction rate, a smaller amount of actual heat release, an unconcentrated reaction process, a high initial temperature (>900 ◦ C), a low energy release rate, and a compromised mechanical strength [2]. Research on fluorine-containing aluminothermic agents has received extensive attention recently. Studying the application of fluorinated polymers in thermite, Li [8] found that the low boiling point of AlF3 could prevent it from covering the Al particle surface and hindering the reaction. Puts and Crouse [9] investigated the effect of metal fluoride on PTFE decomposition, concluding that the catalytic effect of AlF3 could accelerate the reaction process and further promote the decomposition by inducing a 30 ◦ C drop for the reaction

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Discussion

Conclusion