A comparative study on the mechanical and reactive behavior of three fluorine-containing thermites.

Thermite serves as a kind of representative energetic material, which is extensively applied in the civil and military fields. In this paper, PTFE/Al/FeO, PTFE/Al/MnO and PTFE/Al/MoO, solid fluorine-containing thermite with different PTFE content, were successfully fabricated by referring to the traditional thermite and adding PTFE as a binder or matrix. Quasi-static compression tests were performed to investigate the mechanical and reactive behavior of fluorine-containing thermite. SEM and XRD were employed to analyze and characterize the energetic composites and reaction residuals. The results show that all types of fluorine-containing thermite exhibited different mechanical behavior. PTFE/Al/MnO exhibited the lowest yield strength and strain hardening modulus, but the highest compressive strength and toughness. With the increase of PTFE content, the strength of fluorine-containing thermite improved. No reaction occurred when the PTFE content was 60 vol%, while fluorine-containing thermite with a PTFE content of 80 vol% experienced a severe exothermic reaction under quasi-static compression. The ignition of PTFE/Al/MoO and PTFE/Al/FeO actually attributed to the reaction of Al and PTFE, and the reaction between Al and FeO or MoO was not excited due to the insufficient input energy. The thermite reaction between Al and MnO as well as the reaction of MnO and PTFE, was induced because PTFE/Al/MnO possessed excellent ductility and absorbed the most energy during compression, accompanied with the production of Mn and MnF.