Experimental Study of Mechanical Properties and Impact-Induced Reaction Characteristics of PTFE/Al/CuO Reactive Materials

Abstract

Metal/fluoropolymer materials are typical reactive materials. Polytetrafluoroethylene (PTFE)/Al/CuO reactive materials were studied in this research. Scanning electron microscopy (SEM), quasi-static compression, the Split Hopkinson pressure bar test, and the drop hammer test were used to study the mechanical properties and induced reaction characteristics of the reactive materials with different Al/CuO thermite contents and different particle sizes. SEM images of the samples demonstrate that the reactive materials were mixed evenly. The compression test results show that, if the particle size of PTFE was too small, the strength of reactive materials after sintering was reduced. After sintering, with the increase in the content of Al/CuO thermite, the strength of the micro-sized PTFE/Al/CuO firstly increased and then decreased. The Johnson-Cook constitutive model can be used to characterize the reactive materials, and the parameters of the Johnson-Cook constitutive model of No. 3 reactive materials (PTFE/Al:Al/CuO = 3:1) were obtained. The reliability of the parameters was verified by numerical simulation. Drop hammer tests show that the addition of Al/CuO aluminothermic materials or the use of nano-sized PTFE/Al reactive materials can significantly improve the sensitivity of the material. The research in this paper can provide a reference for the preparation, transportation, storage, and application of reactive materials.found that adding a high-strength metal material, such as W, with a similar particle size to the PTFE/Al reactive material, can effectively increase the strength of the reactive materials. Cai et al. [12] used a drop hammer to find that the W particle-PTFE interface separation provided initiation and propagation of cracks. In general, the addition of W can increase the strength of the reactive material but reduce the energy density. Thus, people considered adding materials that can release energy, such as Ni. After adding Ni to PTFE/Al, Wu et al. [16] found that Ni makes the reactive material brittle, but it can increase the strain-hardening modulus and compressive strength of the material, while the heat released by the material also increased. However, the energy density of PTFE/Al reactive material is very high, and the energy of PTFE/Al reactive material cannot be significantly increased by adding Ni. If the energy release efficiency of the PTFE reactive materials can be effectively improved, it will be beneficial for their application. PTFE filler metal is a very common type of engineering material. The C-F bonds in PTFE are usually stable and do not react with metals. Under high-temperature conditions, PTFE rapidly decomposes into small-molecule fluorides and undergoes a rapid exothermic reaction with active metals [18]. Experiments by Ames [19] showed that, when the PTFE/Al reactive material impacts the target at a velocity of 1.2 km/s, the energy release efficiency still does not exceed 20%. Therefore, one of the biggest problems with PTFE/Al reactive materials is that the energy release ...

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