Investigation on the microstructures, mechanical properties and impact initiation characteristics of Al/PTFE reactive materials reinforced by TiH2 particles

Abstract

Aluminum/Polytetrafluoroethylene (Al/PTFE) is a representative energetic material, which can be used in many fields including defense weapon fragments, insensitive penetrator or oil-well perforation. However, the insufficient mechanical strength of traditional ingredient has seriously restricted its penetration ability, and traditional additives improve its compressive strength at the expense of reactivity. Hence, innovative component design and advanced manufacturing technology should be applied to Al/PTFE composite. In this investigation, TiH2 as a new reinforcement is introduced into Al/PTFE to improve both strength and reactivity. Quasi-static and dynamic compressive tests were conducted, and the impact reaction process was recorded by high-speed camera. The results shown Al/PTFE/TiH2 composites are all elasto-plastic materials, significant strain hardening and strain rate hardening phenomenon were observed. The compressive strength increased first and then decreased with increase in TiH2 content, reached the maximum of 185.1 MPa at the strain rate of 5000 s−1 when TiH2 content was 30 %, which increased by 30.4 % compared to traditional Al/PTFE. A newly-developed drop-weight device was used to quantitatively characterize reactivity, and the reaction efficiency reached 8.2 % when TiH2 content was 30 %, increased by 43.2 % compared to Al/PTFE. The formation of oriented PTFE nano-fibers was considered the important strengthening mechanism. The established Johnson–Cook model was agreed well with experimental results. Combining the results of thermogravimetry-differential scanning calorimetry (TG-DSC) tests with X-ray diffraction (XRD) analysis of reaction residues, the reaction mechanism was clarified. The impact initiation reaction was in a mechano-chemical manner and the reactivity was speculated to be the results of multiple actions between Al/PTFE and TiH2.