Chemical Reaction Mechanism and Mechanical Response of PTFE/Al/TiH₂ Reactive Composites

In order to improve the energy density of polytetrafluoroethylene/aluminum (PTFE/Al), titanium hydride (TiH₂) was added as a high-energy additive, and thermogravimetry–differential scanning calorimetry (TG-DSC), quasi-static compression and Split-Hopkinson pressure bar (SHPB) tests were conducted to investigate the chemical reaction mechanism and mechanical response of PTFE/Al/TiH₂. The results of TG-DSC indicate that TiH₂ first decomposes to form titanium and hydrogen, and titanium reacts with PTFE to produce TiF₃, and then with the temperature rising, titanium reacts with carbon and excessive aluminum to generate TiC and Al₃Ti. Under quasi-static compression, the strength of PTFE/Al/TiH₂ specimens can reach 108.8 Mpa, 14.2% higher than that of PTFE/Al, the special burning flames during the reaction and XRD patterns of the reaction residues consistently indicate that TiH₂ has participated in the reaction and react completely, achieving its purpose as a high-energy additive. Under dynamic compression tests, PTFE/Al/TiH₂ composites show obvious strain hardening and strain rate hardening effects, and the yield strength and compressive strength are sensitive to strain rates; the established Johnson-Cook (JC) constitutive model can describe the mechanical response of PTFE/Al/TiH₂ material well. In addition, the ignition threshold of PTFE/Al/TiH₂ drops to 22.78 m/s, less than that of PTFE/Al (23.74 m/s), and the ignition delay time is advanced from 650-700 to 100-150 μs as the impact velocity increase.