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

Abstract

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.