Improving the energy release characteristics of PTFE/Al by doping magnesium hydride

Abstract

Magnesium hydride (MgH2) was doped into PTFE/Al to improve the energy release characteristics of the material system and strive for better application in military engineering. Five types of PTFE/Al/MgH2 reactive materials with different MgH2 content were prepared by molding sintering method. The dynamic mechanical properties of the materials were studied by performing split-Hopkinson pressure bar (SHPB) tests and scanning electron microscope characterizations. The thermal behavior, reaction energy, reaction process and reaction mechanism were systematically investigated by conducting thermogravimetry-differential scanning calorimetry tests, oxygen bomb calorimeter measurements, X-ray diffraction and SHPB tests. The results show that MgH2 particles less than 10% content contribute to heightening the dynamic mechanical properties of PTFE/Al system. The product Mg generated by decomposition of MgH2 can not only react with gas phase C2F4+ but also undergo a Grignard-type reaction with condensed PTFE. The reaction energy and ignition threshold of PTFE/Al/MgH2 reactive materials enhance monotonously as MgH2 content rose. With the increase of MgH2 content from 0% to 20%, the reaction time is prolonged as well as the reaction intensity is enhanced dramatically arising from the massive water vapour produced by the reaction between O2 and H2. The gaseous products generated can form a high pressure shortly after the reaction, which helps to elevate the damage effect of the PTFE/Al system.