Graphene-Like Nanoflakes for Shock Absorption Applications

Abstract

The effects of high-pressure shock waves generated by the detonation of explosives are of major interest to the strategic sector. We report interaction of transonic shock waves (1.1 Mach speed; peak pressure >1.5 GPa) with graphene-like nanoflakes (GNFs). GNF samples, obtained after chemical vapor deposition of a biomass, were studied using optical/electron, force microscopy, Raman, and Brunauer–Emmett–Teller/Barrett–Joyner–Halenda studies. Following this, GNF samples were subjected to high-strain-rate measurements, using a split Hopkinson pressure bar technique to measure variations in the stress, strain, and strain rate. Numerous dynamic mechanical parameters are derived under a classical Lagrange–Rankian–Hugoniot framework together with collecting statistics on the lateral flake size, number of layers, defect density, wrinkle, slip characteristics, etc. Broadly, the incident shock energy was dampened by ∼65% of absorption loss with ∼15% transmittance. It has implications on the GNF microstructure by reducing the flake squareness, area (by ∼50%), and exfoliating layer conjugation by around 5 times. The in-plane impact was more profound compared to the out-of-plane. Dislocation/slip dynamics showed significant modification in prismatic loops (from buckled to ruck and tuck), with twinning exhibiting a lowering of the Peierls–Nabarro stress to make disorder glissile. At the molecular level, dynamic deformation dramatically modified the force constants with bond elongation at −C–C– by ∼80% and at −C═C– by >150% compared to pristine. An interactive model is presented.