Blast mitigation properties of porous nano-carbon

Abstract

Designing and development of a superior shock mitigation nano–material shield is an emerging armour building technology. We report, the effect of Kolsky bar simulated blast waves, onto the shock damping characteristics of the porous nano–carbon (abbreviation: PNC), synthesized by pyrolysis of biomass precursor. Measurement of stress (σ)–strain (ε), constitutive variables reveal the elasto–plastic behaviour suggesting moderate built–up, and accumulation of stress; independent of applied strain before reaching a yield ~50 MPa. Gruneisen fatigue parameter is estimated to be less (~0.92) over a theoretical Rayleigh limit with >80% post impact damage of porous component. The loci of dictated shock states derived from Rankine–Hugoniot formulism demonstrates the hydrodynamic interplay between pressure (P), volume (V), shock (US) and particle (UP) velocity. For PNC, Rayleigh slope is observed to be reduced, whereas, US became pressure independent over 10 GPa. Behaviour of P–UP hydrodynamic equation displays 30% variation in shock states and predicts a reduction of sound speed by a factor of ~0.25 in porous matrix. Behind the shock wavefront, matrix particles attend a max–speed of 100 km–s−1. The value of elastic limit for PNC is ~8.62 GPa as obtained by analysing the actual shock profile, with an evidence of phase transformation. Electron and force microscopy studies show reduction in an area, effectively, by 20–30%, thickness by six–fold factors with a rise in topological disorder. Hydro–physical variables inferred from Raman, scanning electron, transmission electron, and atomic force microscopy is comparatively discussed for PNC and other nano–carbons. Shock topology obtained by pressure–time signal processing shows ~30% impact of the shock onto PNC and manifested as shock echo. Details of the analysis are presented.