The Energy Release Characteristics of Shock-Induced Chemical Reaction of Al/Ni Composites

In this paper, the energy release mechanism of shock-induced chemical reaction (SICR) of Al/Ni composites was investigated. The Al/Ni composites with two additives, namely Teflon (PTFE) and copper (Cu), were considered in both theoretical calculations and experiments to investigate their influence on SICR characteristics of Al/Ni composites system. Assuming the SICR process is controlled by shock temperature rising in the materials, the reaction efficiency of Al/Ni composites was calculated by Arrhenius reaction rate and Avrami–Erofeev reaction models. Hugoniot curves and the temperature rise under shock compression were calculated to analyze the mechanism of the influence on SICR characteristics by additives. Impact-initiated experiments of Al/Ni composites were carried out to study SICR characters at various impact velocities. The parameters of SICR model were determined by using corresponding experimental results. The calculation results showed that for the SICR process of Al/Ni, the critical shock temperature for initiation of SICR (Tcr = 452 K) and the apparent activation energy (Ea = 90.9 kJ/mol) appeared much lower than the values of normal ignition process (Tig= 990 K, Eiga = 351.6 kJ/mol). The additive of Cu decreased the shock temperature significantly in Al/Ni composites, which led to the increase of critical shock conditions for initiation of SICR and the decrease of reaction efficiency at the same shock pressure. On the other hand, the additive of PTFE to Al/Ni composites decreased the critical shock conditions for initiation of SICR and increased the chemical reaction efficiency by participating in the reactions.