Reaction Behavior of Polytetrafluoroethylene/Al Granular Composites Subjected to Planar Shock Wave

Abstract

The shock‐compression responses of PTFE (polytetrafluoroethylene)/Al granular composites subjected to planar shock waves of various pressures are investigated. A 57‐mm diameter single‐stage gas‐gun and 50‐mm diameter plane‐wave lenses are employed to perform planar shock wave experiments. High frequency manganin piezoresistance stress gauges are used to monitor the stress (regarded as pressure in consideration of the high pressure state) at four Lagrangian positions of the PTFE/Al granular composites specimens. Planar shock wave experiments show characteristics of densification at measured input pressure of 0.5 GPa to 1.27 GPa using single‐stage gas‐gun and shock‐induced reaction (SIR) indicated by growth of shock pressure and specific volume expansion at measured input pressure of 7.29 GPa to 12.25 GPa using plane‐wave lenses. The pressure and relative volume states behind the shock wave front are calculated from the experimental recorded pressure profiles using Lagrangian analysis method, which are used to determine the reaction ratios under different shock pressures by comparing with partial reacted Hugoniot calculations. It was shown that the reaction ratios obtained in this research have good agreement with the thermochemical modeling calculations. The corresponding results indicate that the shock‐induced reactions of PTFE/Al granular composites occur in the shock wave rising period and the reaction ratios are intimately related to the shock wave pressure.

Sensitivity of Al‐PTFE upon Low‐Speed Impact

“…The former includes drop weight tests and SHPB tests, and the latter includes plate impact and blast loads. Guo et.al [7] observed that reactions of Al-PTFE occurred in the rising period of the input shock wave generated by plane-wave lense, which means the reaction was directly triggered by the intense shock wave within 2.5-5 ms. According to their ex-perimental results, the amplitude of the shock wave required to trigger this kind of reaction is at least 8-10 GPa, which is very difficult to be achieved in drop weight tests or in SHPB tests.…”

“…They observed a significant decrease of the initiation threshold stress from 2.6 GPa to 0.7 GPa when reducing the Al particle size from 120 mm to 9 mm. Guo et.al [7] performed planar shock wave experiments on Al-PTFE by gas-gun and plane-wave lenses. They found that reactions of Al-PTFE occurred in the rising period of the input shock wave, which confirmed the SIR process of Al-PTFE under high-speed impact.…”

Study on the blast impulse characters of high explosive charge with reactive metal casing

“…For example, when designing the prefabricated fragment structure to improve the power and efficiency of the high explosive charge, the prefabricated fragment can be prepared with reactive materials, which can greatly improve the damage efficiency of the high explosive charge [9, 10]. Compared with traditional inert fragments, reactive fragments not only penetrate and destroy the target by relying on their kinetic energy, but also produce a chemical reaction and release energy under the strong impact, to enhance the damage ability to the target [11, 12]. If the projectile casing is replaced with reactive material, compared with the traditional inert casing, the fragments produced by the reactive metal casing can not only produce kinetic energy damage but also couple this kinetic energy with the secondary energy release generated by the rapid chemical reaction during fragment impact, resulting in an additional strengthening effect on the air shock wave [13].…”

Study on the Impact-Induced Energy Release Characteristics of Zr68.5Cu12Ni12Al7.5 Amorphous Alloy

“…As a result of its excellent properties and good application prospects, MESMs have been widely concerned and vigorously studied all over the world [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Wang et al [ 6 ] have done a lot of theoretical and experimental research on the impact-induced reaction characteristics of fluoropolymer-based energetic reaction fragments.…”