Research On Dynamic Compression Behavior And Energy Release Characteristics Of Enhanced Al/PTFE

Aluminum/polytetrafluoroethylene(Al/PTFE)reactive material is a kind of high energy and insensitive composite material,which has been widely concerned by national and international scholars due to its good mechanical properties,chemical properties and unique energy release properties.The fragments made of reactive materials will release a large amount of chemical energy to enhance the damage effect of target when while causing damage to the target by relying on kinetic energy.Therefore,reactive materials have great application potential in the military field.However,the reactive materials Al/PTFE manufactured according to the traditional mass ratio(Al,PTFE has a mass ratio of 26.5%:73.5%)have insufficient compression strength and unclear energy release mechanism under strong impact,which has become a key problem restricting the engineering application of fluoropolymer based reactive materials.In this paper,the dynamic mechanical properties of Al/PTFE reactive materials were regulated by adjusting the particle size of Al particles and adding reinforcement(Zr fiber).The dynamic mechanical properties of Al/PTFE energetic materials and the energy release characteristics under strong impact were studied by experimental test and theoretical analysis.The main research results are as follows:(1)The dynamic response testing system of reactive materials and the impact release energy measurement system was constructed.The dynamic response testing system for Al/PTFE reactive materials is composed of a separate Hobson pressure bar and a high speed camera.The impact release energy measurement system is composed of a two-stage light gas gun loading system,a self-made quasi-airtight container,an infrared thermal imager and an overpressure sensor.(2)The dynamic mechanical properties of Al/PTFE and Zr(fiber)/Al/PTFE(Al,5um)reactive materials were tested by hopkinson pressure bar experiment system.The internal micro morphology and impact reaction process of the materials were observed by scanning electron microscope(SEM),high-speed camera and infrared thermography.When the strain rate is between 2500?4000s^-1,the Zr(fiber)/Al/PTFE specimen shows similar elastoplastic mechanical behavior to that of Al/PTFE specimen,and the addition of Zr fiber can improve the dynamic compressive mechanical property of Al/PTFE specimen.When the volume of Zr fiber is 3%,the compression strength(or compressive strength)of Zr(fiber)/Al/PTFE specimen is increased from 64MPa to110MPa,with an increase of about 70%,and the initiation mode of the reactive material is hot spot initiation.(3)Al/PTFE and Zr(fiber)/Al/PTFEreactive materials(the volume fraction of Zr fiber is 4%,16%,29%)with a particle size of 50nm were prepared.The influence of volume fraction of Zr fiber on the dynamic mechanical properties,internal microstructure and energy release characteristics of Al/PTFE uner impact was studied.The results show that the compression strength of Al/PTFE reactive material increases with the increasing of volume fraction of Zr fiber,and the compression strength of specimen containing 29%Zr fiber is 282.1MPa.Based on the mixing law,the strengthening mechanism of Al/PTFE reactive material was clarified,and the correlation law between the content of Zr fiber and the strength of specimens was obtained.The impact energy release characteristics of Al/PTFE and Zr(fiber)/Al/PTFE were studied,and the influence of fiber content on the failure morphology and energy dissipation characteristics was revealed.(4)The evolution of Zr(fiber)/Al/PTFE impact reaction temperature field was recorded by infrared thermography.During the impact,the temperature around the target rose rapidly,and then returned to normal with the expansion of gas and heat exchange.The maximum temperature was about 1200K.The impact energy release experiment of Zr(fiber)/Al/PTFE projectile under different loading speeds was carried out,and the reaction energy per unit mass of Zr(fiber)/Al/PTFE projectile under1.25km/s,1.44km/s,1.7km/s and 1.85km/s was obtained,which were 7466.16k J,8981.61k J,9020.11k J and 8468.52k J,respectively.