A Study on the Mechanical Properties and Impact-Induced Initiation Characteristics of Brittle PTFE/Al/W Reactive Materials

Polytetrafluoroethylene/aluminum/tungsten (PTFE/Al/W) reactive materials of three different component mass ratios (73.5/26.5/0, 68.8/24.2/7 and 63.6/22.4/14) were studied in this research. Different from the PTFE/Al/W composites published elsewhere, the materials in our research were fabricated under a much lower sintering temperature and for a much shorter duration to achieve a brittle property, which aims to provide more sufficient energy release upon impact. Quasi-static compression tests, dynamic compression tests at room and elevated temperatures, and drop weight tests were conducted to evaluate the mechanical and impact-induced initiation characteristics of the materials. The materials before and after compression tests were observed by a scanning electron microscope to relate the mesoscale structural characteristics to their macro properties. All the three types of materials fail at very low strains during both quasi-static and dynamic compression. The stress-strain curves for quasi-static tests show obvious deviations while that for the dynamic tests consist of only linear-elastic and failure stages typically. The materials were also found to exhibit thermal softening at elevated temperatures and were strain-rate sensitive during dynamic tests, which were compared using dynamic increase factors (DIFs). Drop-weight test results show that the impact-initiation sensitivity increases with the increase of W content due to the brittle mechanical property. The high-speed video sequences and recovered sample residues of the drop-weight tests show that the reaction is initiated at two opposite positions near the edges of the samples, where the shear force concentrates the most intensively, indicating a shear-induced initiation mechanism.

[1]  E. B. Orler,et al.  The effect of crystallinity on the fracture of polytetrafluoroethylene (PTFE) , 2006 .

[2]  Z. Tong Preparation and Performance of PTEF/Al Reactive Materials , 2008 .

[3]  K. Vecchio,et al.  Particle size effect on strength, failure, and shock behavior in polytetrafluoroethylene-Al-W granular composite materials , 2008, 0806.1775.

[4]  W. Proud,et al.  High-strain, high-strain-rate flow and failure in PTFE/Al/W granular composites , 2008 .

[5]  Jin-Xu Liu,et al.  Investigation on reaction energy, mechanical behavior and impact insensitivity of W–PTFE–Al composites with different W percentage , 2016 .

[6]  Qingming Li,et al.  About the dynamic strength enhancement of concrete-like materials in a split Hopkinson pressure bar test , 2003 .

[7]  Jing Cai Properties of heterogeneous energetic materials under high strain, high strain rate deformation , 2007 .

[8]  Yan Li,et al.  Experimental Study on Impact-Induced Reaction Characteristics of PTFE/Ti Composites Enhanced by W Particles , 2017, Materials.

[9]  Fengming Xu,et al.  Quasi‐Static Compression Properties and Failure of PTFE/Al/W Reactive Materials , 2017 .

[10]  R. Ames Energy Release Characteristics of Impact-Initiated Energetic Materials , 2005 .

[11]  Weinong W Chen,et al.  Pulse shaping techniques for testing brittle materials with a split hopkinson pressure bar , 2002 .

[12]  Wei Zhang,et al.  The mechanical behaviors of polytetrafluorethylene/Al/W energetic composites , 2009, Journal of physics. Condensed matter : an Institute of Physics journal.

[13]  F. J. Davis,et al.  Impact ignition of nano and micron composite energetic materials , 2009 .

[14]  P. M. Ku,et al.  New Test Techniques for Evaluating the Compatibility of Materials with Liquid Oxygen under Impact , 1968 .

[15]  W. Mock,et al.  Impact Initiation of Rods of Pressed Polytetrafluoroethylene (PTFE) and Aluminum Powders , 2005 .

[16]  Chao Ge,et al.  Microscale Simulation on Mechanical Properties of Al/PTFE Composite Based on Real Microstructures , 2016, Materials.

[17]  S. C. Hunter,et al.  The Dynamic Compression Testing of Solids by the Method of the Split Hopkinson Pressure Bar , 1963 .

[18]  H. Kolsky An Investigation of the Mechanical Properties of Materials at very High Rates of Loading , 1949 .

[19]  Zongwei Liu,et al.  Impact-induced initiation and energy release behavior of reactive materials , 2011 .

[20]  Hai-fu Wang,et al.  Demolition Mechanism and Behavior of Shaped Charge with Reactive Liner , 2016 .

[21]  D. Bohl,et al.  Reactive Materials Studies , 2006 .

[22]  Xiang Fang,et al.  Reactions of Al-PTFE under Impact and Quasi-Static Compression , 2015 .

[23]  W. Proud,et al.  The Use of Glass Anvils in Drop‐Weight Studies of Energetic Materials , 2015 .

[24]  G. Gray High‐Strain‐Rate Testing of Materials: The Split‐Hopkinson Pressure Bar , 2012 .

[25]  Z. Guan,et al.  Experimental study of the compression properties of Al/W/PTFE granular composites under elevated strain rates , 2013 .

[26]  K. Vecchio,et al.  The influence of metallic particle size on the mechanical properties of polytetraflouroethylene-Al–W powder composites , 2007, 0709.2172.

[27]  W. Dong,et al.  The Effect of Crystallinity on Compressive Properties of Al-PTFE , 2016, Polymers.