A crack-induced initiation mechanism of Al-PTFE under quasi-static compression and the investigation of influencing factors

Bin, Feng; Li, Yuchun; Wu, Shuangzhang; Wang, Huai-xi; Tao, Zhong-ming; Fang, Xiang

doi:10.1016/j.matdes.2016.06.125

Cited by 59 publications

(46 citation statements)

References 24 publications

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“…The crack propagation speed can reach 200 m/s to 800 m/s and the temperature of the crack tip can reach 300 ∘ C to 1000 ∘ C [17] and the high temperature can greatly promote the reaction. Feng et al proposed a crackinduced initiation mechanism of Al-PTFE under quasi-static compression, which can also explain the reaction mechanism of PTFE/Al/Fe 2 O 3 system [15]. As can be seen from the XRD analysis in Figure 7, the reaction products showed that Fe 2 O 3 was not involved in the reaction; the initiation phenomenon was actually caused by PTFE and Al.…”

Section: Reaction Behavior Under Quasi-static Compressionmentioning

confidence: 95%

“…The specimen after reaction is displayed in Figure 6(a), the black part corresponds to the reacted region, which is marked with "initiation." Moreover, the opening crack and shear plane caused by compression are clearly visible, which are closely related to the ignition phenomenon [15]. Although there has been much controversy about the mechanical initiation of explosions over these years, many scholars believe that the initiation is due to the existence of "hot spots."…”

Section: Reaction Behavior Under Quasi-static Compressionmentioning

confidence: 99%

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The Mechanical and Reaction Behavior of PTFE/Al/Fe₂O₃ under Impact and Quasi-Static Compression

Huang

Fang

et al. 2017

Advances in Materials Science and Engineering

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Quasi-static compression and drop-weight test were used to characterize the mechanical and reaction behavior of PTFE/Al/Fe 2 O 3 composites. Two kinds of PTFE/Al/Fe 2 O 3 composites were prepared with different mass of PTFE, and the reaction phenomenon and stress-strain curves were recorded; the residuals after reaction were analyzed by X-ray diffraction (XRD). The results showed that, under quasi-static compression condition, the strength of the materials is increased (from 37.1 Mpa to 77.2 Mpa) with the increase of PTFE, and the reaction phenomenon occurred only in materials with high PTFE content. XRD analysis showed that the reaction between Al and Fe 2 O 3 was not triggered with identical experimental conditions. In drop-weight tests, PTFE/Al/Fe 2 O 3 specimens with low PTFE content were found to be more insensitive by high-speed photography, and a High Temperature Metal Slag Spray (HTMSS) phenomenon was observed in both kinds of PTFE/Al/Fe 2 O 3 composites, indicating the existence of thermite reaction, which was confirmed by XRD. In PTFE/Al/Fe 2 O 3 system, the reaction between PTFE and Al precedes the reaction between Al and Fe 2 O 3 .

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Section: Reaction Behavior Under Quasi-static Compressionmentioning

confidence: 95%

Section: Reaction Behavior Under Quasi-static Compressionmentioning

confidence: 99%

The Mechanical and Reaction Behavior of PTFE/Al/Fe₂O₃ under Impact and Quasi-Static Compression

Huang

Fang

et al. 2017

Advances in Materials Science and Engineering

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“…The characteristic strength of the Al-PTFE acquired from quasi-static compression tests [9] are superimposed on Figure 2. (The characteristic strength is an artificially defined parameter, the details of which could be found in section 5.1.)…”

Section: The Influence Of Sintering Temperature On Impact Sensitivitymentioning

confidence: 99%

“…Feng et.al [8] found that Al-PTFE could be ignited under quasi-static compression, and the reaction was dominated by the hot-spots generated at the crack tip of the mode-I fracture rather than by shock wave. Further investigation shows that the reaction sensitivity of Al-PTFE under quasi-static compression is hugely dependent upon the material and fabrication parameters, and in general the specimen with higher strength is more sensitive to ignition [9].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Al‐PTFE upon Low‐Speed Impact

Bin¹,

Qiu²,

Zhang³

et al. 2019

Propellants Explo Pyrotec

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Al‐PTFE (Aluminum‐Polytetrafluoroethylene) is a promising composite as a kind of impact initiated energetic materials. The impact sensitivity of Al‐PTFE was characterized by drop weight tests. By varying the sintering temperature, Al mass ratio and Al particle size, the sensitivity of Al‐PTFE changes significantly from 25.78 J to 87.34 J. It was found that in general Al‐PTFE specimens with higher strength tend to be more sensitive to low‐speed impact. The SHPB test was carried out on the baseline Al‐PTFE specimen, and the stress ignition threshold was found to be 116 MPa, which is not high enough to trigger a shock‐induced reaction (SIR). Moreover, multiple evidences, including the high‐speed camera records, prove that crack‐induced ignition mechanism, rather than SIR, dominates the ignition of Al‐PTFE upon low speed impact.

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“…Eventually, a mechanism was proposed in which tensile stresses resulting from compressive and shear waves cause the Al shells to crack open, consequently allowing hot PTFE to react with Al. Feng et al [13,14] discovered that Al-PTFE mixtures through special heat treatment could go through severe reaction under quasistatic compression. e influence of sintering temperature and equivalence ratio on reaction of Al-PTFE was ascertained.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Mechanical Properties and Reaction Characteristics of Al‐PTFE Composites with Different Al Particle Size

Fang

Gao

et al. 2018

Advances in Materials Science and Engineering

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Al-PTFE (aluminum-polytetrafluoroethylene) serves as one among the most promising reactive materials (RMs). In this work, six types of Al-PTFE composites with different Al particle sizes (i.e., 50 nm, 1∼2 μm, 6∼7 μm, 12∼14 μm, 22∼24 μm, and 32∼34 μm) were prepared, and quasistatic compression and drop weight tests were conducted to characterize the mechanical properties and reaction characteristics of Al-PTFE composites. e reaction phenomenon and stress-strain curves were recorded by a high-speed camera and universal testing machine. e microstructure of selected specimens was anatomized through adopting a scanning electron microscope (SEM) to correlate the mesoscale structural characteristics to their macroproperties. As the results indicated, in the case of quasistatic compression, the strength of the composites was decreased (the yield strength falling from 22.7 MPa to 13.6 MPa and the hardening modulus declining from 33.3 MPa to 25 MPa) with the increase of the Al particle size. e toughness rose firstly and subsequently decreased and peaked as 116.42 MJ/m 3 at 6∼7 μm. e reaction phenomenon occurred only in composites with the Al particle size less than 10 μm. In drop weight tests, six types of specimens were overall reacted. As the Al particle size rose, the ignition energy of the composites enhanced and the composites turned out to be more insensitive to reaction. In a lower strain rate range (10), Al-PTFE specimens take on different mechanical properties and reaction characteristics in the case of different strain rates. e formation of circumferential open cracks is deemed as a prerequisite for Al-PTFE specimens to go through a reaction.

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A crack-induced initiation mechanism of Al-PTFE under quasi-static compression and the investigation of influencing factors

Cited by 59 publications

References 24 publications

The Mechanical and Reaction Behavior of PTFE/Al/Fe₂O₃ under Impact and Quasi-Static Compression

The Mechanical and Reaction Behavior of PTFE/Al/Fe₂O₃ under Impact and Quasi-Static Compression

Sensitivity of Al‐PTFE upon Low‐Speed Impact

Investigation on Mechanical Properties and Reaction Characteristics of Al‐PTFE Composites with Different Al Particle Size

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A crack-induced initiation mechanism of Al-PTFE under quasi-static compression and the investigation of influencing factors

Cited by 59 publications

References 24 publications

The Mechanical and Reaction Behavior of PTFE/Al/Fe2O3 under Impact and Quasi-Static Compression

The Mechanical and Reaction Behavior of PTFE/Al/Fe2O3 under Impact and Quasi-Static Compression

Sensitivity of Al‐PTFE upon Low‐Speed Impact

Investigation on Mechanical Properties and Reaction Characteristics of Al‐PTFE Composites with Different Al Particle Size

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The Mechanical and Reaction Behavior of PTFE/Al/Fe₂O₃ under Impact and Quasi-Static Compression

The Mechanical and Reaction Behavior of PTFE/Al/Fe₂O₃ under Impact and Quasi-Static Compression