Experimental study and simulation of the reaction mechanism of Al–PTFE mechanically activated energetic composites

Tao, Jun

doi:10.1039/d3ra02509h

Cited by 7 publications

(2 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, PTFE can be used as both a binder and an oxidizer in thermites. Generally, the reactivities of Al/PTFE or other similar thermites are complex due to their diverse microstructures, which can be classified based on the factors such as the particle size [25][26][27], particle shape (e.g., flake-like [13,28]), and interface (coated [19,29] and layered [30,31]), among others. However, the reactivity and combustion properties of Al/PTFE could not be fully satisfied by a specific microstructure.…”

Section: Introductionmentioning

confidence: 99%

Combustion characteristics of Al/PTFE materials with different microstructures

Zhou,

Zhen,

et al. 2024

Mater. Res. Express

View full text Add to dashboard Cite

The microstructures play a crucial role in the combustion of aluminum/polytetrafluoroethylene (Al/PTFE) materials. Mechanically activated Al/PTFE typically demonstrates higher reactivity but a lower combustion rate compared to physically mixed Al/PTFE. Recently, the combustion performance of fuel-rich Al/PTFE has been well explained by the microexplosion mechanism. In this study, the combustion characteristics of stoichiometric Al/PTFE (26.5:73.5 wt%) materials with varying microstructures were investigated to further the understanding of their combustion mechanism and offer insights for their potential applications in metal cutting. The Al/PTFE materials with different microstructures were prepared using sonication and ball milling methods. The results of scanning electron microscope (SEM) analysis suggest that the sonicated Al/PTFE (s-Al/PTFE) containing spherical Al particles displayed a loosely dispersed structure, while the milled Al/PTFE (m-Al/PTFE) exhibited a densely layered structure with flake-like Al particles coated by the PTFE matrix. The milled Al/PTFE was found to be mechanically activated. Combustion in quartz tubes was recorded using a high-speed camera and a video. Combustion of s-Al/PTFE demonstrated a high-temperature flame (~2346 K) and obvious microexplosions featuring hot particles ejection, while combustion of m-Al/PTFE showed a weak flame (~2037 K) and slow-burning, featuring dense carbon smoke. Increasing the powder density was observed to slightly decrease (~100 K) flame temperature. Microstructure and phase analysis of combustion products were systematically conducted to elucidate the combustion behaviors. The results suggest that the residue of s-Al/PTFE contained high AlF3 and low carbon content, whereas the residue of m-Al/PTFE exhibited the opposite condition. The results of the combustion tests suggest that microexplosions promoted the oxidation of hot Al particles and carbon products, consequently leading to a fast reaction, high flame temperature, and enhanced heat transfer capability.

show abstract

Section: Introductionmentioning

confidence: 99%

Combustion characteristics of Al/PTFE materials with different microstructures

Zhou,

Zhen,

et al. 2024

Mater. Res. Express

View full text Add to dashboard Cite

show abstract

“…Regarding specific reaction mechanisms, Losada [ 9 ] studied the reaction between PTFE monomer C 2 F 4 and Al under anaerobic/aerobic conditions using quantum mechanics, identifying intermediate products and final products. Jun [ 10 ] employed molecular dynamics to simulate the pyrolysis of PTFE and the reactions between pyrolysis products and Al, indicating the CF 3 + Al/CF 2 + AlF reaction pathway as the most feasible. However, these studies did not consider the oxide layer surrounding the aluminum particles.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Chemical Reaction Mechanism and Kinetic Model of Al/PTFE

Guo,

Li,

Chen

et al. 2024

Polymers

View full text Add to dashboard Cite

In order to study the microscopic reaction mechanism and kinetic model of Al/PTFE, a reactive force field (ReaxFF) was used to simulate the interface model of the Al/PTFE system with different oxide layer thicknesses (0 Å, 5 Å, 10 Å), and the thermochemical behavior of Al/PTFE at different heating rates was analyzed by simultaneous thermal analysis (TG-DSC). The results show that the thickness of the oxide layer has a significant effect on the reaction process of Al/PTFE. In the system with an oxide layer thickness of 5 Å, the compactness of the oxide layer changes due to thermal rearrangement, resulting in the diffusion of reactants (fluorine-containing substances) through the oxide layer into the Al core. The reaction mainly occurs between the oxide layer and the Al core. For the 10 Å oxide layer, the reaction only exists outside the interface of the oxide layer. With the movement of the oxygen ions in the oxide layer and the Al atoms in the Al core, the oxide layer moves to the Al core, which makes the reaction continue. By analyzing the reaction process of Al/PTFE, the mechanism function of Al/PTFE was obtained by combining the shrinkage volume model (R3 model) and the three-dimensional diffusion (D3 model). In addition, the activation energy of Al/PTFE was 258.8 kJ/mol and the pre-exponential factor was 2.495 × 1015 min−1. The research results have important theoretical significance and reference value for the in-depth understanding of the microscopic chemical reaction mechanism and the quantitative study of macroscopic energy release of Al/PTFE reactive materials.

show abstract

Dynamic Constitutive Model of Tungsten‐Whisker‐Reinforced Aluminum/Polytetrafluoroethylene Composite Material and Quantitative Determination of Impact Reaction Release Energy in Vacuum Environment

Tang,

Deng,

Wang

et al. 2024

Adv Eng Mater

View full text Add to dashboard Cite

To meet the strength requirements of aluminum/polytetrafluoroethylene (Al/PTFE) in practical applications, tungsten (W) whisker is added into the traditional formula Al/PTFE (26.5%/73.5%) to improve the dynamic compressive strength of the reactive material. Mechanical properties of reactive material specimens prepared by sintering are tested. In the results, it is shown that the dynamic compressive strength of Al/PTFE‐reactive material reinforced by tungsten whisker with volume fraction of 13.1% can reach 141 MPa at strain rate of 1800 s−1. The constitutive model of dynamic compression for tungsten‐whisker‐enhanced Al/PTFE‐reactive material is constructed, and the results are basically consistent with the experimental results. The quantitative impact energy release of reactive material specimens under vacuum environment are performed by using the two‐stage light gas gun loading system, and the quantitative impact release energies of Al/PTFE‐reactive material reinforced by tungsten whisker under different whisker percentage content and diameter are obtained.

show abstract

Experimental study and simulation of the reaction mechanism of Al–PTFE mechanically activated energetic composites

Abstract: The density functional theory (DFT), reactivity test system and laser-induced breakdown spectroscopy were applied to study the mechanism of reaction between the components of Al-PTFE mechanically activated energetic composites.

Cited by 7 publications

References 28 publications

Combustion characteristics of Al/PTFE materials with different microstructures

Combustion characteristics of Al/PTFE materials with different microstructures

Microscopic Chemical Reaction Mechanism and Kinetic Model of Al/PTFE

Dynamic Constitutive Model of Tungsten‐Whisker‐Reinforced Aluminum/Polytetrafluoroethylene Composite Material and Quantitative Determination of Impact Reaction Release Energy in Vacuum Environment

Contact Info

Product

Resources

About