Qianqian He,Jun Wang,Yaofeng Mao,Huamo Yin,Wei Cao,Fude Nie
The incorporation of aluminum (Al) into explosives represents a facility and efficient way to enhance the energy output through the secondary reaction between Al and the detonation products of explosive. The Al/O ratio and microstructure of HMX/Al play critical roles in combustion performance and energy output. Herein, a gradient structured HMX/Al composite has been designed and fabricated via 3D printing technology using well-dispersed HMX/Al-based ink. For HMX/Al lines, the second reaction heat increases from 196.5 J/g to 1644.8 J/g and the burning rate would decrease from 14.6 to 12.0 mm/s with Al content increased from 10 to 30 wt%. For gradient structured HMX/Al, the burning rate could be controlled by varying the component ratio and the burning rate of each component in the gradient structure was higher than that of the normal HMX/Al counterpart. Furthermore, a gradient evolution of pressure output was monitored for gradient structured HMX/Al cylinder ignited by the laser. These results indicate that the gradient structure as an effective approach can tune combustion performance and energy output of HMX/Al.
Qianqian He,Jun Wang,Yaofeng Mao,Wei Cao,Jie Chen,Fude Nie
To improve and adjust the combustion and energy output of HMX/Al, graphite fluoride (CF) as oxidizer was introduced in HMX/Al and gradient structured HMX/Al/CF was prepared by additive manufacturing technology . For HMX/Al added with CF, a significantly exothermic peak is observed ranging from 860 to 950 °C due to the reaction of Al and fluorine derived from CF decomposition, and the heat release increases by 106.63% compared to that of HMX/Al. The fourth exothermic heat increases from 161.48 to 955.25 J/g with the increased Al content from 10 to 30 wt%. Moreover, the combustion rate and pressure output of HMX/Al have been improved by introducing CF. For HMX/Al added with CF, the combustion time decreases from 10.3 to 2.5 s, which is dependent on the Al content from 10 to 30 wt%. And the highest peak pressure is 1712.2 kPa when Al content is 20 wt% in HMX/Al/CF composites. Furthermore, gradient structured HMX/Al/CF consisting of three layers with Al content of 10, 20 and 30 wt% was prepared to improve combustion and pressure output. The combustion rate and peak pressure of gradient structured HMX/Al/CF are higher than those of single structured HMX/Al/CF. The highest peak pressure (∼2.24 MPa) is obtained when the Al content of the middle layer and outer layer is 30 wt% and 20 wt% in the gradient structured HMX/Al/CF cylinder, respectively. Finally, the reaction intermediates and combustion reaction products were fully characterized to understand the enhanced effect of CF in HMX/Al. This work provides a promoting way to improve and regulate the combustion reaction performance and pressure output of HMX/Al.
To understand the thermal decomposition and combustion characteristics of HMX/aluminum (Al) composites, this study prepared the HMX/Al composites with different Al contents and carried out the thermal decomposition and combustion performance tests of these composites. The thermal analysis results showed that the activation energy of the HMX/Al composites increased from 483.94 kJ·mol −1 to 541.60 kJ·mol −1 when the Al content increased from 0 to 30 wt%. However, the change in the Al content had little effect on the heat flow of the HMX/Al composites. The combustion results showed that the calorific value of HMX/Al-30 composite reached 16,860 J·g −1 . The flame height and burning intensity gradually increased with an increase in the Al content, and the burning duration of HMX/Al-10, HMX/Al-20, and HMX/Al-30 gradually decreased by 0.21, 0.57 ms and 0.91 ms, respectively. The results showed that Al powder as metal fuel can control the combustion reactions and energy output of HMX-based explosives.
Biological approaches for the synthesis of a hybrid explosive–nanothermite energetic composite have attracted greater scientific attention because of their advantages, including their moderate reactions and the absence of secondary pollution. In this study, a simple technique was developed to fabricate a hybrid explosive–nanothermite energetic composite based on a peptide and a mussel-inspired surface modification. Polydopamine (PDA) was easily imprinted onto the HMX, where it maintained its reactivity and was capable of reacting with a specific peptide used to introduce Al and CuO NPs to the surface of the HMX via specific recognition. The hybrid explosive–nanothermite energetic composites were characterized using differential scanning calorimetry (TG-DSC), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy(XPS), and a fluorescence microscope. A thermal analysis was utilized to investigate the energy-release properties of the materials. The[email protected]@CuO, which benefitted from an enhanced interfacial contact in comparison with the physically mixed sample (HMX-Al-CuO), demonstrated a 41% lower HMX activation energy.Keywords:biological self-assembly;polydopamine;peptide;green preparation;activation energy
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