Effect of Solids Loading on Resonant Mixed Al‐Bi₂O₃ Nanothermite Powders

Abstract

Sensitive nanoenergetic powders, such as nanothermites, have traditionally been processed by ultrasonic mixing of very low solids loaded suspensions in organic solvents, which has restricted their use and application due to high solvent content and associated handling issues. In this work, we report on the performance and mixing quality of nanothermite mixtures prepared in a LabRAM resonant mixer at high solids loadings as compared to ultrasonic mixing. Specifically, the aluminum‐bismuth(III) oxide (Al/Bi2O3) system processed in the polar solvent N,N‐dimethylformamide (DMF) was investigated. It was found that the performance and overall quality of mixing was strongly correlated to the volumetric solids loading during processing; increasing volumetric solids loading decreases separation of particles, leading to more particle interaction and more intimate mixing. The measured performance of this system processed at 30 vol‐% was similar to traditionally ultrasonicated mixtures. Increasing the solids loading above 30 vol‐% yielded diminishing returns in performance and may introduce additional safety concerns since dry powders are very sensitive to electrostatic discharge. This mixing approach uses significantly less solvent than traditional ultrasonic mixing, results in a higher density final material, and is amenable to scaling. In addition, solvent wetted nanothermite mixed at 30 vol‐% solids loading can be mixed and deposited from a single applicator and was observed to be over five orders of magnitude less sensitive to electrostatic discharge than dry powders. This relative insensitivity enables the safe deposition of high density nanothermite ink onto devices.

Nanoenergetics as pressure generator for nontoxic impact primers: Comparison of Al/Bi2O3, Al/CuO, Al/MoO3 nanothermites and Al/PTFE

“…Moreover, compared to conventional explosives, one asset of nanoenergetic materials is the possible adjustment of the energy density, power release and pressure generation by a suitable choice of fuels, oxidizers, material geometries and reactant compaction [3,[14][15][16][17][18][19][20][21][22]. Until recently, very few reports have considered the dynamic pressures developed by the gas expansion during nanothermites reactions [11,[23][24][25]. The objective of this study is to find the best Al/Oxide system to be applied in nontoxic impact primers.…”

A novel nano-energetic system based on bismuth hydroxide

“…Aluminum is one of the most popular metals utilized as a fuel, although Mg is also used occasionally [15,16]. Although much research has been performed to investigate the properties of metal oxide based nano thermites [17][18][19][20][21][22], another closely related systems based on metal hydroxides were surprisingly overlooked. However, these systems undoubtedly deserve attention for several reasons.…”

Nanothermites: A short Review. Factsheet for Experimenters, Present and Future Challenges

“…Some authors use sieves for breaking these agglomerates and for obtain-ing a powder with a better defined macroscopic grain size. This last step is hazardous, especially with nanothermites which are very sensitive to friction [71]. The careful crushing of large agglomerates with a spatula seems a better option for this purpose, because nanothermites are less sensitive to compression than to friction.…”