Silicon Nanoparticles for the Reactivity and Energetic Density Enhancement of Energetic-Biocidal Mesoparticle Composites

Abstract

Biocidal nanothermite composites show great potential in combating biological warfare threats because of their high-energy-release rates and rapid biocidal agent release. Despite their high reactivity and combustion performance, these composites suffer from low-energy density because of the voids formed due to inefficient packing of fuel and oxidizer particles. In this study, we explore the potential of plasma-synthesized ultrafine Si nanoparticles (nSi, ∼5 nm) as an energetic filler fuel to increase the energy density of Al/Ca­(IO3)2 energetic-biocidal composites by filling in the voids in the microstructure. Microscopic and elemental analyses show the partial filling of mesoparticle voids by nSi, resulting in an estimated energy density enhancement of ∼21%. In addition, constant-volume combustion cell results show that nSi addition leads to a ∼2–3-fold increase in reactivity and combustion performance, as compared to Al/Ca­(IO3)2 mesoparticles. Oxidation timescale analyses suggest that nSi addition can promote initiation due to faster oxygen transport through the oxide shell of Si nanoparticles. At nSi loadings higher than ∼8%, however, slower burning characteristics of nSi and sintering effects lead to an overall degradation of combustion behavior of the composites.

Rerouting Pathways of Solid-State Ammonia Borane Energy Release

“…Ammonia borane (AB) and other chemical hydrides − possess higher enthalpy of oxidation than commonly employed metallic or metalloid fuels in solid-state propellants such as Al, Ti, Si, and Mg, − on both a gravimetric and molar basis (Figure ). Owing to its high gravimetric hydrogen content (19.6%) and low hydrogen generation temperature, AB has found considerable interest in the hydrogen storage application communities as has investigation of its dehydrogenation mechanism. − However, for its application in solid-state propellants, complete oxidation of the constituent boron in addition to hydrogen is essential to exploit its high energy content.…”

Progress in Electrohydrodynamic Atomization Preparation of Energetic Materials with Controlled Microstructures

“…Therefore, filling these voids with energetic components can compensate for the reduced volumetric energy density. To this end, Ghildiyal [ 40 ] used 5.0 wt% plasma-synthesized Si nanoparticles (~5 nm) as the void filler of Al/Ca(IO 3 ) 2 /PVDF, an energetic-biocidal composite, as shown in Figure 3 f. The addition of nano-Si led to a ~21% enhancement in energy density and a 2~3-fold increase in pressurization characteristics, benefiting from the oxygen diffusion kinetics of the nano-Si. Xiao [ 41 ] increased the mass content of RDX (30 wt%) to fill the voids of the Al/CuO/PVDF mesoparticles and increase the density of the particles, as shown in Figure 3 g.…”

Direct Imaging and Simulation of the Interface Reaction of Metal/Metal Oxide Nanoparticle Laminates

“…One of the difficulties in understanding how powder composites of reactive fuel/oxidizer − systems behave is the lack of control of the mixing length. On the other hand, there is a considerable body of work on the formation of nanolaminate structures with alternating reactive layers typically created by sputter deposition.…”