Aluminum Burn Rate Modifiers Based on Reactive Nanocomposite Powders

Abstract

Aluminum powders have long been used as additives in propellants, pyrotechnics, and explosives. Aluminum has a high enthalpy of combustion but relatively low burn rate. Addition of reactive nanocomposite powders can increase the burn rate of aluminum and thus the overall reaction rate of the energetic formulation. Replacing only a small fraction of the fuel by a nanocomposite material can enhance the reaction rate with little change to the thermodynamic performance of the formulation. This research showed the feasibility of the above concept using nanocomposite powders prepared by arrested reactive milling (ARM), a scalable "top-down" technique for manufacturing reactive nanomaterials. The nanocomposite materials used in this study were 2B þ Ti, and Al-rich thermites: 8Al þ 3CuO, and 8Al þ MoO 3 . The reactive nanocomposite powders were added to micrometer-sized aluminum powder and the mixture was aerosolized and burned in a constant volume chamber. The combustion atmosphere was varied using oxygen, nitrogen, and methane. The resulting pressure traces were recorded and processed to compare different types and amounts of modifiers. Additives of nanocomposite powders of 8Al þ MoO 3 and 2B þ Ti to micrometer-sized aluminum were found to be effective in increasing both the rate of pressure rise and maximum pressure in the respective constant volume explosion experiments. It was observed that 20 wt.-% of additive resulted in the best combination of the achieved burn rate and pressure.

Ignition of aluminum powders by electro-static discharge

“…Indeed, a brief review of the available literature data for MIE for Al powders shows a broad range of the reported values varied from 1 to 600 mJ [15][16][17][18][19]. This range includes the value of 25 mJ identified using the current setup [20] and following the testing methodology of the MIL-1751A Standard [10].…”

Preparation and characterization of copper azide nanowire array

“…Similarly, in the area of energetic materials, the initiation and detonation properties of explosives are strongly influenced by their microscopical properties. Many published works on EMs suggest that reducing the particle size to the nanoscale may result in reduction of the masstransport rate and therefore would increase the burning rates [6][7][8][9][10][11]. Reducing the particle size can also increase density, calory, stability and mechanical properties.…”

Modeling the Pressure Generation in Aluminum‐Based Thermites

“…Alumino-thermite is an oxidation-reduction reaction involving am etal (fuel) and am etallic oxide (or possibly an on-metallic oxide) that forms as table product after reaction.Thermite materials have been actively investigated for aw ide range of potential applications including railroad welding, materials processing to form refractory materials, additives in propellants, explosives and pyrotechnics [1][2][3], and more recently also for micro initiation [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20],e nvironmentally clean primers, and in situ welding [21].Among the numerous possible exothermic metal/oxide pairs listed in the literature [22],t he most investigated ones mix Al with MoO 3 ,C uO, Bi 2 O 3 ,F e 2 O 3 ,M nO 2 ,W O 3 ,a nd I 2 O 5 .F or the last two decades most of the research efforts aimed at reducing metal and oxide components size, improving their intimacy,t oi ncrease the reaction rate and decrease the ignition delay while improving safety.More recently,t hermite materials were also considered to produce gas species or pressure bursts, opening new potential fields of application such as pressure mediated molecular delivery [23,24],b iological agent inactivation [25][26][27],h ydrogen production [28,29],o rp ropulsion systems [7][8][9].Af ew teams demonstrated experimentally that Al/Bi 2 O 3 and, to al esser extent, Al/I 2 O 5 mixtures generate the highest pressure pulses [27,30,31] in comparison with other thermites. Martirosyan [31] considered tha...…”