TY - JOUR
T1 - Electro-static discharge ignition of monolayers of nanocomposite thermite powders prepared by arrested reactive milling
AU - Monk, Ian
AU - Williams, Rayon
AU - Liu, Xinhang
AU - Dreizin, Edward L.
N1 - Funding Information:
This work was supported by the Army Research Office (ARO), Award W911NF-12-1-0161.
Publisher Copyright:
Copyright © Taylor & Francis Group, LLC.
PY - 2015/8/3
Y1 - 2015/8/3
N2 - Reactive nanocomposite powders with aluminum as a fuel and copper, bismuth, iron, and molybdenum oxide as oxidizers: 2Al·3CuO, 2.35Al·Bi2O3, 2Al·Fe2O3, and 2Al·MoO3, were prepared by arrested reactive milling, placed in monolayers on a conductive substrate, and ignited by an electro-static discharge (ESD) or spark in air, argon, and vacuum. The ESD was produced by discharging a 2000 pF capacitor charged to a voltage, which varied from 5 to 20 kV. Emission from ignited particles was monitored using a photomultiplier equipped with an interference filter. Experimental variables included particle sizes, milling time used to prepare composite particles, surrounding environment, and starting ESD voltage. All materials ignited in all environments, producing individual burning particles that were ejected from the substrate. The spark duration varied from 1 to 5 μs; the duration of the produced emission pulse was in the range of 80-250 μs for all materials studied. The longest emission duration was observed for the nanocomposite thermite using MoO3 as an oxidizer. The reaction rates of the ESD-initiated powders were defined primarily by the scale of mixing of and reactive interface area between the fuel and oxidizer in composite materials rather than by the external particle surface or particle dimensions. In vacuum, particles were heated by ESD while remaining on the substrate until they began generating gas combustion products. In air and argon, particles initially pre-heated by ESD were lifted and accelerated to ca. 100 m/s by the generated shock wave; the airborne particles continued self-heating due to heterogeneous redox reactions.
AB - Reactive nanocomposite powders with aluminum as a fuel and copper, bismuth, iron, and molybdenum oxide as oxidizers: 2Al·3CuO, 2.35Al·Bi2O3, 2Al·Fe2O3, and 2Al·MoO3, were prepared by arrested reactive milling, placed in monolayers on a conductive substrate, and ignited by an electro-static discharge (ESD) or spark in air, argon, and vacuum. The ESD was produced by discharging a 2000 pF capacitor charged to a voltage, which varied from 5 to 20 kV. Emission from ignited particles was monitored using a photomultiplier equipped with an interference filter. Experimental variables included particle sizes, milling time used to prepare composite particles, surrounding environment, and starting ESD voltage. All materials ignited in all environments, producing individual burning particles that were ejected from the substrate. The spark duration varied from 1 to 5 μs; the duration of the produced emission pulse was in the range of 80-250 μs for all materials studied. The longest emission duration was observed for the nanocomposite thermite using MoO3 as an oxidizer. The reaction rates of the ESD-initiated powders were defined primarily by the scale of mixing of and reactive interface area between the fuel and oxidizer in composite materials rather than by the external particle surface or particle dimensions. In vacuum, particles were heated by ESD while remaining on the substrate until they began generating gas combustion products. In air and argon, particles initially pre-heated by ESD were lifted and accelerated to ca. 100 m/s by the generated shock wave; the airborne particles continued self-heating due to heterogeneous redox reactions.
KW - Heterogeneous reactions
KW - Ignition delay
KW - Reactive materials
KW - Spark ignition
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U2 - 10.1080/00102202.2015.1035373
DO - 10.1080/00102202.2015.1035373
M3 - Article
AN - SCOPUS:84929245023
SN - 0010-2202
VL - 187
SP - 1276
EP - 1294
JO - Combustion Science and Technology
JF - Combustion Science and Technology
IS - 8
ER -