Using magnesium to maximize heat generated by reactive Al/Zr nanolaminates

Overdeep, Kyle R.; Livi, Kenneth J. T.; Allen, David J.; Glumac, Nick; Weihs, Timothy P.

doi:10.1016/j.combustflame.2015.03.023

Cited by 23 publications

(14 citation statements)

References 68 publications

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“…We attribute its appearance to the evaporation of Mg from the samples during reaction propagation, and its deposition on the sample surface. This has been observed in other materials this group has studied [52]. There is no difference in the final phases for the 2.54 and 6.35 mm samples, suggesting that the swaging process maintains a chemistry that is uniform enough to fully react and form the same final phases on the time scale of the self-propagating reaction fronts.…”

Section: Resultssupporting

confidence: 55%

Properties of reactive Al:Ni compacts fabricated by radial forging of elemental and alloy powders

Gibbins

Stover

Krywopusk

et al. 2015

Combustion and Flame

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a b s t r a c tWe explore rotary swaging of powders into solid compacts as an inexpensive means of producing reactive materials with refined microstructures and improved properties. Rotary swaging is a cold forging process that reduces the diameter of tubes, and in this study the tubes are packed with reactive combinations of elemental and alloy powders. The diameter reductions create a nearly fully dense compact from the powders and also reduce the average reactant spacing through plastic deformation. The extent of diameter reduction controls the microstructural refinement, observed through cross-sectional imaging. We correlate the observed changes in microstructure with reaction properties that are characterized using differential scanning calorimetry (DSC), hot-plate ignition studies, and velocity measurements. Exothermic peaks in DSC scans all shift to lower onset temperatures; hot plate ignition temperatures decrease; and reaction velocities rise as the degree of swaging is increased. We vary the shape of the initial reactants by substituting Ni flakes for Ni powders and find no improvement in microstructure or reaction properties, due to clumping of the Ni flakes during the initial compaction steps. We also vary chemistry by substituting Al-Mg alloy powders for Al powders and find that the alloy powders yield lower DSC exothermic peak temperatures, lower ignition temperatures, and higher reaction velocities compared to similar compacts with pure Al powders. This combination of results suggests that rotary swaging is an effective technique for producing reactive materials at low cost.

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Section: Resultssupporting

confidence: 55%

Properties of reactive Al:Ni compacts fabricated by radial forging of elemental and alloy powders

Gibbins

Stover

Krywopusk

et al. 2015

Combustion and Flame

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“…A similar sputtering process of nanolaminate foils is described in [19] and was modified as described below for this study to obtain the compositions of interest. PVD particles were fabricated using 99.7 at.% Zr targets with either Al-1100 (minimum 99 at.% Al), Al-8at.%Mg, or Al-38at.%Mg targets (Plasmaterials Inc., Livermore, CA, USA) [46]. The powers to the two cathodes, located on either side of the chamber, were adjusted to achieve a 50/50 atomic ratio between Zr and the desired Al or Al-Mg chemistry (denoted Al:Zr, Al-8Mg:Zr, and Al-38Mg:Zr).…”

Section: Particle Synthesismentioning

confidence: 99%

“…However, these studies lacked a measure of combustion efficiency, which is performed for the first time at small scales in this study. Other work has added Mg to generate an Al/Mg/Zr composite in order to assess the effect on combustion efficiency, maximum temperatures, burn rate, and so on [21,46]. Mg has also been added to Al and has been shown to decrease ignition delays and increase burn rates [47][48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

Measuring Heat Production from Burning Al/Zr and Al/Mg/Zr Composite Particles in a Custom Micro-Bomb Calorimeter

et al. 2020

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Al:Zr, Al-8Mg:Zr, and Al-38Mg:Zr nanocomposite particles fabricated by physical vapor deposition (PVD) and ball milling were reacted in 1 atm of pure O2 within a custom, highly-sensitive micro-bomb calorimeter. The heats of combustion were compared to examine the effect of particle size and composition on combustion efficiency under room temperature and in a fixed volume. All particles yielded ~60–70% of their theoretical maximum heat of combustion and exhibited an increase in heat over composite thin films of similar compositions, which is attributed to an increase in the surface area to volume ratio. The effect of particle size and geometry are mitigated owing to the sintering of the particles within the crucible, implying the importance of particle dispersion for enhanced performance. Vaporization of the metal species may transition between two diffusion flame species (Mg to Al). As Mg content is increased, more vaporization may occur at lower temperatures, leading to an additional stage of sintering. Physically intermixed Al and Mg oxides have been observed coating the surface of the particles, which implies a continuous transition of these vaporization processes. Such nano-oxides imply high vapor-flame combustion temperatures (>2700 K) and suggest viability for agent defeat applications.

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“…Other issues include the reaction initiation effect during RMS handling, premature intermixing at the interfaces of stacked RMS reactant layers [12,[16][17][18], and RMS ignition in a strong explosive exothermic reaction leading to the vaporization or ejection of the reaction product [19][20][21][22]. It should also be noted that the partly self-reacted RMS and preintermixed reactant layer interfaces are considered to be among the main factors preventing the reliable initiation of self-propagating exothermic reactions at room temperature in integrated RMSs [12,[16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Integrated Reactive Multilayer Systems for Bonding in Microsystem Technology

2021

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For the integration of a reactive multilayer system (iRMS) with a high exothermic reaction enthalpy as a heat source on silicon wafers for low-temperature bonding in the 3D integration and packaging of microsystems, two main conflicting issues should be overcome: heat accumulation arising from the layer interface pre-intermixing, which causes spontaneous self-ignition during the deposition of the system layers, and conductive heat loss through the substrate, which leads to reaction propagation quenching. In this work, using electron beam evaporation, we investigated the growth of a high exothermic metallic Pd/Al reactive multilayer system (RMS) on different Si-wafer substrates with different thermal conduction, specifically a bare Si-wafer, a RuOx or PdOx layer buffering Si-wafer, and a SiO2-coated Si-wafer. With the exception of the bare silicon wafer, the RMS grown on all other coated wafers underwent systematic spontaneous self-ignition surging during the deposition process once it reached a thickness of around 1 m. This issue was surmounted by investigating a solution based on tuning the output energy by stacking alternating sections of metallic reactive multilayer Pd/Al and Ni/Al systems that have a high and medium enthalpy of exothermic reactions, respectively. This heterostructure with a bilayer thickness of 100 nm was successfully grown on a SiO2-coated Si-wafer to a total thickness of 3 m without any spontaneous upsurge of self-ignition; it could be electrically ignited at room temperature, enabling a self-sustained propagating exothermic reaction along the reactive patterned track without undergoing quenching. The results of this study will promote the growth of reactive multilayer systems by electron beam evaporation processing and their potential integration as local heat sources on Si-wafer substrates for bonding applications in microelectronics and microsystems technology.

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Using magnesium to maximize heat generated by reactive Al/Zr nanolaminates

Cited by 23 publications

References 68 publications

Properties of reactive Al:Ni compacts fabricated by radial forging of elemental and alloy powders

Properties of reactive Al:Ni compacts fabricated by radial forging of elemental and alloy powders

Measuring Heat Production from Burning Al/Zr and Al/Mg/Zr Composite Particles in a Custom Micro-Bomb Calorimeter

Investigation of Integrated Reactive Multilayer Systems for Bonding in Microsystem Technology

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