Impact-initiated combustion of aluminum

dc.contributor.advisor Thadhani, Naresh N.
dc.contributor.author Breidenich, Jennifer L.
dc.contributor.committeeMember Sanders, Thomas H.
dc.contributor.committeeMember Gokhale, Arun M.
dc.contributor.committeeMember Dwivedi, Sunil
dc.contributor.committeeMember Peiris, Suhithi
dc.contributor.department Materials Science and Engineering
dc.date.accessioned 2016-01-07T17:36:02Z
dc.date.available 2016-01-07T17:36:02Z
dc.date.created 2015-12
dc.date.issued 2015-11-11
dc.date.submitted December 2015
dc.date.updated 2016-01-07T17:36:02Z
dc.description.abstract This work focuses on understanding the impact-initiated combustion of aluminum powder compacts. Aluminum is typically one of the components of intermetallic-forming structural energetic materials (SEMs), which have the desirable combination of rapid release of thermal energy and high yield strength. Aluminum powders of various sizes and different levels of mechanical pre-activation are investigated to determine their reactivity under uniaxial stress rod-on-anvil impact conditions, using a 7.62 mm gas gun. The compacts reveal light emission due to combustion upon impact at velocities greater than 170 m/s. Particle size and mechanical pre-activation influence the initiation of aluminum combustion reaction through particle-level processes such as localized friction, strain, and heating, as well as continuum-scale effects controlling the amount of energy required for compaction and deformation of the powder compact during uniaxial stress loading. Compacts composed of larger diameter aluminum particles (~70µm) are more sensitive to impact initiated combustion than those composed of smaller diameter particles. Additionally, mechanical pre-activation by high energy ball milling (HEBM) increases the propensity for reaction initiation. Direct imaging using high-speed framing and IR cameras reveals light emission and temperature rise during the compaction and deformation processes. Correlations of these images to meso-scale CTH simulations reveal that initiation of combustion reactions in aluminum powder compacts is closely tied to mesoscale processes, such as particle-particle interactions, pore collapse, and particle-level deformation. These particle level processes cannot be measured directly because traditional pressure and velocity sensors provide spatially averaged responses. In order to address this issue, quantum dots (QDs) are investigated as possible meso-scale pressure sensors for probing the shock response of heterogeneous materials directly. Impact experiments were conducted on a QD-polymer film using a laser driven flyer setup at the University of Illinois Urbana-Champaign (UIUC). Time-resolved spectroscopy was used to monitor the energy shift and intensity loss as a function of pressure over nanosecond time scales. Shock compression of a QD-PVA film results in an upward shift in energy (or a blueshift in the emission spectra) and a decrease in emission intensity. The magnitude of the shift in energy and the drop in intensity are a function of the shock pressure and can be used to track the particle scale differences in the shock pressure. The encouraging results illustrate the possible use of quantum dots as mesoscale diagnostics to probe the mechanisms involved in the impact initiation of combustion or intermetallic reactions.
dc.description.degree Ph.D.
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/54403
dc.language.iso en_US
dc.publisher Georgia Institute of Technology
dc.subject IR
dc.subject CTH
dc.subject HEBM
dc.subject CdTe
dc.subject Combustion
dc.subject Aluminum
dc.subject Explosives
dc.subject Compact
dc.subject Reaction
dc.subject High strain rate behavior
dc.subject Structural energetic materials
dc.subject Intermetallic forming mixtures
dc.subject Rod-on-anvil
dc.subject Powder
dc.subject Mechanical pre-activation
dc.subject High energy ball milling
dc.subject Spectroscopy
dc.subject Gas gun
dc.subject Pressure
dc.subject Light emission
dc.subject Microstructure-based simulations
dc.subject Particle-particle interactions
dc.subject Particle-level process
dc.subject Compaction
dc.subject Deformation
dc.subject Impact
dc.subject Quantum dots
dc.subject Laser-accelerated flyer
dc.subject Shock compression
dc.subject Blueshift
dc.subject Mesoscale diagnostic
dc.subject Heterogeneous materials
dc.title Impact-initiated combustion of aluminum
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Thadhani, Naresh N.
local.contributor.corporatename School of Materials Science and Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication ec14adca-203a-4973-b6ac-65dab1b1f44d
relation.isOrgUnitOfPublication 21b5a45b-0b8a-4b69-a36b-6556f8426a35
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
thesis.degree.level Doctoral
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
43.18 MB
Adobe Portable Document Format
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
3.87 KB
Plain Text