Synthesis of Novel NanoEnergetics and Study of Their Reactant Interfaces
Abstract
Recent experiments by the PIs have combined flame and ionic-liquid electrodeposition syntheses to produce novel arrays of composite nanostructures, namely metal-oxide nanowires coated with nanolayers of aluminum. Such nano-thermite geometry not only presents a way to tailor heat- release characteristics because of anisotropic arrangement of fuel and oxidizer, but also excludes or minimizes the existence of an interfacial Al2O3 passivation layer. The energetic nanocomposite displays strong exothermicity, thereby being useful for fundamental study of aluminothermic reactions, as well as augmenting combustion attributes. Moreover, contrary to the notion that nano-thermites are only characterized by enhanced heat- release rate rather than increased energy density, this aspect may not be the case for our novel nanostructures. If the interface is abrupt with large lattice mismatch between the reactive metal and the metal-oxide, there may exist significant strain energy which can be liberated during reaction to augment the total heat release. Thus, a key objective of this work is to investigate the interfaces of such novel nano-thermites, where strain energy can be released, along with their ignition and combustion behaviors. In our novel thermite nanostructure, the passivation layer is minimized between reactants for fundamental study. However, challenges in the application of nanodimensional fuels and oxidizers are the attainment of long-term passivation and unwanted ignition, without losing the benefits of faster reaction rate. Oxide layers result in energy loss, decreased reactivity, and additional dead weight. On the other hand, a separating graphene layer can be placed between the reactants, providing an energy barrier, but also delivering heat release during the combustion process. Therefore, another objective is to investigate interfaces where the nano-scale reactants are separated by graphene layer(s), along with their ignition and combustion behavior. In complement with the thermite nanostructures described above, we propose to investigate planar configurations based on materials that we can readily synthesize, i.e. intermetallic such as Al-Ni and metallic-polymer such as Al-Teflon, separated by graphene. The proposed program focuses on investigating the interfaces and ignition/combustion attributes of novel nanoenergetics, such as co-axial thermite nanowires (with built-in strain energy) and planar nanoenergetics separated by graphene. The research components are to: (a) Use flame synthesis (in counterflow and multiple-diffusion-flames configurations) to synthesize nanowires of MoO3, CuO, WO3, Fe2O3, Bi2O3, and MnO2. The effects of fuel composition, flame temperature, inert addition, hydrogen addition, oxygen concentration, strain rate, pressure, and other controllable process parameters on nanowire properties will be examined; (b) Use ionic liquids to electrodeposit nanolayers of Al on the flame-synthesized MoO3, CuO, WO3, Fe2O3, Bi2O3, and MnO2 nanowires; and study the resulting interfaces. Strain mapping will be conducted. (c) Synthesize and electrodeposit Al on other metal-oxide nanostructures, such as nanoplates (e.g. MoOx), nanocones, nanoribbions, etc. (d) Characterize ignition and combustion behavior of the novel nanocomposites. Laser ignition with spectroscopic analysis, along with high-speed imaging, will be employed. (e)Fabricate nanoenergetics with graphene separating reactants, e.g. Al/graphene/Ni (intermetallic) and Al/graphene/Teflon (metal-polymer). Their interfaces and ignition/combustion characteristics will be studied.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 31, 2018
- Source ID
- W911NF1710111
Entities
People
- Stephen Da-Yen Tse
Organizations
- Army Contracting Command
- Rutgers University
- United States Army