Engineered Metastable Intermolecular Composites: Microstructures, Combustion and Applications

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The proposed research program targets the development of new nano-aluminum based energetic materials, or metastable intermolecular composites (MICs), to enable their reliable uses in emerging civil and defense applications such as nanosatellites and microelectronic devices. These composites, made of nanosized aluminum powders (n-Al) and a nanostructured oxide component such as CuO, Fe2O3, NiO or MnO3, are engineered with specific chemical and physical properties. After ignition, n-Al reacts rapidly with the metal-oxide and forms new material phases, accompanied by intensive energy release and, subsequently, generation of a pressure wave in a constrained environment. In comparison with monomolecular materials such as TNT and RDX, MIC possesses a much greater volume based energy density and has proven applications in propulsion and powering microelectromechanical system (MEMS) based devices. Two major objectives of the proposed research program are, to seek a breakthrough in fundamental understanding of the correlations between the microstructures of n-Al based MICs and their ignition and solid-state reaction kinetics, and to explore innovative mixing and fabrication technologies for producing engineered MIC patterns with controlled flame propagation rates for potential applications in MEMS energy supply and advanced material joining. Over the next five years, the proposed research program will address both theoretical and experimental studies in pursuit of the above objectives. The first task focuses on characterizing the micro-structures and material properties of MICs. Various metal oxide nanostructures including nanoparticles, nanowires and nanorods will be synthesized. After being mixed with n-Al, the particle size distribution and morphology, crystalline structures and chemical compositions of MICs will be characterized with analytical chemistry techniques, in order to identify the correlations among nanoparticles (types and shapes, etc.), microstructures and MIC properties. The second task focuses on investigating ignition and reaction characteristics and flame propagation of the MIC powder and patterns. A novel size-resolved nanoparticle-gas chemical analysis apparatus will be developed to investigate ignition and combustion of individual n-Al. Experimental investigations will also be performed in a Thermogravimetric analyzer (TGA) with thermal ignition and in a constant-volume vessel with electrical and laser ignition, respectively. The density functional theory and molecular dynamics method will be implemented to reveal the surface reactions and atomic diffusion and volume expansion processes. The third task focuses on exploring the applications of MICs. The photolithography technique will be adopted and optimized, satisfying the material and structural properties of MICs, to effectively implant MICs on specified locations on a target chip. Then the localized heat generation, ignited with a preferable source, will be quantified and investigated to provide energy for material joining and act as a power pulse source to actuate MEMS components. Canada is falling behind in the research and development of next-generation engineered MICs, and is particularly lacking in programs that will contribute a basic understanding of ignition and reaction characteristics of engineered metastable intermolecular composites. The proposed project will address this critical gap and produce a world-class research team which will potentially make Canada a global leader in this field.