EAGER: Properties and Manufacturing of Transformative Aluminum Nanocomposite Electrical Conductors

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Electricity transmission and distribution losses average about 6 percent of the electricity that is transmitted and distributed annually in the United States. The aluminum overhead power cables, currently dominant for electricity transmission and distribution, have remained almost unchanged for roughly 100 years. The ever increasing demand for electric power has created congestion on the current power grid. There is an urgent need for a new way of increasing the capacity of current transmission lines. This award supports fundamental research to enable manufacturing of transformative aluminum electrical conductors enhanced by nanoparticles. These conductors can offer superior power transmission capacity with a high operating temperature limit, and significantly reduce construction costs and increase reliability of future power transmission grids. They can also be used for other renewable energy and energy storage systems. The first research objective is to establish relationships between electron scattering effects of nanoparticles uniformly dispersed in aluminum substrates and the material type, size, shape, and volume percentage of the nanoparticles. To achieve this objective, both theoretical and experimental studies will be conducted. Mathematical equations of electron scattering by nanoparticles will be developed by examining electron transport at different size scales, and will be used to predict electrical conductivity of aluminum nanocomposites. A standard 4-point probe will be used to measure the electrical conductivity of aluminum conductors containing 0.1-10 vol percent spherical nanoparticles (such as TiB2) with a size of 5-60 nm. Some predicted values of electrical conductivity will be compared against measured values. The second research objective is to determine the interaction potentials (interfacial energy, van der Waals potential, and thermal energy) among nanoparticles (such as TiB2, TiC, and Ti5Si3) and molten aluminum. To achieve this objective, analytical models based on intermolecular interactions will be established while experimental measurements will be carried out using the sessile-drop method and atomic force microscope. The third research objective is to establish relationships among properties (tensile strength, thermal conductivity, and heat capacity), microstructure (phase, nanoparticle dispersion, and size and morphology of grains), and manufacturing process parameters for aluminum nanocomposites. Solidification processing of aluminum nanocomposites will be assisted by a molten salt method. Nanocomposite ingots will be cold drawn into wires. Tensile testing on the nanocomposite wires will be conducted. Thermal conductivity and heat capacity of the nanocomposite will be measured using the laser flash method and differential scanning calorimetry, respectively. Microstructure of the nanocomposites will be examined by optical and electron microscopes and X-ray diffraction.