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Physics and Astronomy

Physics & Astronomy Colloquium

3:30 PM, Friday, September 26, 2008
Room 155, Chem-Phys Building

Dr. Y. T. Cheng
Department of Chemical and Materials Engineering
University of Kentucky, Lexington

From Nano to Macro: Examples from Studies of Nanostructured Materials for Automotive Applications
We will present several examples from our recent studies of nanostructured materials. Although these studies were mainly motivated by automotive applications, the examples helped unveil several general relationships between the growth, structure, and property of nanostructured materials that may be useful to other applications. (1) Nanocomposite coatings and nanowires by physical vapor deposition. By co-deposition and controlled phase-separation, we have synthesized nanocomposite thin films with enhanced mechanical, tribological, and electrical properties. We have also demonstrated that the residual stress in the co-deposited films could be exploited to grow nanowires. The nanocomposite coatings and nanowires have applications in areas such as friction reduction, magnetic recording, and energy conversion. (2) Microscopic shape memory and superelastic effects. Using micro- and nano-indentation techniques, we have demonstrated the existence of shape memory and superelastic effects under complex loading conditions at the micro- and nano-meter scales. These effects form the basis for using shape memory alloys as "self-healing" surfaces and "metallic-based adhesion" materials. The microscopic shape memory effect can also be exploited to create surfaces with reversible roughness and texture for applications such as friction control and information storage. (3) Thin films and coatings for batteries and fuel cells. Thin film materials are also used for high power density and durable batteries and fuel cells. We have used vapor deposition techniques to make crystalline and amorphous La-Ni and Ni-Zr alloys and investigated their hydrogen storage capacity. We have also studied the "superhydrophobic" behavior of Lotus leaves for creating bio-inspired hydrophobic coatings for fuel cell applications. These examples illustrate the myriad possibilities of using nanostructured materials for industrial applications. They also demonstrate the multidisciplinary nature of materials research.

Refreshments will be served in CP 155 at 3:15 PM