|
Current Research
|
|
|
• Microfluidics • Brain Imaging • Functional Surface • Thermal Switch |
|
|
Past Research | |
|
• Micro & Nano Scale Thermosciences • Energy Harvesitng • Information Sciences |
|
Energy Harvesting |
|
| Heat Transfer in Nanostructured Materials(Super-Thermal Barriers) | |
| TOP | |
|
We are investigating energy transport in nanostructured materials, especially nanolaminates consisting of alternating layers of disparate materials. Nanolaminates are promising as thermal barrier coatings and components of thermoelectric devices because heat conduction is strongly impeded by the thermal interface resistance. Nanolaminates are attractive as thermal protection coatings for gas turbine blades, machining tool bits, and gun barrels since they do not incorporate pores or microscale defects that compromise mechanical or chemical protection properties. They are also well-suited as thermal barrier layers in nanoscale electronic and data storage devices that have stringent roughness requirements. Heat conduction across metal-dielectric interfaces is also of great fundamental interest. The type of dominant heat carriers switches between phonons and electrons across the interfaces, a situation very different from semiconductor superlattices and quantum wells where phonons are dominant heat carriers throughout the entire thickness. We have experimentally determined the thermal resistance of nanolaminates synthesized through controlled oxidation of nanoscale metal films. The thermal conductivity of the nanolaminates is well below the minimum thermal conductivity limit of the constituent materials and among the lowest achieved for nonporous inorganic materials. Our work demonstrates that nanolaminates offer a promising approach to realizing superior thermal barrier coatings. |
|
|
Our theoretical work also demonstrates the impact of spatial nonequilibrium between electrons and phonons near the interface
on heat conduction across metal-dielectric nanolaminates. The spatial non-equilibrium results in extra thermal resistance
for a metal layer sandwiched between two dielectric materials.The extra thermal resistance is a function of the electron phonon-coupling
length
|
|
