| About this Abstract |
| Meeting |
MS&T21: Materials Science & Technology
|
| Symposium
|
Development of Light Weight Alloys and Composites
|
| Presentation Title |
Non-Rule-of-Mixtures Thermal Diffusivity in Core-Shell-based Nanocrystalline Composite Ceramics |
| Author(s) |
James A. Wollmershauser, Kevin P Anderson, Benjamin L Greenberg, Heonjune Ryou, Edward P Gorzkowski, Boris N Feigelson |
| On-Site Speaker (Planned) |
James A. Wollmershauser |
| Abstract Scope |
Nanocrystalline ceramics demonstrate property improvements over larger-grain-sized ceramics such as increased hardness, strength, and, potentially, damage tolerance. These property improvements result from “confinement” effects of modes of strain accommodation and crack propagation. Combining two or three different ceramic materials into a nanocrystalline composite ceramic provides the opportunity to design other properties that are generally expected to follow a rule-of-mixtures law, such as thermal conductivity, while capitalizing on mechanical property improvements inherent to nanocrystalline materials. Recent work at NRL has combined particle atomic layer deposition (pALD) with Environmentally Controlled – Pressure Assisted Sintering (EC-PAS) to synthesize dense nanocomposite ceramics from core-shell nanopowders. Limited experiments suggest that thermal diffusivity (proportional to thermal conductivity) of these nanocomposites do not follow a simple rule-of-mixtures law. Instead, the thermal properties of the nanocrystalline constituent with a lower thermal diffusivity controls the thermal diffusivity of the nanocomposite ceramic. |