Novel Strucutres in Nanocrystalline Ceramic Materials
EMSL Project ID
3385
Abstract
The exceptional mechanical, thermal and electrical properties of single-wall carbon nanotubes (SWCNs) have prompted intense research into a wide range of applications in materials, electronics, chemical processing, and energy management. SWCNs possess extraordinary mechanical properties such as stiffness (a Young's modulus of 1,400 GPa) and strength (a tensile strength well above 100 GPa). There have been many predictions of the reinforcing effects of carbon nanotubes in various composite matrices but large improvements in properties have not yet been convincingly demonstrated. It is the first time that we have successfully realized this possibility in reinforcing nanocrystalline ceramic nanocomposites by spark-plasma-sintering (see Zhan et al., Nature Mater., 2, 38-42, 2003). Fully dense SWCN/Al2O3 nanocomposites with nanocrystalline alumina matrix have been fabricated at sintering temperatures as low as 1150oC by spark-plasma-sintering. A dramatic increase in toughness of nearly 200% as compared to pure nanocrystalline alumina has been achieved in the 10vol.% SWCN/Al2O3 nanocomposite. We are planning to investigate the following items for carbon nanotube-ceramic nanocomposites:
(1) It will be necessary to investigate the bonding conditions between the carbon nanotubes and the ceramic matrix by HRTEM and the chemical changes of carbon nanotubes after consolidation by EELS.
(2) Electron microscopy investigations of in-situ crack propagation will also help to elucidate the toughening mechanisms.
Moreover, processing of nanocrystalline ferroelectric and piezoelectric materials is another exciting area in the field of nanostructured materials. However, it is very difficult to obtain fully dense nanocrystalline materials (grain size less than 100 nm) by conventional methods due to explosive grain growth. We have successfully produced nanocrystalline BaTiO3 and Nd2Ti2O7 materials by spark-plasma-sintering. These nanostructured materials show novel properties but there is less information about their nanostructures, phases, and chemistry. It would also be very interesting to observe their domain structure in nano-scale range by CBED.
Project Details
Project type
Exploratory Research
Start Date
2003-03-26
End Date
2005-04-04
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Kouprine AP, L Cheng, Z Altounian, DU Ryan, and MH Engelhard. 2005. "Magnetic Properties of Cu/Fe Multilayers upon Transition to Island Structure of Fe layers." Physical Review. B, Condensed Matter.