2000 Fiscal Year Final Research Report Summary
Addition of New Functions to Ziroconia Ceramics by Nano-sized Metal Dispersion
| Project/Area Number |
11650718
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Structural/Functional materials
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
SEKINO Tohru ISIR, Osaka University Assoc.Prof., 産業科学研究所, 助教授 (20226658)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Keywords | nanocomposites / multi-functionality / zirconia / internal reduction technique / nanocomposite powder / mechanical properties / ferromagnetic property / stress-magnetic interaction |
|---|
| Research Abstract |
In this project, I have focused on the development of multi-functional zirconia-based nanocomposite materials. For over the decades I have concentrated to design and to develop ceramic/metal nanocomposite, in which nanometer-sized metal dispersed within Al_2O_3, MgO and so on. Based on this concept I have applied this technique to zirconia-based nanocomposite. Zirconia is well known to show high-strength and toughness due to its stress-induced phase transformation toughening. To enlarge the application of this ceramic, addition of new functions or realizing multifunctionality may be necessary. Therefore, I have investigated to develop transition metal dispersed zirconia nanocomposite in order to achieve above-mentioned purposes. Here, I selected Ni as dispersed functional metal nanoparticles. Several kinds of fabrication processing have been applied.
In this research, followed results have been obtained.
(1) Proposed ZrO_2/Ni nanocomposites have been successively prepared by using reduct
… More
ion and sintering method for various ZrO_2/NiO composite powders. Large enhancement of fracture strength of zirconia was achieved when small amounts of Ni nanoparticles were dispersed into zirconia. Ferromagnetism of nanosized-Ni was also compatible in this nanocomposite. Magnetic coercivity was dominantly increased with decreasing particle size of Ni. In addition, magnetization was found to be sensitive to applied stress, showing the possibility of non-destructive remote sensing of deformation/fracture of nanocomposites.
(2) When very small amount of NiO dopant was added into zirconia, dens solid solution with tetragonal structure was prepared, which had improved toughness. This is due to the control of stability of crystal structure of zirconia by small amount of NiO dopant. This fact indicates that phase transformation behavior can be controlled. In addition, zirconia/Ni nanocomposites could also be obtained by atmosphere-controlled heat-treatment of this solid solution ; Nanosized Ni particles were successively in-situ precipitated. This nanocomposite was found to show both high-toughness and ferromagnetism, implying the advantage of this newly developed "internal reduction method" for making ceramic/metal nanocomposites.
(3) Powder preparation for zirconia/nickel nanocomposite was also investigated by using solution chemical route. Appropriate control factors for this chemical processing have been clarified. This method allowed us to obtain nanocomposite powder of ZiO_2-NiO with nanometer-size, which is more useful for developing ZiO_2/Ni nanocomposite and related materials.
In conclusion this research project has successively conducted to develop novel multifunctional zirconia/nickel nanocomposites. This material exhibited both excellent mechanical properties and magnetic functionalities. All these new preparation techniques are considered to be applicable to another ceramic nanocomposite systems. Less
|
