| Project/Area Number |
62850132
|
|---|
| Research Category |
Grant-in-Aid for Developmental Scientific Research
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
金属材料(含表面処理・腐食防食)
|
|---|
| Research Institution | University of Tokyo |
|---|
Principal Investigator |
SAKUMA T. Professor, Dept. of Materials Science, Fac. of Engeneering University of Tokyo, 工学部, 教授 (50005500)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
正木 孝樹 東レ, 開発部, 主任研究員
MASAKI T. Chief Scientist, Development Division Toray
|
|---|
| Project Period (FY) |
1987 – 1988
|
| Project Status |
Completed (Fiscal Year 1988)
|
| Budget Amount *help |
¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1987: ¥5,500,000 (Direct Cost: ¥5,500,000)
|
|---|
| Keywords | partially-stabilized zirconia / phase transformation / fracture toughness / microstructure / 混合組織 / マルテンサイト変態 / 結晶粒成長 |
|---|
| Research Abstract |
Microstructure and mechanical properties in partially-stabilized zirconia were examined. The main results obtained are as follows,
(1) The optimum composition for attaining the highest fracture toughness was determined to be -2mol% for ZrO_2-Y_2O_3, -5 mol% for ZrO_2-CeO_2 and -4.5 mol% (Y_2O_3 + CeO_2) for ZrO_2-Y_2O_3-CeO_2 with CeO_2/Y_2O_3 ratio 2.
(2) heat treatment in the t-ZrO_2/c-ZrO_2 two-phase region rusklted in two types of microstructures, usual precipitation structure and fine-grained polycrystals when the equilibrium partitiong was attained between t-ZrO_2 and c-ZrO_2 grains during geating. Generation of dual-phase struture was effective for suppressing the grain growth. Intercritical annealing to produce the dual-phase structure was found to be useful for fabricating the commercial toughened zirconia ceramics.
(3) The diffusionless cubic-to-tetragonal transition accompanied two types of microstructures, the domain structure and the thin-plate or lenticular structure. This transition had a nature of second-order phase transition which was always completed during cooling. The unique nature of this transition was closely related to the resultant microstructures.
|
