1990 Fiscal Year Final Research Report Summary
Surface modification of ceramics by means of ion-irradiation
| Project/Area Number |
01550540
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | Hokkaido University |
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Principal Investigator |
OHNUKI Somei Hokkaido Univ., Fac.of Eng. Ass.Prof., 工学部, 助教授 (10142697)
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| Co-Investigator(Kenkyū-buntansha) |
KINOSHITA Hiroshi Hokkaido Univ., Fac., of Eng.Res.Associ., 工学部, 助手 (40177895)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Ion-irradiation / Ceramics / Surface Modification / Amorphous Formation / Defect Cluster / Surface Softening / Surface Hardening / Atomic Bonding |
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| Research Abstract |
The change of surface structure of ion-beam irradiated three typical ceramics has been investigated to cralify the effect on (a) irradiation-produced micro-structures, (b) amorphous formation and (c) surface hardness.
In the case of single crystal of alumina (Al_2O_3), the surface hardness was increased by low dose of the irradiation, clarify with increasing of the dose, and finally saturated at higher doses. The microstructural observation can explain as follo13EA\ : ws ; the hardening at initial stage is caused by defect cluster formed with high number density, and the softening at higher doses is lead by the amorphous formation. This property of hardening is affected by the presence of grain boundaries, i.e. p13EA\ : olycrystals showed larger hardness and smaller softening. In the case, the amorphous formation started at grain boundaries. This phenomena can be explained that silica (SiO_2) located at grain boundaries is easy to tern to amorphous.
In the case of silicon nitride (Si_3N_4), which is a typical covalent-bonding materials, the properties of hardness were same, and the critical doses for amorphous formation was quite low.
In the case of zirconia (ZrO_2) which is a typical ionic-bonding materials, ion-irradiation produced only hardening. In this material defect clusters were formed, but amorphous was not produced during the irradiation.
These results can cralified that the modification of surface properties is caused by the amorphous formation from the accumulation of irradiation-defects, not by the increase of the internal stress.
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