1999 Fiscal Year Final Research Report Summary
MECHANO-ELECTROCHEMISTRY OF MICRO-SURFACE AREA OF MATERIALS
| Project/Area Number |
09305047
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SEO Masahiro Grad. School of Eng., Hokkaido Univ., Prof., 大学院・工学研究科, 教授 (20002016)
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| Co-Investigator(Kenkyū-buntansha) |
FUSHIMI Koji Grad. School of Eng., Hokkaido Univ., Inst., 大学院・工学研究科, 助手 (20271645)
AZUMI Kazuhisa Grad. School of Eng., Hokkaido Univ., Asso. Prof., 大学院・工学研究科, 助教授 (60175875)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Mechano-electrochemistry / Nanoindentation / Passive Film / Load-depth Curv / Mechanical Property / Iron / Titanium / Anodic Oxide fil |
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| Research Abstract |
Nanoindentation tests were performed for the single crystal iron (100) surfaces electrochemically controlled in pH 8.4 borate solution to measure the load-depth curves from which the mechanical properties such as hardness and elastic modulus of the iron surfaces were evaluted to obtain the fundamental knowledge for estabilshment of mechano-electrochemistry. The hardness of the iron surfaces was fluctuated depending on the position of nano-surface area. The average value of hardness, however, took a minimum at 0.25 V in the passive potential region. At the potential above 0.25 v, the average hardness increased linearly with increasing the potential, I.e., the thickness of passive film. The hardness of film itself could be separated from that of the substrate iron by using the linear relation between average hardness and film thickness. Moreover, the nanoindentation tests were performed for the single crystal iron (100) and (110) surfaces passivated at 1.0 V in pH 8.4 borate solution to
… More
investigate the depedence of hardness on crystal orientation of the surface. However, no significant differences in hardness was observed between single crystal iron (100) and (110) surfaces.
The hardness of the polycrystalline titanium surfaces subjected to anodic oxidation in various electrolyte solutions was measured as a function of formation potential of anodic oxide film. The hardness increased with increasing the film formation potential up to 8 V. The hardness decreased rapidly above 8 V at which the local breakdown of the film would take place. Moreover, the largest hardness was observed for the titanium surfaces subjected to anodic oxidation in sulfuric acid. The stresses generated in the anodic oxide film on titanium were measured by a laser-beam deflection method to investigate the relation between stress in the film and hardness. The largest compressive stresses were generated in anodic oxide film on titanium in sulfuric acid. Therfore, it is found that there is a good correlation between compressive stress and hardness. The partial release of the compressive stresses were observed at the potential above 8 V at which the local breakdown of anodic oxide film took place. The rapid decrease in hardness at the potential above 8 V was ascribed to the partial release of compressive stress ue to local breakdown of anodic oxide film. Less
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