1997 Fiscal Year Final Research Report Summary
A Fundamental Study on Cavitation Erosion Using a Magnesium Oxide Single Crystal
| Project/Area Number |
08650193
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Fukui University |
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Principal Investigator |
HATTORI Shuji Fukui University, Mech.Eng., Associate Professor, 工学部, 助教授 (00143933)
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| Co-Investigator(Kenkyū-buntansha) |
MAEKAWA Norihide Fukui University, Mech.Eng., Technician, 工学部, 教務職員 (20262610)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Cavitation / Cavitation Erosion / Magnesium Oxide Single Crystal / Metal / Bubble Collapse Pressure / Stress Distribution / Plastic Deformation / Dislocation |
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| Research Abstract |
Cavitaion erosion is a phenomenon of progressive mass loss of original material from a solid surface due to continued exposure to cavitation, but it remains unclear how the pressure act on the surface. In this study, the pressure distribution was analyzed by using a magnesium oxide single crystal (100) surface exposed to cavitation. The size of the plastically deformed region and the distances of dislocation-etch-pits were measured. The results shows that the pressure acts normal to the surface, but not parallel, thus no shear stress acts on the surface for cavitation erosion. The maximum pressure ranges from 500MPa to 1000MPa. The high pressure region is very large, but the affected region is very large. The pressure distribution was confirmed to be reasonable by comparing it with pits observed on some metals with different yield strength. Moreover, when a material is exposed to cavitation for a long time, the surface is eroded like a sponge. Magnesium oxide single crystal polished with four grades of emery paper were exposed to cavitation. It is concluded that the growth of spongelike eroded surface is responsible for the dense dislocation rows initiated at the dents of uneven surface.
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