1999 Fiscal Year Final Research Report Summary
Nanoscopic study and application of tribo-plastic deformation mechanism
| Project/Area Number |
10650725
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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 |
Material processing/treatments
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| Research Institution | RIKEN |
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Principal Investigator |
IKE Hiroshi RIKEN, Materials Fabrication Lab., Senior Research Scientist, 素形材工学研究室, 先任研究員 (30087431)
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| Co-Investigator(Kenkyū-buntansha) |
KOHNO Akio RIKEN, Surface and Interface Lab., Senior Research Scientist, 表面界面工学研究室, 先任研究員
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| Project Period (FY) |
1998 – 1999
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| Keywords | surface microgeometry / plastic deformation / boundary lubrication / tribology / AFM / plasto-hydrodynamic lubrication / mirror surface / indentation hardness |
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| Research Abstract |
To fully utilize a microscopic aspect of plastic deformation as being represented by dislocation theory, a metalforming technique that controls surface roughness at a molecular film thickness and deforms the specimen plastically under a rigid constraint is required. In the present project a surface formation process in a nanometer order avoiding problems of surface damage during sliding and excess lubricant present over contact interface is studied. Furthermore, nanometer-scale metalforming process is to be exemplified for a special geometry.
From a theoretical study of plasto-hydrodynamic lubrication, an indentation-and-sliding process of a wedge with 150°apex angle is adopted. A wedge tool from ultra-fine cemented tungsten carbide is lapped to a surface roughness of 20 nm Rx. A rectangular block specimen of oxygen-free half-hard copper with 12mm wide is finished by a waterproof abrasive paper to have the surface roughness of 150 nm Ra. The wedge tool is indented into a specimen at a low speed to form a valley of about 1.4mm wide. Then the tool is slid up to 0.5 mm along the tool ridge direction under a constant normal load.
It was found that the geometrical transfer from tool to specimen is made in two ways. (1) Microscopic flattening proceeds leaving valleys of several micron wide. The ratio of boundary contact ranges from 80 % to 95% depending on the lubricants. (2) Nanoscopic flattening proceeds over a boundary contact region without showing any surface damage under AFM to form a surface roughness of 0.5 to 1nm Ra over 500nm x 500nm square, which is almost the same as the tool surface. It is exemplified that nanometer-scale precise transfer of surface roughness is possible by the indentation-and-sliding of a blunt wedge. A further study is required to clarify the effects of lubricant structure and the distance of sliding.
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