2007 Fiscal Year Final Research Report Summary
Preparation and Molecular Dynamics Evaluation of Super Hard BN Film by Ion-Beam-Assisted Deposition
| Project/Area Number |
17560078
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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 |
Materials/Mechanics of materials
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| Research Institution | University of Hyogo |
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Principal Investigator |
UCHIDA Hitoshi University of Hyogo, Graduate School of Engineering, Professor (30047633)
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| Co-Investigator(Kenkyū-buntansha) |
YAMASHITA Masato University of Hyogo, Graduate School of Engineering, Associate Professor (60291960)
HANAKI Satoshi University of Hyogo, Graduate School of Engineering, Assistant Professor (20336829)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Materials / Ion beam processing / Extension of life / Molecular dynamics / Analysis and evaluation |
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| Research Abstract |
BN films were prepared by depositing B vapor under simultaneous irradiation of N ions, that is ion mixing and vapor deposition (IVD) technique. The effect of processing parameters on morphology, composition, chemical bonding, crystal structure, Knoop hardness and volume resistance are evaluated. For the processing parameters, transport ratio B/N, acceleration energy of N ions, beam angle, crystallite orientation and temperature of substrate are selected and the optimum condition for the formation of cubic BN is searched. From MR analysis, it is revealed that the mixture phase of cBN and hBN, which shows very high Knoop hardness, is formed at low acceleration voltage and high transport ratio.
The compressive internal stress of BN films were estimated using the Newton ring method. The New-ton rings were measured with the optical microscope which was equipped with a Michelson interferometer. As a result, high compressive stress is measured at low acceleration voltage and high transport ratio B/N, which corresponded to the condition for formation of cBN.
The molecular dynamics analysis was applied to investigate the generation mechanism of internal stress. According to the electron distribution of BN crystal obtained by ab-initio calculation, interaction between B and N atom shows angle dependence. Therefore, Albe potential, an empirical many-body potential, is applied in this study. Numerical results suggested that cBN structure is generated by transition of crystal structure from hBN or rBN. Besides, increase of volume was measured by the penetration of N ions and formation of sp3 bonds during transition. Therefore, it is concluded that the high internal compressive stress of cBN film is caused by formation of sp3 bonds during transition of crystal structure
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Research Products
(22 results)
