2000 Fiscal Year Final Research Report Summary
Synthesis and Nanotribology of Superhard Carbon Nitride Films
| Project/Area Number |
10355028
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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 | 展開研究 |
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| Research Field |
Material processing/treatments
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| Research Institution | Nagoya University |
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Principal Investigator |
TAKAI Osamu Nagoya Univ., Materials Proc.Eng., Professor, 工学研究科, 教授 (40110712)
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| Co-Investigator(Kenkyū-buntansha) |
HOZUMI Atsushi National Industrial Research Institute of Nagoya, Ceramic Technology, Researcher, セラミックス応用部, 研究員
INOUE Yasushi Nagoya Univ., Materials Proc.Eng., Research Associate, 工学研究科, 助手 (10252264)
SUGIMURA Hiroyuki Nagoya Univ., Materials Proc.Eng., Associate Professor, 工学研究科, 助教授 (10293656)
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| Project Period (FY) |
1998 – 2000
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| Keywords | carbon nitride / arc plasma / amorphous / superhard material / shielded arc ion plating / nanoindentation / tribological properties / chemical bonding states |
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| Research Abstract |
We have succeeded to synthesize amorphous carbon nitride (a-C : N) thin films by using the shielded arc ion plating process developed by ourselves. In this study, fundamental investigations were performed in order to apply the a-C : N thin films as novel super hard coatings. Chemical compositions and bonding states of the deposited films were characterized both by infrared spectroscopy and by X-ray photoelectron spectroscopy. The nanomechanical properties were made clear by using Triboscope.
<Chemical Bonding States>
We varied a nitrogen gas pressure and a substrate bias as deposition parameters. As increasing the nitrogen pressure, the nitrogen composition increased up to the N/C composition ratio of 0.45. However the C-C and C-N bonds became graphite-like and piligine-like states, respectively, which had 2D plane network structures. Applying negative substrate biases invoked ion bombardments on the growing film surfaces, which caused formation of the sp^3 bonding states in the films. A
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n excess of the negative bias, however, raised both a graphitation of the sp^3 bonding states and a decrease in the nitrogen composition at the same time. In the condition of the high nitrogen pressure, the effect of the negative bias was reduced due to the short mean free path of the ions in the arc plasma. Thus the sp hybridizing ratio and the N/C composition ratio was able to control by the nitrogen gas pressure and the negative substrate bias.
<Nanomechanical Properties>
By using Triboscope, we measured nanohardness of the a-C : N films prepared at various nitrogen gas pressures and negative substrate biases. The film thickness was unified at 150 nm for all samples. The nanohardness was degraded with increase both in the nitrogen pressure and in the negative substrate bias. This result was consistent with the fact that the high nitrogen pressure makes the C-N bonds in the films be the piligine-like states instead of the 3D C-N networks, and that the excess of the negative substrate bias makes the carbon networks in the films sp^2-like bonding states. The hardest a-C : N thin film showed a nanohardness greater than the TiN film which is widely used as hard coating materials. The nano-wear property was also investigated by Triboscope. After a region of 1μm x 1μm on the film surface was scanned by a Vercobich-type diamond tip in a low load, the wear depth of the region was observed by an atomic force microscope. The nano-wear property was much more excellent than that of the diamondlike carbon films which have been already applied as wear-resistant coatings. From these results, the a-C : N thin films synthesized in this study was proved to be useful in the fields related in tribology. Less
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