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Yamamoto S.,Sankei Giken Kogyo Co. | Kawana A.,Japan Coating Center Co. | Masuda C.,Waseda University
Surface and Coatings Technology | Year: 2013

Two types of diamond-like carbon (DLC) were evaluated for their tribological behavior in terms of the tribometer input energy. The DLC samples were prepared from methane (denoted DLC[CH4]) or benzene (denoted DLC[C6H6]) as a gas source on tungsten-carbide (WC) substrates by radio-frequency plasma chemical vapor deposition (rf-PCVD). The hydrogen contents of the DLCs were measured by Elastic Recoil Detection Analysis (ERDA). The DLC structures were investigated by Raman spectrometry and X-ray photoelectron spectroscopy (XPS). The basic mechanical properties, such as the hardness and the Young's modulus, were obtained by a nano-indenter. The DLC films against alumina were tribo-tested by a ball-on-disk. The input energy was calculated using the applied load, the friction coefficient, and the sliding distance in each tribo-test. The wear behavior of the DLC[CH4] sample was better than that of the DLC[C6H6], even though the hardness of DLC[CH4] was lower than that of DLC[C6H6]. The wear loss of DLC[CH4] and DLC[C6H6] was evaluated by the input energy, and the wear resistance difference of the DLCs was characterized in terms of the input energy. © 2013 Elsevier B.V.

Yamamoto S.,Sankei Giken Kogyo Co. | Kawana A.,Japan Coating Center Co. | Masuda C.,Waseda University
Tribology - Materials, Surfaces and Interfaces | Year: 2013

The tribological behaviour of stainless steel (SUS 440C) relative to that of diamond-like carbon (DLC) was investigated in terms of tribometer input energy. The DLC was prepared on tungsten carbide (WC) substrates using radio frequency plasma chemical vapour deposition with benzene (C6H6) as a gas source. The stainless steel ball, as the counterpart, was tribotested. The input energy was calculated using the applied load, friction coefficient and sliding distance obtained from each tribotest. The wear loss of the ball increased as the sliding distance increased, whereas wear loss of the DLC was not directly observed. During evaluation of the input energy, the wear rate of the stainless steel ball decreased as the input energy increased. We propose a method for evaluating tribological properties using the input energy and discuss the wear behaviour of the stainless steel based on the input energy. © 2013 W. S. Maney & Son Ltd.

Yamamoto S.,Sankei Giken Kogyo | Kawana A.,Japan Coating Center Co. | Ichimura H.,Kanagawa Institute of Technology | Masuda C.,Waseda University
Surface and Coatings Technology | Year: 2012

The correlation between the wear resistance and the chemical states of the elements of nitrogenated diamond-like carbon (NDLC) is characterized and discussed in this paper. NDLCs have been deposited on tungsten-carbide, silicon and glass substrates by radio frequency plasma chemical vapor deposition (rf PCVD) from benzene (C 6H 6)-nitrogen mixtures with four different ratios. The nitrogen concentration in the films measured by electron microprobe analysis was found to be proportional to the nitrogen flow rate. The friction coefficients of the films determined by the ball-on-disk test increased with adding nitrogen contents. Such friction coefficient dependent on load was not observed in each film. The DLC showed adhesive wear. However, the wear mode of NDLCs changed from the adhesive wear to the abrasive wear at the critical load point. The film hardness measured by nano indentation decreased with increasing nitrogen. The sp 3/sp 2 measured by X-ray photoelectron spectroscopy (XPS) was reduced by adding nitrogen and as a result, the tribological behaviors such as the hardness, the wear resistance and the critical point were also decreased. © 2012 Elsevier B.V.

Ban M.,Nippon Institute of Technology | Hasegawa N.,Nippon Institute of Technology | Hasegawa N.,Japan Coating Center Co.
Diamond and Related Materials | Year: 2012

Diamond-like carbon (DLC) thin films containing photocatalytic titanium dioxide (TiO 2) nanoparticles were deposited by the plasma chemical vapor deposition method, which was developed by our group, using a colloidal solution as the precursor. It was found from the results of Raman spectroscopy, SEM observation and surface analyses that a bias voltage applied to the substrate had considerable effect on TiO 2 nanoparticle inclusion in the matrix DLC thin film, and the optimal bias voltage was in the range from - 50 to - 175 V. The depth profiling with Auger electron spectroscopy for the DLC thin film deposited at the bias voltage of - 100 V suggested that TiO 2 nanoparticles were contained not only on the surface but also inside of the matrix thin film. To evaluate the photocatalytic properties of the deposited DLC thin films, methylene blue degradation, contact angle measurement, and antibacterial tests were performed. The results indicated that the DLC thin film containing TiO 2 nanoparticles exhibited the abilities to decompose methylene blue dye, make the surface more hydrophilic and kill Escherichia coli cells under ultraviolet light irradiation. © 2012 Elsevier B.V. All rights reserved.

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