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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 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. | Egashira M.,Japan National Institute of Materials Science | Kondoh K.,Osaka University | Masuda C.,Waseda University
Tribology - Materials, Surfaces and Interfaces | Year: 2015

In this work, we evaluated the different energy consumption rates associated with the total frictional energy for a ball sliding on a flat surface. The energy generated by the sliding two bodies in contact is dissipated into the materials in various forms. The wear consumption energy for a steel ball against a diamond-like carbon surface was evaluated by the wear coefficient of the wear volume–energy input equation. The strain energy generated in the steel ball as a result of being made to slide under a certain load was calculated using the Hertzian theory. The chemical reaction energy was estimated based on iron oxidation. Finally, the frictional energy dissipated as heat was obtained by subtracting the wear and the strain energies from the total frictional energy. © 2015 Institute of Materials, Minerals and Mining and W. S. Maney & Son Ltd.


Yamamoto S.,Sankei Giken Kogyo Co. | Okuaki T.,Sankei Giken Kogyo Co. | Egashira M.,Japan National Institute of Materials Science | Kondoh K.,Osaka University | Masuda C.,Waseda University
Tribology - Materials, Surfaces and Interfaces | Year: 2015

Temperature rise in carbon steel (SUJ2-ASTM E52100) and stainless steel (SUS440C-ASTM 440C) balls sliding against diamond like carbon was evaluated using thermal simulation. On the premise that most of the friction energy was consumed as friction heat, the temperature distribution in the steel balls was simulated by ANSYS thermal conduction analysis using the friction energy measured by the ball on disc test. The interior temperatures of the steel balls were also monitored by a thermocouple during the tribotest. The simulation data, calibrated by the heat partition rate based on the Peclet number, were compared to the experiment data, and good accordance of both data was demonstrated. © 2015 W. S. Maney & Son Ltd.


Ando F.,Kanagawa University | Gunji T.,Kanagawa University | Fujima H.,Kanagawa University | Takeda T.,Sankei Giken Kogyo Co. | And 3 more authors.
Chemistry Letters | Year: 2015

PtPb ordered intermetallic nanoparticles (NPs) were deposited on titanium oxide (TiO2)/cup-stacked carbon nanotubes (CSCNT) to improve the activity of the electrochemical oxygen reduction reaction (ORR). The use of CSCNTs as a support material resulted in high loading of PtPb NPs/TiO2. The PtPb NPs/TiO2/CSCNTs were prepared by the step-by-step preparation method, viz. first annealing under an inert atmosphere with Ti-alkoxide to obtain TiO2, then Pt NP photodeposition, and finally microwave synthesis to prepare ordered intermetallic PtPb NPs on TiO2 via reaction of Pb2+ with Pt/TiO2. The new particles enhanced ORR electrocatalytic activity. © 2015 The Chemical Society of Japan.

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