Tribology Online
Online ISSN : 1881-2198
ISSN-L : 1881-218X
Volume 6 , Issue 7
Showing 1-9 articles out of 9 articles from the selected issue
Editorial
  • Masabumi Masuko
    2011 Volume 6 Issue 7 Pages iv
    Published: July 31, 2011
    Released: August 15, 2011
    JOURNALS FREE ACCESS
    The Japanese Society of Tribologists is pleased to announce that the 2010 Paper Award of Tribology Online was awarded to:

    Acoustic Emission Signals and Wear Phenomena on Severe-Mild Wear Transition,” by Alan Hase, Masaki Wada and Hiroshi Mishina, Vol. 3, No. 5 (2008) 298-303.

    and

    Measurements of Impact-Induced Fracto-Emission from Soda-Lime Glass and Simultaneous Observation of the Cracking Process by High-Speed Photography, ," by Seisuke Kano, Yuji Enomoto and M. Munawar Chaudhri, Vol. 5, No. 2 (2010) 111-117.

    The Award Medals were presented to the authors by Prof. Shigeyuki Mori, the former President of the Japanese Society of Tribologists, at the JAST Annual Meeting on 17th May, 2011.


    The Paper Award of Tribology Online is given annually to the author(s), either the JAST members or non-members, of the paper(s) judged as the best paper(s) published in Tribology Online (TROL) for the previous three years. All papers that appeared in TROL for the three years are reviewed by the JAST Awards Committee.
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Article
  • Ken Nakano, Kazuyoshi Manabe
    2011 Volume 6 Issue 7 Pages 277-283
    Published: August 31, 2011
    Released: August 31, 2011
    JOURNALS FREE ACCESS
    Breakdown processes of boundary films formed by lubricating oils containing oiliness additives were studied in a steel-mercury interface under quasi-static loading. Simultaneous measurements of the thickness and breakdown ratio of the films were carried out using an electrical impedance method. Different breakdown processes were obtained for different lubricating oils. At a concentration of 10-3 mass%, the lubricating oils formed residual films with a thickness of a few tens of nanometers that support a normal load without any hydrodynamic effects. A possible mechanism for this is the osmotic pressure created by the concentration difference between the bulk oil and residual film. Friction coefficients of a steel-on-steel contact lubricated by the lubricating oils in a boundary lubrication regime were related to the breakdown processes in the steel-mercury interface using multiple regression analysis. Lubricating oils that showed low-rate breakdown processes showed low friction coefficients. This indicates that the breakdown rate of boundary films is an important factor in the mechanism of boundary lubrication.
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  • Auezhan Amanov, Young Sik Pyun, Bin Zhang, Jeong Hyeon Park, Jiri Noha ...
    2011 Volume 6 Issue 7 Pages 284-290
    Published: August 31, 2011
    Released: August 31, 2011
    JOURNALS FREE ACCESS
    One of the conclusively presumed effects of micro-scale dimples under oil-lubricated conditions is that can serve as oil reservoirs and play a role in promoting the retention of a lubricating film. Ultrasonic nanocrystal surface modification (UNSM) technology is an emerging effective method for producing micro-scale dimples on a workpiece surface and improving the tribological performance of lubricated friction units. The main object of this research is to understand the effect of micro-scale dimple size on tribological characteristics under oil-lubricated sliding contacts. The current study investigated the effect of micro-scale dimple size on friction and wear reduction through micro-scale dimples. The tribological characteristics of silicon nitride ceramic (Si3N4) ball and S45C carbon steel disk combination in a defined ball-on-disk configuration were determined. It was recognized that friction property has a connection with the size of micro-scale dimple. Overall micro-scale dimpled disk specimens showed better tribological properties in terms of reduced friction coefficient and wear volume loss comparing to the polished specimen.
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  • Hiraku Tanimoto, Hiroyoshi Tanaka, Joichi Sugimura
    2011 Volume 6 Issue 7 Pages 291-296
    Published: September 15, 2011
    Released: September 15, 2011
    JOURNALS FREE ACCESS
    This paper describes an experimental study on permeation of hydrogen into bearing steel through fresh surface with thermal desorption spectroscopy. Sliding experiments using a lapping machine with and without lubricant were conducted to generate fresh surfaces. Desorption spectra were taken before and after sliding, and the surfaces were analyzed with X-ray photoelectron spectroscopy. It was found that oxide and/or hydroxide film was formed on the surface, whereby hydrogen was generated and diffused into the bulk steel. When heated, some of hydrogen in the steel reacted with the surface film to be desorbed as water, while some other hydrogen was desorbed in the form of hydrogen molecules. Hydrogen desorption spectra in combination with water desorption spectra thus provides information not only on hydrogen permeated but also on surface oxide/hydroxide film.
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Short Communication
  • Yuko Hibi, Miki Nakano, Hisato Ogiso
    2011 Volume 6 Issue 7 Pages 297-300
    Published: October 15, 2011
    Released: October 15, 2011
    JOURNALS FREE ACCESS
    Aluminum metal matrix composite disks reinforced with alumina (Al2O3) were slid against silicon carbide (SiC) pins in water and in ethanol to evaluate the wear resistance. The wear of the composite slid against SiC in water was higher than that in ethanol. Oxidized aluminum compounds were formed by tribo-oxidation on the composite disk surfaces worn both in water and in ethanol. The amount of the oxidized aluminum compounds deposited on the wear tracks in water was much larger than that in ethanol. The significant oxidative wear took place in water, while oxidative wear and wear due to plastic deformation took place in ethanol.
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Article
  • Rupesh Roshan, Martin Priest, Anne Neville, Ardian Morina, Xin Xia, Ch ...
    2011 Volume 6 Issue 7 Pages 301-310
    Published: November 15, 2011
    Released: November 15, 2011
    JOURNALS FREE ACCESS
    A predictive friction model has been developed in boundary lubrication conditions to understand the sensitivity of the model to molybdenum dithiocarbamate (MoDTC), a friction modifying additive and zinc dialkyldithiophosphate (ZDDP), an antiwear additive in engine oil. Controlled experiments were performed on a block-on-ring tribometer to record the friction performance of the tribofilms produced by ZDDP and MoDTC additives under conditions representative of boundary lubrication conditions in the cam and follower interface. A statistical approach was used to develop an empirical friction model. The boundary lubrication friction model considers ZDDP and MoDTC additive concentration in an ester-containing polyalphaolefin (PAO) base oil, temperature and sliding speed as the factors affecting friction. The friction significantly depends on ZDDP, MoDTC, speed and temperature; showing a ZDDP/MoDTC synergetic effect on reducing friction. The results show good agreement between the measured and the predicted friction values, with a high correlation coefficient.
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  • Takefumi Otsu, Hiroyoshi Tanaka, Katsu Ohnishi, Joichi Sugimura
    2011 Volume 6 Issue 7 Pages 311-316
    Published: November 30, 2011
    Released: November 30, 2011
    JOURNALS FREE ACCESS
    A new test system was developed with which a variety of simple contact tests in controlled environment could be made to gain understanding of the complex processes involved in rolling contact fatigue. Cyclic normal contact tests were conducted with SCM435 steel disc and SUJ2 ball in hydrogen, air and in vacuum, and the specimens were analyzed with sector type secondary ion mass spectrometry. It was found that the amount of hydrogen permeated into the subsurface at the contact area under cyclic contact is greater than that at the surface in non contact test in hydrogen environment. The permeated hydrogen in the subsurface for the tests in hydrogen was diffusive hydrogen.
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  • Kaori Niki, Mai Kobayashi, Hitoshi Shindo
    2011 Volume 6 Issue 7 Pages 317-322
    Published: December 15, 2011
    Released: December 15, 2011
    JOURNALS FREE ACCESS
    Frictional force was measured using Bowden-Leben apparatus with a sapphire stylus at directional (1 0 -1 4) surface of magnesite crystal. Deformation patterns formed during the scratch in ± [4 2 -1] directions were observed with optical microscopy. With the normal load up to 460 mN, no trace of slip or cleavage was observed and the friction coefficient remained at 0.0085. Frictional asymmetry due to the tilt of carbonate ions was not recognized in this range. At higher normal loads, new components were added to the frictional force, with the appearance of traces of slip, and then, cleavage on {1 0 -1 4} faces. In contrast with the case of calcite, traces of the slip remained within the width of the stylus. Traces of the cleavage, on the other hand, reached far outside the wear track, and asymmetry was recognized in the pattern formation. In indentation experiments, the cleavage occurred in four directions, but slip on (0 0 0 1) was not recognized. In contrast with isostructural but softer calcite crystal, the difficulty in the (0 0 0 1) slip with magnesite keep the friction coefficient low toward higher normal loads.
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Editorial
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