JOURNAL OF JAPANESE SOCIETY OF TRIBOLOGISTS
Online ISSN : 2189-9967
Print ISSN : 0915-1168
ISSN-L : 0915-1168
Volume 59 , Issue 4
Special Issue on Tribological Technology to Protect from Earthquake and Vibration
Showing 1-21 articles out of 21 articles from the selected issue
Announcement
Contents
Winners of 2013
The 4th Tribology Heritage
Serial Messages to Tribologists
Special Issue on Tribological Technology to Protect from Earthquake and Vibration
Explanation
Essay The Tribo-Soshi, Essays from Tribologists
Up-to-date News Essay for Overseas Experience in Tribology -Around the World-
Original Contribution
  • ―Determination of Concept for New Coating―
    Yoshiyuki SAITO, Takeshi YAMADA, Yoshiyuki UMEMOTO
    2014 Volume 59 Issue 4 Pages 231-238
    Published: April 15, 2014
    Released: April 28, 2018
    JOURNALS FREE ACCESS

    Multi-layer Cr coating with Al2O3(MCC) and Mo plasma sprayed coating are widely used for the piston ring coatings of the large bore marine diesel engine. Each of these coatings has its merits and demerits. The coating life of MCC is much longer than that of Mo plasma sprayed coating, whereas the scuffing resistance of MCC is lower than that of Mo plasma sprayed coating. The ship owners request the coating life of over 2.5 years (maintenance dock interval) these days. However, even MCC, the coating life is not enough. Furthermore, the scuffing problem of the cylinder liners and the piston rings is also one of the most important subjects in order to secure reliability due to the high cylinder pressure and the low quality fuels in these days. Therefore, both of the long coating life and scuffing durability is desired. Wear and scuffing mechanism of MCC and Mo plasma sprayed coating are studied in this study. According to the mechanism, the new concept for the innovative coating which has much longer coating life and much durability to the scuffing is proposed.

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  • Takashi NOGI
    2014 Volume 59 Issue 4 Pages 239-250
    Published: April 15, 2014
    Released: April 28, 2018
    JOURNALS FREE ACCESS

    In the starved lubrication regime, the film thickness can be much less than the fully flooded film thickness. The film thickness reduction is related to the inlet meniscus distance. The inlet meniscus and the film thickness can be computed for a given inlet film thickness distribution which is generally non-uniform. The inlet film thickness distribution, which is essentially the outlet film thickness distribution of the previous contact, is affected by the surface tension. In this paper, a modified Coyne-Elrod boundary condition is used to calculate the inlet film thickness distribution, taking the surface tension into account. A numerical analysis of EHL point contacts is carried out and solutions of the inlet meniscus and the film thickness are presented. At lower capillary numbers, side bands formed by reflow in the outlet region can replenish the contact owing to reflow in the inlet region. At higher capillary numbers, the side bands move away from the center of the track and the inlet distance decreases. This is a main cause of starvation in EHL point contacts. A good agreement is found between the numerical solutions and experimental results.

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