The Japanese Society of Tribologists organizes domestic Tribology Conferences named “JAST Tribology Conference” in spring and autumn every year. The 2009 Autumn Conference was held at Nagoya as “JAST Tribology Conference, Nagoya, September 2008.” A total of 266 presentations were made with seven parallel sessions.
At every Tribology Conference, JAST publishes a bound volume of proceedings, which includes extended abstracts of all the papers presented. However, the pages are limited to two pages for each paper and most of them are written in Japanese. In order to distribute their high-quality research works worldwide, JAST invited the authors to write their works in English to submit to Tribology Online.
The papers thus submitted to the Tribology Online have subsequently undergone the normal peer review process by multiple reviewers. The International session was also held at this conference, and the selected papers submitted and reviewed were already published in Vol. 3, No. 7, 2008. This special issue is planed for the ordinary technical sessions.
On behalf of the Editorial Committee, I, Editor-in-Chief, acknowledge the authors' efforts to submit their papers to this International Journal. In addition, I would like to express my sincere thanks to the Associate Editors, the Reviewers, and the Publication Coordinators for their effort to complete the peer-review processes and the publication work under the tight schedule.
High temperature (hot) and high humidity (wet) effects on perfluoropolyether lubricants, Z-dol and Z-tetraol, were investigated using the high speed spin-tester. The study has shown that: (1) higher humidity accelerates the lubricant spin-off on the disk surface, (2) in the case of Z-tetraol, oxidative reaction occurs under the hot-dry condition, but not under the hot-wet condition, (3) aforementioned phenomenon occurs only when the mobile fraction is present, and (4) the oxidation occurs the more strongly, the closer the location is to the spindle shaft. An NMR analysis of bulk materials heated in 150 oC revealed that the oxidative chemical changes are confined within the end-groups of Z-tetraol. No change was observed from bulk Z-dol heated similarly.
For mechanical devices in micro or nanometer scale, interactions between surfaces have become very important. When two surfaces approach each other, in the presence of meniscus bridges by liquid film on the surface or condensed water from humid air, strong attractive force arises. And, the force heavily influences the operation of micro/nano devices. In this study, particle based numerical simulation was carried out to investigate the dynamic behavior of the meniscus bridge. By using Moving Particle Semi-implicit (MPS) method, it is easy to identifying the large deformation of the liquid surface. The results obtained are compared with experiments. The dynamic process of the meniscus bridge formation and breakage with large deformation of the liquid surface is qualitatively simulated.
Relationship between cavitation in elastohydrodynamic lubrication and surrounding gas was investigated in order to understand lubrication in various gas environments. Lubricated point contact sliding test was conducted in a sealed chamber. Gases used were air, carbon dioxide, argon and helium. It was found the cavity length increased with time. It was also found that the cavity length in gas with higher gas solubility, such as carbon dioxide, was larger than that in gas with lower gas solubility. These results suggested that dissolved gas in lubricant was gradually released into the cavity with time, and the cavity length depended on the amount of dissolved gas in the lubricant.