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380 results on '"Itoh, Shintaro"'

12. Effects of Polarity of Polymers on Conformation and Lubricating Film Formation of Adsorbed Films

Author

Song, Yuxi, Fukuzawa, Kenji, Hirayama, Tomoko, Yamashita, Naoki, Yamada, Norifumi L., Itoh, Shintaro, Azuma, Naoki, Zhang, Hedong, Song, Yuxi, Fukuzawa, Kenji, Hirayama, Tomoko, Yamashita, Naoki, Yamada, Norifumi L., Itoh, Shintaro, Azuma, Naoki, and Zhang, Hedong

Abstract

The conformations and lubricating film formation ability of adsorbed films on metal surfaces formed by poly(alkyl methacrylate) (PAMA) homopolymers with different polarities from nonpolar lubricant oil were investigated. It was found that as the polarity of the polymers became higher, the chains in the adsorbed films adsorbed more loosely to the surfaces (i.e., they formed more loops and tails). The loosely adsorbed chains temporarily trapped free polymer chains flowing into the gap between sliding surfaces, resulting in a much thicker lubricating film. Thus, the sliding surfaces were better protected from wear caused by direct contact. On the other hand, flattened chains occupying in the adsorbed film formed by low polarity-polymers could not trap free polymer chains, resulting in a thinner lubricating film.

Published
2024

49. Nonuniform distribution of molecularly thin lubricant caused by inhomogeneous buried layers of discrete track media

Author

Fukuzawa, Kenji, Muramatsu, Takuro, Amakawa, Hiroaki, Itoh, Shintaro, and Zhang, Hedong

Subjects
Magnetic recorders and recording -- Analysis, Equilibrium (Economics) -- Analysis, Business, Electronics, Electronics and electrical industries
Abstract

A method of estimating the thickness distribution on a surface with inhomogeneous buried layers is presented. It revealed that the lubricant distributes nonuniformly on discrete track media (DTM). First, the estimation method was theoretically developed. To balance the disjoining pressures of the lubricants in the track and off-track regions, the lubricant takes different film thicknesses in the two regions because the regions consist of different materials and have different intermolecular interactions. Formulating the balance of the disjoining pressures by using the theory for intermolecular force, we obtained the thicknesses in the two regions. Next, the validity of the theoretical estimation was experimentally verified. When a nonpolar lubricant was applied to a nanometer-thick oxide layer on a silicon surface, which was locally fabricated by probe oxidation, AFM images showed that the lubricant height in the oxide region decreased and the thickness distribution agreed well with that predicted by theory. Using the developed theory, we estimated the lubricant thicknesses on DTM. Even if lubricant is uniformly applied onto the disk, it moves from the off-track to track regions due to the pressure balance. Thus, the theory predicts that the lubricant is thicker in the track regions than the off-track region at equilibrium. Index Terms--Discrete track media, disjoining pressure, head-disk interface, lubricant, magnetic recording.

Published
2008

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