Heigo Ishihara

Design of Carbon Surface Functional Groups on the Viewpoint of Lubricant Layer Structure

Chemical modification technique with X-ray photoelectron spectroscopy has been used for a quantitative analysis of surface functional groups of the carbon overcoats. As the nitrogen content in the carbon overcoat layer increases, the total abundance of functional groups on the carbon overcoat surface increases. The increase of the functional groups leads to an increase of a physisorbed lubricant layer ratio. Increase of the physisorbed layer ratio on the carbon overcoat surface showed a higher durability on the head/disk interface, and decreased the spin-off of the lubricant on a high rotation of the disk. The increase of the physisorbed layer leads to a higher recovery of the lubricant defect by the wear, and the increase of functional groups on the carbon overcoat surface leads to a stronger interaction of the lubricant with the carbon overcoat surface is estimated. Presented as a Society of Tribologists and Lubrication Engineers Paper at the ASME/STLE Tribology Conference in Seattle, Washington, October 1–4, 2000

Method for magnetic orientation of magnetic recording medium using Meissner effect of high Tc superconductor

A method for magnetic orientation of a magnetic recording medium using Meissner effect of a superconductor and a system therefor and a magnetic recording medium produced thereby. The magnetic particles of plate hexagonal barium ferrite in the magnetic coating are allowed to orient in the longitudinal direction thereof so that a magnetic recording medium having a magnetic orientation in such direction with the magnetic particles can be obtained.

Ultrafiltered Perfluoropolyether lubricant under molecular weight distribution control

There are many problems to be overcome when storage devices are used at high-speed rotation and very small spacing between the head and disk. One of them is lubricant spin-off. Lubricant spin-off and lubricity have a close relation to the molecular weight distribution. The commercial Perfluoropolyether (PFPE), which is widely used as a lubricant for magnetic disks, has a wide molecular weight distribution from several hundred to over ten thousand. In order to improve performance regarding spin-off and lubricity, it is necessary to control the molecular weight distribution. This paper discusses the relation between molecular weight of lubricants and spin-off, and stiction. The molecular weight at which spin off occurs easily is found to cause a high stiction. Furthermore, molecular weight distribution control by ultrafiltering is investigated. Presented as a Society of Tribologists and Lubrication Engineers Paper at the ASME/STLE Tribology Conference in Seattle, Washington, October 1–4, 2000

Formation of pyrene crystalline thin films assisted by helium ion bombardment

This paper reports on the effect of low energy He+ ion‐beam bombardment upon the structure of pyrene thin films formed on quartz substrates. Films are prepared by vacuum evaporation during ion bombardment at room temperature. The structure of the film is controlled by the kinetic energy and current density of the ions. The colorless and transparent crystalline films preferentially oriented with their {001} plane parallel to the substrates are obtained by bombardment of 350 to 500 eV, 60 nA/cm2 He+ ions. Ion‐beam irradiation of the higher ion current density enhances intermolecular chemical reactions and, as a result, a crystalline polymer with its {001} plane parallel to the substrate is produced.