Youichi Inoue

Ultra-hydrophobic fluorine polymer by Ar-ion bombardment.

A study has been made of the improvement of the hydrophobicity of a fluorine-polymer (polytetra-fluorinethylene, PTFE) by Ar-ion bombardment. Ar-ion bombardment to PTFE) by Ar-ion bombardment. Ar-ion bombardment to PTFE sheets was carried out at the fluences ranging from 3.1x10(20) to 18.3x10(20) ions/m(2). The beam current densities were ranged from 1.25 to 7.5 A/m(2). The hydrophobicity of modified materials has been investigated by means of a sessile drop method of water. The roughness, morphology and structure of bombarded specimens have been estimated as a function of beam current density and acceleration energy. It was found that Ar-bombardment causes the contact angle of water to increase from the original value 103 to 170 degrees. The results indicate that Ar-bombardment at an optional condition results in the formation of ultrahydrdophobic surfaces. The effects of Ar-bombardment to hydrophobicity of PTFE are discussed with the relationship among roughness, morphology and chemical bonding states of the surfaces.

An active-head slider with a piezoelectric actuator for controlling flying height

The current design of magnetic-disk head sliders needs an extra margin of flying height for manufacturing tolerance or environmental variation. To reduce this margin, we have developed active-head sliders. These sliders carry an unimorph piezoelectric microactuator, and their flying height can be controlled. After simulating the piezoelectric deflection of the actuator and flying characteristics of air-bearing surfaces, we designed two types of active-head sliders (five-pad type and four-pad type) and fabricated them by silicon microelectromechanical system (MEMS) processing. In tests, the sliders flew over a glass disk, and the observed stroke of the actuator (30 nm/5 V) was considered large enough to control the flying height. The large area at the rear end of the four-pad-type slider structure is sufficient to carry conventional read/write heads. Moreover, the slider fabrication process will not destroy the heads. We, thus, conclude that the active-head sliders can be applied for practical use easily, and their flying height will be significantly lower than that of conventional disk head sliders.

Evaluation of the Wear Process of Cast Iron Coated with Manganese Phosphate

The authors investigated the wear property and wear process of a JIS-FC250 cast-iron surface coated with manganese phosphate, sliding against JIS-SKH51 steel by using an oscillating-rotation wear test rig and SEM-EDX surface analysis. The materials that appeared on the friction surface indicate that the wear process can be divided into three phases, the wear of the coating, the wear of the mixed layer (consisting of cast-iron and the coating) and the wear of the cast iron. The authors found that the value of parameter M, which is the exposure ratio of iron to the coating on the friction surface measured by SEM-EDX analysis, was found to characterize each phase quantitatively. The authors also found that changes in the wear rate are related to parameter M. The best wear resistance of the coated iron was found in the second phase of the wear process, where the exposure ratio on the friction surface ranged from 40 to 80%. The authors obtained the lowest wear rate when the exposure ratio M was 45% and it was less than 11300 that of the original coated surface. Presented as a Society of Tribologists and Lubrication Engineers Paper at the ASME/STLE Tribology Conference in Cancun, Mexico October 27–30, 2002