The wettability of a solid surface is governed by two factors, that is, its surface morphology and composition. Ultra water-repellent polymeric substrates [poly(ethylene naphthalate) and polystyrene] have been fabricated while retaining their transparency by a two-step plasma process combining oxygen plasma etching and plasma-enhanced chemical vapor deposition (PECVD). In order to avoid optical scattering, appropriate nanotextures were prepared on the polymeric substrates through the oxygen plasma etching. Subsequently, a hydrophobic layer was coated on the nanotextured surfaces by PECVD using an organosilane source. The modified surfaces were certainly ultra-water-repellent, showing water contact angles greater than 150°.
A prototype circuit board with micro-metal patterns was fabricated by laser irradiation and an electrochemical technique. An aluminum specimen covered with porous type oxide films was irradiated with a pulsed laser beam, using a convex lens with a focal length of 10mm. The oxide film was removed in an irregularly shaped area, using a 1.5mm diameter laser beam, while the oxide film was removed in a circle with 5μm diameter, using a 1.0mm diameter laser beam, due to an aberration of the convex lens. The diameter of the film-removed area decreased with decreasing laser power and laser irradiation time. Laser irradiation with a beam expander and a doublet lens caused the removal of the oxide film in a circle with 3μm diameter. Fine metal patterns with 4μm line width was fabricated on the epoxy resin board by successive steps of aluminum anodizing, laser irradiation, electroplating, resin attaching, and removal of the aluminum substrate and oxide film.
In recent years, diamond-like carbon (DLC) films are attracting attention as excellent tribomaterials due to their excellent characteristics, such as their high hardness, smooth surface, antiwear property, and lubrication characteristics, and they are used in various fields. However, both the friction coefficient and endurance life of DLC films are in sufficient, depending on the application environment. Therefore, in this study, with the aim of improving tribological characteristics, we fabricated WS2/DLC films by co-sputtering under various conditions, using a multicathode sputtering system, with graphite and WS2 as targets. Cross sections of the films fabricated were observed by transmission electron microscopy. In addition, the composition and structure of the films were analyzed by Raman spectroscopy and Auger electron spectroscopy. Measurement of the friction and wear characteristics of the films was performed using a ball-on-disk friction tester. As a result, we found that the films show a nano-dispersed structure, a nano-layered structure or a random-layered structure, depending on the deposition conditions. Films having a nano-dispersed structure or nano-layered structure show friction and wear characteristics superior to those of a DLC-only film.
A thermo hydrolysis process was recently applied to the waste water treatment for effluent containing ferro-cyanide. This process is effective for harmless cyanide, but ammonia and formate, which are harmful materials, are produced. Due to regulation for limiting nitrogen released to water, it became necessary to treat not only the cyanide, but also ammonia, in waste water. A catalytic wet oxidation process is applied for the cyanide and the ammonia, but this process has to use 2 stages of treatment, one each for cyanide and ammonia. A high temperature oxidation process was developed for the waste water treatment of effluent with ferro-cyanide and ammonia.
We studied the environmentally friendly Anomag process of anodizing onto AZ91D magnesium alloy. This process uses mainly a phosphate solutions without the need for deleterious materials such as heavy metals or fluoride. We also investigated the characteristics of the coatings formed, such as their structure, composition, and corrosion resistance. X-ray diffraction analysis revealed that the anodizing coatings had an amorphous of glass-like structure. In salt spray tests, these coatings, which had an average thickness of 10 μm, retained their anticorrosive performance over 1000 hours. This excellent corrosion resistance is attributable to the dense transition layer present at the interface between the coating and the base material.