Effects of various surface treatments on the mechanical properties of the 2017-T4 aluminum alloys were evaluated using Slow Strain Rate Technique（SSRT）tensile tests and rotary bending fatigue tests. For the 2017-T4 alloy, Thermal Desorption Analysis（TDA）analysis revealed that each plating causes hydrogen absorption into the substrate. Effects of the various plating types on the maximum strength, fracture strength, and elongation at breakage of the 2017-T4 alloy in SSRT tensile tests were not found to be significant in any case. However, the fatigue strength of the specimen plated with high-phosphorus-type Ni-P was markedly lower than that of the un-plated specimen. This reduction in fatigue strength might be attributable to hydrogen embrittlement caused by introducing hydrogen into the specimen during plating. Therefore, when repetitive loads are applied, caution is in order when applying Ni-P plated high phosphorus types to 2017-T4 alloy.

The practical application of plastic glazing, intended for replacing inorganic glass with polycarbonate, is being explored for weight reduction of automobile bodies. Using vacuum ultraviolet （VUV） light irradiation from an excimer lamp, Nojiri and others developed a technique for forming a SiO₂-based modified layer on the surface of a silicone hard coat over polycarbonate. This study assessed the relation between wear resistance and surface composition of two commercially available silicone hard coats, samples A and B, before and after VUV irradiation. According to the Taber abrasion test for compliance with ASTM D1044 standards, the wear resistance of sample A improved with VUV irradiation, meeting the criteria for a front window, whereas sample B deteriorated. Fourier transform infrared spectra peaks related to Si-O stretching vibrations were decomposed into inorganic glass and organic silicone components, revealing that the inorganic glass ratios in sample A were approximately 40% - 47%, whereas those of sample B exceeded 49%. Correlation was confirmed between the wear resistance and the inorganic glass ratio, which is expected to be approximately 41% - 48% after VUV irradiation to satisfy wear resistance criteria for a front window.

Self-lubricating Al₂O₃/MoS₂ composite films were prepared on Al-Si-Cu-Ni-Mg casting alloys through successive anodization and anodic electrolysis. Changes of the high-temperature oxidation resistance of the composite films were investigated using heat treatments in argon and air atmospheres at 250-350 ℃ for 2 hr. Friction tests confirmed that the filling of molybdenum disulfide （MoS₂） into porous anodic oxide films improved the composite films' lubricity and wear resistance effectively. Moreover, results demonstrated that heat treatment in Ar atmosphere greatly enhanced the oxidation resistance of MoS₂ on the composite film surface while maintaining the excellent lubricity and wear resistance of composite films. The improved oxidation resistance of MoS₂ was attributed mainly to MoS₂ crystallization under oxygen-free conditions during heat treatment, which slowed the chemical transformation from MoS₂ to crystalline molybdenum trioxide （MoO₃） effectively. These findings were confirmed using field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy.

Because diamond has high hardness and excellent wear resistance, it has been applied as a surface protective coating material for nonferrous metals and ceramics in a wide scope of mechanical tools. Particularly it is used for cutting tools for carbon fiber reinforced plastics: an excellent material for structural parts of aircrafts and automobiles. However, the resulting cutting tool performance is insufficiently high. Improvement is necessary. Earlier reports have described that the addition of boron to diamond films improves their mechanical properties such as wear resistance and fatigue strength. The origin of the wear property is complicated because the property comprises abrasive wear and chemical wear attributable to reaction with work materials. Numerous reports have described abrasive wear of diamond, but very few reports have described investigations of chemical wear for tools. For this study, we investigated the heat resistance and chemical wear characteristics of boron-doped diamond films synthesized using the hot filament CVD method. Results of these tests clarified that the addition of boron to the diamond film improves oxidation resistance and chemical wear characteristics remarkably.