This study presents an anodizing process controlling a pore size and surface porosity for injection molded direct joining（IMDJ）. IMDJ is a technique of direct joining between an injection-molded plastic component and a surface-treated metal plate. A surface treated metal plate has a micro-/nano-structure on its surface, which can provide micro-/nano-interlocking with an injectionmolded plastic component. Controlling geometry of a micro-/nano-structure is important to understand how the joining is formed. This study adopted an anodizing process as a surface treatment because it can produce nano-structures, the geometry of which is precisely controlled. To fabricate nano-structures being suitable for IMDJ, a wide variety of conditions for an anodizing process were investigated. Resultantly, we fabricated the nano porous structures that have different sizes but similar porosity: pore diameters of tens nm, 200 nm, and 400 nm approximately. Using the three kinds of metal plates, we investigated the effect of molding condition on joining strength. The results showed that the injection speed, which is one of the molding parameters, had a negative correlation with the strength in any cases of nano-structures. The injection speed effects were also confirmed by an atomic force microscopy of the plastics infiltrating the nano-structures. Under the smaller structures（ tens nm and 200 nm）, we could see same tendency. However, the tendency changed under the 400 nm porous structure condition. The results in the current state cannot give the perfect interpretation of the mechanism of joining occurrence; however it leads the further understanding in future.

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In this study, we investigated the deterioration behavior of epoxy resin and its adhesive joint with Ni by water absorption. The water absorption characteristic was evaluated by an immersion test, and the deterioration behavior of the Ni/resin interface was evaluated by a tensile test after a thermal humidity test（ THT）. As a result, it was clarified that the water absorption behavior of the epoxy resin obeys the Fick's second law and the tensile strength of the resin decreases by water absorption. The tensile strength of the Ni/resin interface tended to decrease by the THT, and the main fracture mode was the interfacial fracture. Furthermore, in order to evaluate the deterioration life of the Ni/resin interface, Fourier transform infrared spectroscopy analysis of the fracture surface after the tensile test was conducted to determine the water absorption degree（D_w）. The apparent activation energy was calculated from the Arrhenius plot obtained by the deterioration lifetime defined by the specific value of D_w. The apparent activation energy due to deterioration of the Ni/resin interface was 11.5 kJ/mol.

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This study introduces a new type of high Tg epoxy resin material. Firstly, the viscoelastic behavior of the resin material was investigated through dynamic mechanical analysis and the Tg value of the resin material was determined. Secondly, the effect of temperature and aging treatment on the mechanical properties of the resin material was investigated by tensile test. The results showed that as the temperature increases, the movement of the polymer chains in the resin material changes from obstruction to flow, and the Tg value is approximately 230℃. With an increase in the experimental temperature, the elastic modulus and tensile strength of the resin decrease, and the fracture strain increases. With an increase in the aging time, the elastic modulus of the resin increases, while the tensile strength and fracture strain decrease. This is due to the oxidative decomposition reaction of the resin with oxygen in the air during the aging process, which embrittles the resin material. FE-SEM analysis of the fracture surface after the tensile test was performed to determine the state of the resin material under different experimental conditions.

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A molten metal behavior on the underside of a workpiece in the gas cutting process was observed by a high-speed camera to clarify the effects of preheating gas and cutting speed on the behavior. Moreover, the molten metal behavior was modeled using a particle method. As a result, the molten metal behavior and the dross detachability were different for each preheating gas when the cutting speed was set to be 150 mm/min. From computational results, it was clarified that the molten metal showed different behavior because the cutting groove shape was different for each heat source. When hydrogen gas was used as the preheating gas, the molten metal indicated similar behavior regardless of increase of the cutting speed. However, it became hard to remove the dross from the underside of the workpiece. In addition, computational results showed that the average oxidation ratio of the dross surface which was jointed to the underside of the workpiece was different for each cutting condition. From these tendencies of the oxidation ratio and dross detachability, it was suggested that the oxidation ratio of the dross surface was one of factors to determine the dross detachability.

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