Polyphenylene sulfide（PPS）, a heat-resistant crystalline polymer with a simple chemical construction, has a high melting point of about 280 ℃, outstanding chemical resistance, and noncombustibility established by an industry flammability test with no flame retardant chemicals. Furthermore, PPS is widely used in various fields based on its properties. When the PPS is plated, surface roughening is conventionally treated with a solution of hydrofluoric acid. However, the waste solution of this acid is difficult to treat correctly. It is therefore necessary to resolve this difficulty. This study investigated the plating process on PPS treated using atmospheric UV irradiation. High-quality electroless NiP plating was visually confirmed on the PPS resin surface by surface modification using atmospheric UV treatment. Adhesion strength of about 0.8 kN m－1 was obtained for the treatment. Therefore, plating on the PPS resins was possible after atmospheric UV irradiation, which is environmentally friendly.
A novel nitriding method using a pulsed laser was developed to resolve several shortcomings of conventional nitriding: difficulty of local processing and batch processing, and the need for high-temperature treatment. Specifically, this report describes pulsed laser nitriding of stainless steel at atmospheric pressure using only nitrogen gas. The samples were irradiated at 20 kHz by a focused beam（spot diameter 0.7 μm）of 355 nm laser pulses（<15 ns duration）. The experimental parameters were scanning speed, pulse energy, and nitrogen concentration in a shielding gas. Results show that surface modification occurs when the distance between laser shots is less than the spot diameter, and that removal processing occurs when the distance is greater than the spot diameter. The laser nitriding layer consists of nitrogen solid solution matrix and some fine crystal grains of 1 μm or less. The laser nitriding layer exhibited no nitrogen concentration gradient from the surface to the inside, in contrast to the diffusion layer formed in conventional nitriding. Crystal grain refinement and the nitrogen solid solution produce a laser nitriding layer that is four times harder than the original stainless steel matrix.
Mesoporous carbon nanofilament（CNF）can maintain capacitance in a higher sweep rate area than microporous carbon（activated carbon）. Therefore, synthesized mesoporous CNF is applicable as an electrode material in electric double layer capacitors. For this study, the porous structure and surface area of mesoporous CNF, synthesized by decomposition of C2H4 using metallic complex at a mild temperature, were controlled using a catalyst. Results show that the capacitance of the mesoporous CNF per unit of specific surface area is higher than that of activated carbon, demonstrating that it is a suitable electrode material that can improve the rate characteristics of electric double layer capacitors.
We used case study analyses and corrosion tests to assess the corrosion resistance of stainless steel type 304 pipes in tap water and hot water facilities. Circulating test equipment used for corrosion tests and two types of samples, plates, and straight pipe specimens were examined in changing conditions of residual chlorine concentration in the test water. Case study analysis results demonstrated that high degrees of pitting corrosion occurred on straight pipes with inner diameter of less than 50 mm. Results of corrosion tests show that the residual chlorine concentration around the pitting corrosion of stainless steel type 304 was greater than 0.5 mg/L in the plate, irrespective of the residual chlorine concentration in the straight pipe specimens. Results suggest that straight pipes have higher corrosion susceptibility because of bending during production.