To improve adhesive properties, we developed a nickel electroplating process for modifying the surface of titanium substrate. This process involves copper-strike and nickel plating followed by heat treatment in a vacuum to ensure the mutual diffusion of Ni, Cu and Ti in low temperature ranges, e.g., 823K. This process provided a titanium/nickel interface having exellent adhesion. Diffusion treatment in a vacuum after nickel plating builds up intermetallic compounds such as TiNi₃, TiNi, Ti₂Ni and Cu₄Ti at the interface between titanium and plated Ni and Cu, leading to a property with a gentle change from substrate to nickel. It was eventually confirmed that the process gaul superior adhesive properties on Ti substrate to conventional process.

View full abstract

Copper-coated stainless steel is used in switches requiring a strong film in adhesion. The adhesion of the film prepared by electron shower was at least 100 times higher than that prepared by conventional thermal vapor deposition. To obtain a film with a high adhesion, we irradiated an electron shower on the substrate before evaporating the copper, which enhanced the formation of chromium oxide on the surface of the stainless steel substrate. The highly adhesive copper film was to form copper oxide with the oxygen atoms of the chromium oxide, but the thermal diffusion effect on adhesion was low, because thermal diffusion of copper was suppressed by chromium oxide. When the substrate was contaminated by carbon and chromium carbide formed instead of chromium oxide, no adhesive film could be formed, even with the use of the electron shower.

View full abstract

We estimated the size of porous silicon pores by the adsorption of krypton and n-butylbenzene vapor. Four types of samples were prepared by anodically oxidizing a single crystal p-type wafer in a solution containing hydrofluoric acid. We measured the inside pore volume, estimated from the extent of adsorption/desorption hysteresis caused by capillary condensation, and the inside surface area of pores, obtained by the difference between the total surface area including the inside pore area and the outer surface area excluding the inside pore area. The total surface area was estimated using the krypton/BET method and the outer surface area using the n-butylbenzene/gradient method. Thus, the pore size was calculated from the inside pore volume and the inside pore area estimated. Unclear beginning points of the capillary condensation were assigned in a way consistent with the Kelvin equation with the pore size estimated. We found that the relative pressure at the capillary condensation end point was fairly equal to the square root of the relative pressure at the capillary condensation start point in all samples. From the features of adsorption/desorption isotherms with hysteresis, we found the pores to be uniform in size from top to bottom and for all of the pores in a sample, the size estimated at 9.7 to 1.7nm for the samples involved.

View full abstract

COD-bearing organic compounds must be eliminated in the electroless plating solution, and electrical oxidation is used to reduce high COD concentrations. Removal efficiency greatly decreases at low COD concentrations, which has led to the treatment of low COD concentrations by UV light irradiation.
COD was removed in the following sequence: ultralow→low→high-pressure mercury lamps. Efficiency is increased by adding ferrous or ferric ions to the treated solution. The removal rate is even further improved by treatment using hydrogen peroxide in combination with ultraviolet-ray exposure.

View full abstract

This paper describes the inhibition of Fe³⁺ formed in electroless Ni-Fe alloy plating solutions for soft magnetic films.
Solutions were improved by elimination the dissolved oxygen in plating solutions. To prevent the oxidation of Fe²⁺ ion in solutions.
L-sodium ascorbate was added to standard electroless Ni-Fe-P and Ni-Fe-B plating solutions, which were purged by N₂ gas. In these cases, the changes in dissolved oxygen concentration, plating rate, film compositions and magnetic properties were investigated.
In conclusion a satisfactory improvement in electroless Ni-Fe alloy plating solutions was achieved by both adding L-sodium ascorbate and purging solutions with, N₂ gas.

View full abstract

Antimicrobial materials were synthesized with a silver thiosulfate complex on silica gel. Their thermal stability was improved by coating the surface with hydrolyzed tetraethoxysilane. The chemical interaction was presumed present on silica gel with coated materials based on the improvement with the increasing amount of TEOS used and the absence of improvement with the coating by less interactive materials.

View full abstract

A study of the effect of a magnetic field on the electrodeposition of nickel using a quartz crystal microbalance (QCM) showed that the efficiency of electrodeposition was decreased by the magnetic field, and that this decrease was effective at a cathode charge below 0.1C/cm².

View full abstract