Tsugito Yamashita

Photochemical modification of silicone films using F2 laser for selective chemical etching

Silicone ([SiO(CH3)2]n) films were photochemically modified into SiO2 by irradiation with a 157 nm F2 laser. The dissociation of Si–CH3 bonds of silicone simply depended on the photon number of the F2 laser. The quantum yield of the modification was estimated to be approximately 1×10-2. Mechanisms of oxidation and O–H production in the modified films were clarified. The depth of the modification was not limited by the absorption coefficient of silicone because SiO2 of the modified films is transparent for the F2 laser. A fine pattern of the 1.5-µm-thick silicone films could be fabricated by immersing the modified samples in 0.2 wt% hydrogen fluoride solution.

Effect of electrolytic conditions on the deposition of nickel hydroxide

Abstract Electrolytic impregnation of nickel hydroxide into porous sintered nickel plaque from nickel nitrate solutions was carried out at various current densities under room or high temperatures. The morphology of the deposited surface was observed with an electron microscope and the surface products were analyzed by means of X-ray diffraction. The loading level of nickel hydroxide as active materials has attained 1.6 g cm−3 void volume and the appearance of the electrode surface has the black bivalent nickel hydroxide. However, the amount of nickel hydroxide decreased with number of impregnation times, because the bath composition was not necessarily uniform. From the result of discharge capacity analysis, it was considered that the cell capacity was dependent on the surface morphology of active materials.

White-Light Emission from Silicone Rubber Modified by 193 nm ArF Excimer Laser

The photochemical surface modification of silicone ([SiO(CH3)2]n) rubber has been successfully demonstrated using a 193 nm ArF excimer laser, and white light of strong intensity was emitted upon exposure to a 325 nm He–Cd laser. The photoluminescence spectra of the modified silicone showed broad peaks centered at 410, 550, and 750 nm wavelengths. The modified surface was carbon-free silicon oxide, and the chemical composition ratio of O/Si was approximately 2. However, the surface was not silica glass (SiO2), as clarified by IR spectroscopy. Instead, nanometer-size particles of silicon oxide were formed on the surface of the modified silicone rubber.

F2-laser-induced surface modification of iron thin films to obtain corrosion resistance

Rustproof, chemical-resistant pure-iron thin films were successfully fabricated by the 157 nm F2-laser-induced surface modification of 50-nm-thick iron thin films. An approximately 2-nm-thick Fe3O4 layer underneath a native Fe2O3 layer of approximately 0.6 nm in thickness was formed on the iron thin films after F2 laser irradiation, as confirmed by X-ray photoelectron spectroscopy. The anodic polarization measurement in a 3 wt % NaCl aqueous solution (quasi-seawater) was conducted; the F2-laser-irradiated samples showed high corrosion resistance to the quasi-seawater. Moreover, no rust was observed on the samples after the immersion test in quasi-seawater for 48 h and longer. The measurement also revealed that the F2-laser-irradiated samples showed high corrosion resistance to a HNO3 aqueous solution. Thus, the micropatterning of iron thin films was demonstrated by the combination of F2 laser irradiation and subsequent HNO3 chemical etching.

Nanoscale smooth interface maintained metallisation of polyimide using low concentration ozone micro–nano bubbles dispersed in water

Abstract In order to induce adhesion of electroless CuNiP deposition to polyimide (PI) film substrate, surface modification of PI film with an aqueous dispersion of ozone micro–nano bubbles was investigated. The treatment resulted in maximum adhesion strength of 1·14 kN m−1 for a treatment time of 5 min. Structure of the modified PI surface, the PI/plating interface, mechanism for adhesion and laminate properties were analysed. Despite increased adhesion, surface roughness of PI was not notably changed by the ozone induced surface modification. Contact of PI surface with high ozone concentration micro–nano bubbles with sufficient frequency was found to modify the surface with a low total ozone concentration of the aqueous dispersion. Cross-sectional observation of the interface suggested that formation of a thin nanoporous anchor layer on the PI surface was responsible for plating adhesion. This method provides an environment friendly and improved process for plating on PI using low concentration ozone treatment.

F2-laser-induced micro/nanostructuring and surface modification of iron thin film to realize hydrophobic and corrosion resistant

Nanoswellings of 60 nm height and 500 nm diameter on average of an iron thin film deposited on a silica glass substrate at regular intervals of 2.5 µm were fabricated by the irradiation of a 157 nm F2 laser. The F2 laser was focused on the iron thin film by each microsphere made of silica glass of 2.5 µm diameter, which covered the entire surface of the films. The surface of the silica glass substrate underneath the F2-laser-irradiated iron thin film selectively swelled to push up the film. After the laser-induced micro/nanostructuring, the F2 laser was again irradiated onto the entire surface of the periodic micro/nanostructured iron thin film to form an approximately 2-nm-thick Fe3O4 modified layer. As a result, the samples showed hydrophobicity and high corrosion resistance to 3 wt % NaCl aqueous solution (quasi-seawater). No rust was observed on the samples after the immersion test in the quasi-seawater for 24 h.

Surface modification of iron thin films into corrosion resistant property by F 2 laser

A vacuum-UV F2 laser of 157 nm wavelength induced strong oxidation of Fe thin film surface to show the chemical resistance to pseudo seawater and HNO3 aqueous solution for selective metallization on silica glass substrate. The strong oxidation reactions on the surface and in the depth direction were confirmed by X-ray photoelectron spectroscopy. The corrosion resistance of the F2 laser irradiated samples was also supported by an electrochemical test. A fine pattern of the F2 laser irradiated Fe thin film was successfully formed after the HNO3 chemical etching.

Decomposition of methylene blue with photocatalytic TiO2 thin films deposited by pulsed laser deposition

Photocatalytic titanium dioxide (TiO2) thin films with large specific surface area were deposited on Si wafers by pulsed laser deposition with sintered TiO2 targets in oxygen gas atmosphere. Angular distributions of the number of droplets and the film thickness were examined. The surface roughness and the film thickness depended on the oxygen gas pressure. Photocatalytic effect of the films deposited at various substrate temperatures was evaluated by photobleaching of methylene-blue-aqueous solution. The TiO2 film deposited at the substrate temperature of 250°C was anatase-type crystal and this film indicated the highest photocatalytic effect.

The effect of lorentz force on copper electrodeposition from copper-EDTA baths.

The influence of magnetic fields on the structure of electrodeposits from complex, and on the mechanism of cathodic and anodic reactions with the electrodeposits were examined. Magnetic fluxdensity was 0.3T on the working electrode. It became clear that the action of Lorentz force accounted for the major part of magnetic field effect. The pH 12 electrolytic baths used were composed of 0.05-0.5mol·dm-3 CuSO4+0.1-1.0mol·dm-3 EDTA solutions including 0.2mol·dm-3 sodium sulfite. Anodic reactions were independent of magnetic field, but cathodic reactions were affected. The most important of these influences were as follows: The stability constant of the Cu(II)-EDTA complex became larger. Limiting current density increased. The (111) face of the deposits increased. The grain of the deposits was fine. Exchange current density decreased. Charge transfer resistance decreased. The temperature in the vicinity of the cathode dropped and that in vicinity of the anode rose. This was attributed to decrease in the thickness of the diffusion layer due to Lorentz force.

Effect of Small Amount of lon on the Electrodeposition of Zinc

The effect of inorganic compounds on the electrocrystallization of zinc has been studied. lt was found that the growth of the mossy and dendritic crystals of zinc was inhibited by the presence of tellurium and lead ions in the electorolyte. The grain size of the deposits was shown to be decreased with increasing of concentration of the additives. In the presence of tellurium ion in the electrolyte, bright deposit was obtained. Fine crystal deposit, t of zinc was obtained by addition of lead ion. The overpotential for electrodeposition of zinc was increased by these ions.It was noticed that the current efficiency for the deposition of zinc did not decrease appreciably even though the tellurium and lead were codeposited with zinc during electrolysis.