The purpose of this paper is forming a plating film excellent in self-lubricity in high temperature by making acetylene black particles codeposit in a nickel tungsten alloy film which shows outstanding heat-resistivity and oxidation-resistivity. Since acetylene black particles as received showed hydrophobicity and it was hard to disperse them into a plating bath, the acid functional group was first introduced on the surface of particles by thermal oxidation, and condensation of the 2-amino ethanol was also carried out. As a result, an amino group was introduced on the surface of particles, and particles came to show hydrophile property. When these particles were added to the plating bath and the electrodeposition was performed, the particles only thermally oxidized did not codeposit, but the particles which introduced the amino group were codeposited in the nickel tungsten film. It became clear that an amino group interacts with nickel ion in the domain beyond pH=4 by the analysis using the potentiometric titration method. The hardness of the film which acetylene black particles codeposited was comparable to a film which does not contain particles, and a possibility of obtaining an outstanding film with lubricity in high temperature was shown, without spoiling the characteristics of the nickel tungsten alloy.
It would be expected that the corrosion phenomenon may also be altered among the planes, since the zinc is deposited in preferred orientation. In the present study, we investigated the effect on adhesion between the orientation of zinc plating on copper foils and peel loss after HCl immersion, after the electro-galvanized copper foils were exposed to the aging atmosphere (313 K, 90%RH, 7 days). The experimental results indicated that the foils plating (0002) oriented zinc basal plane had a lower peel loss after HCl immersion than the other orientations. The XPS (X-ray Photoelectron Spectroscopy) and rf-GDOES (rf-Glow Discharge Optical Emission Spectroscopy) studies were performed to support the mechanism of the peel loss after HCl immersion. It was found that it was difficult to oxidate the zinc layer of the (0002) oriented specimen, rather than the other orientations, after the aging test. It is considered that the oxidation of zinc results in a change of the layer structure on the surface of the foils, and hence the peel loss took place after HCl immersion.
We have considered a method to collect and sterilize bacteria using a positively-charged carbon fiber electrode. The feature of this method is that it can sterilize spores, which could not be sterilized by heating or bactericidal agents. However, the capacity to collect Bacillus subtilis spores decreased in the silica solution. To investigate this matter, we measured the effective surface area and bacteria affinity of the carbon fiber dipped in 100 ppm silica solution for 24 hr, and investigated the method to improve the collecting capacity. The results were as follows. The surface coverage of silica was 57%, calculated from the weight change, or 53%, calculated from the electrolytic current change. The zeta potential of the carbon fiber decreased from −11 mV to −15 mV, and Bacillus subtilis spores were not adsorbed into the carbon fiber on their own. When a constant cathodic current of 1 A was applied to the carbon fiber, the capacity to collect the Bacillus subtilis spores increased from 88.05% to 99.88%, and the surface coverage of silica was about 5%. Therefore, it was considered that silica was dissolved in water, and the capacity to collect bacteria could be recovered.
Wet oxidation of hypophosphite and phosphite was conducted at a fixed temperature of 453 K under a partial oxygen pressure of 0.5-5 MPa, with the initial hypophosphite and phosphite concentrations of 0.1 mol/dm3. As a result, it was found that hypophosphite was only slightly oxidized under an N2 atmosphere, but that hypophosphite was decreased to 5% after 180 minutes of reaction time under an O2 atmosphere of 1 MPa. For the wet oxidation of phosphite under an O2 pressure of 0.5-5 MPa, the conversion of phosphite to phosphate was increased with an increase in the partial pressure of O2. It was also found that the conversion of phosphite to phosphate was increased with a decrease in the initial pH value from 6.05 to 1.04. In the pH range between pH6.05 and 7.01, the conversion of phosphite to phosphate after 180 minutes of reaction time increased from 9.2% to 78%, which was further increased with an increase in the pH value. Furthermore, when Ca(OH)2 was added to phosphite during wet oxidation, the concentration of phosphorus at 360 minutes was decreased to 6 mg/dm3, which was less than 8 mg/dm3 of the daily phosphorus emission standard.
The electrochemical reactions of carbon steel in LiBr solution have been investigated by electrochemical impedance spectroscopy. Inductive and capacitive loops were described in the Nyquist plots of electrochemical impedance at low and high frequency regions, respectively. On the basis of observation by confocal laser microscope, it was found that the localized corrosion site increased with the electrode potential, and that the dissolution rate of carbon steel increases with the increase of the localized corrosion. The electrochemical impedance spectra can be simulated with the empirical equation of the localized corrosion site and the electrode potential and equivalent circuit for the dissolution model of carbon steel.
The current efficiency of long-term iron electroplating was evaluated using an in situ quartz crystal microbalance (QCM). The current efficiency was compared for different plating conditions such as the use of carbon or iron anodes and the pH control of plating bath. Constant current efficiency was obtained when the pH of the bath was controlled to be 1.8 and an iron anode was used.