In order to improve the coating properties of polypropylene (PP) surfaces, three types of polypropylene--homopolymer (JHH-G), block copolymer with ethylene (BJH-G), and random copolymer with ethylene (GFL-G)--were ozonized at ozone concentrations of 1.38, 0.64, 0.41mol%. The ozonized samples were ultrasonically washed with chloroform and coated with various paints. Adhesion strengths of the coatings were evaluated by the peeling test method. The following results were obtained: 1) The adhesion of paints onto polypropylenes was greatly improved. 2) The increase in adhesion strength was dependent on the substrates in the order of BJH-G>GFL-G>JHH-G. 3) Optimum ozonization conditions were found to exist for each of the polypropylenes. 4) Reactive paints such as epoxy and acryl urethane resins afford better adhesion strength than conventional ones (acryl or PVC resin).
Studies were conducted on the suspension condition of fine particles and on the mechanism of electron transmission between particles in order to determine the conditions under which particle plating can be carried out with high current efficiency and high current density. The following results were obtained: 1) The factor influencing current efficiency most is not the concentration of particles in the suspension (space ratio) but the dispersion of particles or a stationary bed (bed expansion). This suggests that electrons are mainly transmitted between particles by means of contact rather than by collision. 2) When current density per unit of particle surface area is low, current efficiency is extremely poor, and then the current density is comparatively high, current efficiency improves. 3) When the suspension condition is inappropriate, particle plating dose not proceed at all. All that occurs is particle dissolution by bipolar phenomena and dispersion plating on the cathode.
A study was conducted on reducing particle plating costs by decreasing the cell voltage at the time of electroplating and increasing productivity by means of high-current-density plating. The following results were obtained; 1) When bath temperature was higher, good electroconductive bath is more concentrated and the distance between both electrodes is near. Particle plating can be achieved with fairly low cell voltage provided. 2) The occurrence of the hydrogen gas at the time of high current density plating is able to be inhibitted by using titanium as a cathode material. And the plating of high current efficiency become possible. 3) The structure and crystal orientation of electroplating layer fairly change by addition of brightener and current density. However, plating layer with high current density is more smooth than low current density. It is possible to reduce the production cost remarkably with the improvement of production efficiency by both high current density and high current efficiency, and the consumption electric power reduces by decreasing of cell voltage.
The applicability of a method of activation using colloid aggregates of Ni(OH)2-Cu(OH)2 was examined for various plastics and for flake-like natural graphite. Furthermore, this activation method was applied to the electroless plating of nickel, cobalt, and nickel-cobalt alloy onto ABS plastic. The main results were as followed: The plastics, including polypropylene, polystyrene, polycarbonate, polyethylene, and polyvinyl chloride, and the flake-like natural graphite containing ash were satisfactorily activated with colloid aggregates of Ni(OH)2-Cu(OH)2 for electroless plating of copper. These results suggest that the surface-electrochemical mechanism of the activation process previously proposed by the authors is reasonable. When ABS plastic was activated with the colloid aggregates of Ni(OH)2-Cu(OH)2 prepared at high concentration ratios of Ni(II) to Cu(II), the Ni films formed on the ABS plastic were amply competitive with those activated by a conventional SnCl2-PdCl2 method. Similar results were obtained for the electroless plating of cobalt on ABS plastic using the colloid aggregates of Co(OH)2-Cu(OH)2. This activation method was also found to be applicable to the electroless plating of nickel-cobalt alloy on ABS plastic.
A computer-aided coulostatic method was employed for the in-situ monitoring the deposition rate of electroless nickel. The relationship between deposition rate (ielp) and polarization resistance (Rp) was given by the equation; ielp=K/Rp. The K-values were empirically determined from pairs of ielp and Rp values, which were measured both by weight gain due to electroless plating and also by the coulostatic method. The K-value relating to the electroless nickel deposition was found to be 10-20mV depending on temperature, pH and acetate concentration as well as stirring, but it was substantially independent of hypophosphite concentration. Once a K-value was established, the deposition rate could be successfully monitored by this method. The empirical K-value agreed fairly well with theoretical one which was calculated from Tafel slopes (ba, bc) measured by the galvanostatic trangent and a modified coulostatic method by using the equation; K=ba·bc/2.3 (ba+bc). The increase in K-value with rising pH was essentially ascribed to an increase in Tafel slopes. The pH dependence of the Tafel slopes was more pronounced in cathodic reactions than in partial anodic reactions. The coulostatic method is found to be useful not only for monitoring the deposition rate of electroless nickel, but also for elucidating the mechanisms of the deposition process.
Alloy films of Ti-Ni-Cr (Cr: 0-11 at.%) and Ti-Ni-W (W: 0-21 at.%) were prepared by RF sputtering on water-cooled glass substrates to investigate the effect of the alloying element (chromium or tungsten) on the corrosion behavior of the alloy films. Structural analysis of the samples was made by X-ray diffraction and Auger electron spectroscopy (AES), and their corrosion resistance was evaluated by means of an immersion test in HCl solutions. The results obtained are as follows: 1) Ti-Ni-Cr and Ti-Ni-W alloy films were confirmed by X-ray diffraction analysis to be amorphous over the whole range of compositions in this study. 2) Corrosion resistance of Ti-Ni-Cr alloy films was increased markedly by the addition of chromium in 1N-HCl. After annealing at 600°C, crystallization was observed with a slight decrease in corrosion resistance. 3) No increase in corrosion resistance was observed with the addition of chromium in 6N-HCl. 4) In the case of Ti-Ni-W alloy films, the addition of tungsten produced no increase in corrosion resistance in 1N-HCl, but resulted in a remarkable increase in 6N-HCl.
Ti-Ni alloy films were prepared by RF sputtering on water-cooled aluminum substrates. It was anticipated that for metal substrates, the corrosion resistance of an amorphous film having a high corrosion resistance, would be changed by the roughness of the substrate surface, and by interdiffusion between the substrate and the coating layer. Accordingly we investigated the influence of the roughness of aluminum substrates and the diffusion of the coating layer and the substrate, on the corrosion resistance of coatings. The results obtained are as follows: 1) Films of 54 and 68 at.% Ti-Ni alloy on aluminum substrates were confirmed by X-ray diffraction and TEM analysis to be amorphous. 2) As the roughness of the aluminum substrate increased, the corrosion resistance of the coating was degraded significantly. Even for the coating that exhibited the best corrosion resistance in this experiment, a certain amount of aluminum as a substrate material was dissolved. This means that a Ti-Ni alloy coating of 1μm in its thickness dose not provide sufficient protection against corrosion. 3) After the coating layers were annealed at 500°C for 3 hours, interdiffusion with the substrate was found, and dissolution of titanium, nickel and aluminum increased slightly.
The role of chloride ion in the plating of nickel has been studied by using a special electrolytic cell which permits continuous measurement of the amount of hydrogen evolved during electrodeposition. It was found that an increase in the concentration of chloride ion accelerated the deposition of nickel and inhibited the co-evolution of hydrogen, and these effects of chloride were especially remarkable at high pH values. The kinetic parameters for the electrodeposition of nickel were fully explained by a kinetic equation derived by assuming a chloride-containing adsorbed intermediate. It is considered highly probable that the number of effective sites for hydrogen evolution is reduced by adsorption of the reaction intermediate during the electrodeposition of nickel
A previous papers reported on the enhancing effects of metal hydrides for the determination of metals that require high atomization temperature such as beryllium salt by flameless atomic absorption spectrometry in N, N-dimethylformamide (DMF). The present paper proposes a method of quantitative estimation of mixing ratios in mixed solutions chromium (III) and (VI) ions by flameless atomic absorption spectrometry, utilizing the different effects lithium hydride and sodium boro hydride by in DMF. That is to say the relation between increased sensitivity and the amount of lithium hydride added differed for chromium (III) and chromium (VI) ion. A calibration curve was drawn for each ion concentration, and the ratio of chromium (III) and chromium (VI) ions in the solution was determined by using the difference in the effects of lithium hydride on the two ions. The proposed method provided a satisfactory analytical result for chromium (III) and (VI) in general chromium plating baths. The coefficient of variation by this method was 4.4% (n=5) for a mixed ion solution containing 0.5ppm chromium.
XMA and ESCA measurement was carried out for anodized films on Al-Mn alloy plates (99.99%Al+1%Mn). XMA plane analysis showed that Mn was dispersed like islands of which diameters were a few μm. ESCA spectra indicated that Mn peak shifted 2.6eV in the plus direction. It is possible that Mn is in an oxidized state (Mn(III)).