A fundamental investigation was carried out on electrolytic oxidation of the electroless copper plating waste. The electroless copper plating waste from which EDTA has been recovered still contains the unrecovered EDTA, formaldehyde, methanol and formic acid and is high in COD. Any of these components was readily oxidized using a lead dioxide anode at an anodic current density of 1-6 A/dm² and at a pH of 1.0-7.0. Recovery of EDTA from the electroless copper plating waste followed by electrolytic oxidation under the same conditions as above reduced COD from 1, 400ppm to 10ppm and at the same time caused deposition of the residual metal ions on the cathode. Furthermore, the waste treated in this manner did not interfere with the subsequent chemical treatment for removal of heavy metals and could be discharged after such treatment.

抄録全体を表示

Electrodeposition of aluminum has been investigated from solutions of aluminum bromide in cumene-ethylbenzene baths. In comparison with the hydride type baths, this mixed solvent bath has advantages in preparation of the solution, low bath voltage and good stability. Silver-white deposits of aluminum were obtained from the bath consisting of AlBr₃ 3.07-3.33M/l, 10vol-% cumene-90 vol-% ethylbenzene mixed solvent, at 10-20mA/cm² and 20-30°C, with stirring. The effective additives were found to be L-ascorbic acid, tannic and polystyrene. Specifiic conductivity of the bath, solubility of aluminum bromide were ca 6.0×10^-3mho/cm, 6.1M/l respectively. It was shown by X-ray diffraction analysis that the preferred orientation of the Al deposits was strong in (101). The mean lattice constant and grain size of the deposits were found to be 4.04-4.05Å and 36-80Å, respectively.

抄録全体を表示

A. C. electropainting has not been commercially applied because of the following reasons due paimarily to the presence of reverse direction current: (1) low paint deposition rate, (2) low coulombic yield, and (3) high electric power loss. The present work is concerned with the development of a new electropainting process utilizing a specially made electrode which has a function of both rectifier and condenser of high capacity. The features of this new electropainting process may be summarized as follows: (1) A special electrode is prepared by forming anodic oxide film of certain thickness on either Ta, Nb, Zr, Ti, Al or their alloys so that it warks as both condenser and rectifier. (2) Percentage of reverse direction current is kept within 20% of right direction current by controlling the area ratio of the electrodes or the thickness of anodic oxide film. (3) Phase angle (φ) of bath current under reverse direction voltage is kept at π/3≤φ≤π/2.

抄録全体を表示

The action of dibasic lead phosphite for thermal stabilization of PVC has been investigated from the view point of the thermal decomposition. In the thermal degradation at 170°C, the tensile strength change was not appreciable, but the degree of yellowing extremely increased with prolonged heating. However, the absorption band due to carbonyl group was found at 1725cm^-1 in the IR spectrum, though the absorption band owing to polyene in the vicinity of 1600cm^-1 was not observed. Moreover, reduction of the molecular weight with prolonged thermal degradation time was slight, and the molecular weight of the PVC degradated for 120 minutes was 133, 100 against 149, 200 of the initial molecular weight. From the observations by electron microscope, it was also found that the acicular crystal of dibasic lead phosphite became small after thermal degradating for 120 minutes and then diffused into PVC.

抄録全体を表示

Al specimens were anodically oxidized in solutions of (1) 10%-H₂SO₄, (2) 2%-H₂C₂O₄⋅2H₂O and (3) 10%-H₂SO₄+2%-H₂C₂O₄⋅2H₂O by applying a constant c. d. of 9.4mA/cm² at 27°C, and the time-variation in the ammount of dissolved Al ions, W_d, was measured by the oxinate extraction method. The weight and geometrical structure of the oxide were also examined at time intervals during anodization. The applied anode potentials were 12.0, 45.0 and 13.5V (vs·SCE) for solutions (1), (2) and (3), respectively. The geometrical structure (cell size, pore-wall thickness, pore-radius etc.) of the porous oxide formed in solution (3) was much more like that formed in solution (1) than to that formed in solution (2). The densities of the oxides formed in solutions (1), (2) and (3) were estimated to be 2.7, 2.8and 3.0, respectively. The dissolution rate of oxide at the pore-wall, v_s, and that at the pore base v_b, were calculated from W_d in the manner reported previously. The result shows that v_s decreases from solution (1) through (2) to (3), whereas v_b decreases in the order, (2), (3), (1). Thus, it is advantageous to add a small amount of oxalic acid to sulfuric acid anodizing solution. The reason of this is summarized as follows: a) Current effciency for the formation of oxide considerably increases. Powdering of the oxide could be prevented because of a small value of v_s. b) Electric power does not increase very much, and it is much smaller than that consumed in the anodization in oxalic acid solutions. c) Density of oxide increases remarkably and it is even higher than that obtained by anodization in oxalic acid solutions.

抄録全体を表示

For the purpose of improving the adhesion of polymer coatings to metal surfaces, electrodeposited composite metal substrates containing organic polymer particles have been investigated. The composite coatings were obtained by using suitable surfactants which provide the suspended polymer particles in the plating baths with possitive charge. Effectiveness of the composite films, such as stylene-butadiene copolymer/zinc, epoxy resin/copper, and phenol resin/zinc, as painting and lining substrates has been demonstrated from the data of peel strength and observations of fracture surfaces by scanning electron microscopy.

抄録全体を表示