In vacuum deposition, the temperature rise of the coating substrates, due to the radiation energy from the evaporation source, is an important problem in case the deposition of metals is made on the materials poor in thermal resitivity. The temperature rise is influenced by the deposition rate, configuration of the evaporation source, and innner surface states of the bell jar. A shelter placed between the evaporation souce and substrates can prevent the temperature rise of the substrates to some extent. A metal plate placed very close to the evaporation source, on the other hand, can minimize the temperature rise due to the radiation energy to a greater extent; the evaporation characteristics is also improved. Optimum conditions for reducing the temperature rise, determined experimentally, are described, and the reason for the reduction in radiation heat is discussed in terms of geometrical view factor.

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Correlation between the differential capacity and the luster of plated tin was studied in the electrodeposition of tin from acidic tin plating bath containing organic brightners. The luster appeared when the plating potential agreed almost with the desorption potential of the brightner in cathodic direction on the potential vs. differential capacity curve. The differential capacity in the electrodeposition of tin was discussed in connection with the adsorption of effective brightners on the tin electrode. The finest luster was obtained in the bath with 0.3g/l benzalacetone at the plating potential of -800mV (vs. S. C. E.).

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The electrophoretic deposition method is very useful for the coatings of metallic and nonmetallic materials which are impossible to be electroplated. Electrophoretic deposition of aluminum powder on steel plate has been reported in our previous papers, and in this paper the mechanism of this coatings has been studied. The solution employed was composed of 99.5% ethylalcohol and 0.4% water, and the bath temperature was kept at 20°C. Mild steel plate was used as cathode and carbon plate as anode. The electrophoretic deposition was done at the bath voltages such as 80, 160, 300 volt. The influence of the concentration of various additional electrolytes such as HCl, MgCl₂, AlCl₃ and SnCl₄ on the amount of the powder deposits, the minimum bath voltage for deposition and the electrophoretic mobility of the aluminum particles have been examined. Moreover, the time dependencies of the amount of the powder deposits and the cathode current density have been measured, and the following conclusions were deduced from the results of these experiments: the factors affecting the amount of powder deposits are the repulsive force among the aluminum particles and the zeta potential of the surface of the alumiunm particles, hence the deposition of aluminum powder can occur when the electrophoretic force given by the electric field is stronger than the repulsive force among aluminum particles or the surface charge of the aluminum particles is canceled. The products on the cathode plate were not essential for the electrophoretic deposition.

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Hydrogen evolution overpotential of the cobalt plated cathode in a 3.0mol/dm³ NaOH solution at 80°C was studied by comparing polarization curves. For a 20A/dm² plating current density with 3.0mol/dm³ urea added to the cobalt citrate plating bath, a low hydrogen overpotential value was obtained. The value was same to that of rhodium electrode. Vanadium or molybdenum co-deposited cobalt plating cathode had lower hydrogen overpotential than above mentioned pure cobalt plated cathode. Suitable plating conditions for low hydrogen overpotential cathodes were above 4×10^-3 mol/dm³(about 0.8g/dm³) vanadium pentoxide or ammonium molybdate addition and above 30A/dm² plating current densities. Value of overpotential at 25A/dm² current density was 0.1V. This is a comparable value with that of platinized platinum cathode.

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Impedance of aluminum oxide films anodized in a sulfuric acid bath is measured in nickel sulfate-boric acid mixed aqueous solution. When the oxide films are not cathodically polarized, the measured impedance is mainly the impedance of barrier layer, and the phase angle is 84°. This impedance is a capasitive impedance. When cathodic voltage is applied on the oxide films, the impedance suddenly decreases. During cathodic polarization, the impedance gradually increases and phase angles are in the range between 10°to 40°. This impedance is ohmic impedance. Separation of non-Faradic impedance and Faradic impedance was impossible in this study.

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The rate of plating of copper in an iminodiacetate bath for electroless plating use was measured with the polarization resistance method for the monitoring of aging of the bath. The polarization resistance method well accepted in the field of corrosion study has been applied to the electroless plating. The rate of copper deposition estimated from the polarization resistance method was compared with that obtained from the gravimetric method in various concentrations of copper ion and formaldehyde, at different pH values and plating time. Results showed that the polarization resistance was inversely proportional to the average plating rate estimated from weight gain, as expected from the equation of polarization resistance;
R_p=b_ab_c/2.3i_pl(b_a+b_c)=K/i_pl
where R_p is the polarization resistance, i_pl the plating rate, b_a and b_c are the Tafel slopes of anodic and cathodic polarization curves respectively, and K a constant. The iminodiacetate bath yielded 0.12 for K, the value of which depends on the species of metallic ions, reductants and ligands. It is concluded that in laboratory tests the polarization resistance method can be used for the measurement of the rate of plating of copper in the electroless plating bath as well as for the monitoring of the aging of the electroless plating bath.

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