The deposition characteristics in a low-temperature electroless cobalt-nickel-phosphorus alloy plating bath and some properties of the deposited films were investigated. After a screening test on many chelating agents, sodium pyrophosphate-ammonia comlex system was selected as an optimum complexing agent in the low-temperature plating bath. The results obtained are as follows; 1) Preferable plating conditions were obtained in the solution of 0.1M cobalt sulfate+nickel sulfate, 0.2M sodium hypophosphite 0.4M sodium pyrophosphate and 0.5M ammonium sulfate at operating temperature of 60-70°C. Underthese conditions, relatively high deposition rate and bath stability were obtained. 2) A film of desired composition was obtained by controlling the ratio of the concentration of nickel to cobalt ion in the bath. The content of phosphorus in this alloy films varied in the range of 3-4%. 3) Addition of nickel to cobalt plated film bellow 20% improved the magnetic properties of the deposited films. 4) The magnetic properties of the films were affected by the change in its metallurgical structure such as grain size and anisotropy caused by the addition of nickel.

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Polarographic reduction of chromium (III) chloride hexahydrate (CrCl₃⋅6H₂O) has been studied in N, N-dimethylformamide (DMF) and dimethylsulfoxide (DMSO) containing 0.1M (C₂H₅)₄ NCl as the supporting electrolyte. Chromium (III) chloride hexahydrate exhibited two reduction waves with wave height ratios of 1:2, and the limiting currents for these two reduction waves were diffusion controlled in the above solutions. In DMF, the first wave (the reciprocal slop of log-plot, large value) was irreversible, the second wave (the reciprocal slop: ca. 41mV) is reversible. In DMSO, the first wave (the reciprocal slop of log-plot: ca. 60mV), and the second wave (the reciprocal slop: ca. 36mV) are both reversible. In DMF, and DMSO, controlled potential coulometry at a potential on the plateau of the first, and the second waves showed an uptake of one electron, and three electrons per molecule, respectively. These facts suggest that the two reduction waves of chromium (III) chloride hexahydrate correspond to the reduction of Cr (III) to Cr (II) and Cr (0), respectively.

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Measurements of the ductility of Ni and Ni-Fe alloy films have been made by using a mechanical bulge type ductility tester, and the effects of film thickness on the ductility have been studied. The Ni and Ni-Fe alloy films were electrodeposited from Watts type bath and sulfate-chloride bath, respectively at 3Adm^-2, 53°C, pH 2.7-3.0. The ductility of Ni and Ni-Fe alloy films was found to increase with increasing film thickness up to about 30μm. An addition of a small amount of saccharin in the bath produced the bright deposits and increased the ductility of Ni and Ni-Fe alloy films. Even though the ductility of Ni-Fe alloy films was found to be independent on Fe content, the hardness of the Ni-Fe alloy films increased with Fe content up to 25%. It is concluded that a mechanical bulge type ductility tester can be used to evaluate the ductility of hard thin films such as Ni and Ni-Fe deposits.

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The purpose of this study was to form reproducible color films on stainless steel (SUS 304) in 10mol/kg NaOH solution by anodic polarization. Interference colored films were obtained at 70°C by polarizing the electrode from a potential in the secondary active region (-50mV vs. Hg/HgO) to a potential in the secondary passive region (+480mV vs. Hg/HgO). For the development of the interference color, 0.2C/cm² was needed for the anodic oxidation in the secondary passive region. The composition of the colored films was examined by electron microscopy, spectrophotometry and electron probe microanalysis. The film composition was found to depend on the potential applied during the anodic oxidation. In the case of anodic oxidation in the secondary active region, Fe content in the film was lower but the Cr, Ni and Si contents higher than in the metal. In the third active region, Fe and Cr contents were lower but Ni and Si were higher.

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Gold-palladium alloy plating was investigated in strongly agitated solutions containing 0.211M EDTA-2Na, 0.198M Na₂SO₃, 0.012M NaAsO₂, 0.021M Au(SO₃)₂^3-and 0.024M Pd(en)₂³⁺ under condition of Dc: 0.03-0.10A·dm^-2, pH: 7-8 and 50°C. The composition of gold-palladium alloy deposits was affected by pH, temperature and agitation of solution and metal ion concentration ratio in the solution. However, gold-palladium alloy deposit (96.4:3.6) was obtained at high current efficiency of 83.5% and a current density of 0.10A·dm^-2. Further, the alloy deposit showed preferential orientation of (220) crystal plane, and were fine grained and bright. Thus, gold-palladium alloy plating is advantageous as a substitute for expensive gold in the industry, and for noncyanide plating.

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Current distributions at anode and cathode electrodes in Hull cell is correctly measured by means of a rather simple process, analogical method using conducting paper and two-contact probe. Current distributions obtained in this method agree fairly well with the values from a solution of the wellknown Laplace's equation, while not agree with the one calculated from the empirical equation, for example, after DIN 50957.

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