The study of magnetic field effects is a relatively new branch of electrochemistry, and although it has grown rapidly in recent years, literature is still fragmentary. Whether or not magnetic field effects are exerted on metals, or on electrolytes, or on both is unknown. The present state of understanding of the effect exerted by magnetic fields on electrodeposition of metals is reviewed. Experimental data have disclosed interesting phenomena. Particular emphasis is placed on the effects of combined electrical and magnetic fields on the qualities and properties of electroplated metals, electrolyte properties, mass transport, electrode kinetics and metal finishing.

抄録全体を表示

The anodization of aluminum was investigated in 15w/v% sulfuric acid baths in which were dispersed ferromagnetic metal oxides (CrO₂, Fe₃O₄), with and without a magnetic field.
Anodization was carried out at a constant current density of 2A/dm² and at bath temperature of 5-30°C.
Electrolysis time was 30 minutes.
It was found that both the thickness and hardness of the films were increased over the usually hard anodic coating of aluminum in the presence of Fe₃O₄ or CrO₂ under magnetic field.
The use of TiO₂, which unmagnetized metal oxide, however resulted in no difference.
The effect on film thickness and hardness increased in order of Fe₃O₄>CrO₂.
Optimum conditions were with 5% Fe₃O₄, magnetic field as large as possible, and a bath temperature of about 5°C.

抄録全体を表示

When metal surfaces are washed with an organic solvent, heat marks often appear and these are of interest since they cause swelling when the surface is electroplated. Very few have researchers, however, have investigated the formation mechanism of the heat marks. In order to obtain heat mark-free metal surfaces, therefore, the authors have studied 1) the dependence of the rate of heat mark formation on washing conditions and time; 2) the amount of organic solvent and oil on the surface, (using the gas discharge method); 3) the rate of evaporation of organic solvent against the mole fraction of oil in the organic solvent-oil system; 4) the interaction between organic solvent and oil (using the infrared adsorption spectrum method); and 5) the metal oxides and other products by organic solvent decomposition on surface (by electron spectroscopy for chemical analysis). It was found that heat marks are formed in three steps; 1) Organic solvent remains in the oil on the metal surface; 2) The oil prevents the evaporation of the organic solvent, which decomposes to form metal chloride when heated in air; and 3) The metal chloride prevents the formation of metal oxide, and becomes visible as a heat mark because it is less shiny than the metal oxide surface. The authors have succeeded in cleaning metal surfaces sufficiently using alkali or organic solvents to produce surfaces that were free of heat marks.

抄録全体を表示

The effect of thallium on palladium electrodeposition was investigated by the addition of thallium ion to ethylenediamine-palladium (II) complex solutions. Thallium ion resulted in underpotential deposition on copper and palladium electrodes and shifted the current-potential curves of the palladium electrodeposition to the more noble side. It also activated the electrodeposition of palladium and inhibited hydrogen evolution, so that the hydrogen content of deposits was decreased. In addition, thallium ion influenced the nucleation and growth processes of crystals so that the crystal size of deposits increased with greater overpotential, and it also changed the morphology of the deposits. Thus it is concluded thallium has catalytic effects on the electrodeposition of palladium.

抄録全体を表示

For the purpose of obtaining a new type of electrical contact material, layers of Au-ZrB₂ composite were electrodeposited from an acidic Au plating bath containing suspended ZrB₂ particles, which have such advantageous properties as a high melting point, excellent hardness, good corrosion-and oxidation-resistance and high electrical conductivity. Some properties of the codeposited surface layers were investigated.
It was observed by scanning electron microscope that the diameter of the ZrB₂ particles codeposited with Au on the substrate was about 5μm or less, independent of the size of the ZrB₂ particles in the plating bath. Using a micro Vickers hardness tester, the hardness Hv of 165-180 of the ZrB₂ composite layer was found to be clearly different from the value of 120 for a pure Au deposit layer. In abrasion tests using a tester of our own devising, 35μm layers of pure Au deposit were completely worn down but Au-ZrB₂ composite layers retained over 90% of their thickness after the same number of rotations of the rub head. Some test pieces of Cu substrate covered with Au-ZrB₂ were set in the contact points of relay switches and a 100V, 50Hz, 60W resistive load (candescent light bulb) was switched on and off in accordance with JIS C 5441. After 5×10⁵ switching cycles very little change was detected in contact resistance, or in the surface roughness of the contact points caused by the heat of arc discharge.
These facts indicate that a composite layer of Au-ZrB₂ may be suitable for use in contact material for electronic devices.

抄録全体を表示

Cathodic polarization curves were measured using electrolytes of 0.01-0.05mol·dm^-3 Pb (CH₃COO)₂-0.5-3mol·dm^-3CH₃ COONH₄ containing 0-0.5g/dm^-3 gelatin. At a magnetic flux density of 0.12T, polarization decreased, the limiting current density increased, and the formation of dendrites was inhibited. Current efficiency increased by 10%. It was considered that the thickness of the diffusion layer decreased due to Lorentz force.

抄録全体を表示