中性食塩水中における銅, ニッケルメッキの腐食挙動

抄録

Polarization characteristics and corrosion behavior of electro-plated copper and nickel were determined in neutral NaCl solution saturated with air. By the determination of steady-state potential, current-potential curves, and corrosion rate of each test piece of electroplated Cu and Ni, the following conclusions were reached.
In NaCl solution, the steady-state potential of nickel was obtained within 24h, but even if very small cathode current was applied, the steady potential of Ni could hardly be attained in more than 24h.
On the other hand, it was found that steady-state potential of Cu was given within 8h with or without application of external current in the same NaCl solution.
It was also found that corrosion of electroplated nickel in neutral NaCl solution was very little when no external current was applied; whereas, copper gave a considerable loss of weight in the same solution.
It was observed that the polarity of the electrode potential in Cu-Ni couple was reversed in NaCl solution; i. e., Cu was anodically dissolved. The result would be explained by the gradual change of the static potential of each electrodeposited metal with the time in the above solution.
For steel-Cu couple, galvanic corrosion of steel was remarkably accelerated, because steell was always anodic to Cu in NaCl solution. Whereas, for steel-Ni couple, the corrosion of steel was found to be not so remarkable in the same solution.