塩化物浴鉄めっきへの隔膜電解プロセスの適用

概要

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Application of membrane method to high speed iron electroplating from concentrated aqueous FeCl_2 baths of 105∿210 g/l Fe^<2+> at temperatures between 25∿100℃ with cathode current densities up to 100A/dm^2 was examined. The same electrolyte as catholyte and HCl solutions of different concentrations were used as anolyte. When FeCl_2 solutions with pH 1.11∿1.73 were used as anolyte, emission of Cl_2 gas from Pt anode was completely suppressed in contrast to HCl anolytes. Also with FeCl_2 anolyte, the catholyte pH and iron deposition efficiency were kept almost constant during electrolysis. Thus, FeCl_2 solutions are preferable as anolyte. The potential drop within the fluorinated membrane became larger with the increase of FeCl_2 concentration and the electrolyte temperature. It also increased with the decrease in the water content of the membrane. However, the potential drop was only about 2V (14% of the total cell voltage), when plating was conducted in the 158 g/l Fe^<2+> bath at 100℃ with 100A/dm^2. Therefore, it can be concluded that the membrane method using FeCl_2 solutions as anolyte is beneficial to iron plating at high current densities.
1990-12-01