Seong Ho Han

A study on effect of hydrogen reduction reaction on the initial stage of Ni electrodeposition using EQCM

Electrodeposition of Ni from acidic sulfate solution with/without the addition of boric acid was studied by electrochemical quartz crystal microbalance (EQCM) to further investigate the initial stage of Ni deposition. EQCM analysis showed that nickel hydroxide was formed due to the pH increase near the electrode caused by hydrogen evolution in the absence of boric acid. In the presence of boric acid, nickel hydride was formed. EQCM was found to be a useful in-situ tool for investigating the effects of the evolution and absorption of hydrogen on metal deposition and separating the charge used for Ni deposition and for hydrogen reduction.

Determination of Current Efficiency of Anodic Film Formation in the Molten Melt by ICP-AES

The results of the current efficiency measurements using the ICP-AES technique are described in this paper. The specimen, of known surface area, was anodized in the anodizing cell containing a known melt volume. After anodizing, trace amounts of any aluminum ions in the melt were analyzed by the ICP-AES technique. From Faradays law, when the amount of aluminum in the melt after anodizing is zero, the current efficiency of the film formation is 100 %. When the amount of aluminum in the electrolyte is not zero, the charge carried by these aluminum ions is effectively wasted, i.e. such ions are not employed in solid film growth, and the current efficiency falls from 100 %. Anodic films were formed at various anodizing conditions in the molten melt under the following conditions;