Nickel Electroplating Bath Using Citric Acid

A new nickel electroplating bath called a “Nickel citrate bath” uses citric acid in place of boric acid. In order to clarify its properties, a Hull cell test and measurements of current efficiency and pH titration curves were performed. The results were compared with those obtained from a Watts bath. The citric acid in a Nickel citrate bath consists of various ratios of citrate ion and nickel-citrate complexes forming complex equilibrium at various pH levels. A Nickel citrate bath with a concentration of citric acid above 0.06M has a good appearance, current efficiency, and pH buffering action for the bath. The results were almost the same as those obtained with a Watts bath under the same conditions. This result is attributed to interaction of nickel-citrate complexes at the electrode surface in the Nickel citrate bath.