抄録
The properties of the film obtained from nickel electroplating bath called a “Nickel citrate bath” using citric acid in place of boric acid were investigated. A Nickel citrate bath is composed of 1.07M nickel sulfate, 0.19M nickel chloride and 0.08M citric acid. The results were compared with those obtained from a Watts bath under the same conditions. The film obtained from a Nickel citrate bath was widely different from that of a Watts bath in surface morphology, hardness, microstructure of cross section, and X-ray diffraction pattern. The film obtained from a Nickel citrate bath is harder than that of a Watts bath. The microstructure and orientation of deposit obtained from a Nickel citrate bath exhibited a near random orientation. This is attributed to the finer-grained deposit obtained from a Nickel citrate bath. As a reason, nickel-citrate complexes in a Nickel citrate bath and a complex formed between boric acid and nickel ion in a Watts bath are adsorbed in the same way on the cathode, resulting in the inhibition of the hydrogen evolution reaction. But it is thought to be due to the adsorptive interaction of the former being stronger in comparison with the latter.
