Nickel electroplating on steel from acidic citrate baths

Electroplating of nickel onto steel substrates from citrate baths has been investigated under different conditions of bath composition, current densit y, pH and temperature, A detailed study has been made of the influence of t hese variables on the potentiodynamic cathodic polarization curves, cathodi c current efficiency and throwing power, as well as the throwing index of t hese baths. The optimum conditions for producing sound and satisfactory nic kel deposits are: NiSO4 . 6H(2)O 100 g/L, trisodium citrate 25 g/L and citr ic acid 20 g/L at pH 5.0, with i = 2 A/dm(2) and at 25 degrees C. Moreover, the effect of sinusoidal a.c. superimposed on d.c. on electroplating of ni ckel from the optimum citrate bath has been investigated. The surface morph ology of the as-plated nickel was investigated by using scanning electron m icroscopy (SEM) while the structure was studied by using X-ray diffraction analysis and anodic stripping voltammetry (ASV) techniques.