Abstract
The effects of nickel ion contents on the electrodeposition, composition, structure and properties of palladium–nickel alloys were studied from a nearly neutral Pd(NH3)2Cl2–NiSO4.6H2O bath by adjusting the Ni2+/Pd2+ ion mole ratios. The results demonstrate that coatings with 17·1–44·0 wt-%Ni can be successfully electrodeposited by simply adjusting the Ni2+/Pd2+ ion mole ratios from 0·5∶1 to 2·5∶1. The coatings are bright, pore-free and crack-free with fine and compact grains. The structure of the coatings is a solid solution in a face-centred cubic structure; its lattice constant gradually decreases with a corresponding increase in the Ni content. The coatings exhibit a comparable corrosion resistance in a 3·5%NaCl solution, where the corrosion potentials Ecorr are between −0·010 and −0·064 V(saturated calomel electrode). Corrosion current densities jcorr slightly increased from 9·8 to 21·3 μA cm−2, with the Ni content increasing from 17·1 to 44·0 wt-%. The microhardness of the coatings increased with a corresponding increase in their Ni contents, and shows the highest value of 511 kg mm−2 with 44·0 wt-%Ni. The coatings exhibit comparable contact resistances of 0·2–0·4 mΩ.
Published Version
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