Morphology, roughness and microhardness of nickel electrodeposits produced in sulfate media on 316Â L SS or Ti cathodes

The current paper describes the effect of key operating variables (i.e. pH, presence of sodium sulfate, boric acid and sodium lauryl sulfate - SLS) on important features of nickel deposits by means of morphologic and surface roughness analyses and indentation hardness tests. Two substrates (cathodes) were used: 316 L stainless steel (SS) or titanium (grade 2). Only changes of pH and additions of Na2SO4 and SLS to the electrolyte largely affected the morphology of the deposits, regardless of substrate type. At pH 3, a condition in which relatively high values of current efficiencies were obtained, the addition of 155.9 g L− 1 of Na2SO4 or 10 mg L− 1 of SLS to the electrolyte lead to the production of Ni deposits with few hydrogen pits on the surface and regular edges. However, the presence of 155.9 g L− 1 of Na2SO4 in the electrolyte caused an increase of the average roughness of the deposits in the order of 27 and 54% when 316 L SS or Ti cathodes were used, respectively. By adding 10 mg L− 1 of SLS to electrolyte containing 155.9 g·L− 1 of Na2SO4 and 8 g L− 1 of H3BO3, the surface roughness decreased about 24 and 17% when 316 L SS or Ti cathodes were used, respectively, without any effect on the materials' microhardness. The results of this work suggest that only the replacement of 316 L SS blank cathodes by Ti may not represent significant benefits in terms of product quality.