Effects of Insoluble Anode on Deposition Behavior and Corrosion Resistance of Zn-Ni-SiO2 Composite Electroplating from a Sulfate Bath

Zinc-nickel-SiO 2 electrodeposition was done using an acid sulfate bath to examine the effects of an insoluble anode on SiO 2 co-deposition behavior and the corrosion resistance of plating.The presence of SiO 2 nanoparticles in the plating bath apparently changes the alloy deposition behavior and improves the macrothrowing power of plating.At an early stage of electrodeposition, the SiO 2 nanoparticle apparently acts as a nucleus of precipitation.The SiO 2 amount co-deposited in the plating film by the iridium oxide electrode was greater than that by the platinum electrode.Furthermore, these SiO 2 nanoparticles did not disperse uniformly in a plating film, but instead distributed only in the SiO 2 rich layer formed beneath the surface.Therefore, the anticorrosive performance of the plating film with much SiO 2 co-deposited amount by the iridium oxide electrode was superior to that obtained using a platinum electrode.For the curtailment of zinc use, results show that an iridium oxide electrode is preferable to a platinum electrode as an anode for zinc-nickel-SiO 2 electrodeposition.