Effect of sodium citrate addition an corrosion properties of plasma electrolytic oxidation nanocomposite coatings on 1010

A study has been carried out to investigate the incorporation of sodium citrate into coatings formed on 1010 aluminum using DC plasma electrolytic oxidation (PEO). The effects of sodium citrate as electrolyte’s additive into silicate-base electrolyte, on the voltage response, microstructure, compositions and corrosion resistance of PEO coatings were investigated by scanning electron microscopy (SEM), energy-dispersive spectrum (EDS), X-ray diffraction (XRD) and cyclic polarization tests. To improve the corrosion resistance, Si3N4 nanopowder was added to electrolyte as suspension to fabricate nanocomposite coating. Results indicated that adding sodium citrate into electrolyte and its incorporation into the coatings will lead to more noble corrosion potential than samples without additive. Corrosion current density increased by adding this additive but current of anodic branch in maximum potential for all samples except one, was decreased by increasing of additive’s concentration.