Electrodeposition of multi-layer Pd-Ni coatings on 316L stainless steel and their corrosion resistance in hot sulfuric acid solution

Pd-Ni coating shows good corrosion resistance in strong corrosion environments. However, in complex aggressive environments, the performance of the coatings is limited and further improvement is necessary. The effects of the applied plating current density on the composition, structure and properties of Pd-Ni coatings were studied. By changing the current density in the same bath, multi-layer Pd-Ni coatings were prepared on 316L stainless steel. Scanning electronic microscopy, weight loss tests, adhesion strength, porosity and electrochemical methods were used to study the corrosion resistance of the films prepared by different coating methods. Compared with the single layer Pd-Ni coating, the multi-layer coatings showed higher microhardness, lower internal stress, lower porosity and higher adhesive strength. The multi-layer Pd-Ni coating showed obviously better corrosion resistance in hot sulfuric acid solution containing Cl−.