Electrochemical investigations of the anticorrosive behaviour of the phosphated electrogalvanized steel additionally coated with conversion layer of cerium oxide

Abstract

The anticorrosive behaviour of the electrogalvanized carbon steel with PZn, PZnCa and PZnNi phosphate layers additionally coated with the conversion layers of cerium oxide in chloride-contaminated media has been studied. The composition and structure of investigated samples were characterized by scanning electron microscope SEM, while the corrosion behaviour was investigated applying voltammetric and electrochemical impedance spectroscopy EIS measurements. The data obtained have shown that all investigated samples additionally coated with cerium oxide conversion coatings exhibited better protective abilities. To summarize the results of electrochemical and SEM measurements it was stated that the most porous (F = ~1–2%) PZnNi/Ce coating exhibited the best protective abilities in a chloride-contaminated solution. Therefore, cerium ions are able to penetrate into the substrate, which is zinc coated steel, through the open pores of the PZnNi layer.