Insight into the role of Ce incorporation into energy-efficient flash-PEO films for the corrosion protection of additive-manufactured Al10SiMg

Abstract

This study reports the development of a thin and energy-efficient plasma electrolytic oxidation (PEO) protective coating on additively manufactured Al10SiMg using an electrolyte composed of Na3(P3O6)3, KOH, Na2EDTA and Ce2(SO4)3. The oxidation period was varied from 100 s to 300 s to understand the correlation between energy consumption and cerium incorporation, as well as its impact on the structural and corrosion resistance of the PEO film. To obtain a mechanistic understanding of the role of cerium, the structural properties before and after immersion in 3.5 wt% NaCl solution were analyzed to determine how cerium functions as an active corrosion inhibitor when incorporated into the PEO layer. The findings revealed successful and uniform cerium incorporation throughout the PEO coating (up to a 200 s oxidation time). The inhibitory effect of Ce was evidenced by the increase in the impedance modulus (Z0.01 Hz), which was up to twice as effective as that of PEO without cerium. The Ce-doped PEO protective film, with its intrinsic surface porosity, provides substantial dry and wet adhesion to organic coating systems, making it an eco-friendly priming layer for practical applications requiring post-treatment.