Unveiling the role of SiC particle reinforcement on aluminum matrix composites surface: insights into PEO coating growth, electrical insulation, and corrosion resistance

In this work, the SiC particle size in the SiC_p/Al substrate is controlled in both basic electrolyte and nanoparticle-containing electrolyte to explore the coating microstructure and performance. The results indicate that larger SiC particles strongly hinder plasma discharge breakdown on the substrate surface, which negatively affects the dense growth of coatings in the basic electrolyte but promotes the densification of plasma electrolytic oxidation (PEO) reactive co-deposition coatings. The coatings formed in the basic electrolyte achieve a thickness of 40 μm, with increasing SiC particle size leading to higher porosity inside the coating. In contrast, the PEO reactive co-deposition coatings reach a thickness of up to 130 μm, and their porosity decreases with increasing SiC particle size. Regarding electrical insulation properties, the PEO reactive co-deposition coatings follow a similar trend to those in the basic electrolyte. While, their breakdown voltage is nearly double that of the coatings formed in the basic electrolyte, and their electrical resistivity is approximately threefold higher. Additionally, the two types of coatings demonstrate contrasting trends in corrosion resistance. Compared to the coatings formed in the basic electrolyte, the PEO reactive co-deposition coatings show a one-order-of-magnitude reduction in corrosion current and a nearly fourfold increase in polarization resistance.