Abstract
SiC-reinforced Mg metal matrix composites (SiC/Mg MMCs) show mechanical advantages but suffer from severe corrosion. Protective self-sealing plasma electrolytic oxidation (PEO) coatings were developed using a phosphate-zirconium-fluoride (P-Zr-F) electrolyte, where additives (F− and ZrF62−) were strategically introduced to form low-melting MgF2 and stable ZrO2 phases. The findings revealed two orders of magnitude increase in corrosion resistance and achieved 5.3 GPa hardness after PEO treatment. The coating on MMC exhibited exceptional tribocorrosion resistance, attributed to partial reactive SiC incorporation into coating and MgF2-stabilized friction at sliding interfaces. Accelerated Mg dissolution in MMC promoted MgF2 formation during PEO process, while SiC restricted inward coating growth, enabling outward fluoride-rich layer development. This work advances surface-tailoring strategies for MMCs in extreme environments.
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