Enhancing the corrosion resistance of MAO ceramic film by regulating the microstructure via in situ synthesis of ZrO2 nanoparticles

The inherent corrosion issues of light alloys hinder their application in harsh environments, making ceramic coatings typically necessary to address the shortcomings in corrosion sensitivity for practical engineering deployment. In this study, ZrO 2 /Al 2 O 3 micro-arc oxidation (MAO) composite films were in situ synthesized by adjusting the concentration of K 2 ZrF 6 in the electrolyte, and the effect on the microstructure, mechanical properties, and corrosion resistance of the MAO films were studied. The addition of K 2 ZrF 6 enhanced the intensity of the MAO reaction, thereby increasing the film thickness. With increasing K 2 ZrF 6 concentration, the porosity and film thickness increased. Al 2 O 3 and ZrO 2 was predominantly formed in the MAO film, and the incoherent interface formed between ZrO 2 and Al 2 O 3 at the interface significantly hindered dislocation movement, exhibiting excellent interfacial strengthening. This improved the mechanical performance of the ceramic film, with Al 3 Zr particles forming at the interface region. The relationship between K 2 ZrF 6 concentration, discharge behavior, oxide film growth, phase transformation and coating microstructure were established. High-quality prepared ceramic films showed almost no cracks even after 96 h of immersion, demonstrating potential for providing long-term protection to 5A06 Al alloy. More importantly, this simple technique offered a new strategy for preparing corrosion-resistant ceramic films on light alloys, showing significant application potential across a wide range of engineering fields and paving the way for designing new alloy systems for extreme conditions. • ZrO 2 /Al 2 O 3 ceramic film was synthesized in situ by MAO process. • ZrO 2 /Al 2 O 3 ceramic film exhibited excellent interface strengthening through incoherent edge-pinning. • Zr element diffused into the surface metal, forming Al 3 Zr phases and enhancing the interfacial bonding strength.