Effect of nano-ZnO coating on hardness, ductility, and corrosion performance of AA6070 aluminum alloy

The present study systematically investigates the impacts of hierarchical nano-ZnO coatings, synthesized via a hydrothermal method and subsequently modified with polydimethylsiloxane, on AA6070 aluminum alloy. Significant enhancements were observed in surface hardness, corrosion resistance, and hydrophobicity. The surface hardness of the nano-ZnO-PDMS coated alloy improved remarkably, increasing from 96 HV in uncoated alloys to 186 HV, demonstrating an approximate 94% enhancement attributed to hierarchical nanostructural reinforcement. Electrochemical assessments revealed considerable improvements in corrosion protection, with the corrosion potential shifting positively from -1.42 V to -1.42 V and the corrosion current density reducing from 8.76×10⁻⁷ A/cm² to 2.81×10⁻⁷ A/cm² in aggressive chloride environments. Moreover, ductility was minimally affected, preserving sufficient elongation (fracture elongation remained nearly unchanged), thus effectively balancing hardness and flexibility. The modified surfaces exhibited exceptional hydrophobicity, with contact angles increasing substantially from 78° for untreated alloys to approximately 158°, indicating strong superhydrophobic behavior. These combined property enhancements underline the multifunctional advantages of nano-ZnO coatings for aluminum alloy protection. This research contributes foundational insights into coating-substrate interactions and their multifunctional behavior, including anti-icing and self-cleaning properties, suggesting significant potential for broader industrial applications.