A new strategy to improve the anticorrosion performance of waterborne polyurethane coating on AA7075

In this study, Ce³⁺ functionalised halloysite nanotubes (HNTs) were prepared, and their impact on the anticorrosion properties of waterborne polyurethane (WPU) coating on 7075 aluminium alloy (AA7075) was investigated. HNTs were grafted by 3-aminopropyltriethoxysilane (APTES) to enhance Ce³⁺ loading, which was confirmed by X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) spectrum. The release behaviour of Ce³⁺ from HNTs was tested by inductively coupled plasma optical emission spectrometry (ICP-OES), and the inhibition effect of Ce³⁺-loaded HNTs for AA7075 was tested by polarization plots. The anticorrosion property of WPU doped with Ce³⁺-loaded HNTs was investigated by electrochemical impedance spectroscopy (EIS) and pull-off adhesion test. The results showed that APTES modification improved the Ce³⁺ loading amount on HNTs, and Ce³⁺ acts as an effective cathodic inhibitor for AA7075. After soaking for 40 days, the |Z|_0.01Hz of Ce-HNTs/WPU was two orders of magnitude higher than that of pure WPU, while wet put-off adhesion was higher than pure WPU.