Shanshan Chen, Kun Tan, Yutian Zhang
A Zr-Modified TESPT coating was prepared on 2618 aluminum alloy by dip-coating under conditions of TESPT 4 vol.%, Zr/TESPT molar ratio 1:4, pH 4.0, and 12 h hydrolysis. Electrochemical impedance spectroscopy yielded polarization resistance values of 4.21 × 10 6 Ω·cm 2 , 7.53 × 10 5 Ω·cm 2 , and 5.91 × 10 4 Ω·cm 2 for the Zr-Modified TESPT, TESPT, and bare alloy, respectively. Potentiodynamic polarization gave corrosion current densities of 1.13 × 10 -8 A·cm -2 , 2.20 × 10 -7 A·cm -2 , and 4.20 × 10 -6 A·cm -2 for the corresponding specimens. The constant phase element parameter decreased from 3.33 × 10 -6 F·cm -2 to 1.78 × 10 -8 F·cm -2 , with the dispersion exponent n decreasing from 0.921 to 0.909 and then to 0.853. Following 48 h neutral salt spray exposure, the Zr-Modified TESPT appeared intact over the majority of the exposed area, with degradation features observed at the periphery and edges, whereas the TESPT coating exhibited sporadic pitting distributed across the entire surface. XPS detected Zr 4+ signals on the coating surface; the assignment of these signals to specific chemical species requires additional spectroscopic investigation. These findings characterize the electrochemical and morphological response under the specific preparation and test conditions employed, and further validation is warranted to establish predictive correlations with long-term field performance.