Modification of the single tetraethoxysilane-treated anodized aluminum by the trimethoxy(propyl)silane retreatment for corrosion protection

In this study, we retreated a hydrophilic surface (i.e., tetraethoxysilane-treated substrate) by trimethoxypropylsilane (TMPSi) sol to offer a bilayer surface and investigate the effects of the second layer. The characterization of samples was through X-ray diffraction, field emission scanning electron microscopy (FESEM), Map analysis of Si elements, energy-dispersive X-ray spectroscopy and scanning electron microscopy results beside the elemental linear scan. The mean roughness value (Ra) and water contact angle (WCA) represented the outlying features. After modification by TMPSi, a relatively porous finish was demonstrated by FESEM images. Considering the SEM cross-sectional micrographs, the finished layer was about twofold in thickness. An increase in Ra quantity from 0.70 to 0.90 mu m revealed that the final TMPSi layer delivers a rough finish compared to the first layer. This phenomenon improved the hydrophobicity of the first layer. To determine the electrochemical response of the samples in a 3.5% NaCl solution, electrochemical impedance spectroscopy was adopted. The charge transfer resistance (R-ct) was increased dramatically to 446 k Omega from a 153 k Omega value. [GRAPHICS] .

Automated summary

In this study, a hydrophilic surface was treated with trimethoxypropylsilane (TMPSi) sol to create a bilayer surface, resulting in enhanced hydrophobicity. The surface roughness increased after modification and the charge transfer resistance dramatically rose, indicating improved performance.