Superhydrophilic Hybrid Sol–Gel Coating for Improved Corrosion and Surface Properties of AZ31 Mg Alloy

In this study, the structural, morphological, mechanical, and electrochemical properties of 3-aminopropyltriethoxysilane–tetraethylorthosilicate-based hybrid sol–gel coating applied to the surface of AZ31 Mg alloy are investigated. In order to determine the properties of the obtained film, Fourier transform infrared spectroscopy (FTIR), SEM, energy dispersive X-ray spectroscopy, surface hardness, surface roughness, contact angle, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) tests are performed. As a result of SEM analysis, it is determined that the hybrid film coating is spread homogeneously on the surface and formed a dense film layer of ≈1.4 μm thickness. FTIR analysis reveals the presence of Si-O-Si, Si-OH, and -NH2 functional groups, confirming that the hybrid structure is successfully formed in the obtained film. The microhardness tests show that the hybrid-coated AZ31 Mg alloy provided 68% hardness to the surface and significantly improved the mechanical performance. The low value of the static contact angle obtained in the coated film, 7.85°, determined that the coating is superhydrophilic. EIS analysis shows that the hybrid coating formed a high impedance barrier to the AZ31 Mg alloy and provided effective protection by increasing the total polarization resistance by 79 times. © 2025 Wiley-VCH GmbH.