Self-assembled hybrid silane/ZnO coatings for corrosion protection of resorbable magnesium alloy

Abstract

This study aimed to evaluate the potential of an exclusive hybrid coating, based on a silane network, which was developed by sol-gel technique and embedded with nano ZnO to protect the corrosion of an AZ31 magnesium alloy intended for use as biodegradable implants. The coated substrates were subjected to various characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray (SEM-EDS) analysis, and contact angle measurements. The corrosion resistance of applied coatings were evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electrochemical microscopy (SECM) in a PBS solution at physiological temperatures. The chemical composition of the coatings was examined using X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) was carried out to examine the surface topography of the alloy after the polarization test. The results revealed that these coatings significantly improved the anti-corrosion behavior of AZ31 alloy. It was observed that a mixture of silanes offered superior corrosion protection performance owing to the development of a dense cross-linked layer that developed at the interface between the coating and the substrate. The existence of ZnO nanoparticles further enhanced the protective barrier characteristics of the coatings. The outcomes offer a novel approach to the design of hybrid silane coatings with suitable corrosion resistance for biodegradable Mg alloys used as implants.