Enhancing Electrochemical Corrosion Resistance of Epoxy Coatings on Magnesium Alloy in Saline Solution via Integration of ZnO Nanoparticles and Graphene Oxide Nanosheets
摘要
This study investigates the enhancement of the anti-corrosive performance of Epoxy coatings through the incorporation of ZnO nanoparticles and their modification with GO nanosheets by assessing electrochemical corrosion measurements. Various weight ratios of ZnO and GO were optimized to develop a ZnOx/GOy nanocomposite that functions as an effective barrier within the Epoxy matrix. The most significant improvement was achieved with the ZnO4.1/GO0.05/Epoxy formulation, which exhibited a markedly reduced corrosion current density (Icorr) of 3.485 × 10−9 A/cm2, a lower corrosion rate (CR) of 7.952 × 10−11 mmpy, and a higher charge transfer resistance (Rct) of 1,746,500 Ω cm2. These results represent a substantial improvement compared to both the ZnO4.1/Epoxy and pure Epoxy coating. This improvement is attributed to the dual-barrier effect provided by the GO nanosheets, offering both impermeability and mechanical reinforcement, as well as the dual-function action of ZnO nanoparticles, which reduce porosity and seal corrosive pathways. The superior anti-corrosion performance of the ZnO4.1/GO0.05/Epoxy coating was further confirmed after 72 h of immersion in a 3.5 wt.% NaCl aqueous solution, it maintained a low corrosion current density (Icorr) of 46.6 × 10−9 A/cm2, a lower corrosion rate (RC) of 10.62 × 10−11 mmpy, and a higher charge transfer resistance (Rct) of 1,592,855 Ω. These results significantly enhanced resistance to degradation compared to other formulations. The morphological, structural, thermal, and mechanical properties of the prepared coatings were characterized using Scanning Electron Microscopy (SEM) coupled with energy-dispersive x-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), Thermogravimetric Analysis (TGA), water droplet contact angle, and Microhardness tests. The designed ZnO4.10/GO0.05 nanocomposite coating exhibited significant improvements in microhardness, hydrophobicity, and thermal stability, as well as exceptional corrosion protection, by effectively reducing the current density and enhancing charge transfer resistance, which inhibits coating failure in harsh environments.