Protective graphene-based coatings for Zamak: Physical and electrochemical analysis

Concerns surrounding the widespread use of hazardous materials have increased over time and have led numerous states to implement regulations aimed at preserving human and environmental health. In response, industries like metallurgy have gradually transitioned from traditional, hazardous technologies to safer alternatives, such as using polymeric coatings to protect metals from corrosion. This study focuses on evaluating the protective properties of non-functionalized graphene oxide-based coating (GC) and functionalized graphene oxide-based coating (FGC) on the zamak samples. First, the powders were analyzed from structural, morphological, and spectroscopic perspectives. The formation of amino-silica groups on the graphene oxide sheets was confirmed through SEM-EDS, XRD, and FTIR analyses, validating the success of the functionalization process. Granulometric analysis demonstrated a good dispersion of fillers in the mixtures. Cross's theoretical model was applied to the rheological experiments to find the optimum way of coating application on metallic substrates. The corrosion resistance of the coatings was evaluated using OCP, LSV, PS, EIS, and salt spray experiments. The results revealed that the functionalized graphene oxide coating provided superior corrosion protection compared to other coatings on Zamak samples. AFM topographic images, along with roughness measurements, indicated a significantly less corroded surface when using the functionalized graphene oxide coating. Additionally, Raman spectroscopy confirmed the protective effectiveness of the FGC coating against corrosion.