Unveiling the anti-corrosion properties of Zn-eggshell particle composite coatings on mild steel in seawater-simulated solution using starch as a modifier

Abstract

This study investigates the development and efficacy of Zn-eggshell particle (ESAp) coatings on mild steel, utilizing starch extract as a modifier to enhance anti-corrosion properties. Coatings with varying ESAp content (0, 2, 4, 6, and 8%) and a fixed addition of 2% starch were successfully applied via electrodeposition. The findings reveal that increasing the ESAp content results in thicker coatings, with the Zn-8% ESAp + 2% starch coating exhibiting the greatest thickness. SEM analysis confirmed the high quality of the coatings, showing no external surface defects. The Zn-8% ESAp + 2% starch-coated sample demonstrated a 46.45% increase in hardness (100.3 HB) and achieved superior corrosion protection efficiencies of 82.92% and 94.69% for Zn-8% ESAp and Zn-8% ESAp + 2% starch coatings, respectively. Electrochemical tests indicated that the coated samples shifted towards higher positive potential values, suggesting enhanced corrosion resistance. The results underscore the potential of using starch extract and waste eggshells to develop robust anti-corrosion coatings, with Zn-8% ESAp + 2% starch identified as the optimal formulation for superior protection and mechanical properties. Further research is recommended to explore the matrix–particle interactions and adhesion properties using advanced microscopic and electrochemical techniques.