Functionalized Cocos nucifera L shell particulate enhancement on the nanocrystalline and anticorrosion performance of Zn-Al2O3-CSP on mild steel for extended application

The degradation of mild steel in corrosive environments necessitates innovative, eco-friendly protective coatings. This study aims to enhance the corrosion resistance and mechanical properties of mild steel by developing a Zn-Al 2 O 3 nanocomposite coating reinforced with functionalized coconut shell particulates (CSP: 0, 2, 4, 6 g) constant-current electrodeposition (1.5 A/cm 2 ). The coatings were characterized for corrosion behavior in 3.65 % NaCl using linear polarization resistance (LPR) and open circuit potential (OCP), while hardness, microstructure, and phase composition were assessed via Brinell hardness testing, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Results revealed that Zn-20Al 2 O 3 -6CSP significantly outperformed uncoated steel, with polarization resistance increasing from 23.5 Ω cm 2 to 97.2 Ω cm 2 and corrosion rate decreasing from 9.98 mm/year to 1.16 mm/year. Hardness improved by 92 % (to 261.8 kgf/mm 2 ) due to reduced voids and intermetallic phases (ZnO, Al 2 O 3 , MgO, FeO). These findings position CSP as a promising sustainable additive for advanced anti-corrosion coatings, warranting further exploration in marine applications.