Corrosion performance of epoxy-Cu-Zn-AI2O3 nanocomposite as coating for welded steel

Applying an epoxy coating can provide corrosion protection to welded steel. The use of an epoxy-composite filler coating is a promising solution that may facilitate homogenous dispersion over the surface of a welded joint by giving long-term protection and preventing microcrack problems from occurring. The epoxy-Cu-Zn-Al2O3 coating and its corrosion performance on welded steel are developed and characterized in this work. The aim of this study is to evaluate the effectiveness of epoxy coating added Cu-Zn-Al2O3 powder at different compositions (0.5wt%, 0.7wt%, 1.0wt%, and 2.0wt%). Cu-Zn-Al2O3 reinforcement was milled at 300 rpm for 40 h, then combined with epoxy to create a film that was applied on the welded steel surface. The as-milled Cu-Zn-Al2O3 and epoxy-Cu-Zn-Al2O3 nanocomposite films were characterized for their phase identification, morphology, and functional group. An immersion test was carried out for 30 days for all the coated welded steel. The study indicated that the Cu-Zn-Al2O3 nanocomposite powder undergoes structural and morphological changes during the milling process. The particles are homogenously distributed in the epoxy and play an important role in changing its structure, shape, and functional group. The nanocomposite with 2.0 wt% Cu-Zn-Al2O3 in epoxy has the highest hardness that is 50.2H and is suitable for a welded steel protective coating due to its hardening effect. The higher amount of Cu-Zn-Al2O3 improves the hardenability of the reinforced phase and contributes to slightly reduced weight loss during immersion in NaOH.