CeO2-Bi2O3 nanocomposite integrated zinc phosphate coating for mitigation of corrosion and wear of mild steel in high-salinity environment

Zinc phosphate coatings are choice of preference in many industrial sectors for their robust anticorrosion performance under harsh conditions. However, the non-uniform thickness and cracks formed in the phosphate crystal layer are the main drawbacks of this coating. The present research details the development of novel zinc phosphate coatings through incorporation of newly synthesized CeO 2 -Bi 2 O 3 nanocomposite. Concentration of this additive was varied between 0.3 g L -1 and 0.9 g L -1 and the performance of resultant coatings were compared with unmodified coating. This nanomaterial enhanced both anticorrosion and wear characteristics of the coatings applied on mild steel. Besides, this additive improved the coating homogeneity, compactness and micro hardness. Exhaustive corrosion analyses results revealed that this additive was most effective at 0.3 g L -1 where it reduced the corrosion current density (I corr ) from 90.55 μA cm -2 to 0.88 μA cm -2 and corrosion rate (CR) from 1.065 mm per year to 0.010 mm per year and increased the polarisation resistance (R p ) from 518 Ω cm 2 to 20568 Ω cm 2 and charge transfer resistance (R ct ) from 114 Ω cm 2 to 23640 Ω cm 2 . The enhanced corrosion protection was supported by durability assessments i.e., accelerated salt-spray and long-term stability tests. The proven modified coating exhibited better tribological properties; it showed 37.5 % reduced friction coefficient and 57 % reduced wear rate compared with unmodified coating for 15 N applied loads under dry condition. The better tribo characteristics of the modified coating recorded under wet condition significantly outperforming the unmodified coating. • CeO 2 –Bi 2 O 3 nanocomposite was proved as a dual functional additive for ZnP coating. • This additive reduced the corrosion rate remarkably compared to unmodified coating. • This additive reduced friction coefficient by 38 % compared to unmodified coating. • Wear rate was reduced by 57 % upon addition of this compound to phosphating bath.