Electrodeposited ZIF-67 Reinforced Polypyrrole Coating on Ferritic Stainless Steel Substrate with Durable Anticorrosion Performance

Abstract

The harsh acidic environment containing chloride ions has created serious corrosion hazards for ferritic stainless steels. Zeolitic imidazole frameworks (ZIFs) are a promising material for corrosion protection due to their microstructural and physicochemical properties. In this study, we proposed the electrodeposited ZIF-67 reinforced polypyrrole (PPY) coating (PPY/ZIF-67) for corrosion protection of 430 ferritic stainless steel (430SS). The morphology, microstructure, and anticorrosion behavior of the pristine PPY and hybrid PPY/ZIF-67 coating systems were characterized. The potentiostatically deposited ZIF-67 nanoparticles on top of the PPY layer facilitated the coatings’ homogeneity and enhanced both the barrier and active inhibition functions of the coating. The protective performance of PPY/ZIF-67 coatings was assessed by electrochemical tests, the results indicated that the anticorrosion efficiency of PPY/ZIF-67 coating (with 0.4 mol/L pyrrole monomer content) reached to 99%, and the coating demonstrated a long-term protection ability (744 h) in 0.1 mol/L HCl solution. Such performance of can be attributed to the combined effect of the anodic protection provided by the inner PPY film, the active corrosion inhibiting properties of the ZIF-67 nanoparticle layer, and the hindrance of aggressive species by the compact coating structure over the prolonged service time.

Keywords: ZIF-67, Polypyrrole, coating, inhibitor, Anticorrosion behavior