Electrodeposited ZIF-67 reinforced polypyrrole coating on ferritic stainless steel substrate with durable anticorrosion performance

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 successful electrodeposition of ZIF-67 nanoparticles on the surface of the PPY layer resulted in a uniform distribution and a compact coating structure, which contributed to the overall uniformity of the coating and enhanced both the barrier and activity inhibition functions of the coating. The protective performance of PPY/ZIF-67 coatings was evaluated through 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 durable corrosion 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.