Enhanced Anticorrosion, Antifouling, and Tribological Properties of PANI Composite Coating Reinforced by PVA, 2-Aminophenol, and Acrylic to Fabricate Sustainable Passive Film on 304 SS

An anti-corrosion and electroactive coating of PANI/PVA was electrodeposited on the 304 SS to improve the interface passive film. However, due to poor physical stability and tribological properties, PANI/PVA is copolymerized by various amounts (0.25–1 M) of 2-aminophenol (2-AP) and covered by a thin layer of acrylic (AC). According to the results, not only is the corrosion resistance of PANI/PVA/AP@AC about 100 times higher than PANI/PVA in 3.5 wt % NaCl (EIS), but its wear rate has also decreased by ∼60% (pin-on-disk). Moreover, the friction coefficient of PANI/PVA/AP@AC has increased by 40% compared to PANI/PVA. The adhesion energy of PANI/PVA/AP@AC to the substrate is ∼34% higher than that of PANI/PVA (pull-off). In addition, the nickel content of passive film under PANI/PVA/AP@AC reached 4.7% from ∼0% for PANI/PVA (EDS). The defect density of the passive film decreased ∼100 times by increasing the concentration of 2-AP to 1 M (Mott–Schottky). Moreover, uncoated 304 SS was protected galvanically with SS@PANI/PVA/AP@AC (with noise corrosion resistance of Rn ∼ 106 Ω according to the galvanic corrosion evaluation). Finally, PANI/PVA/AP@AC remained intact after 160 h of immersion in the NaCl, and its potential reached +200 mV (electrochemical potentiometry). Therefore, PANI/PVA/AP@AC as a hybrid composite coating can sustain in situ anodic protection of 304 SS under harsh environmental conditions.