Effect of thermal treatment on the corrosion resistance of polyaniline in H2SO4–HF acid mixture solution

The corrosion resistance and conduction properties of polyaniline (PANi)-coated 316L stainless steel were improved by the thermal treatment. Electrochemical analyses of the PANi specimens demonstrated excellent corrosion resistance with high protection efficiency (⩾96.21%) and charge transfer resistance, as well as a very low corrosion current density (<1 μA/cm2). In addition, it also performed better conductive properties due to lower contact and surface resistance (<5 Ω cm2), comparing with untreated specimens. These were attributed to the presence of the interaction of the carbonyl group with the NH group in PANi as a physical barrier layer, which provides passivity protection in polymer coatings.