Enhanced corrosion resistance of copper by synergetic effects of silica and BTA codoped in polypyrrole film

Conductive polypyrrole (PPy) composite films were electrodeposited on copper together with BTA or/and silica by cyclic voltammetry in salicylate solution. The corrosion resistance and electrical conductivity of the composite films were assessed by use of polarisation curves, open circuit potential (OCP) measurements and electrochemical impedance spectroscopy in 5 wt% NaCl solution. It was found that the sole doping of benzotriazole (BTA) or silica in PPy film merely improved corrosion resistance slightly, but the codoping of BTA and silica in PPy film can significantly enhance the corrosion resistance and electrical conductivity of the composite film. Salt spraying test (SST) confirmed that the ternary composite film exhibited the best anti-corrosion performance and durability, which was attributed to the synergetic effect from the physical barrier of silica and the active protection of BTA inhibitor.