The inhibitive effect of polyelectrolyte on the corrosive performance of brass within acid solution

Electrochemical measurements were performed to investigate the effectiveness of the anionic polyelectrolyte (polianethol sulphonate) NaPAS as a corrosion inhibitor for Cu40Zn alloy within a simulated urban rain solution (pH = 5). Two different electrochemical methods were used, classical potentiodynamic measurement and electrochemical impedance spectroscopy. ATR-FTIR analysis was utilised to confirm the presence of some functional groups present in the formed adsorbed layer on the Cu40Zn surface which could act as an active corrosion inhibitor. The concentrations of polyelectrolyte NaPAS (chosen as an inhibitor) which were added to the corrosive medium were 0.01, 0.05 and 0.1 wt%. A reduction of the corrosion current of an order of magnitude icorr was observed for the chosen mixtures compared to the blank solution. Polarisation curves reveal that the chosen inhibitors are a mixed type of inhibitor when the concentration of added NaPAS was higher than 0.01 wt%. The mixtures studied showed good inhibition properties for the sampled system, increasing from 40 to 90%.