The effect of phosphate ions on the electrochemical behaviour of brass in sulphate solutions

In this study, we have investigated the effect of phosphate ions on the corrosion behaviour of brass in 0.1 M Na2SO4 solution in acidic (pH 2.1), neutral (pH 7.2) and alkaline (pH 12.3) solutions. For this purpose, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) techniques were used. The surface morphology of the metal surface after exposed to corrosive medium was investigated by scanning electron microscopy (SEM). The effect of temperature has also studied in the temperature range from 293 K to 353 K. Some thermodynamic parameters were calculated and discussed. It was found that, PO43− ions could inhibit the corrosion of brass in Na2SO4 solution. However, the inhibition efficiency decreased with increasing temperature. The inhibition effect of PO43− ions was explained by complex formation between phosphate ions and corrosion products which physically adsorbed on the metal surface.