The Inhibitive Effect of Cerium Carbonate on the Corrosion of Brass in 3% NaCl Solution

We investigated the protective efficiency of a new class of 'green' corrosion inhibitors on Copper-Zinc alloy (Brass). The inhibition effect of cerium carbonate (CAC) on Brass in 3% NaCl solution was investigated at room temperature both by potentiodynamic polarisation and impedance spectroscopy (EIS) methods and weight loss measurements. The surface analysis was made by scanning electron microscope and micro-Raman spectroscopy. The electrochemical measurements showed that the CAC decreases the density of the corrosion current and thus acts as a mixed type inhibitor. The CAC inhibits the corrosion of Brass by blocking the active sites of the metal surface with a maximum inhibitory efficiency of 84%, obtained with the concentration of 100 ppm of the inhibitor. The corrosion rate decreased by a factor of 3.5 in the presence of CAC, suggesting that the investigated method is promising. The mechanism of inhibition effect is attributed to adsorption of Ce-hydroxides in the excess of OH- production from the cathodic reactions of water reduction and O-2. This hydroxide precipitates subsequently as a barrier against the corrosion of the active regions.