The inhibition effect of calcium as an alloy element of aluminum and its cooperative effect with taitrate in an alkaline solution were systematically investigated by hydrogen collection, polarization curve and EIS. The experimental results show that the corrosion rate decreases with the increase of calcium content. When the electrolyte contains no tartrate, the inhibition effect of calcium on the cathodic process is much stronger than that on the anodic process. However, when the electrolyte contains tartrate (0.05 mol·L~(-1)), both the anodic and cathodic process is greatly inhibited. The analysis on the EIS reveals that the calcium ion or calcium tartrate complex ion takes its effect by reducing the reaction rates on the active sites, which indicates that they probably belong to interface inhibitor rather than interphase one.

Key words: ALUMINIUM, CALCIUM, TARTARIC ACID, CORROSION INHIBITORS, COOPERATIVITY, IMPEDANCE