Inhibiting ability of sodium dodecyl benzene sulfonate to AZ31 magnesium alloy

The electrochemical properties of AZ31 alloy in MgSO4 solution and the inhibiting ability of sodium dodecyl benzene sulfonate (SDBS) to the alloy were investigated by weight-loss measurement, linear sweep voltammetry (LSV), chronopotentiometry and electrochemical impedance spectroscopy (EIS). The results show that a small quantity of SDBS could make the open circuit and active potential more positive, polar resistance bigger, the bubbling of hydrogen on the surface of electrode was. restrained, resulting in the performance of discharge at high current density was improved. In studied concentration range of SDBS, there was an "anti-S" shape rule between the concentration and the inhibiting ability to AZ31 alloy. When the concentration was less than 0.1 mmol/L, the inhibiting ability gradually enhanced; when between 0.1 similar to 0.2 mmol/L, the inhibiting ability reduced; when more than 0.2 mmol/L, the ability increased again. The phenomenon could be attributed to the nonsynchronous change between the resistance of relaxation process of adsorbed species on the electrode surface and the resistance of charge transfer. The current efficiency of discharge at 50 mA/cm(2) was bigger than 73%, which implied the actual utilization of AZ31 alloy in metal fuel cells.