Corrosion behaviour of magnesium sacrificial anode in chloride media and sea water

Full text.The electrochemical behaviour of magnesium sacrificial anode (Mg) was investigated by means of potentiodynamic, potentiostatic techniques, completed by Evan's diagrams (under galvanic coupling conditions) and S.E.M. observations. Corrosion morphology of the anodes is related to the shape of the potentiodynamic polarization curves. Potentiostatic tests were carried out at different characteristic potential regions as defined by Pourbaix concept. Homogenous corrosion has been observed for the Mg anode and the roughness of the surface was related to hydrogen formation. The intentiostatic curves made it possible to evaluate the anodes efficiency as function of the current flow. The obtained Evan's diagrams are discussed taking into account the polarization effects at the electrodes for different experimental conditions