ELECTROCHEMICAL NOISE OF AZ31 MAGNESIUM ALLOY IN NaCl SOLUTION

The corrosion process of AZ31 magnesium alloy in neutral 0.1 mol/L NaCl solutions were investigated using electrochemical noise(EN)technique.The results showed that electrochemical noise signal is composed of distinct types of events which can be classified according to their scales,i.e.their time constants.At the beginning of corrosion,the maximum relative energy is defined in the low-frequency(crystals with high scale)region due to the diffusion processes of aggressive ions to the defects of the original discrete film formed in air,while the D crystals of small timescales also possesses high relative energy due to the pitting corrosion.With the prolongation of immersion time,the structure of corrosion product layer changes(local spallation,growth)due to the influence of H2 and aggressive solutions,the accumulated position of the maximum relative energy changes synchronously.