INFLUENCE OF CONCENTRATION OF Na2CO3 ON CORROSION OF X70 STEEL

The corrosion behavior of X70 steel was studied by means of Tafel polarization,anodic linear potential sweep and EIS.With the increase of concentration of Na2CO3,the corrosion rate decreased firstly and then increased,while the corrosion potential increased firstly and then decreased.When the concentration of Na2CO3 was low,the Nyquist diagram was composed of a capacitive loop and an inductive loop.When the concentration of Na2CO3 was 0.1 mol/L,X70 steel began to be passivated,and the Nyquist diagram consisted of a single capacitive loop.When the concentration of Na2CO3 was higher,the capacitive loop became smaller,and the passivation was more difficult to occur.