Effect of Sodium Laurate on Characters of Deposits on Surface of N80 Steel in NaCl Solutions

The effect of sodium laurate on characters of deposits on the surface of N80 steel in NaCl solution was studied by means of atomic force microscopy(AFM) and ion-selectivity measurement of the deposits.The results showed that C_(12)H_(23)O_2~- could adsorb and migrate into the occluded cavity under the deposit in NaCl solution,therewith decreased the roughness and the phase contrast of the occluded anode surface,and inhibited the corrosion processes on it.C_(12)H_(23)O_2~- could change the deposit layer from anion selectivity to cation selectivity,which prevented Cl~- migrating into OCC,thereby inhibited the auto-catalyzing acidification effect in it.Meanwhile, a hydrophobic layer on the deposit surface could form through directional arrangement of alkyl chain by the adsorption of C_(12)H_(23)O_2~-,which might increase the resistance to ion migration through the deposit.A physical model was proposed to describe the surface of deposits to explain the mechanism of corrosion inhibition of C_(12)H_(23)O_2~- preferably.