A STUDY ON THE EFFECT OF SO^2-₄ ON CREVICE CORROSION OF PURE ALUMINIUM USING WIRE BEAM ELECTRODE

Polarization curves,corrosion potentials and electrochemical impedance spectroscopy inside and outside the crevice of pure aluminium were measured in 2mol/L NaCl and 2mol/L NaCl+0.8mol/L Na2SO4 solutions using potentiodynamic polarization and wire beam electrode techniques.The effect of SO2-4 on crevice corrosion of pure aluminium was studied.Pure aluminium inside and outside the crevice was anode and cathode respectively in NaCl solution.The distribution of corrosion potentials became inhomogeneous gradually with increase of immersion time.Because of the addition of Na2SO4 to NaCl solution,the difference of corrosion potentials inside and outside the crevice decreased and the corrosion rate of pure aluminium was reduced evidently.It was suggested that Na2SO4 was an adsorption inhibitor for pure aluminium in neutral solution,and crevice corrosion of the pure aluminum was restrained availably.