SO₄^2-イオンを含んだ溶液中でのアルミニウム合金の孔食発生に関する電気化学的検討

抄録

To investigate the effect of SO₄^2- ion on pitting corrosion behavior of aluminum and aluminum alloy brazing sheets immersion corrosion test and electrochemical measurements were carried out in the solution of lower chloride concentration containing SO₄^2- ion. As the SO₄^2- ion reduced the anodic and cathodic reaction rate, the pitting corrosion resistance of aluminum increased. The pitting corrosion occurred even in solution containing SO₄^2- when the cathodic reaction was high enough. In that case the pitting corrosion rate was much higher than that in the SO₄^2- ion free solution. Higher pitting corrosion rate induced by SO₄^2- ion was due to the lower pitting corrosion density which was closely related with the thicker oxide film formed on aluminum surface. The probability of pitting corrosion was estimated with the relation between E_corr and E_rep value in anodic polarization measurement in the solution.