Effect of SO₃^2- Concentration on Corrosion Behavior of 5052 AluminumAlloy in Alternating Electric Field with Cyclic Wet-Dry Condition

The corrosive solution containing chlorine with pH 4.0 and 400 kV·m^-1 alternating electric field were used to simulate the industrial transmission environment. The effect of SO₃^2- concentration (0.005,0.010,0.020,0.050,0.100 mol·L^-1) on corrosion behavior of 5052 aluminum alloy in alternating electric field with cyclic wet-dry condition was studied. The results show that with the increase of SO₃^2- concentration, the corrosion mass increment, free-corrosion potential, solution resistance, and charge transfer resistance of 5052 aluminum alloy increased first and then decreased, while the free-corrosion current density and corrosion rate decreased first and then increased. When the concentration of SO₃^2- was from 0.005 to 0.020 mol·L^-1, the main corrosion was the pitting corrosion, and cracked corrosion products of Al₂O₃ and Al₂O₃·3H₂O began to appear in pitting pits. When the concentration of SO₃^2- continued to increase, the corrosion pits on the surface of the alloy were reduced, and the cracked corrosion products being tightly bound to the substrate with composition of Al₂O₃ · 3H₂O were increased. The corrosion rate and degree of the alloy were both the smallest when the concentration of SO₃^2- was 0.020 mol·L^-1.