Properties of a new type A1/Pb-0.3%Ag alloy composite anode for zinc electrowinning

An A1/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corro- sion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode （hard anodizing） dis- plays a more compact interracial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of A1/Pb-0.3%Ag alloy （hard anodizing） and A1/Pb-0.3%Ag alloy （plating tin） at 500 A.m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, A1/Pb-0.3%Ag alloy （hard anodizing）, and A1/Pb-0.3%Ag alloy （plating tin） were 13.977, 9.487, and 11.824 g.m-2.h-1, respectively, in accelerated corrosion test for 8 h at 2000 A-m-2. The anodic oxidation layer of A1/Pb-0.3%Ag alloy （hard anodizing） is more compact than Pb-0.3%Ag alloy and A1/Pb-0.3%Ag alloy （plating tin） after the test.