INVESTIGATION OF THE PROCESSES OF OBTAINING PLASTIC TREATMENT AND ELECTROCHEMICAL-BEHAVIOR OF LEAD ALLOYS IN THEIR CAPACITY AS ANODES DURING THE ELECTRO-EXTRACTION OF ZINC .1. BEHAVIOR OF PB-AG, PB-CA AND PB-AG-CA ALLOYS

The influence of the mode of obtaining and plastic treatment of binary Pb-Ag and Pb-Ca, and ternary Pb-Ag-Ca alloys (used as anodes in Zn el ectro-extraction from sulphate electrolytes) on their electrochemical behaviour and corrosion resistance is studied. It has been established that the rolled Pb-Ag alloys possess a higher corrosion resistance an d lower anodic polarization compared to the cast lead-silver ones due to the structural fineness and homogeneity of the plastic deformed ano des. The plastic deformation of the ternary alloys with calcium conten t of 0.06% causes Pb3Ca precipitation in the solid solution. The hot-r olled alloys form an alpha-solid solution of Pb3Ca with fine-grained s tructure, deformed through the rolling direction. The cold-rolled allo ys possess clearly expressed oriented structures also through the roll ing direction. Cast and plastically deformed Pb-Ca anodes possess bett er electrochemical and corrosion characteristics than pure Pb but a co nsiderably higher anodic polarization and lower corrosion resistance t han Pb-Ag alloys. Both Pb-Ca systems, with a calcium content of 0.08 a nd 0.11% are very appropriate for the preparation of ternary Pb-Ag-Ca alloys. These alloys (Pb-Ag 0.5%-Ca 0.11%) possess better electrochemi cal and corrosion characteristics than binary Pb-Ca ones; Only ternary rolled alloys have equal corrosion and electrochemical properties to those of the alloy Pb-Ag (0.75-1.0%) used in practice.