The influence of tin and silver as microstructure modifiers on the corrosion rate of Pb–Ca alloys in sulfuric acid solutions

Abstract

The effect of microstructure modifiers, Sn and Ag, on the corrosion rate of commercial Pb-Ca alloy in H 2 SO 4 electrolyte was investigated by the potentiodynamic polarization and by the weight loss corrosion rate measurement at the open circuit potential. The effect of microstructure modification of the Pb-Ca alloy, provoked by the alloying with tin and silver as well as by the proper thermo-mechanical treatment, is recorded by optical microscopy. The weight loss experiments have shown three-to five-fold decreases in the corrosion rate of ternary Pb-Ca-Sn and quaternary Pb-Ca-SnAg alloys, compared to the results for primary Pb-Ca alloy. It is largely in accordance with the results of potentiodynamic polarization measurements that showed comparable decrease in the passive current density of the modified alloys. The obtained results are discussed in terms of the synergetic effect of the addition of modifiers and the thermo-mechanical treatment on to the Pb-Ca alloy microstructure refinement, and accordingly the increase in their corrosion resistance.

The Role of Electrolyte Hydrodynamic Properties on the Performance of Lead-Based Anodes in Electrometallurgical Processes

“…Higher conductivity of the lead dioxide layer in the presence of tin can be a reason for this behavior, while calcium has a negative effect on conductivity of the surface layer. 21,35 Furthermore, the presence of tin is shown to modify the PbO 2 layer formed on the surface of the lead anodes. 36,37 Tin increases the ratio of α-PbO 2 / β-PbO 2 in the corroded surface layer.…”

“…This is in agreement with previous observations that the presence of tin results in more formation of α-PbO 2 . 21,23,37 Formation of higher amounts of PbSO 4 and PbO 2 as a result of oxidation shows faster electrochemical reactions on the surface of Pb-Sn-Ca alloy at initial stages of anodic polarization compared to Pb-Ca alloy. Effect of solution hydrodynamics.-Figure 3 shows potential variation of Pb-Sn-Ca and Pb-Ca alloys during anodic polarization in stagnant and stirred solutions (600 and 1000 rpm) under constant current density of 50 mA/cm 2 .…”

“…Pb-1.5-2 wt% Sn shows the best mechanical properties among Pb-Sn alloys. 15,16,[20][21][22] Mohammadi et al 10 concluded that only a small portion of the applied current (0.05-0.1%) is consumed by the electrochemical oxidation of lead to lead sulfate and lead dioxide. An overestimation occurs if the anodes service life is calculated based on this portion of the applied current density.…”

Electrochemical and Metallurgical Behavior of Lead-Aluminum Casting Alloys as Grids for Lead-Acid Batteries

“…Also, this type of alloys allow to make much lighter batteries. M. I. Čekerevac et al [6] and R. David Prengaman [7] have studied the influence of the addition of tin and silver on the corrosion rate of Pb by modifying its microstructure. They have found that, indeed, Pb-Ca-Sn-Ag alloys are more resistant to corrosion in comparison with pure Pb, and that by increasing the concentration of the added Sn and Ag, the microstructure of the primary alloy Pb-Ca is modified in a positive way.…”

Corrosion behaviour and catalytic effectiveness of Pb–Ca–Sn, RuO2–IrO2/Ti and IrO2–Ta2O5/Ti anodes for copper electrowinning

“…The effect of microstructure modifiers, such as Sn and Ag, on the corrosion rate of commercial Pb–Ca alloys in sulphuric acid, was studied by Cekerevac et al 10 Alloying caused a three- to fivefold decrease in the corrosion rate of Pb–Ca alloys due to its effect on the passive CD.…”