The Properties Of Lead-based Rare Earth Alloy Anode For Zinc Electrodeposition

The lead-based porous electrodes made by our group has some advantages compared with the traditional plate electrode, like lower anode potential, better corrosion resistance, less cathode sludge and high quality of zinc, it has great application value. But it cannot apply to industrial production because of the low-strength. Therefore, The research of this article enhancing the material using proper sort, proper quantity of rare earth not only promote lead-based application process of industrialization, but also developing new rare earth applications, broaden the scope of application of rare earth metal.So,it has a great significance.In this article, lead-based rare earth alloys was made by two-step melting of different species (Pr, Gd, Nd, Sm) and content (0.1%,0.5%, 1.0%,1.5%,2.0%) and research of tensile strength, corrosion rate, anode potential, crystal structure, corrosion film morphology, amount of coating film was made to find out how the addition of rare earth affect the properties of lead alloys. And based on this study, we choosed the project of Pr2.0% and Gd2.0%.Then, the properties of lead based Rare earth alloy with different content of silver anode was reserched. So far, The results are as follows.(1) The formation of metal compounds between rare earth and lead can enhance the intensity of lead alloy by refining grains and preventing grain sliding. Among the four rare earth elements, Pr and Gd have a great influence to the enhancing intensity. Compared to pure lead, intensity of alloy content of 2.0% Pr, Gd increased 78.55%,59.4%.(2) Pr, Gd, Sm have inhibiting effect to oxygen evolution reaction, but they can promote the formation of PbO2, make PbO2 layer porosity and restrain the formation of high-impedance PbO and PbSO4, making the potential of lead alloy anode dropped significantly. But the loose film can decrease corrosion resistance of the anode.(3) Low content of Nd can make the film smooth and improve the corrosion resistance of lead anode, but when the content of Nd is more than 1.0%, there comes a lot of dissolving area like crater on the film surface, making the corrosion resistance of lead alloy dropped significantly. Nd can promote the oxygen evolution reaction, high-content of Nd can promote the formation of PbO2 and restrain the formation of high-impedance PbO and PbSO4, making the potential of lead alloy anode dropped significantly.(4) The addition of rare earth elements Pr, Gd can change the crystallization of Pb-Ag alloy, making the a-solid solution phase arranged in grid. Compared with neatly strips of Pb-Ag alloy, the grid structure have a better effect to prevent grain sliding, the intensity of alloy was enhanced consequently. The anode potential of Pb-Ag alloy containing Pr and Gd is lower than Pb-Ag alloy and the corrosion rate is short odds, so we can use rare earth elements to reinforce the porous lead anode.(5) This article presents a new model of formation of anode film under constant current polarization.