Zinc alloy was the main cathodic protection material in concrete environment. Zn-Al alloy, as a sacrificial anode material, had high current efficiency and low polarizability, and its performance was similar to that of pure zinc. However, the existence of impurity elements such as Fe and Cu in the anode material of Zn-Al alloy affected its corrosion solubility and electrochemical performance seriously, which directly affected the service life of reinforced concrete structures. Therefore, the alloying technology to eliminate the influence of impurity elements, could be used to improve the electrochemical and mechanical properties of Zn-Al alloy, besides make its applicance more widely. The development of cathodic protection technology was one of the effective measures for the protection of reinforced concrete structures in the future.This study based on the theory of the alloying of metals, and the combination of sacrificial anode cathodic protection technology in the practical application of anti-corrosion of reinforced concrete structure, starting from the electrochemical performance of cathodic protection materials, anode materials for zinc alloy, effects on the electrochemical properties of impurity element in Zn-Al alloy anode material as the research object, the preparation of different contents of rare earth ( La, Ce) of Zn-Al alloy anode material, and using optical microscope (OM), X-ray fluorescence (XRF) and scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. The effects of mixed rare earth (La, Ce) on the anodic dissolution morphology, corrosion resistance and electrochemical properties of Zn-Al alloy were investigated by electrochemical measurement, such as galvanostatic corrosion test, electrochemical polarization curve test and electrochemical impedance spectroscopy test.Through the analysis of the above different test methods, the research conclusions were as follows: (1) It could be seen from the metallographic structure photos of the anode material of Zn-Al alloy that the addition of rare earth elements (La, Ce) could obviously refine the structure of the anode of Zn-Al alloy and improve the uniformity of the structure; (2) The constant current corrosion experiments showed that rare earth elements addition could increase current efficiency, improve surface morphology dissolving, and make the zinc-Al alloy anode material had the potential of negative work, when rare earth content was 0.6%, the current efficiency was 96.77%, the working potential was -1.02 ~ -1.05 V, the dissolved surface morphology was good and the electrochemical performance was the best; (3) The influence of rare earth elements on the corrosion resistance of Zn-Al alloy anode material was studied by polarization curve test and impedance test. The results showed that the addition of rare earth elements could improve the polarization resistance of Zn-Al alloy anode material, reduce the self-corrosion current density, and thus improve the corrosion resistance of Zn-Al alloy anode material. (4) The results of XRD, SEM of corrosion products, combining with the corrosion reaction mechanism, showed that the addition of rare earth elements could affect the formation of corrosion products and the surface distribution of the compactness. Appropriate addition of rare earth elements could make the corrosion product layer have active anticorrosive performance, reduce the corrosion activity, and thus helped to improve the corrosion resistance of matrix. It could be seen from the SEM images of corrosion products that when the addition amount of rare earth was 0.6%, the surface corrosion product layer was dense, thus the corrosion resistance was better, which also conformed to the results of polarization curve and impedance test. The main reason was that the addition of rare earth elements (La, Ce) had an obvious thinning effect on the anodic structure of Zn-Al alloy, and the corrosion product layer on the surface had an active anti-corrosion performance, which reduced the corrosion activity. The performance optimzation of zinc anode materials was mainly concentrated in alloying methods.And compared with the conventional elements, the rare earth elements could restrain the harmful elements, fine grains, increase the strength of the alloy, hardness and toughness, to provide various performance alloy with a significant role. Therefore, in this paper, by adding mixed rare earth (La, Ce) to Zn-Al alloy, the influence of mixed rare earth on the electrochemical properties of Zn-Al alloy anode was studied, thus providing a relevant reference for the study of rare earth modified Zn-Al alloy anode materials. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.
