ELECTRO-CHEMICAL CORROSION BEHAVIOR OF Zn-BASED ALLOYS FOR MEDICAL APPLICATIONS

Ramona Cimpoesu, Tiberiu Șutic, Romeu Chelariu, Gheorghe Bădărău, Mihai Axinte, Nicanor Cimpoesu

1 Materials Science Department, Materials Science and Engineering Faculty, Technical University Gheorghe Asachi from Iasi, Blv. Mangeron , 700050, Iasi, Romania, nicanor.cimpoesu@academic.tuiasi.ro

Introduction. Zinc-based alloys have emerged as a promising class of biodegradable materials for temporary medical implants, filling the degradation rate gap between magnesium and iron-based alloys [1]. This study focuses on the chemical and electrochemical corrosion behavior of a newly developed Zn-based alloy system, evaluated under simulated physiological conditions.

Experimental. The chemical degradation was assessed through immersion tests in various media, including Dulbecco’s Phosphate Buffered Saline (10xDPBS), Ringer’s solution, and Simulated Body Fluid (SBF) at 37°C.

Results and Discussion. Results indicated a multi-stage degradation process characterized by the initial formation of a passivation layer consisting mainly of zinc phosphates (Zn3(PO4)2), simonkolleite (Zn5(OH)8Cl2·H2O), and carbonates. Chemical analysis revealed that the addition of Mg and Y promotes the formation of a more stable and compact corrosion product layer, which effectively regulates the ion release rate into the surrounding environment. Electrochemical investigations, including Potentiodynamic Polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS), were employed to determine the corrosion kinetics. The polarization curves exhibited typical active-passive behavior, with corrosion currents (Icorr) indicating a moderate degradation rate (0.12–0.25 mm/year), suitable for bone healing timelines. EIS data revealed that the corrosion mechanism is controlled by charge transfer and mass transport through the porous layer of corrosion products. The presence of intermetallic phases, such as Mg2Zn11 and YZn12, was found to initiate localized micro-galvanic cells, influencing the overall pitting resistance [2].

Conclusions. Zn-Mg-Y alloys demonstrate a controllable corrosion behavior dictated by the synergistic effect of their chemical composition and the protective nature of the precipitated surface layers. These findings support the potential of Zn-based alloys as viable candidates for biodegradable orthopedic fixations [3]. 

Acknowledgement: This work was supported by a grant of the Ministry of Education and Research, CCCDI-UEFISCDI, project number PN-IV-P6-6.1-CoEx-2024-0102 within PNCDI IV.

.   

References.

[1] Yang, H.; Jia, B.; Zhang, Z.; Qu, X.; Li, G.; Lin, W.; Zhu, D.; Dai, K.; Zheng, Y. Alloying design of biodegradable zinc as promising bone implants for load-bearing applications. Nature Communications (2020) 11, 401. 

[2] Panaghie, C.; Cimpoes,u, R.; Istrate, B.; Cimpoes,u, N.; Bernevig, M.A.; Zegan, G.; Roman, A.M.; Chelariu, R.; Sodor, A. New Zn3Mg-xY Alloys: Characteristics, Microstructural Evolution and Corrosion Behavior. Materials 2021b, 14, 2505. 

[3] Prakasam, M., Locs, J., Salma-Ancane, K., Loca, D., Largeteu, A., Bezina-Cimdina, L., Biodegradable Materials and Metallic Implants—A Review. Funct. Biomater. 2017, 8(4), 44.