2026-06-08T04:51:30Zhttps://docta.ucm.es/rest/oai/request

oai:docta.ucm.es:20.500.14352/1190232025-03-29T00:57:22Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc Guerra-Mutis, Marlon Hernando author Vega Vega, Jesus Manuel author Barrena Pérez, María Isabel author Matykina, Endzhe author Arrabal Durán, Raúl author 2025-01-31 In this study, a phosphate-based conversion coating (PCC) was applied as a precursor before forming silicate-fluoride (SiF) and silicate-phosphate-fluoride (SiPF) based flash-plasma electrolytic oxidation (Flash-PEO) coatings on AZ31B magnesium alloy. The main novelty is the successful incorporation of calcium, zinc, manganese and phosphate species into the Flash-PEO coatings via a precursor layer rather than using the electrolyte. The precursor also led to longer lasting and more intense discharges during the PEO process, resulting in increased pore size. Corrosion studies revealed similar short-term performance for all coatings, with impedance modulus at low frequencies above 10^7 Ωcm2, and slightly better performance for the SiPF-based coating. Nonetheless, the enlarged pores in the PEO coatings functionalized with the PCC precursor compromised the effectiveness of self-healing mechanisms by creating diffusion pathways for corrosive species, leading to earlier failure. These phenomena were effectively monitored by recording the open circuit potential during immersion in 0.5 wt.% NaCl solution. In summary, this study demonstrates that conversion coatings are a viable option for the functionalization of PEO coatings on magnesium alloys, as they allow for the incorporation of cationic and other species. However, it is crucial to maintain a small pore size to facilitate effective blockage through self-healing mechanisms. M.H. Guerra-Mutis, J.M. Vega, M.I. Barrena, E. Matykina, R. Arrabal, Flash-PEO of magnesium: Phosphate precursor driven functionalization, Journal of Magnesium and Alloys, 13 (2) (2025) 592-612. https://doi.org/10.1016/j.jma.2025.01.007. 10.1016/j.jma.2025.01.007 https://hdl.handle.net/20.500.14352/119023 2213-9567 https://doi.org/10.1016/j.jma.2025.01.007 https://www.sciencedirect.com/science/article/pii/S2213956725000210 Flash-PEO of magnesium: Phosphate precursor driven functionalization