Flash-PEO of magnesium:Phosphate precursor driven functionalization  

作　　者：M.H.Guerra-Mutis J.M.Vega M.I.Barrena E.Matykina R.Arrabal 

机构地区：[1]Departamento de Ingeniería Química y de Materiales,Facultad de Ciencias Químicas,Universidad Complutense de Madrid,28040,Spain

出　　处：《Journal of Magnesium and Alloys》2025年第2期592-612,共21页镁合金学报(英文)

基　　金：support of the PID2021-124341OB-C22/AEI/10.13039/501100011033/FEDER,UE(MICIU);J.M.Vega also acknowledges the Grant RYC2021-034384-I funded by MICIU/AEI/10.13039/501100011033 and by“European Union Next Generation EU/PRTR”.

摘　　要：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 107Ωcm^(2),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.

关 键 词：AZ31B magnesium alloy PHOSPHATES Chemical conversion coating Flash plasma electrolytic oxidation Electrochemical impedance spectroscopy Transmission electron microscopy 

分 类 号：TG174.4[金属学及工艺—金属表面处理]