Calcium Doped Flash-PEO Coatings for Corrosion Protection of Mg Alloy

Metals

卷:10

Endzhe Matykina¹  Raul Arrabal¹  Borja Pillado¹  Ewa Wierzbicka¹  Marta Mohedano¹ 

[1] Departamento de Ingeniería Química y de Materiales, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain;

关键词: magnesium;    coating;    plasma electrolytic oxidation;    flash-PEO;    corrosion;    calcium;   

DOI  :  10.3390/met10070916

来源: DOAJ

【 摘 要 】

This study demonstrates a significant improvement of the corrosion resistance of an AZ31B magnesium alloy achieved by the application of 1 μm-thin coatings generated by an environmentally friendly flash plasma electrolytic oxidation (FPEO) process in Ca-containing electrolytes. Two compounds with different solubility, calcium oxide (CaO) or calcium glycerophosphate (CaGlyP), were used as sources of Ca in the electrolyte. Very short durations (20–45 s) of the FPEO process were employed with the aim of limiting the energy consumption. The corrosion performance of the developed coatings was compared with that of a commercial conversion coating (CC) of similar thickness. The viability of the coatings in a full system protection approach, consisting of FPEO combined with an inhibitor-free epoxy primer, was verified in neutral salt spray and paint adhesion tests. The superior corrosion performance of the FPEO_CaGlyP coating, both as a stand-alone coating and as a full system, was attributed to the formation of a greater complexity of Ca²⁺ bonds with SiO₂ and PO₄³⁻ species within the MgO ceramic network during the in situ incorporation of Ca into the coating from a double chelated electrolyte and the resultant difficulties with the hydrolysis of such a network. The deterioration of the FPEO_CaGlyP coating during immersion was found over ten times slower compared with Ca-free flash-PEO coating.

【 授权许可】

Unknown