Improved bioactivity and corrosion resistance of NbO containing plasma electrolytic oxidation coating on ZM21 Mg alloy

ABSTRACT

The present study reports the effect of niobium oxide (NbO) phase on the microstructure, corrosion, and bioactivity of coating on ZM21 Mg alloy by plasma electrolytic oxidation (PEO) process. NbO containing coatings are obtained by adding Potassium Niobate (KNbO₃) along with the base electrolyte system, while the base electrolyte system consisted of sodium phosphate (Na₃PO₄⋅12 H₂O) and potassium hydroxide (KOH). X-Ray Diffraction (XRD) was used for phase analysis, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) was employed to extract the microstructural features. Tafel curves were generated to study the corrosion behaviour, and bioactivity test was conducted in the simulated body fluid (SBF) for 14 days to study the bioactivity. XRD results revealed that the PEO coatings consisted of MgO phase, whereas the sample coated in the electrolyte containing KNbO₃ showed NbO phase in addition to MgO phase. NbO containing coating showed higher corrosion resistance and excellent bioactivity.

KEYWORDS:

• Plasma electrolytic oxidation
• niobium oxide
• ZM21
• bioactivity
• corrosion

Disclosure statement

No potential conflict of interest was reported by the author(s).