Comparative Study of Strontium- and Chromium-Modified PEO Coatings on Mg Alloys for Photocatalytic Degradation of Methylene Blue
Journal of Ultrafine Grained and Nanostructured Materials, cilt.59, sa.1, ss.41-48, 2026 (Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 59 Sayı: 1
- Basım Tarihi: 2026
- Doi Numarası: 10.22059/jufgnsm.2026.01.04
- Dergi Adı: Journal of Ultrafine Grained and Nanostructured Materials
- Derginin Tarandığı İndeksler: Scopus, Applied Science & Technology Source, Directory of Open Access Journals
- Sayfa Sayıları: ss.41-48
- Anahtar Kelimeler: AZ31B Mg alloy, Methylene blue, Photocatalytic, Plasma electrolytic oxidation (PEO)
- Atatürk Üniversitesi Adresli: Evet
Özet
In this study, plasma electrolytic oxidation (PEO) coatings were developed on AZ31B Mg alloy under a constant current density of 12 A·dm-2 in a phosphate-based electrolyte, with modifications introduced by strontium (Sr) and chromium (Cr) ions. Three coating types were obtained: unmodified (12A), Sr-modified (12A-Sr), and Cr-modified (12A-Cr). All coatings exhibited porous and micro-cracked morphologies, characteristic of oxide ejection and rapid solidification during the PEO process. Grazing-angle X-ray diffraction (GXRD) confirmed the presence of MgO and ZnAl2O4 phases. Surface characterization revealed that the 12A-Sr coating displayed pronounced hydrophobicity (contact angle ≈115°), attributed to chemical and microstructural modifications that enhanced air entrapment. Photocatalytic experiments demonstrated that all coatings were active under visible light, with the Cr-modified coating showing the highest MB degradation efficiency, followed by the unmodified and Sr-modified samples. Electrochemical impedance spectroscopy (EIS) further indicated that visible light irradiation significantly improved charge transfer, as evidenced by reduced Nyquist arc radii, highlighting efficient electron–hole separation and accelerated interfacial reactions. The results demonstrate that Sr- and Cr-modified PEO coatings hold promise for improving photocatalytic wastewater treatment.