GDOES, XPS, and SEM with EDS analysis of porous coatings obtained on titanium after plasma electrolytic oxidation

• Published in: Surface and interface analysis Vol. 49; no. 4; pp. 303 - 315
• Main Authors: Rokosz, Krzysztof, Hryniewicz, Tadeusz, Raaen, Steinar, Chapon, Patrick, Dudek, Łukasz
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.04.2017
• Subjects: Coatings; Copper; Electrolytes; glow discharge optical emission spectroscopy (GDOES); Glow discharges; Optical emission spectroscopy; Oxidation; plasma electrolytic oxidation (PEO); porous coatings; Titanium; X-ray photoelectron spectroscopy; X‐ray photoelectron spectroscopy (XPS)
• ISSN: 0142-2421; 1096-9918
• DOI: 10.1002/sia.6136

In the paper, the glow discharge optical emission spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy results of a commercial purity titanium grade 2 after plasma electrolytic oxidation (PEO), also known as micro arc oxidation (MAO), are presented. The PEO treatment was performed in the electrolyte containing concentrated (85%) phosphoric acid with copper nitrate at the voltage of 450 ± 10 V for 1 min. For the electrolyte, copper nitrate addition from 300 to 600 g/l was used. Porous coatings of specific properties were obtained. The measurements results allow to state that the copper and nitrogen ions can be introduced into the surface layer formed on pure titanium by the plasma electrolytic oxidation. The distributions of these elements were detected to depend on the electrolyte composition, with the highest amounts revealed in the coating created in the electrolyte containing 600 g Cu(NO3)2 in 1 l H3PO4. Three sub‐layers of the coating, displayed in this work by two models, were developed in the study. The analysis performed shows that under the PEO treatment in each of the electrolytes used, the formation of coating with the top sub‐layers always enriched in copper compounds was found. Copyright © 2016 John Wiley & Sons, Ltd. Highlights A new electrolyte, consisting of 85% phosphoric acid within copper nitrate, was used for the plasma electrolytic oxidation (PEO) treatment of titanium. Porous coatings on Ti were created under the PEO treatment. Glow discharge optical emission spectroscopy measurements with the analysis area of 12.56 mm2 were performed for the depth profile analyses The depth profile of hydrogen is presented. New models of PEO coating formed on titanium after the PEO at 450 V are proposed (based on glow discharge optical emission spectroscopy, XPS, SEM, and energy-dispersive X-ray spectroscopy measurement results). Explanation of the mechanism of the porous coating formation (with three sub-layers) is delivered.