Study on coating growth characteristics during the electrolytic oxidation of a magnesium–lithium alloy by optical emission spectroscopy analysis

RSC Advances ◽  
2015 ◽  
Vol 5 (84) ◽  
pp. 68806-68814 ◽  
Author(s):  
Zhongping Yao ◽  
Qixing Xia ◽  
Han Wei ◽  
Dongqi Li ◽  
Qiu Sun ◽  
...  

The aim of this study is to analyze the composition, structure and growth characteristics of plasma electrolytic oxidation (PEO) coatings through optical emission spectroscopy (OES).

2012 ◽  
Vol 9 (1) ◽  
pp. 81-94 ◽  
Author(s):  
Marija Petkovic ◽  
Stevan Stojadinovic ◽  
Rastko Vasilic ◽  
Ivan Belca ◽  
Becko Kasalica ◽  
...  

This paper is a review of our research on the plasma electrolytic oxidation (PEO) process of tantalum in 12-tungstosilicic acid. For the characterization of microdischarges during PEO, real-time imaging and optical emission spectroscopy (OES) were used. The surface morphology, chemical and phase composition of oxide coatings were investigated by AFM, SEM-EDS and XRD. Oxide coating morphology is strongly dependent on PEO time. The elemental components of PEO coatings are Ta, O, Si and W. The oxide coatings are partly crystallized and mainly composed of WO3, Ta2O5 and SiO2.


2018 ◽  
Vol 178 ◽  
pp. 03008 ◽  
Author(s):  
Krzysztof Rokosz ◽  
Tadeusz Hryniewicz ◽  
Sofia Gaiaschi ◽  
Patrick Chapon ◽  
Steinar Raaen ◽  
...  

The Plasma Electrolytic Oxidation (PEO) process may be used to fabricate porous coatings on titanium. The ranges of voltages used in case of these plasma treatments are different. It has been found that for DC PEO processing the voltage must be higher than that in the case of AC PEO treatment. In addition, the shape and frequency of the voltage signal have also an influence. In the paper scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and glow discharge optical emission spectroscopy (GDEOS) were used to characterise obtained coatings. It was found that it is possible to obtain the porous coatings enriched with phosphorus and copper by use of AC-PEO at only 200 Vpp, while increasing the PEO voltage results in non-porous and cracked coatings. Based on GDEOS for 200 Vpp three sublayers were used, with ranges of 0-400, and 400-2400, and 2400-3600 seconds of sputtering time for first, and second, and transition sublayers respectively. XPS spectra for sample processed at 200 Vpp indicate in top 10 nm layer presence of titanium as Ti4+ and phosphorous as phosphates (most likely PO43–, HPO42–, H2PO4–, P2O73–).


Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1375
Author(s):  
Soumya Sikdar ◽  
Pramod V. Menezes ◽  
Raven Maccione ◽  
Timo Jacob ◽  
Pradeep L. Menezes

Plasma electrolytic oxidation (PEO) is a novel surface treatment process to produce thick, dense metal oxide coatings, especially on light metals, primarily to improve their wear and corrosion resistance. The coating manufactured from the PEO process is relatively superior to normal anodic oxidation. It is widely employed in the fields of mechanical, petrochemical, and biomedical industries, to name a few. Several investigations have been carried out to study the coating performance developed through the PEO process in the past. This review attempts to summarize and explain some of the fundamental aspects of the PEO process, mechanism of coating formation, the processing conditions that impact the process, the main characteristics of the process, the microstructures evolved in the coating, the mechanical and tribological properties of the coating, and the influence of environmental conditions on the coating process. Recently, the PEO process has also been employed to produce nanocomposite coatings by incorporating nanoparticles in the electrolyte. This review also narrates some of the recent developments in the field of nanocomposite coatings with examples and their applications. Additionally, some of the applications of the PEO coatings have been demonstrated. Moreover, the significance of the PEO process, its current trends, and its scope of future work are highlighted.


Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 401
Author(s):  
Ruzil Farrakhov ◽  
Olga Melnichuk ◽  
Evgeny Parfenov ◽  
Veta Mukaeva ◽  
Arseniy Raab ◽  
...  

The paper compares the coatings produced by plasma electrolytic oxidation (PEO) on commercially pure titanium and a novel superelastic alloy Ti-18Zr-15Nb (at. %) for implant applications. The PEO coatings were produced on both alloys in the identical pulsed bipolar regime. The properties of the coatings were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The PEO process kinetics was modeled based on the Avrami theorem and Cottrell equation using a relaxation method. The resultant coatings contain TiO2, for both alloys, and NbO2, Nb2O5, ZrO2 for Ti-18Zr-15Nb alloy. The coating on the Ti-18Zr-15Nb alloy has a higher thickness, porosity, and roughness compared to that on cp-Ti. The values of the kinetic coefficients of the PEO process—higher diffusion coefficient and lower time constant for the processing of Ti-18Zr-15Nb—explain this effect. According to the electrochemical studies, PEO coatings on Ti-18Zr-15Nb alloy provide better corrosion protection. Higher corrosion resistance, porosity, and roughness contribute to better biocompatibility of the PEO coating on Ti-18Zr-15Nb alloy compared to cp-Ti.


2017 ◽  
Vol 17 (2) ◽  
pp. 41-54 ◽  
Author(s):  
K. Rokosz ◽  
T. Hryniewicz ◽  
K. Pietrzak ◽  
W. Malorny

AbstractThe SEM and EDS results of porous coatings formed on pure titanium by Plasma Electrolytic Oxidation (Micro Arc Oxidation) under DC regime of voltage in the electrolytes containing of 500 g zinc nitrate Zn(NO3)2·6H2O in 1000 mL of concentrated phosphoric acid H3PO4at three voltages, i.e. 450 V, 550 V, 650 V for 3 minutes, are presented. The PEO coatings with pores, which have different shapes and the diameters, consist mainly of phosphorus, titanium and zinc. The maximum of zinc-to-phosphorus (Zn/P) ratio was found for treatment at 650 V and it equals 0.43 (wt%) | 0.20 (at%), while the minimum of that coefficient was recorded for the voltage of 450 V and equaling 0.26 (wt%) | 0.12 (at%). Performed studies have shown a possible way to form the porous coatings enriched with zinc by Plasma Electrolytic Oxidation in electrolyte containing concentrated phosphoric acid H3PO4with zinc nitrate Zn(NO3)2·6H2O.


Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2438 ◽  
Author(s):  
Myungwon Hwang ◽  
Wonsub Chung

Plasma electrolytic oxidation (PEO) coating was obtained on AZ31 Mg alloy using a direct current in a sodium silicate-based electrolyte with and without a carbon nanotube (CNT) additive. The surface morphology and phase composition of the PEO coatings were investigated through field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The corrosion-resistance properties of the PEO coatings were evaluated using potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution. Furthermore, the heat-dissipation property was evaluated by a heat-flux measurement setup using a modified steady-state method and Fourier transform infrared spectroscopy (FT-IR). The results demonstrate that, by increasing the concentration of CNT additive in the electrolyte, the micropores and cracks of the PEO coatings are greatly decreased. In addition, the anticorrosion performance of the PEO coatings that incorporated CNT for the protection of the Mg substrate was improved. Finally, the coating’s heat-dissipation property was improved by the incorporation of CNT with high thermal conductivity and high thermal emissivity.


Author(s):  
Alex Lugovskoy ◽  
Lyubov Snizhko

In this review, the main kinetics and mechanism regularities of plasma electrolytic oxidation (PEO) of aluminum alloys are discussed. The material and heat balances of the PEO process, including anomalous gas evolution and possible thermochemical reactions are presented for the first time. Side effects accompanying spark discharges from both the surface and the electrolyte sides are analyzed. The influences of electrical regime (direct, alternative, and pulse current) on the rate of coatings growth are summarized from the electrochemical point of view. Different modes of anodic polarization and electrolyte composition (alkaline solutions with inorganic polymers and dispersed constituents) are discussed in the applicative aspect.


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