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Open AccessArticle

Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation

Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice, Poland
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Materials 2018, 11(4), 545; https://doi.org/10.3390/ma11040545
Received: 9 February 2018 / Revised: 25 March 2018 / Accepted: 2 April 2018 / Published: 3 April 2018
(This article belongs to the Special Issue Metals Functionalization via Plasma Electrolytic Oxidation)
Tantalum has recently become an actively researched biomaterial for the bone reconstruction applications because of its excellent corrosion resistance and successful clinical records. However, a bare Ta surface is not capable of directly bonding to the bone upon implantation and requires some method of bioactivation. In this study, this was realized by direct current (DC) plasma electrolytic oxidation (PEO). Susceptibility to corrosion is a major factor determining the service-life of an implant. Therefore, herein, the corrosion resistance of the PEO coatings on Ta was investigated in Ringer’s solution. The coatings were formed by galvanostatic anodization up to 200, 300 and 400 V, after which the treatment was conducted potentiostatically until the total process time amounted to 5 min. Three solutions containing Ca(H2PO2)2, Ca(HCOO)2 and Mg(CH3COO)2 were used in the treatment. For the corrosion characterization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were chosen. The coatings showed the best corrosion resistance at voltages low enough so that the intensive sparking was absent, which resulted in the formation of thin films. The impedance data were fitted to the equivalent electrical circuits with two time constants, namely R(Q[R(QR)]) and R(Q[R(Q[RW])]). The inclusion of W in the circuit helped to fit the low-frequency part of the samples PEO-ed at 400 V, hinting at the important role of diffusion in the corrosion resistance of the PEO coatings described in the research. View Full-Text
Keywords: tantalum; anodization; plasma electrolytic oxidation; biomaterials; corrosion; electrochemical impedance spectroscopy; potentiodynamic polarization tantalum; anodization; plasma electrolytic oxidation; biomaterials; corrosion; electrochemical impedance spectroscopy; potentiodynamic polarization
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Sowa, M.; Simka, W. Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation. Materials 2018, 11, 545.

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