scholarly journals Characterization of Oxide Film of Implantable Metals by Electrochemical Impedance Spectroscopy

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3466 ◽  
Author(s):  
Okazaki
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Oxide Film ◽  
Electrochemical Impedance ◽  
Saturated Calomel Electrode ◽  
Oxide Films ◽  
Relative Dielectric Constant ◽  
Open Circuit ◽  
Thin Oxide Film ◽  
Transmission Electron

The oxide film resistance (RP) and capacitance (CCPE) diagrams of implantable metals (commercially pure Ti, four types of Ti alloys, Co–28Cr–6Mo alloy, and stainless steel) were investigated by electrochemical impedance spectroscopy (EIS). The thin oxide film formed on each implantable metal surface was observed in situ by field-emission transmission electron microscopy (FE-TEM). The Ti–15Zr–4Nb–1Ta and Ti–15Zr–4Nb–4Ta alloys had higher oxygen concentrations in the oxide films than the Ti–6Al–4V alloy. The thickness (d) of the TiO2 oxide films increased from approximately 3.5 to 7 nm with increasing anodic polarization potential from the open-circuit potential to a maximum of 0.5 V vs. a saturated calomel electrode (SCE) in 0.9% NaCl and Eagle’s minimum essential medium. RP for the Ti–15Zr–4Nb–1Ta and Ti–15Zr–4Nb–4Ta alloys was proportional to d obtained by FE-TEM. CCPE was proportional to 1/d. RP tended to decrease with increasing CCPE. RP was large (maximum: 13 MΩ·cm2) and CCPE was small (minimum: 12 μF·cm−2·sn−1, n = 0.94) for the Ti–15Zr–4Nb–(0 to 4)Ta alloys. The relative dielectric constant (εr) and resistivity (kOX) of the oxide films formed on these alloys were 136 and 2.4 × 106–1.8 × 107 (MΩ·cm), respectively. The Ta-free Ti–15Zr–4Nb alloy is expected to be employed as an implantable material for long-term use.

Study on Corrosion Process of Al-Mg Coatings Based on Electrochemical Impedance Spectroscopy

2017 ◽  
Vol 744 ◽  
pp. 380-384
Author(s):  
Hui Tong ◽  
Wen Li Han ◽  
Zhong Ping Xu ◽  
Yan Jun Zhang ◽  
Zhu Lin ◽  
...  
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Corrosion Process ◽  
Corrosion Products ◽  
Passive Films ◽  
Nacl Solution ◽  
Electrochemical Testing ◽  
Immersion Corrosion

Electrochemical impedance spectroscopy (EIS) is a technology of nondestructive electrochemical testing. In this paper, EIS is applied to study the corrosion processes of Al-Mg coatings. In the initial 24 h of immersion in 3.5% NaCl solution, passive films of Al-Mg coatings dissolve quickly. As time passed, corrosion products increase on surface gradually, which can inhibit corrosion. After 480h of immersion, corrosion products fully cover on Al-Mg coatings’ surface. The EIS of different corrosion processes are fitted by three equivalent circuits corresponding to the three corrosion processes. In the test of open circuit potentials (OCP), OCP is instable in the initial 24 h of immersion. As immersion time goes by, OCP tends to stabilization at about -0.90 V. Measurements of scanning electron microscope (SEM) confirm the conclusions of electrochemical measurements.

Effect of the Fe/Cu Relationship Corrosion and low Alloying Elements on Corrosion Behavior of Cast Aluminum Parts

2016 ◽  
Vol 1815 ◽  
Author(s):  
C. Rodríguez-Rivera ◽  
J.A. García-Hinojosa ◽  
F.J. Rodríguez-Gómez
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Aluminum Alloys ◽  
Impedance Spectroscopy ◽  
Corrosion Rate ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Corrosion Morphology

ABSTRACTThe aim of this study is to compare the corrosion rate of aluminum alloys for ornamental pieces. Three Fe/Cu relationships were tested in order to improve hardness and brightness in aluminum pieces since these alloys are used in the making of ornamental pieces. The variation on Fe/Cu content could result in modification on corrosion rate, since a metallographic characterization must be carried out identifying the presence of intermetallic phases. The presence of these elements could result in increasing corrosion rate, or even in modification of corrosion morphology, so localized corrosion could be expected.The assessment of corrosion rate was carried out in saline media, since chlorides are ions that promote localized corrosion. Electrochemical techniques (polarization curves and Tafel plots) were used in order to evaluate the attack in aluminum pieces; electrochemical impedance spectroscopy was also employed with voltage amplitude of 10 mV rms, and a frequency range from 10,000 Hz to 0.01 Hz. A typical three electrodes cell was used, exposing an area of one cm2. Before polarization, open circuit potential was monitored for an hour looking for a steady state. All conditions were tested for triplicate.The behavior of open circuit potential vs. time, and polarization curves was analyzed; a corrosion mechanism is proposed according to the electrochemical control. Polarization rate was calculated by using Tafel plots and, an electrochemical impedance spectroscopy analysis by using equivalent electric circuits is shown. Electrochemical impedance will yield information about corrosion morphology that is backed with microscopic inspection.The objective of this study is to compare the corrosion rate of aluminum alloys for ornamental pieces in order to determine the effect of the relationship Fe/Cu on the corrosion mechanism in aluminum parts for ornamental pieces.

The Manipulation of Properties of Ti Bioalloys at Micro and Nanoscale Using Etching Procedures

2008 ◽  
Vol 396-398 ◽  
pp. 393-396 ◽  
Author(s):  
D. Ionita ◽  
Doina Raducanu ◽  
Mariana Prodana ◽  
Ioana Demetrescu
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Open Circuit ◽  
Electrochemical Study ◽  
Acid Etching ◽  
Equivalent Circuits

The paper is an electrochemical study regarding the influence of different acid etching conditions on the corrosion behaviour of a new Ti based bioalloy with Nb, Ta and Zr. Open circuit, potentiodynamic and electrochemical impedance spectroscopy were the methods performed in a simulated body fluid (SBF) and a stability mechanism was discussed in terms of equivalent circuits.

scholarly journals Corrosion Resistance of Multilayer Coatings Deposited by PVD on Inconel 718 Using Electrochemical Impedance Spectroscopy Technique

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 521 ◽  
Author(s):  
Citlalli Gaona-Tiburcio ◽  
Marvin Montoya-Rangel ◽  
José A. Cabral-Miramontes ◽  
Francisco Estupiñan-López ◽  
Patricia Zambrano-Robledo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Inconel 718 ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Open Circuit ◽  
Inconel 718 Alloy ◽  
Transfer Resistance ◽  
Crn Coatings

AlCrN/TiSi, AlCrN/TiCrSiN and AlCrN/AlCrN + CrN coatings were deposited on Inconel 718 alloy by physical vapour deposition (PVD). The corrosion behaviour of uncoated and coated specimens was evaluated using electrochemical impedance spectroscopy (EIS) at open circuit potential in a 3.5 wt.% NaCl and 2 wt.% H2SO4 solutions. The EIS data acquired were curve fitted and analysed by equivalent circuit models to calculate the pore resistance, the charge transfer resistance and the capacitance. The Nyquist diagrams of all systems showed one part of the semicircle which could relate that reaction is a one step process, except for the AlCrN/TiCrSiN and AlCrN/AlCrN + CrN coatings in H2SO4 solution, for which two semicircles related to active corrosion in substrate alloy were found. However, from the Bode plots, it was possible to identify two the time constants for all systems exposed to NaCl and H2SO4 solutions. According to electrochemical results, the corrosion resistance of the AlCrN/TiSiN coating was better in the NaCl solution, whereas the AlCrN/AlCrN + CrN coating show better performance in the Sulphuric Acid solutions.

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