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The Effect of Sodium Tetrafluoroborate on the Properties of Conversion Coatings Formed on the AZ91D Magnesium Alloy by Plasma Electrolytic Oxidation. Processes (Basel) 2022. [DOI: 10.3390/pr10102089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Magnesium and its alloys are widely used in many areas because of their light weight, excellent dimensional stability, and high strength-to-weight ratio. However, the material exhibits poor wear and corrosion resistance, which limits its use. Plasma electrolytic oxidation (PEO) is an effective surface modification method for producing ceramic oxide layers on Mg and their alloys. The influence of the additions of sodium tetrafluoroborate (NaBF4) and sodium fluoride (NaF) into alkaline-silicate electrolyte on the properties of the conversion layers formed in the magnesium AZ91D alloy has been investigated. Surface morphology and chemical composition were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The anticorrosive properties of the layers were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods in simulated body fluid (SBF). The presence of NaBF4 or NaF in the electrolyte increases the corrosion resistance of the protective layer. However, the best anticorrosive properties show the layers obtained in the presence of NaBF4. This is probably caused by the incorporation of boron and fluorine in the form of Mg (BF4)2 mainly in the barrier layer.
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Gerengi H, Cabrini M, Solomon MM, Kaya E, Gritti L, Yola ML. Chemical, Electrochemical, and Surface Morphological Studies of the Corrosion Behavior of the AZ31 Alloy in Simulated Body Fluid: Effect of NaOH and H 2O 2 Surface Pretreatments on the Corrosion Resistance Property. ACS OMEGA 2022; 7:26687-26700. [PMID: 35936436 PMCID: PMC9352166 DOI: 10.1021/acsomega.2c02998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
Magnesium and its alloys have attracted attention for biomedical implant materials in dental and orthopedic applications because of their biodegradability and similar properties to human bones. The very high rate of degradation in the physiological systems is, however, a major setback to their utilization. Chemical modification is one of the approaches adopted to enhance the corrosion resistance property of Mg and its alloys. In this work, NaOH and H2O2 were used as a pretreatment procedure to improve the corrosion resistance of the AZ31 Mg alloy in simulated body fluid (SBF). Advanced techniques such as dynamic electrochemical impedance spectroscopy (dynamic-EIS), atomic force microscopy, and optical profilometry were used in addition to the classical mass loss, hydrogen evolution, EIS, and polarization techniques to study the corrosion resistance property of the alloy in SBF for 30 h. Results obtained show that the surface treatment significantly enhanced the corrosion resistance property of the alloy. From dynamic-EIS at 30 h, the charge transfer resistance of the untreated AZ31 Mg alloy is 432.6 Ω cm2, whereas 822.7 and 2617.3 Ω cm2 are recorded for NaOH- and H2O2-treated surfaces, respectively. H2O2 is a better treatment reagent than NaOH. The mechanism of corrosion of both untreated and treated samples in the studied corrosive medium has been discussed.
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Affiliation(s)
- Husnu Gerengi
- Corrosion
Research Laboratory, Department of Mechanical Engineering, Faculty
of Engineering, Duzce University, Duzce 81620, Turkey
- Department
of Engineering and Applied Sciences, University
of Bergamo, Dalmine, Bergamo 24044, Italy
| | - Marina Cabrini
- Department
of Engineering and Applied Sciences, University
of Bergamo, Dalmine, Bergamo 24044, Italy
| | - Moses M. Solomon
- Department
of Chemistry, College of Science and Technology, Covenant University, Ota 112104, Ogun State, Nigeria
| | - Ertugrul Kaya
- Corrosion
Research Laboratory, Department of Mechanical Engineering, Faculty
of Engineering, Duzce University, Duzce 81620, Turkey
| | - Luca Gritti
- Department
of Engineering and Applied Sciences, University
of Bergamo, Dalmine, Bergamo 24044, Italy
| | - Mehmet Lutfi Yola
- Department
of Nutrition and Dietetics, Faculty of Health Sciences, Hasan Kalyoncu University, Gaziantep 27010, Turkey
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