Corrosion study of graphene oxide coatings on AZ31B magnesium alloy
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Corrosion study of graphene oxide coatings on AZ31B magnesium alloy Muhammad Faheem Maqsood, Mohsin Ali Raza, Faizan Ali Ghauri, Zaeem Ur Rehman, Muhammad Tasadaq Ilyas
American Coatings Association 2020 Abstract The aim of this study was to produce graphene oxide (GO) coatings on biodegradable AZ31B magnesium (Mg) alloy. GO was synthesized by improved Hummers’ method, and a suspension was prepared in deionized water by ultrasonication. GO coatings were developed on AZ31B Mg alloy by electrophoretic deposition (EPD). The EPD parameters, such as voltage and time, were optimized to obtain uniform GO coatings. Characterization was carried out using Fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy (AFM), and scanning electron microscopy. GO was found to have a thickness of approximately 0.7–1 nm as determined by AFM. Electrochemical behavior of coatings was evaluated by Tafel analysis and electrochemical impedance spectroscopy (EIS) in Ringer’s lactate solution. GO coatings improved the corrosion resistance of the AZ31B Mg alloy by 169 in Ringer’s lactate solution as compared to bare Mg alloy. Keywords Magnesium alloys, Improved Hummers’ method, Graphene oxide, Coatings, Atomic force microscopy, Ringer’s lactate, Corrosion
Introduction Magnesium (Mg) and its alloys have attained much attention due to their unique combination of properties, i.e., low specific gravity, specific strength, high rigidity, dimensional stability, and good machinability.1–3 Mg and its alloys are suitable materials for numerous applications in the field of transportation, M. F. Maqsood, M. A. Raza, F. A. Ghauri, Z. U. Rehman (&), M. T. Ilyas Department of Metallurgy and Materials Engineering, University of the Punjab, Lahore, Pakistan e-mail: [email protected]
aerospace, electronics, etc.4 Moreover, their Young’s modulus and compression strength are comparable to natural bone, which make them potentially useful for biomedical implant applications.5 Mg is needed for many biochemical reactions in the body; therefore, its biodegradation causes no tissue loss or damage to the body. Being nontoxic, Mg plays a supporting role in the growth of tissues, unlike nonbiodegradable permanent metallic implants that produce physical irritation in the body and have poor adaptability to tissue growth.6,7 A notable disadvantage of Mg metal in many engineering applications is its high electrochemical activity (low corrosion resistance) especially in aqueous environments. However, this is a significant advantage for biodegradable medical implants. Currently, acceptable metallic biomaterials include stainless steels, titanium, and cobalt–chromium-based alloys.8 These metallic biomaterials are limited in their use as body implants due to possible release of toxic metallic ions and/or particles in the body via corrosion or wear processes. Mg alloy-based body implants have an advantage over these alloys as their in vivo corrosion results in the release of soluble, nontoxic ions that are not only harmless to the body but a
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