Electrochemical Behaviors of Micro-arc Oxidation Coated Magnesium Alloy PDF Download
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Author: Jiayang Liu
Publisher:
ISBN:
Category : Biomedical materials
Languages : en
Pages : 262
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Book Description
In recent years, magnesium alloys, due to their high strength and biocompatibility, have attracted significant interest in medical applications, such as cardiovascular stents, orthopedic implants, and devices. To overcome the high corrosion rate of magnesium alloys, coatings have been developed on the alloy surface. Most coating methods, such as anodic oxidation, polymer coating and chemical conversion coating, cannot produce satisfactory coating to be used in human body environment. Recent studies demonstrate that micro-arc oxidation (MAO) technique can produce hard, dense, wear-resistant and well-adherent oxide coatings for light metals such as aluminum, magnesium, and titanium. Though there are many previous studies, the understanding of processing conditions on coating performance remains elusive. Moreover, previous tests were done in simulated body fluid. No test has been done in a cell culture medium, which is much closer to human body environment than simulated body fluid. In this study, the effect of MAO processing time (1 minute, 5 minutes, 15 minutes, and 20 minutes) on the electrochemical behaviors of the coating in both conventional simulated body fluid and a cell culture medium has been investigated. Additionally a new electrolyte (12 g/L Na2SiO3, 4 g/L NaF and 4 ml/L C3H8O3) has been used in the MAO coating process. Electrochemical behaviors were measured by performing potentiodynamic polarization and electrochemical impedance spectroscopy tests. In addition to the tests in simulated body fluid, the MAO-coated and uncoated samples were immersed in a cell culture medium to investigate the corrosion behaviors and compare the difference in these two kinds of media. The results show that in the immersion tests in conventional simulated body fluid, the 20-minute MAO coated sample has the best resistance to corrosion due to the largest coating thickness. In contrast, in the cell culture medium, all MAO coated samples demonstrate a similar high corrosion resistance behavior, independent of MAO processing time. This is probably due to the organic passive layers formed on the coating surfaces. Additionally, a preliminary finite element model has been developed to simulate the immersion test of magnesium alloy in simulated body fluid. Comparison between the predicted corrosion current density and experimental data is discussed.
Author: Jiayang Liu
Publisher:
ISBN:
Category : Biomedical materials
Languages : en
Pages : 262
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Book Description
In recent years, magnesium alloys, due to their high strength and biocompatibility, have attracted significant interest in medical applications, such as cardiovascular stents, orthopedic implants, and devices. To overcome the high corrosion rate of magnesium alloys, coatings have been developed on the alloy surface. Most coating methods, such as anodic oxidation, polymer coating and chemical conversion coating, cannot produce satisfactory coating to be used in human body environment. Recent studies demonstrate that micro-arc oxidation (MAO) technique can produce hard, dense, wear-resistant and well-adherent oxide coatings for light metals such as aluminum, magnesium, and titanium. Though there are many previous studies, the understanding of processing conditions on coating performance remains elusive. Moreover, previous tests were done in simulated body fluid. No test has been done in a cell culture medium, which is much closer to human body environment than simulated body fluid. In this study, the effect of MAO processing time (1 minute, 5 minutes, 15 minutes, and 20 minutes) on the electrochemical behaviors of the coating in both conventional simulated body fluid and a cell culture medium has been investigated. Additionally a new electrolyte (12 g/L Na2SiO3, 4 g/L NaF and 4 ml/L C3H8O3) has been used in the MAO coating process. Electrochemical behaviors were measured by performing potentiodynamic polarization and electrochemical impedance spectroscopy tests. In addition to the tests in simulated body fluid, the MAO-coated and uncoated samples were immersed in a cell culture medium to investigate the corrosion behaviors and compare the difference in these two kinds of media. The results show that in the immersion tests in conventional simulated body fluid, the 20-minute MAO coated sample has the best resistance to corrosion due to the largest coating thickness. In contrast, in the cell culture medium, all MAO coated samples demonstrate a similar high corrosion resistance behavior, independent of MAO processing time. This is probably due to the organic passive layers formed on the coating surfaces. Additionally, a preliminary finite element model has been developed to simulate the immersion test of magnesium alloy in simulated body fluid. Comparison between the predicted corrosion current density and experimental data is discussed.
Author: Marta Mohedano
Publisher: MDPI
ISBN: 3036505520
Category : Science
Languages : en
Pages : 172
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Book Description
Plasma electrolytic oxidation (PEO), also known as micro-arc oxidation (MAO), functionalizes surfaces, improving the mechanical, thermal, and corrosion performance of metallic substrates, along with other tailored properties (e.g., biocompatibility, catalysis, antibacterial response, self-lubrication, etc.). The extensive field of applications of this technique ranges from structural components, in particular, in the transport sector, to more advanced fields, such as bioengineering. The present Special Issue covers the latest advances in PEO‐coated light alloys for structural (Al, Mg) and biomedical applications (Ti, Mg), with 10 research papers and 1 review from leading research groups around the world.
Author: B.L. Jiang
Publisher: Elsevier Inc. Chapters
ISBN: 0128089466
Category : Technology & Engineering
Languages : en
Pages : 43
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Book Description
Micro-arc oxidation (MAO) is a novel and attractive surface engineering process for magnesium (Mg) alloys. In an electrolytic bath with high electric energy, the surface of a magnesium alloy can be converted into a dense and hard ceramic oxide coating. The MAO process can be used in diverse applications as a corrosion control technique. Due to its simplified pre-treatment, superior corrosion resistance performance and environmentally safe coating process, MAO technology has emerged as an important alternative to anodizing techniques in certain areas. This chapter presents a review of MAO techniques for Mg alloys from the scientific, technological and application points of view.
Author: E. McCafferty
Publisher: Springer Science & Business Media
ISBN: 1441904549
Category : Science
Languages : en
Pages : 583
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Book Description
This textbook is intended for a one-semester course in corrosion science at the graduate or advanced undergraduate level. The approach is that of a physical chemist or materials scientist, and the text is geared toward students of chemistry, materials science, and engineering. This textbook should also be useful to practicing corrosion engineers or materials engineers who wish to enhance their understanding of the fundamental principles of corrosion science. It is assumed that the student or reader does not have a background in electrochemistry. However, the student or reader should have taken at least an undergraduate course in materials science or physical chemistry. More material is presented in the textbook than can be covered in a one-semester course, so the book is intended for both the classroom and as a source book for further use. This book grew out of classroom lectures which the author presented between 1982 and the present while a professorial lecturer at George Washington University, Washington, DC, where he organized and taught a graduate course on “Environmental Effects on Materials.” Additional material has been provided by over 30 years of experience in corrosion research, largely at the Naval Research Laboratory, Washington, DC and also at the Bethlehem Steel Company, Bethlehem, PA and as a Robert A. Welch Postdoctoral Fellow at the University of Texas. The text emphasizes basic principles of corrosion science which underpin extensions to practice.
Author: Benjamin M. Wilke
Publisher:
ISBN:
Category : Biomedical materials
Languages : en
Pages : 182
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Book Description
Recent research in orthopedic implant materials has focused on the use of magnesium alloys as a base material due to its mechanical properties similar to that of human bone. Rapid corrosion of magnesium materials in aqueous environments poses a significant hurdle to their application as a biomedical implant. A variety of coatings have been shown to improve the corrosion resistance of magnesium based materials in simulated body fluid environments including microarc oxidation and polymer coatings. However, formulation and corrosion rates vary significantly between solution types. Furthermore, in vivo results have shown that many common in vitro solutions over estimate corrosion rates. In addition to variations between solutions needing to be resolved, there has been little work performed to characterize large sample corrosion under stress. This is an essential step in evaluating concept performance at a macro scale, for application as a human implant. The experiments performed and presented in this thesis primarily involve the comparison of conventional simulated body fluid (c-SBF) and Earle's balanced salt solution (EBSS). Samples evaluated in these environments are microarc oxidation (MAO) coated AZ31 magnesium alloy and polycaprolactone dip-coated AZ31. MAO coated samples were created for a range of process settings to observe the effect of processing on corrosion performance. A dependence of MAO coating thickness on process voltage was found which augmented the initial corrosion resistance values observed via electrochemical testing. Both MAO and PCL coatings were found to improve the corrosion resistance of the samples as compared to uncoated AZ31. It was found that all variations (MAO, PCL, and uncoated) showed a reduced corrosion rate in EBSS as compared to c-SBF. This corrosion reduction was apparent through potentiodynamic scanning, electrochemical impedance spectroscopy, and visual inspection. Preliminary mechanical corrosion results, in the form of constant extension testing, showed no dependence of corrosion on stress level. Future work may be aimed towards expanding modes of mechanical testing and further refining simulated body fluids to fit with in vivo test results.
Author: Mahmood Aliofkhazraei
Publisher: BoD – Books on Demand
ISBN: 9535128973
Category : Technology & Engineering
Languages : en
Pages : 252
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Book Description
Magnesium alloys usually have desirable properties including high chemical stability, easy processing and manufacturing, and also lightweight. Magnesium alloys weigh about 70% of aluminum alloy weight and 30% of iron and steel weight. Most of these alloys are used for fabrication of structures in aerospace industries. Magnesium belongs to the second main group of the periodic table of elements (alkaline earth metal) and therefore can't be found in pure state in nature and only exists as a chemical composition. This book collects new developments about magnesium alloys and their use in different industries.
Author: G L Song
Publisher: Woodhead Publishing
ISBN: 9781845697082
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
The use of magnesium alloys is increasing in a range of applications, and their popularity is growing wherever lightweight materials are needed. This book provides a comprehensive account of the corrosion of magnesium alloys. It covers not only the corrosion performances and mechanisms of Mg alloys in conventional environments, such as sodium chloride solutions, but also looks at their corrosion behaviours in special media, like engine coolants and simulated body fluids. Part one covers fundamentals such as the corrosion electrochemistry, activity and passivity of magnesium and its alloys. Part two then considers the metallurgical effect in relation to the corrosion of magnesium alloys, including the role of micro-structure and earth-rare elements, the corrosion behaviour of magnesium-based bulk metallic glasses, and the corrosion of innovative magnesium alloys. Part three goes on to describe environmental influences on the corrosion of magnesium alloys, such as atmospheric corrosion, stress corrosion cracking, creep and fatigue behaviour, and galvanic corrosion. Finally, part four is concerned with various means of protecting magnesium alloys against corrosion through the use of aluminium electrodeposition, conversion and electrophoretic coatings, and anodisation. With its distinguished editor and team of contributors, this book is an invaluable resource for metallurgists, engineers and designers working with magnesium and its alloys, as well as professionals in the aerospace and automotive industries.
Author: G.-L. Song
Publisher: Elsevier Inc. Chapters
ISBN: 0128089407
Category : Technology & Engineering
Languages : en
Pages : 42
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Book Description
Magnesium (Mg) alloys have low corrosion resistance and exhibit unusual corrosion behavior in aqueous environments. Because of this unique corrosion performance, some special corrosion prevention techniques have to be employed for Mg alloys in their applications. This chapter briefly summarizes the corrosion characteristics of Mg alloys, and also presents a strategy and methodologies to mitigate the corrosion damage of Mg alloys in applications.
Author: T.S.N. Sankara Narayanan
Publisher: Elsevier
ISBN: 1782420835
Category : Medical
Languages : en
Pages : 461
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Book Description
The development of biodegradable implants which can remain in the human body to fix a problem and subsequently dissolve, or be absorbed, consumed or excreted, without warranting a secondary surgery, is very appealing to scientists. Due to their excellent biocompatibility and biodegradability, magnesium implants provide a viable option many problems associated with permanent metallic implants such as, restenosis, thrombosis, permanent physical irritation, and inability to adapt to growth and changes in human body. Volume 2 of this important new book explores practical issues of magnesium and magnesium alloys, physical and mechanical modification and coatings to enhance this material for biomedical applications. Includes expert analysis on chemical solution deposition of hydroxyapatite (HAp) and octacalcium (OCP) phosphate coatings for magnesium Comprehensive coverage of biomimetic modifications, surface functionalization of biomolecules, natural, conducting and biodegradable polymeric coatings Lucid dissection of chemical, physical, mechanical and electromechanical modifications of magnesium and its alloys for biomedical applications
Author: Manoj Gupta
Publisher: John Wiley & Sons
ISBN: 1118102703
Category : Technology & Engineering
Languages : en
Pages : 271
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Book Description
A look at the current and future uses of magnesium-based products and their role in the world's environmental and technological revolution The lightest of all structural metals, having one-fourth the density of steel and two-thirds that of aluminum, magnesium has already been adopted as an alternative construction material in applications as far ranging as automotive and sports equipment, electronics, and space technology. In a world concerned with minimizing the environmental impact of products, the choice of light-weight, energy-saving, and high-performance materials, like magnesium, would seem a small, significant step towards improving life on this planet. Magnesium, Magnesium Alloys, and Magnesium Composites introduces the science and current applications of this important metal, shedding light on the magnesium-based composites developed over the last fifteen years. Chapters include in-depth discussion of: The characteristics of pure magnesium—including atomic properties and crystal structure as well as physical, electrical, and mechanical properties Magnesium alloys—and the effects of the alloying elements, such as aluminum, lithium, copper, nickel, and silicon The properties of magnesium-based composites—and the effects of different types (metallic, ceramic, interconnected, and intermetallic) of reinforcements of varying length (from micron scale to nanometric length) Corrosion aspects of magnesium-based materials Magnesium-based products in medicine, sports equipment, and the automotive, aerospace, and electronics industries Bringing together, for the first time, the science, properties, and technologies relating to the current and future uses of magnesium, this important reference also offers readers a glimpse of a not-too-distant world in which environmental safety and sound engineering are a reality.
