Corrosion Resistance Of Aluminum And Magnesium Alloys

Valuable information on corrosion fundamentals and applications of aluminum and magnesium Aluminum and magnesium alloys are receiving increased attention due to their light weight, abundance, and resistance to corrosion. In particular, when used in automobile manufacturing, these alloys promise reduced car weights, lower fuel consumption, and resulting environmental benefits. Meeting the need for a single source on this subject, Corrosion Resistance of Aluminum and Magnesium Alloys gives scientists, engineers, and students a one-stop reference for understanding both the corrosion fundamentals and applications relevant to these important light metals. Written by a world leader in the field, the text considers corrosion phenomena for the two metals in a systematic and parallel fashion. The coverage includes: The essentials of corrosion for aqueous, high temperature corrosion, and active-passive behavior of aluminum and magnesium alloys The performance and corrosion forms of aluminum alloys The performance and corrosion forms of magnesium alloys Corrosion prevention methods such as coatings for aluminum and magnesium Electrochemical methods of corrosion investigation and their application to aluminum and magnesium alloys Offering case studies and detailed references, Corrosion Resistance of Aluminum and Magnesium Alloys provides an essential, up-to-date resource for graduate-level study, as well as a working reference for professionals using aluminum, magnesium, and their alloys.

To improve the corrosion resistance of magnesium (Mg) alloys, surface modification is applied in an attempt to produce a corrosion resistant barrier. In this chapter, a new method to deposit aluminum (Al) film on a Mg alloy surface is demonstrated. Electrodeposition of Al on AZ91D Mg alloy, using an acidic aluminum chloride–1-ethyl-3-methyl-imidazolium chloride ionic liquid (AlCl3–EMIC), has been shown to be feasible. The existence of Al coating can cause a substantial increase in corrosion resistance, reducing the susceptibility of Mg alloy to aqueous corrosion. The results of electrochemical impedance spectroscopy show that Al coating leads to an increase in the polarization resistance of a bare Mg alloy by one order of magnitude in 3.5wt% NaCl solution. Furthermore, the potentiodynamic polarization results show that Al-coated Mg alloy can be passivated, and a wider passive region with a lower passive current density can be obtained if the Al is electrodeposited at a lower applied current or a low cathodic overpotential. The passivity of the co-deposited Al/Zn film is slightly inferior to that of the pure Al coating.

Magnesium is the lightest of all the metals and the sixth most abundant on Earth. Magnesium is ductile and the most machinable of all the metals. Magnesium alloy developments have traditionally been driven by requirements for lightweight materials to operate under increasingly demanding conditions (magnesium alloy castings, wrought products, powder metallurgy components, office equipment, nuclear applications, flares, sacrificial anodes for the protection of other metals, flash photography and tools). The biggest potential market for magnesium alloys is in the automotive industry. In recent years new magnesium alloys have demonstrated a superior corrosion resistance for aerospace and specialty applications. Considering the information above, special issues on magnesium alloys are exposed in this book: casting technology; surface modification of some special Mg alloys; protective carbon coatings on magnesium alloys; fatigue cracking behaviors of cast magnesium alloys and also, magnesium alloys biocompatibility as degradable implant materials.

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.

This memorandum deals with the corrosion protection of magnesium and magnesium alloys. The corrosion resistance of these alloys in many natural environments, while not as good as that of copper, nickel, stainless steel, and aluminum, is in the same range as that of the iron and plain carbon steels. Some type of additional corrosion protection is often necessary and, as with steel, the protective measures usually involve some type of coating system and/or surface treatments. Also, magnesium can suffer accelerated attack when coupled, in the presence of a conductive electrolyte, to most metals below it in the galvanic series. This galvanic effect complicates the problem of corrosion protection. A number of coating systems have been proposed and used satisfactorily. Depending upon the application, these coating systems include the use of conversion coatings, organic coatings, metallic coatings, and others. In addition, special designs can be employed to improve the over-all corrosion resistance of the systems. This memorandum describes many of the coating systems and design methods which are used to reduce corrosive attack on both galvanically coupled and uncoupled magnesium assembliesd (Author).

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. Provides a comprehensive account of the corrosion of magnesium alloys covering fundamentals such as the corrosion electrochemistry, activity and passivityReviews the metallurgical effect in relation to the corrosion of magnesium alloys, including the role of micro-structure and earth-rare elementsAssesses environmental influences such as atmospheric corrosion, stress corrosion cracking, creep and fatigue behaviour, and galvanic corrosion

A resistance of magnesium alloys to surface degradation is paramount for their applications in automotive, aerospace, consumer electronics and general-purpose markets. An emphasis of this book is on oxidation, corrosion and surface modifications, designed to enhance the alloy surface stability. It covers a nature of oxides grown at elevated temperatures and oxidation characteristics of selected alloys along with elements of general and electrochemical corrosion. Medical applications are considered that explore bio-compatibility of magnesium alloys. Also techniques of surface modifications, designed to improve not only corrosion resistance but also corrosion fatigue, wear and other behaviors, are described. The book represents a valuable resource for scientists and engineers from academia and industry.