Corrosion And Protection Of Metals

Introduction and Scope-During the last few decades, an enormous effort has been made to understand corrosion phenomena and their mechanisms, and to elucidate the causes that dramatically influence the service lifetime of metal materials. The performance of metal materials in aggressive environments is critical for a sustainable society. The failure of the material in service impacts the economy, the environment, health, and society. In this regard, corrosion-based economic losses due to maintenance, repair, and the replacement of existing structures and infrastructure account for up to 4% of gross domestic product (GDP) in well developed countries. One of the biggest issues in corrosion engineering is estimating service lifetime. Corrosion prediction has become very difficult, as there is no direct correlation with service lifetime and experimental lab results, usually as a result of discrepancies between accelerated testing and real corrosion processes. It is of major interest to forecast the impact of corrosion-based losses on society and the global economy, since existing structures and infrastructure are becoming old, and crucial decisions now need to be made to replace them. On the other hand, environmental protocols seek to reduce greenhouse effects. Therefore, low emission policies, in force, establish regulations for the next generation of materials and technologies. Advanced technologies and emergent materials will enable us to get through the next century. Great advances are currently in progress for the development of corrosion-resistant metal materials for different sectors, such as energy, transport, construction, and health. This Special Issue on the corrosion and protection of metals is focused on current trends in corrosion science, engineering, and technology, ranging from fundamental to applied research, thus covering subjects related to corrosion mechanisms and modelling, protection and inhibition processes, and mitigation strategies.

Considerable progress has been made in the past 20 years toward understanding the basic mechanisms of corrosion, and the application of this knowledge to its control. From the very beginning, educational institutions and industrial research laboratories have contributed greatly toward determining and elucidating the fundamental principles of corrosion reactions. Some of the basic principles involved in cor rosion of metals can be credited to early investigators. Michael Faraday in 1830-1840 studied the relationship between the quantity of a metal dissolved and the electric current which was produced by this reaction. He also proposed that the passivation of iron was through the formation of a film and that the dissolution of a metal was electro chemical in nature. Sir Humphrey Davy in 1824 worked out the funda mentals of galvanic corrosion of ships' hulls and applied sacrificial zinc anodes to protect them from sea water corrosion. Richard Arlie in 1847 demonstrated that corrosion produced by oxygen at the surface of iron in a flowing stream generated a current. With the fundamental knowledge available to him from these early investigators, Willis Rodney Whitney developed and expressed, in its most useful form, one of the basic scientific principles which provides modern corrosion specialists with a fundamental basis of corrosion control. Dr. Whitney concluded that corrosion of iron is electrochemical, and that the rate is simply a function of the electromotive force and resistance of the circuit.

Corrosion may be defined as an unintentional attack on a material through reaction with a surrounding medium. The term can refer to a process or to the damage caused by such a process. According to this general definition, materials other than metals, such as ceramics, plastics or concrete, may also be subject to corrosion (or corrode). When no particular reference is made to the material, however, it is normally understood that a metal is being attacked. It is entirely in this limited sense that the term is used in this book. There are good reasons for treating the corrosion of metals separately, apart from deterioration or decay of other materials. Since metals have a high electric conductivity, their corrosion is usually of an electrochemical nature. The chemical deterioration of electrically non-conducting ma terials, such as plastics and ceramics, is governed by other physico-chemical principles. It is necessary to devote more attention to metallic corrosion nowadays than earlier, due to 1. An increased use of metals within all fields of technology. 2. The use for special applications, e.g. within the atomic energy field, of rare and expensive metals, whose preservation requires particular precautions. 3. A more corrosive environment due to the increasing pollution of air and water. 4. The use of metallic constructions of more slender dimensions which do not tolerate corrosive attacks to the same extent as did the heavy constructions used in the old days.

Electrocorrosion, the corrosion of metallic constructions by external currents, is the most significant factor in conductive aggressive environments. Corrosion of underground and underwater metal constructions by stray currents has been comprehensively studied in the past decades and is considered here only in the form of a review. The primary attention is on corrosion, by external anodic (mainly) and cathodic currents, of metal constructions in the highly aggressive environments typical for electrochemical plants, where penetration of the external currents (leakage currents) from the electrolytic baths into metal constructions is unavoidable. A new approach to the problem of electrocorrosion protection of passive structural metals is considered in this book, keeping the metals attacked by external currents in the boundaries of their passive field. The systems, developed in accordance with this approach, are based on the modification of existing and elaboration of new methods of electrocorrosion protection. These systems take into account corrosion and electrochemical characteristics of the aggressive media (redox potential, conductivity etc.) and of the passive metal (corrosion and activation potentials, current density in a passive state, etc) as well as the sizes and distribution character of the external currents. The book covers analysis of leakage current distributions in electrochemical plants, their influence, methods to estimate corrosion stability of metallic structures subject to external currents and presents many concrete examples of the successful introduction of corrosion protection systems in operating plants. A new approach to protection from electrocorrosion, taking into account the passive state of the metal in aggressive media Newly developed and modifications of well known methods of electrocorrosion protection are presented. Systematized data on electrocorrosion and protection of metals, especially in electrochemical plants, allow corrosion engineers, researchers and personnel maintaining the equipment of electrochemical plants to analyze the corrosion state of metallic equipment and prevent electrocorrosion.

The use of conducting polymers for the anticorrosion protection of metals has attracted great interest during the last 30 years. The design and development of conducting polymers-based coating systems with commercial viability is expected to be advanced by applying nanotechnology and has received substantial attention recently. This book begins with corrosion fundamentals and ends with an emphasis on developments made in conducting polymer science and technology using nanotechnology. Additionally, it gives a detailed account of experimental methods of corrosion testing.

Corrosion Protection at the Nanoscale explores fundamental concepts on how metals can be protected at the nanoscale by using both nanomaterials-based solutions, including nanoalloys, noninhibitors and nanocoatings. It is an important reference resource for both materials scientists and engineers wanting to find ways to create an efficient corrosion prevention strategy. Nanostructure materials have been widely used in many products, such as print electronics, contact, interconnection, implant, nanosensors and display units to lessen the impact of corrosion. Traditional methods for protection of metals include various techniques, such as coatings, inhibitors, electrochemical methods (anodic and cathodic protections), metallurgical design are covered in this book. Nanomaterials-based protective methods can offer many advantages over their traditional counterparts, such as protection for early-stage, higher corrosion resistance, better corrosion control. This book also outlines these advantages and discusses the challenges of implementing nanomaterials as corrosion protection agents on a wide scale. Explains the main methods of detection, monitoring, testing, measurement and simulation of corrosion at the nanoscale Explores how metals can be protected at the nanoscale using nanotechnology and nanomaterials Discusses the major challenges of detecting and preventing corrosion at the nanoscale

Principles of Metal Surface Treatment and Protection deals with the principles of metal surface treatment and protection. Topics covered range from electrodeposition and hot dip coating to diffusion and non-metallic coatings, as well as oxide and conversion coatings. The theory of corrosion protection is also discussed. Comprised of eight chapters, this volume begins with an overview of the corrosion of metals and the scope of protection against corrosion, followed by a detailed treatment of electrodeposition. The discussion then turns to the principles of hot dipping as a coating method; the formation of a diffusion coating; and the role of a non-metallic coating in corrosion protection. Subsequent chapters focus on the protection of oxide films against corrosion by means of anodizing, phosphatizing, and the use of tin free steel; testing and selection of a particular coating for corrosion resistance applications; and the theory of corrosion protection. This book is intended for metal-finishing scientists and students of metallurgy and metal finishing.