Electrocorrosion And Protection Of Metals

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.

Electrocorrosion and Protection of Metals, Second Edition, compiles theoretical and practical information, outlines the specific problem, and presents the available solutions related to corrosion by external currents. Basic data on the behavior of different metals under the attack of anodic, cathodic, direct and alternating currents is considered, as are the problems of electrocorrosion—from the identification of corrosion damage and detection of the external current sources, to the selection of optimal means and methods of mitigation, monitoring and protection of different metallic structures and structures of reinforced concrete. This book includes comprehensive information and provides necessary links to more detailed, original sources, thus enabling users to solve either general or particular problems of electrocorrosion and protection of metals. Provides a comprehensive listing of all possible sources of external currents which attack metallic equipment, piping and other metallic structures Outlines the sources of corrosion damage for fast and reliable analysis Provides technical examples and case studies related to electrocorrosion Presents new data and methods of electrocorrosion control and monitoring using computerized techniques and technologies Includes original methods—only considered in this publication—of metals protection against electrocorrosion

This book introduces corrosion mechanisms and protection technologies for metallic and non-metallic materials. A focus lies on the protection of high-tech materials with applications in space and environments exposed to unclear radiation and biological hazards. The determination, measurement and control of different corrosion mechanisms are discussed in detail. Combining theories with case studies, it is an essential reference for material scientists and engineers.

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.

The corrosion protection of metallic materials is of great importance in many fields, especially also when it comes to environmental issues. The book focuses on organic and inorganic coatings, metallic coatings and new methods for the deposition of protective thin layers. Coating techniques and methods for testing and assessing corrosion behavior are presented. Keywords: Anticorrosion Coating, Metal Corrosion, Electrochemical Corrosion , Biochemical Corrosion, Atmospheric Corrosion, Underground Corrosion, Aqueous Corrosion, Corrosion Involving Mechanical Stress, Microbiological Corrosion, Metal Passivation, Metallic Layers, Spray Metal Coatings, Diffusion Coatings, Cladding Coatings, Inorganic Layers, Organic Layers, Phosphating, Oxidation, Chromating, Enamelling, Painting, Varnishing, Bituminous Coatings, Protective Thin Layers, PVD Method, Layers by Thermal Evaporation, Cathodic Spray Deposition, CVD Method, Wear Resistant Thin Layers, Decorative Thin Film Deposition.

Covering the essential aspects of the corrosion behavior of metals in aqueous environments, this book is designed with the flexibility needed for use in courses for upper-level undergraduate and graduate students, for concentrated courses in industry, for individual study, and as a reference book.