(Engineering Materials) Pietro Pedeferri Corrosion Science and Engineering Springer International Publishing (2018) PDF

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Engineering Materials Pietro Pedeferri Corrosion Science and Engineering Edited by Luciano Lazzari and MariaPia Pedeferri Engineering Materials The “Engineering Materials” series provides topical information on innovative, structural and functional materials and composites with applications in optic...

Description

Engineering Materials

Pietro Pedeferri

Corrosion Science and Engineering Edited by Luciano Lazzari and MariaPia Pedeferri

Engineering Materials

The “Engineering Materials” series provides topical information on innovative, structural and functional materials and composites with applications in optical, electronical, mechanical, civil, aeronautical, medical, bio and nano engineering. The individual volumes are complete, comprehensive monographs covering the structure, properties, manufacturing process and applications of these materials. This multidisciplinary series is devoted to professionals, students and all those interested in the latest developments in the Materials Science field.

More information about this series at http://www.springer.com/series/4288

Pietro Pedeferri

Corrosion Science and Engineering Edited by Luciano Lazzari and MariaPia Pedeferri In Cooperation with Marco Ormellese, Andrea Brenna, Silvia Beretta, Fabio Bolzoni, Maria Vittoria Diamanti

123

Pietro Pedeferri (Deceased) Politecnico di Milano Milan, Italy

ISSN 1612-1317 ISSN 1868-1212 (electronic) Engineering Materials ISBN 978-3-319-97624-2 ISBN 978-3-319-97625-9 (eBook) https://doi.org/10.1007/978-3-319-97625-9 Library of Congress Control Number: 2018950812 © Springer Nature Switzerland AG 2018 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

This Pedeferri’s Corrosion Science and Engineering textbook is the English edition of Pietro Pedeferri’s Corrosione e Protezione dei Materiali, Polipress, Milano (2007), with many integrations made by his collaborators of the PoliLaPP, the Laboratory of Corrosion of Materials that Pedeferri founded. The main goal while translating and integrating the original Italian book, so far very appreciated in Italy with about 2000 copies printed, is to give a modern and updated handbook on corrosion and corrosion prevention for a twofold use: as a teaching textbook and a modern, technical support for industrial applications. This textbook stands as an ideal learning resource for students of corrosion courses in chemical, mechanical, energy and materials engineering at graduate and advanced undergraduate levels, as well as a valuable reference for engineers. This English edition, integrated and updated, contains 30 chapters, dealing with corrosion theory (9 chapters), forms of corrosion (7), corrosion control and prevention methods (3), applications in different environments as waters, air, soil, concrete (4), and industrial applications as petrochemical plants, refinery and high temperature (2) as well as corrosion of implants in the human body. Four chapters are dedicated to design, corrosion monitoring, laboratory tests and the statistical processing of corrosion data. Chapters dedicated to the on-field applications propose an overview of the most used metals and relevant case histories. Emphasis has been devoted to cathodic protection and corrosion of reinforced concrete to give merit to the pioneering works carried out by Pietro Pedeferri. Each chapter is enriched by pictures of corrosion case studies analysed by PoliLaPP; most of the samples are actually available at the “Corrosion Museum”, where Pietro Pedeferri and his school have collected the most significant corrosion case studies. The book offers the reader and the user many case histories and an important number of questions and exercises to help check the acquired knowledge. Questions and exercises included in each chapter represent the experience gathered by Pedeferri and his school over the last 50 years as a fruit of teaching, research, consultancy on material selection, failure analysis and corrosion engineering. Answers and solutions of exercises for readers will be available on PoliLaPP website (http://polilapp.chem.polimi.it). v

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Finally, a warm thank to all collaborators Andrea Brenna Silvia Beretta, Fabio Bolzoni, Maria Vittoria Diamanti for their hard, precious and tenacious work in contributing to the translation, integration and revision of the chapters and the effort spent on collecting more than 300 exercises. Special mention to Marco Ormellese for the unparalleled contribution. Thanks to Roberto Chiesa for reviewing the chapter related to corrosion in the human body, Giorgio Re for the suggestions on chapters dedicated to environmental-assisted cracking, Eleonora Faccioli for the drawing of figures and tables and Davide Prando for the collection of the original pictures. Milan, Italy June 2018

Luciano Lazzari MariaPia Pedeferri

Contents

1

General Principles of Corrosion . . . . . . . . . . . . . . 1.1 Corrosion as Metallurgy in Reverse . . . . . . . 1.2 The Economic Impact of Corrosion . . . . . . . 1.3 Corrosion Forms . . . . . . . . . . . . . . . . . . . . . 1.3.1 Uniform or Generalized Corrosion . 1.3.2 Localized Corrosion . . . . . . . . . . . 1.3.3 Stress Corrosion Cracking . . . . . . . 1.4 Corrosion Rates . . . . . . . . . . . . . . . . . . . . . 1.4.1 Uniform Corrosion . . . . . . . . . . . . 1.4.2 Localized Corrosion . . . . . . . . . . . 1.5 Corrosion Mechanisms . . . . . . . . . . . . . . . . 1.6 Questions and Exercises . . . . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Electrochemical Mechanism . . . . . . . . . . . 2.1 Electrochemical Processes . . . . . . . . 2.2 Historical Notes . . . . . . . . . . . . . . . 2.2.1 Evans’s Experiences . . . . . 2.3 Local Cell Theory . . . . . . . . . . . . . . 2.3.1 Mixed Potential Theory . . . 2.4 Corrosion Reactions . . . . . . . . . . . . 2.4.1 Anodic Process . . . . . . . . . 2.4.2 Cathodic Processes . . . . . . 2.4.3 Other Cathodic Processes . 2.4.4 Complementary Processes . 2.5 Stoichiometry (Faraday Law) . . . . . . 2.5.1 Corrosion Current Density . 2.6 Change of the Environment . . . . . . . 2.7 Questions and Exercises . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . .

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3

Thermodynamics of Aqueous Corrosion . . . . . . . . . . . . . 3.1 Driving Voltage and Free Energy . . . . . . . . . . . . . . 3.2 Corrosion and Immunity Condition . . . . . . . . . . . . 3.3 Standard Potential . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Potential of an Electrochemical Reaction . . . . . . . . 3.5 Potential of Metal Dissolution Reaction . . . . . . . . . 3.5.1 Corrosion and Immunity Conditions . . . . 3.6 Potential of Cathodic Processes . . . . . . . . . . . . . . . 3.6.1 Potential of Hydrogen Evolution Reaction 3.6.2 Potential of Oxygen Reduction Reaction . 3.6.3 Applications of Thermodynamic Criteria . 3.7 Insoluble Products and Complexing Species . . . . . . 3.8 Reference Electrodes . . . . . . . . . . . . . . . . . . . . . . . 3.9 Electrochemical Cells . . . . . . . . . . . . . . . . . . . . . . 3.9.1 Concentration Cells . . . . . . . . . . . . . . . . . 3.10 Questions and Exercises . . . . . . . . . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Pourbaix Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Oxygen Reduction and Hydrogen Evolution . . . . . . . . . . . 4.2 Metal Immunity, Corrosion and Passivation . . . . . . . . . . . 4.2.1 Equilibrium Between Immunity and Corrosion . . 4.2.2 Equilibrium Between Immunity and Passivation . 4.2.3 Equilibrium Between Corrosion and Passivation . 4.3 Amphoteric Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1 Electrochemical Dissolution in Alkaline Solution 4.3.2 Chemical Dissolution in Alkaline Solution . . . . . 4.4 Pourbaix Diagrams of Some Metals at 25 °C . . . . . . . . . . 4.5 Final Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Questions and Exercises . . . . . . . . . . . . . . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Kinetics of Aqueous Corrosion . . . . . . . . . . . . . . . . . . . . . . . 5.1 Driving Force and Corrosion Rate . . . . . . . . . . . . . . . . 5.2 Dissipations in Corrosion Systems . . . . . . . . . . . . . . . . 5.3 Activation Overvoltage . . . . . . . . . . . . . . . . . . . . . . . . 5.3.1 Exchange Current Density and Tafel Law . . . 5.3.2 Potential-Current Density Diagrams (or Characteristic Curves) . . . . . . . . . . . . . . . . . . 5.3.3 Oxidation or Reduction of a Metal . . . . . . . . . 5.3.4 Hydrogen Evolution (Activation Overvoltage) 5.3.5 Oxygen Reduction (Activation Overvoltage) . . 5.4 Concentration Overvoltage . . . . . . . . . . . . . . . . . . . . . . 5.4.1 Oxygen Reduction: Limiting Current . . . . . . .

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Contents

5.4.2 Total Oxygen Overvoltage . Other Cathodic Processes . . . . . . . . . Passivation and Passivity . . . . . . . . . . 5.6.1 Film Formation Mechanisms 5.6.2 Oxide Properties . . . . . . . . . 5.6.3 Active-Passive Metals . . . . . 5.6.4 Passivity-Related Parameters 5.7 Questions and Exercises . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . 5.5 5.6

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6

Evans Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Evans Diagrams of Active Metals . . . . . . . . . . . . 6.3 Corrosion Conditions in the Presence of an Ohmic 6.4 Multiple Cathodic Processes . . . . . . . . . . . . . . . . 6.5 Imposed Polarization . . . . . . . . . . . . . . . . . . . . . . 6.6 Experimental Polarization Curves . . . . . . . . . . . . . 6.7 Questions and Exercises . . . . . . . . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

Corrosion Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Metal Affecting Factors . . . . . . . . . . . . . . . . . . . . . . 7.1.1 Modification of Metal Surface Composition 7.1.2 Nobility by Alloying . . . . . . . . . . . . . . . . . 7.1.3 Overvoltage of Cathodic Processes . . . . . . 7.1.4 Cathodic Alloying . . . . . . . . . . . . . . . . . . . 7.1.5 Reduction of Anodic Areas . . . . . . . . . . . . 7.1.6 Passivation Induced by Alloying . . . . . . . . 7.2 Environment Affecting Factors . . . . . . . . . . . . . . . . . 7.2.1 Conductivity . . . . . . . . . . . . . . . . . . . . . . . 7.2.2 pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.3 Differential Aeration . . . . . . . . . . . . . . . . . 7.2.4 Salt Formation/Precipitation . . . . . . . . . . . . 7.2.5 Cation Displacement . . . . . . . . . . . . . . . . . 7.2.6 Microorganisms . . . . . . . . . . . . . . . . . . . . 7.3 Metal/Environment Affecting Factors . . . . . . . . . . . . 7.3.1 Temperature . . . . . . . . . . . . . . . . . . . . . . . 7.3.2 Condensation . . . . . . . . . . . . . . . . . . . . . . 7.3.3 Corrosion Products and Deposits . . . . . . . . 7.3.4 Flow Regime . . . . . . . . . . . . . . . . . . . . . . 7.3.5 Active–Passive Related Parameters . . . . . . 7.4 Questions and Exercises . . . . . . . . . . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Contents

8

Uniform Corrosion in Acidic and Aerated Solutions . 8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 Acidic Solutions . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 Strong Acids . . . . . . . . . . . . . . . . . . 8.2.2 Carbonic Acid . . . . . . . . . . . . . . . . . 8.2.3 Hydrogen Sulphide . . . . . . . . . . . . . . 8.2.4 Organic Acids . . . . . . . . . . . . . . . . . 8.2.5 Corrosion of Passive Metals . . . . . . . 8.3 Aerated Solutions . . . . . . . . . . . . . . . . . . . . . . 8.3.1 Oxygen Limiting Diffusion Current . . 8.3.2 Presence of Chlorine . . . . . . . . . . . . . 8.3.3 Dimensionless Number Approach . . . 8.3.4 Corrosion of Noble Metals . . . . . . . . 8.3.5 Corrosion of Non-noble Metals . . . . . 8.3.6 Corrosion of Passive Metals . . . . . . . 8.4 Questions and Exercises . . . . . . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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9

Macrocell Corrosion Mechanism . . . . . . . . . . . 9.1 Electrical Field in Uniform Corrosion . . . 9.2 Electrical Field in a Macrocell . . . . . . . . 9.2.1 Pure Ohmic Systems . . . . . . . . 9.2.2 Two-Electrode Macrocell . . . . 9.3 Current Distribution . . . . . . . . . . . . . . . 9.3.1 Primary Current Distribution . . 9.3.2 Secondary Current Distribution 9.4 Throwing Power . . . . . . . . . . . . . . . . . . 9.5 Typical Geometries . . . . . . . . . . . . . . . . 9.5.1 Inside a Pipe . . . . . . . . . . . . . 9.5.2 Outside a Pipeline . . . . . . . . . . 9.5.3 On a Plate . . . . . . . . . . . . . . . 9.6 Maximum Surface Area Ratio . . . . . . . . 9.7 Questions and Exercises . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . .

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10 Galvanic Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1 Effects on Metal Corrosion . . . . . . . . . . . . . . . . . . . . 10.2 Galvanic Effects on Less Noble Metal . . . . . . . . . . . . 10.3 Galvanic Effects on More Noble Metal . . . . . . . . . . . . 10.4 Galvanic Coupling Representation by Evans Diagrams 10.5 Four Main Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.1 Practical Nobility . . . . . . . . . . . . . . . . . . . . 10.5.2 Cathodic Overvoltage on More Noble Metal 10.5.3 Surface Area Ratio and Maximum Corrosion Rate . . . . . . . . . . . . . . . . . . . . . .

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