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환경 과 재료 ( Environmental Effects on the Degradation of Materials) “06 Spring Semester

MS 657. 환경 과 재료 ( Environmental Effects on the Degradation of Materials) “06 Spring Semester. Meets : Mon ., 09:00 - 10:30, and Wed., 09:00 -10:30, Appl. Eng. Bldg., Rm. 2425 Instructor : Kwon, HyukSang, Professor Rm. 2404, Appl. Eng. Bldg.

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환경 과 재료 ( Environmental Effects on the Degradation of Materials) “06 Spring Semester

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  1. MS 657 환경 과 재료(Environmental Effects on the Degradation of Materials)“06 Spring Semester

  2. Meets: Mon., 09:00 - 10:30, and Wed., 09:00 -10:30, Appl. Eng. Bldg., Rm. 2425 • Instructor : Kwon, HyukSang, Professor Rm. 2404, Appl. Eng. Bldg. Tel : 869-3326 E-mail : hskwon@kaist.ac.kr • Prerequisites : MS 214 and MS 215 • Text Book: Principles and Prevention of Corrosion, Denny A. Jones, Prentice Hall, 2nd ed., 1996

  3. References1. Corrosion Engineering, Mars G. Fontana, Mcgraw-Hill Co., 3rd ed., 1987 2. Corrosion and Corrosion Control, H. H. Uhlig and R. W. Revie, John Wiley & Sons, 3rd ed., 1985.3. The Fundamentals of Corrosion,J. C. Scully, Pergamon Press, 3rd ed.,19904. Basic Corrosion and Oxidation,J. M. West, Ellis Horwood Publishers, 2nd ed., 1986.5. Corrosion and Environmental Degradation Vol. I &II Materials Sci. and Tech. 6. Corrosion, Vol. I and Vol. II, L. L. Shreir, ed., Newnes-Butterworths Co., 2nd ed., 1976.7. Corrosion and Oxide Films ed. A.J. Bard & M. Stratmann, 20018. The Electrochemistry of Corrosion, D. L. Piron, NACE, 1994.9 Electrochemical Methods A.J.Bard, L.R. Faulkner, 2nd ed. JOHN WILEY & SON INC, 20019. 10 Modern Electrochemistry J. O’M Bockris and A. K. N. Reddy, Plenum Press, 2nd ed., 1998.11 Metals Handbook Vol. 13, Corrosion, ASM International, 1987.12 Uhlig's Corrosion Handbook, Edited by R.Winston Revie, 2nd ed. JOHN WILEY & SON INC, 2000

  4. Journals 1. Corrosion Science and Technology 2. Corrosion, NACE International. 3. Materials Performance, NACE International. 4. Corrosion Science, Pergamon Press. 5. Journal of the Electrochemical Society. 6. Electrochimica Acta

  5. GoalsApplies thermodynamics and kinetics of electrode reactions to environmental effects on the failures of metals and alloys. Specific topics comprising thermodynamics and kinetics of electrode reactions, mixed potential theory, passivity, galvanic corrosion, crevice corrosion, pitting, stress corrosion, hydrogen embrittlement, corrosion-resistant-alloy design and corrosion prevention are discussed. • Grading PolicyMid-term exam(40)+Final exam(40)+Homework(20)

  6. Topics ( no. of class):Introduction (1) Electrochemical aspects of corrosion (1) Thermodynamics of corrosion processes (2) Pourbaix diagrams ( 2) Electrode kinetics (2) Corrosion kinetics, Mixed potential theory (2) Prediction of corrosion behavior using mixed potential theory (2) Galvanic corrosion (1) Passivity (2) Photoelectrochemical analysis of passive film (1) Localized corrosion (3) Intergranular corrosion (1) Hydrogen damage (3) Stress corrosion cracking & Corrosion fatigue (2) Micro-probe corrosion analysis (1) Corrosion-resistant alloy design (1) Corrosion control (2)

  7. Air & Gas Env. TemperatueHumidityPO2 Radiation Material Material Surface Condition Alloying Com.MicrostructuresStress Aqueous Env. Soil TemperatureAcidityPO2[Cl-]Bacteria TemperaturepH [O2][Cl-]Flow velocityConductivity 1. Introduction 1.1 Material & Environments

  8. Metallurgical Corrosion Resistance Mechanical Electrochemical Thermodynamics 1.2 Definition of Corrosion The destructive attack of a metal by chemical or electrochemical reaction with its environment. Corrosion returns the metal to its oxidized state or combined state in chemical compounds that are similar or even identical to the minerals from which the metals are extracted.  Aqueous corrosion : Zn + 2HCl ZnCl2 + H22Al + 3H2O  Al2O3 + 6H+ Oxidation : 2Fe + 3O2Fe2O3 High Temperature Corrosion : Fe + CO2(gas) FeO + CO  Rusting : 2Fe + 2H2O + O2 2Fe(OH)2 2Fe(OH)2 + H2O + O2 2Fe(OH)3

  9. Cost of Corrosion

  10. Cost of Corrosion in USA

  11. 1.3 Cost of Corrosion  Direct loss :Approximately 3 - 5% of GNP in developed countries. About 15 - 25% of this expense could be avoided if currently available corrosion technology were effectively applied.  Cost of corrosion in U. S. about $ 276 billion in 2002. 3.1 % of GNP.  Cost of corrosion to oil and gas producers in U. S.  $ 2 billion that are increasing because of deeper wells and more hostile env.(500 F, H2S).  Cost of corrosion in paper industry  $6-7/ton  Automobile industry  $ 2 billion /yr  Nuclear industry $ 0.25 billion /yr in U.S. Average capacity loss factor : 6 ~18% in BWR 5 ~ 8 % in PWR  Indirect loss  Plant shutdown.  Loss of product.  Loss of efficiency  Contamination.  Overdesign.

  12. Pressurized water reactor

  13. 1.4. Electrochemical Nature of Corrosion Consider what happens when Zn is placed in dilute HCl solution : Zn + HCl  ZnCl2 + H2 : Cl- is not involved in the reaction. Zn + 2H+ Zn2+ + H2 (1) Reaction (1) can be separated into half cell reactions : Zn  Zn2+ + 2e- .............anodic or oxidation reaction : (2) 2H+ + 2e- H2 ...............cathodic or reduction reaction : (3) An electrochemical cell consists of the followings : Electrode : the interface between a metal and a solution across which a charge transfer results from an electrochemical reaction. - Anode : the electrode on which an anodic oxidation reaction occurs. - Cathode : the electrode on which a cathodic reduction reaction occurs. Electrolyte : an ionic conductor.

  14. During metallic corrosion the rate of oxidation equals the rate of reduction.  Anodic reactions in corrosion :• Metal Corrosion : M  M+n + ne-• Ferrous ion oxidation : Fe2+ Fe3+ + e-• Oxygen evolution : 2H2O  O2+ 4H+ + 4e-  Cathodic reactions in corrosion :• hydrogen evolution in acid sol. : 2H+ + 2e  H2• oxygen reduction in acid sol. : O2+ 4H+ + 4e  2H2O• oxygen reduction in neutral or basic sol. : O2+ 2H2O + 4e  4OH-• metal ion reduction : M+3 + e  M+2• metal deposition : M+ + e  M Ex. ) Corrosion of Zn in an aerated HCl solution. • Two cathodic reaction :hydrogen evolution rx., oxygen reduction rx. • The oxygen reduction simply provides a new means of electrondisposal. •Increasing the total reduction rate increases the rate of corrosion. Thus,it is possible to reduce corrosion by reducing the rate of either reaction: - removing oxidizer - coating the surface of metal with paint or nonconducting film. - addition of corrosion inhibitors- Supplying electron to Zn : cathodic protection During corrosion, more than one oxidation and one reduction may occur :

  15. Microstructure Environment Stress Geometry Time 1.5 Forms of Corrosion Factors affecting forms of corrosion :    

  16. Forms of Corrosion(1) Stainless screw v cadmium plated steel washer

  17. Forms of Corrosion (2) Stress Corrosion Cracking (SCC) in a U-bend sample of 316 stainless steel exposed to Supercritical Water Oxidation (SCWO) environment Exfoliation in aluminum aircraft alloy

  18. Forms of Corrosion (3) Corroded reinforced concrete water main Intergranular SCC of an Inconel heat exchanger tube with the crack following the grain boundaries

  19. Forms of corrosion (4) Electronic circuit corrosion

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