Lecture 17 - CHAPTER 17: CORROSION AND DEGRADATION ISSUES...

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Chapter 17 - 1 ISSUES TO ADDRESS. .. Why does corrosion occur ? What metals are most likely to corrode? How do temperature and environment affect corrosion rate? How do we suppress corrosion? CHAPTER 17: CORROSION AND DEGRADATION
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Chapter 17 - 2 Corrosion : -- the destructive electrochemical attack of a material. -- Al Capone's ship, Sapona, off the coast of Bimini. Cost: -- 4 to 5% of the Gross National Product (GNP)* -- this amounts to just over $400 billion/yr** * H.H. Uhlig and W.R. Revie, Corrosion and Corrosion Control: An Introduction to Corrosion Science and Engineering , 3rd ed., John Wiley and Sons, Inc., 1985. **Economic Report of the President (1998). Photos courtesy L.M. Maestas, Sandia National Labs. Used with permission. THE COST OF CORROSION
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Chapter 17 - 3 Two reactions are necessary: -- oxidation reaction: -- reduction reaction: Zn Zn 2 + + 2 e - 2H + + 2 e - H 2 (gas) Other reduction reactions: -- in an acid solution -- in a neutral or base solution O 2 + 4H + + 4 e - 2H 2 O O 2 + 2H 2 O + 4 e - 4(OH) - Adapted from Fig. 17.1, Callister 7e . (Fig. 17.1 is from M.G. Fontana, Corrosion Engineering , 3rd ed., McGraw-Hill Book Company, 1986.) CORROSION OF ZINC IN ACID Zinc Oxidation reaction Zn Zn 2+ 2e - Acid solution reduction reaction H + H + H 2 (gas) H + H + H + H + H + in the metal
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Chapter 17 - 4 STANDARD HYDROGEN (EMF) TEST
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This note was uploaded on 09/06/2011 for the course EMA 3010 taught by Professor Unknown during the Fall '08 term at University of Florida.

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Lecture 17 - CHAPTER 17: CORROSION AND DEGRADATION ISSUES...

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