EmaCh17 - 1 Chapter 17 1 ISSUES TO ADDRESS • Why does...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 5/1/2008 1 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 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 perm ission. THE COST OF CORROSION 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, Cal ister 7e . (Fig. 17.1 is from M.G. Fontana, Corrosion Engineering , 3rd ed., McGraw-Hil Book Com pany, 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 + flow of e- in the metal Chapter 17 - 4 STANDARD HYDROGEN (EMF) TEST • Two outcomes: o metal V...
View Full Document

This note was uploaded on 03/29/2009 for the course EMA 3010 taught by Professor Unknown during the Spring '08 term at University of Florida.

Page1 / 2

EmaCh17 - 1 Chapter 17 1 ISSUES TO ADDRESS • Why does...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online