Fundamentals of Materials Science and Engineering: An Integrated Approach, 3e

GTBL042-16 GTBL042-Callister-v2 September 13, 2007 13:10

Revised Pages

676 • Chapter 16 / Corrosion and Degradation of Materials

Current density, i (A/cm^2 )

Electrochemical potential,

V (V)

10 –12 10 –10 10 –8 10 –6 10 –4 10 –2 1

–1.0

• 0.8


• 0.6


• 0.4


• 0.2

0

+0.2

+0.4

i 0 (H+/H 2 )

iC

V (H+/H 2 )

Zn

2+ + 2

e–

Zn

H 2

2H+

+ 2

e–

VC

V (Zn/Zn2+)

i 0 (Zn/Zn2+)

Figure 16.10 Electrode kinetic behavior of zinc in an acid solution; both oxidation and

reduction reactions are rate limited by activation polarization. (Adapted from

M. G. Fontana,Corrosion Engineering,3rd edition. Copyright©c1986 by McGraw-Hill

Book Company. Reproduced with permission.)

Log current density, i

Electrochemical potential,

V iC

VC

V (H+/H 2 )

iL

i 0 (M/M2+)

i 0 (H+/H 2 )

V (M/M2+)

Figure 16.11 Schematic electrode kinetic behavior for metal M; the reduction reaction is

under combined activation–concentration polarization control.