When a Z 1, E is equal to E 8 .T he standard single potential E 8 shows the
degree of activity of the metal and gas.
The electrochemical series consists of the arrangement of metals in order
of electrode potential. The more negative the single potential is, the more
active the metal. Table 7.1 provides the standard single potentials of various
metals and nonmetal reactants.
When the electromotive force ( E c K E a )i ss upplied, the corrosionc ell is
formed with the current flowing between the anodea nd the cathode.
The cathodic electrode potential is shifted to the less noble direction. The
shiftingofpotentials is called cathodic and anodic polarization. The reaction
rate curves ( E K i )a re known as cathodic or anodic polarization curves.
The corrosion potential E
c
corr and the corrosion current i corr are given by the
intersection of the cathodic and anodicpolarization curves—indication that
both electrodes react at the same rate in the corrosionprocess.
The polarization curves in the current density rangegreater than i corr are
called external polarization curves, and those in the current density range
less than i corr are called internal polarization curves. By sweepingt he
electrode potential from the corrosion potential to the cathodic or anodic
TABLE 7.1
Standard Single Potentials, E 8 (V,S HE, 258 C)
Active
Inert
Electrode
E 8
Electrode
E 8
Li/Li
C
K 3.01
Mo/Mo
3 C
K 0.2
Rb/Rb
C
K 0.298
Sn/Sn
2 C
K 0.140
Cs/Cs
C
K 0.292
Pb/Pb
2 C
K 0.126
K/K
C
K 2.92
H 2 /H
C
G 0
Ba/Ba
2 C
K 2.92
Bi/BiO
C 0.32
Sr/Sr
2 C
K 2.89
Cu/Cu
2 C
C 0.34
Ca/Ca
C
K 2.84
Rh/Rh
2 C
C 0.6
Na/Na
C
K 2.71
Hg/Hg
C
C 0.798
Mg/Mg
2 C
K 2.38
Ag/Ag
C
C 0.799
Th/Th
4 C
K 2.10
Pd/Pd
2 C
C 0.83
Ti/Ti
2 C
K 1.75
Ir/Ir
3 C
C 1.0
Be/Be
2 C
K 1.70
Pt/Pt
2 C
C 1.2
Al/Al
3 C
K 1.66
Au/Au
3 C
C 1.42
V/V
2 C
K 1.5
Au/Au
C
C 1.7
Mn/Mn
2 C
K 1.05
Zn/Zn
2 C
K 0.763
O 2 /OH
C 0.401
Cr/Cr
3 C
K 0.71
I 2 /I
K
C 0.536
Fe/Fe
2 C
K 0.44
Br 2 /Br
K
C 1.066
Cd/Cd
K 0.402
Cl 2 /Cl
K
C 1.256
In/In
3 C
K 0.34
F 2 /F
K
C 2.85
Ti/Ti
C
K 0.335
S/S
2 K
K 0.51
Co/Co
2 C
K 0.27
Se/Se
2 C
K 0.78
Ni/Ni
2 C
K 0.23
Te/Te
2 C
K 0.92
Coatings
407
CAT8247—CHAPTER 7—17/10/2006—15:02—TRGANESH—XMLM ODEL B–pp. 403–485
degree of activity of the metal and gas.
The electrochemical series consists of the arrangement of metals in order
of electrode potential. The more negative the single potential is, the more
active the metal. Table 7.1 provides the standard single potentials of various
metals and nonmetal reactants.
When the electromotive force ( E c K E a )i ss upplied, the corrosionc ell is
formed with the current flowing between the anodea nd the cathode.
The cathodic electrode potential is shifted to the less noble direction. The
shiftingofpotentials is called cathodic and anodic polarization. The reaction
rate curves ( E K i )a re known as cathodic or anodic polarization curves.
The corrosion potential E
c
corr and the corrosion current i corr are given by the
intersection of the cathodic and anodicpolarization curves—indication that
both electrodes react at the same rate in the corrosionprocess.
The polarization curves in the current density rangegreater than i corr are
called external polarization curves, and those in the current density range
less than i corr are called internal polarization curves. By sweepingt he
electrode potential from the corrosion potential to the cathodic or anodic
TABLE 7.1
Standard Single Potentials, E 8 (V,S HE, 258 C)
Active
Inert
Electrode
E 8
Electrode
E 8
Li/Li
C
K 3.01
Mo/Mo
3 C
K 0.2
Rb/Rb
C
K 0.298
Sn/Sn
2 C
K 0.140
Cs/Cs
C
K 0.292
Pb/Pb
2 C
K 0.126
K/K
C
K 2.92
H 2 /H
C
G 0
Ba/Ba
2 C
K 2.92
Bi/BiO
C 0.32
Sr/Sr
2 C
K 2.89
Cu/Cu
2 C
C 0.34
Ca/Ca
C
K 2.84
Rh/Rh
2 C
C 0.6
Na/Na
C
K 2.71
Hg/Hg
C
C 0.798
Mg/Mg
2 C
K 2.38
Ag/Ag
C
C 0.799
Th/Th
4 C
K 2.10
Pd/Pd
2 C
C 0.83
Ti/Ti
2 C
K 1.75
Ir/Ir
3 C
C 1.0
Be/Be
2 C
K 1.70
Pt/Pt
2 C
C 1.2
Al/Al
3 C
K 1.66
Au/Au
3 C
C 1.42
V/V
2 C
K 1.5
Au/Au
C
C 1.7
Mn/Mn
2 C
K 1.05
Zn/Zn
2 C
K 0.763
O 2 /OH
C 0.401
Cr/Cr
3 C
K 0.71
I 2 /I
K
C 0.536
Fe/Fe
2 C
K 0.44
Br 2 /Br
K
C 1.066
Cd/Cd
K 0.402
Cl 2 /Cl
K
C 1.256
In/In
3 C
K 0.34
F 2 /F
K
C 2.85
Ti/Ti
C
K 0.335
S/S
2 K
K 0.51
Co/Co
2 C
K 0.27
Se/Se
2 C
K 0.78
Ni/Ni
2 C
K 0.23
Te/Te
2 C
K 0.92
Coatings
407
CAT8247—CHAPTER 7—17/10/2006—15:02—TRGANESH—XMLM ODEL B–pp. 403–485