ECHE 571/Fall 2010
Problem Set # 6
EVANS DIAGRAMS
1.
Y. ANGUCHAMI: Construct an E-log(i) Evan’s Diagram for the
corrosion of tin in hydrogen saturated oxygen free solution in which
activity of Sn is 0.4 (molar scale). The data for the cathodic reaction are as
follows:
Given:
Cathodic intercept ac=1.24
Cathodic slope bc=-0.11
Assume:
a) charge transfer kinetics
b) high field approximation applies
c) ba=0.1
d) ioa=10-10 mA/cm2
Calculate:
a) corrosion current
b) exchange current density for hydrogen evolution
c) protection current to prevent corrosion for PH2=1 atm.
The corrosion potential for Sn is –0.08V. If the hydrogen evolution
reaction is limited by the diffusion of H+ species to the metal sites,
reconstruct the Evan’s diagram for this case.
2. Hee JUNG MYUNG : Using the following data construct an E-log(i)
Evan’s Diagram for the corrosion of zinc on hydrogen saturated oxygen
free solution of pH=0.8 and a Zn2+=0.15 M (molar scale).
Assume:
charge transfer kinetics
high field approximation applies
Given:
ioH2=3x10-11 Am-2
ba (  /  log i )=1.24V
bc=-0118 V
corrosion potential=-0.34V
EoH+/H2=0.0
EoZn2+/Zn=0.799=-0.763 V
Calculate:
a) corrosion current
b) exchange current density
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c) protection current required to reduce corrosion current to zero
3. Y. MUTHUKUMURASAMYAY: Using the following data, construct
an E-log(i) Evan’s Diagram for the corrosion of nickel in saturated oxygen
solution of a Ni=0.23 M (molar scale).
Assume:
charge transfer kinetics
high field approximation applies
Given:
corrosion potential=0.1V
exchange current density for nickel dissolution 10-5 A/cm2.
Anodic ba=0.12
Cathodic bc=-0.1
Cathodic intercept ac=0.6
Calculate:
corrosion current
exchange current density for oxygen on nickel dissolution 10-5 A/cm2
the protection current to prevent corrosion for PO2= 1 atm.
4. K. PUNYAWUDHO: Using the following data, construct an E-log(i)
Evan’s Diagram for the corrosion of copper in saturated oxygen solution of
a Cu=10-6M (molar scale) in 1.0 M NaOH
Assume:
a) charge transfer kinetics
b) high field approximation applies
Given:
exchange current density for copper dissolution 10-9 A/cm2.
exchange current density for oxygen reduction 10-8 A/cm2.
Anodic ba=0.1
Cathodic bc=-0.12
Cathodic intercept ac=0.7
Calculate:
corrosion current
Ecorr
the protection current to prevent corrosion for PO2= 1 atm.
5.
John A. STASER: Using the following data, construct an E-log(i)
Evan’s Diagram for the corrosion of cobalt in saturated oxygen solution of
a Co=0.3 M (molar scale).
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Assume:
charge transfer kinetics
high field approximation applies
Given:
corrosion potential=0.2V
exchange current density for nickel dissolution 10-7 A/cm2.
anodic ba=0.12
Cathodic bc=-0.1
Cathodic intercept ac=-0.8
Calculate:
a) corrosion current
b) exchange current density for oxygen on nickel dissolution 10-5
A/cm2
c) the protection current to prevent corrosion for PO2= 1 atm.
Kayse D. BAGWELL: Using the following data, construct an E-log(i)
6.
Evan’s Diagram for the corrosion of iron in saturated oxygen solution of
a Fe-0.3 (molar scale).
Assume:
charge transfer kinetics
high field approximation applies
Given:
corrosion potential=0.2V
exchange current density for nickel dissolution 10-7 A/cm2.
Anodic slope ba=0.12
Cathodic sloep bc=-0.1
Cathodic intercept ac=0.7
Calculate:
corrosion current
exchange current density for oxygen on nickel dissolution 10-5 A/cm2
the protection current to prevent corrosion for PO2= 1 atm.
7. Brian S. CROUT: Using the following data construct an E-log(i) Evan’s
Diagram for the corrosion of zinc on hydrogen saturated oxygen free
solution of pH=0.8 and a Zn2+=0.15 M (molar scale).
Assume:
a. charge transfer kinetics
b. high field approximation applies
Given:
ioH2=3x10-11 Am-2
ba (  /  log i )=1.24V
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bc=-0118 V
corrosion potential=-0.34V
EoH+/H2=0.0
EoZn2+/Zn=0.799=-0.763 V
Calculate:
corrosion current
exchange current density
protection current required to reduce corrosion current to zero
8. Samuel E. HARTZOG: Construct an E-log(i) Evan’s Diagram for the
corrosion of tin in hydrogen saturated oxygen free solution in which activity
of Sn is 0.4 (molar scale). The data for the cathodic reaction are as follows:
Given:
Cathodic intercept ac=1.24
Cathodic slope bc=-0.11
Assume:
e) charge transfer kinetics
f) high field approximation applies
g) ba=0.1
h) ioa=10-10 mA/cm2
Calculate:
d) corrosion current
e) exchange current density for hydrogen evolution
f) protection current to prevent corrosion for PH2=1 atm.
The corrosion potential for Sn is –0.08V. If the hydrogen evolution reaction is
limited by the diffusion of H+ species to the metal sites, reconstruct the Evan’s
diagram for this cas
9. Jacob T. HUNTER: Using the following data construct an E-log(i) Evan’s
Diagram for the corrosion of zinc on hydrogen saturated oxygen free
solution of pH=0.8 and a Zn2+=0.15 M (molar scale).
Assume:
c. charge transfer kinetics
d. high field approximation applies
Given:
ioH2=3x10-11 Am-2
ba (  /  log i )=1.24V
bc=-0.118 V
corrosion potential=-0.34V
EoH+/H2=0.0
EoZn2+/Zn=0.799=-0.763 V
4
Calculate:
d) corrosion current
e) exchange current density
f) protection current required to reduce corrosion current to zero.
10. Carly L. JACKSON: Construct an E-log(i) Evan’s Diagram for the
corrosion of tin in hydrogen saturated oxygen free solution in which activity
of Sn is 0.4 (molar scale). The data for the cathodic reaction are as follows:
Given:
Cathodic intercept ac=1.24
Cathodic slope bc=-0.11
Assume:
i) charge transfer kinetics
j) high field approximation applies
k) ba=0.1
l) ioa=10-10 mA/cm2
Calculate:
g) corrosion current
h) exchange current density for hydrogen evolution
i) protection current to prevent corrosion for PH2=1 atm.
The corrosion potential for Sn is –0.08V. If the hydrogen evolution reaction is
limited by the diffusion of H+ species to the metal sites, reconstruct the
Evan’s diagram for this case.
11. CRAIG JECKEL: Using the following data construct an E-log(i) Evan’s
Diagram for the corrosion of zinc on hydrogen saturated oxygen free
solution of pH=0.8 and a Zn2+=0.15 M (molar scale).
Assume:
e. charge transfer kinetics
f. high field approximation applies
Given:
ioH2=3x10-11 Am-2
ba (  /  log i )=1.24V
bc=-0.118 V
corrosion potential=-0.34V
EoH+/H2=0.0
EoZn2+/Zn=0.799=-0.763 V
Calculate:
g) corrosion current
h) exchange current density
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protection current required to reduce corrosion current to z
12. Joshua P. MCLURE: Using the following data, construct an E-log(i)
Evan’s Diagram for the corrosion of cobalt in saturated oxygen solution of
a Co-0.3 (molar scale).
Assume:
c) charge transfer kinetics
d) high field approximation applies
Given:
corrosion potential=0.2V
exchange current density for nickel dissolution 10-7 A/cm2.
anodic ba=0.12
Cathodic bc=-0.1
Cathodic intercept a=-0.8
Calculate:
corrosion current
exchange current density for oxygen on nickel dissolution 10-5 A/cm2
the protection current to prevent corrosion for PO2= 1 atm.
13. Heather MENTZER: Construct an E-log(i) Evan’s Diagram for the
corrosion of tin in hydrogen saturated oxygen free solution in which activity
of Sn is 0.4 (molar scale). The data for the cathodic reaction are as follows:
Given:
Cathodic intercept ac=1.24
Cathodic slope bc=-0.11
Assume:
m) charge transfer kinetics
n) high field approximation applies
o) ba=0.1
p) ioa=10-10 mA/cm2
Calculate:
j) corrosion current
k) exchange current density for hydrogen evolution
l) protection current to prevent corrosion for PH2=1 atm
The corrosion potential for Sn is –0.08V. If the hydrogen evolution reaction is
limited by the diffusion of H+ species to the metal sites, reconstruct the
Evan’s diagram for this case.
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14. Kelvin D. MOORE: Using the following data construct an E-log(i)
Evan’s Diagram for the corrosion of zinc on hydrogen saturated oxygen free
solution of pH=0.8 and a Zn2+=0.15 M (molar scale).
Assume:
g. charge transfer kinetics
h. high field approximation applies
Given:
ioH2=3x10-11 Am-2
ba (  /  log i )=1.24V
bc=-0.118 V
corrosion potential=-0.34V
EoH+/H2=0.0
EoZn2+/Zn=0.799=-0.763 V
Calculate:
i) corrosion current
j) exchange current density
k) protection current required to reduce corrosion current to zero.
15. Joel C. STANFIELD: Using the following data construct an E-log(i) Evan’s
Diagram for the corrosion of zinc on hydrogen saturated oxygen free
solution of pH=0.8 and a Zn2+=0.15 M (molar scale).
Assume:
i. charge transfer kinetics
j. high field approximation applies
Given:
ioH2=3x10-11 Am-2
ba (  /  log i )=1.24V
bc=-0.118 V
corrosion potential=-0.34V
EoH+/H2=0.0
EoZn2+/Zn=0.799=-0.763 V
Calculate:
l) corrosion current
m) exchange current density
n) protection current required to reduce corrosion current to zero.
7