Evans Diagrams

ECHE 571/Fall 2010

Problem Set # 6

EVANS DIAGRAMS

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 Zn2+=0.15 M (molar scale).

Assume:

charge transfer kinetics

high field approximation applies

Given:

ioH2=3x10-11 Am-2

ba ()=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

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 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

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.

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 Co=0.3 M (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 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.

6. Kayse D. BAGWELL: Using the following data, construct an E-log(i) Evan’s Diagram for the corrosion of iron in saturated oxygen solution of 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 Zn2+=0.15 M (molar scale).

Assume:

charge transfer kinetics
high field approximation applies

Given:

ioH2=3x10-11 Am-2

ba ()=1.24V

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 Zn2+=0.15 M (molar scale).

Assume:

charge transfer kinetics
high field approximation applies

Given:

ioH2=3x10-11 Am-2

ba ()=1.24V

bc=-0.118 V

corrosion potential=-0.34V

EoH+/H2=0.0

EoZn2+/Zn=0.799=-0.763 V

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 Zn2+=0.15 M (molar scale).

Assume:

charge transfer kinetics
high field approximation applies

Given:

ioH2=3x10-11 Am-2

ba ()=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

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 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.

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 Zn2+=0.15 M (molar scale).

Assume:

charge transfer kinetics
high field approximation applies

Given:

ioH2=3x10-11 Am-2

ba ()=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 Zn2+=0.15 M (molar scale).

Assume:

charge transfer kinetics
high field approximation applies

Given:

ioH2=3x10-11 Am-2

ba ()=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.