1. Environmental Interactions Chapter 16
Corrosion and Wear
Materials Science for Engineering Students – Traugott Fischer - © 2009

2. Chapter 16 – Corrosion and Wear
The Statue of Liberty
Chapter 16 – Corrosion and Wear

3. Dissolution of Iron in Water
Equilibrium: Fe++ - 2e- double layer establishes E – potential that stops the dissolution.
Chapter 16 – Corrosion and Wear

4. Chapter 16 – Corrosion and Wear
Cell Potential
The 2 metals have different tendencies (DG) to dissolve
Chapter 16 – Corrosion and Wear

5. Effect of Electrode Area
Cathode area must be kept small to avoid corrosion of the anode
Chapter 16 – Corrosion and Wear

6. Chapter 16 – Corrosion and Wear
Cathodic Protection
A: By more anodic material B: By applied potential
Chapter 16 – Corrosion and Wear

7. Cathodic Protection of a Ship
Chapter 16 – Corrosion and Wear

8. Corrosion in a Single Metal
Local variations in electrolyte or metal form electrolytic cells
Chapter 16 – Corrosion and Wear

9. Chapter 16 – Corrosion and Wear
Concentration Cell
Chapter 16 – Corrosion and Wear

10. Acid Corrosion Bronze impeller in 1% sulfuric acid
Chapter 16 – Corrosion and Wear

11. Oxygen Concentration Cell
Chapter 16 – Corrosion and Wear

12. Chapter 16 – Corrosion and Wear
Crevice Corrosion
A: Anode, C: Cathode
Chapter 16 – Corrosion and Wear

13. Corrosion by Chlorine Pitting Corrosion of Stainless Steel
Chapter 16 – Corrosion and Wear

14. Corrosion by Chlorine
Corrosion of aluminum in atmosphere with salt water
Chapter 16 – Corrosion and Wear

15. Corrosion of Rubber Swelling and cracking by exposure to HCl
Chapter 16 – Corrosion and Wear

16. Cavities due to Hydrogen
Unalloyed Iron in water with CO2
Chapter 16 – Corrosion and Wear

17. Chapter 16 – Corrosion and Wear
Ammonia Corrosion
Chapter 16 – Corrosion and Wear

18. Designing to Avoid Corrosion
Chapter 16 – Corrosion and Wear

19. Chapter 16 – Corrosion and Wear
Dry Oxidation
Metal
Metal
A: Metal migrates more rapidly B: Oxygen migrates more rapidly
Chapter 16 – Corrosion and Wear

20. Stresses in Oxide Coatings Upon Cooling
Natural size when cold
Stresses upon cooling
Failure of coating
Coating and Metal are unstressed at high temperature
Thermal expansion of coating A: larger, B: smaller than for metal
Chapter 16 – Corrosion and Wear

21. Erosion Changes of erosion rate with impact angle
Chapter 16 – Corrosion and Wear

22. Chapter 16 – Corrosion and Wear
Cutting Metals
A: Metal is cut by plastic (shear) deformation
B: Typical temperatures in metal and tool
C: Wear patterns in tools
Chapter 16 – Corrosion and Wear