Galvanic corrosion

In this presentation we are talk about Galvanic Corrosion Briefly.

1. FACULTY OF SCINCE AND ENGINEERING SCHOOL OF PETROLEUM AND CHEMISTRY PETROLEUM DEPARTMENT Third stage ( Overview of Galvanic Corrosion ) Prepared by : Kamal Abdurahman Supervised by: Dr.Nabil    

2. Definition Corrosion may be defined as the destruction of a metal or an alloy because of chemical or electrochemical reaction with it's surrounding enviroment or medium

3. Example corrosion

4. Example #2

5. Result of Galvanic Corrosion

6. Corrosion forms 1-Uniform corrosion 2-Galvanic corrosion In this presentation we explain the second form of corrosion which is Galvanic corrosion

7. 2. Galvanic Corrosion

8. Video of Galvanic corrosion Procedure

9. When two dissimilar metals are in contact, the corrosion rate of the more active metal(more negative Ecorr) is accelerated, while the corrosion rate of the noble metal(less negative Ecorr) is reduced. •The higher the difference in Ecorr, the more severe is galvanic corrosion. •Galvanic Series: a list of measured corrosion potentials (Ecorr) of a number of metals and alloys in a given electrolyte.

10. Attractive Video

11. Area effects: –IC= Ia(total current in amps) –ic*Ac= ia* Aa(i in amp/cm2) –or ia∝Ac/Aa(proportional to galvanic corrosion damage) –High Ac/Aaleads to high ia(bad from GC viewpoint) –Example: integrity of mechanical fasteners •Riveted plates of Cu and steel. •Painted steel storage tank

12. Example#2: Storage Tanks

13. Prevention of Galvanic Corrosion:

14. Kinetics of GC: 1-Corroding metal-inert metal couple

15. Galvanic Metallic Coatings

16. Example#1: Galvanized Steel

17. Example#2: Tinned Steel Cans

18. Questions ?

19. Thank you for your attention