1. Fundamental aspects of atmosperic corrosion Important parameters and mechanisms

6. German portal figure made of sandstone from 1702. Left picture taken 1908, right picture taken 1969.

11. Corrosion rate of carbon steel

14. More humid conditions ConditionAmount of water, µm Critical relative humidity 0.01 100 % relative humidity 1 Dew10 Rain100

15. Relative humidity, Uppsala 1866-1945 Hour of the day

16. Influence of temperature, carbon steel Rain Drying of moisture film, 75% relative humidity

18. Corrosion rate Rain Sunshine Dew Sunshine Hour of the day

19. Time of wetness Rh>80% and T>0 o C PlaceRh % ToCToC Tow h / year Gällivare76-1,21600 Prag778,32700 Beijing6011,5840 Chengdu8316,46200 Maximum8766

20. Climate maps Temperature (T)Relative humidity (Rh) Time of wetness (Tow) Tow Rh>80% & T>0 o C

24. Synergistic effects, zinc Source: J.-E. Svensson et al, Chalmers, Göteborg

25. Particulate matter Corrosion of carbon steel due to different salts  0-1 mg  2-5 mg 6-20 mg  21-100 mg x (solid line) is Rh at equilibrium with a saturated solution

26. Corrosion of carbon steel at different levels of salinity

27. Zinc corrosion temperature dependence

28. Effect of rain Carbon steelZinc

34. Summary of important parameters for atmospheric corrosion Climate Air pollutants (gases and particles) Other aggressive substances (clorides) Acid rain wind