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Suppressing corrosion

The purpose of scientific thought is to predict what will happen in given experimental circumstances. All the philosophical discussion is an evasion of the point. – Feynman. Suppressing corrosion . Cathodic protection. example: protecting ship plate. Suppressing corrosion .

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Suppressing corrosion

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  1. The purpose of scientific thought is to predict what will happen in given experimental circumstances. All the philosophical discussion is an evasion of the point. –Feynman

  2. Suppressing corrosion Cathodic protection example: protecting ship plate

  3. Suppressing corrosion Cathodic protection example: protecting hot water heater tanks

  4. Suppressing corrosion Cathodic protection Problem: steel fermentation tank in brewery sacrificial anodes add metallic ions to electrolyte

  5. Suppressing corrosion Cathodic protection Different approach: Impose a voltage across cell formed by tank (cathode) and an inert anode choice of anode material: very inert material like Pt but oxygen gas produced at anode

  6. Suppressing corrosion Cathodic protection Different approach: Impose a voltage across cell formed by tank (cathode) and an inert anode choice of anode material: use carbon - inert C + O2 CO2

  7. Suppressing corrosion Cathodic protection "…..join in a planned discussion of whether it is best to use copper tubing coils or stainless steel tubing coils inside of a stainless steel beer fermenter, the coils being used as a chiller? There has been a discussion in another brewing forum about competing concerns between the two, i.e., copper conducts heat better and is easier to bend, versus copper will slowly dissolve in the acidic environment of beer"

  8. Suppressing corrosion Use passivated materials Ni - NiO Ti - TiO2 Al - Al2O3 COR-TEN: 0.19% C 0.30% Cu 0.40% Ni 0.50% Cr 0.05% V

  9. Suppressing corrosion Anodizing Al & other materials can be anodized very thick oxide coating formed (8-50 microns)

  10. Suppressing corrosion 2300x 540x Thinking again of noble metal coatings, what about Cr plating? Cr plating usually filled w/ microcracks due to stresses in plating

  11. Suppressing corrosion Cr plating frequently a series of layers

  12. Corrosion examples in shuttle mat'ls 60x 1x 235x 1180x

  13. Corrosion examples in shuttle mat'ls

  14. Corrosion examples in shuttle mat'ls

  15. Corrosion examples in shuttle mat'ls

  16. Corrosion examples in shuttle mat'ls

  17. Corrosion examples in shuttle mat'ls Area effect: large cathode & small anode - corrosion accelerated electrochemical cell current density high try to keep potential anodic areas large relative to cathode

  18. Polymers - the nightmare begins I am inclined to think that the development of polymerization is, perhaps, the biggest thing that chemistry has done, where it has the biggest effect on everyday life LORD TODD President of the Royal Society of London

  19. What are polymers? Why important ? • Long chain molecules • Extraordinary range of • physical properties • Many (not all) are cheap

  20. Assignment: Review today's classnotes a. cathodic protection b. passivation c. anodizing d. Cr plating e. corrosion examples f. area effect g. what is a polymer? Read: pp 569-585, 589-591, chapter 14

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