Published for Firgee Engineering
Corrosion is a natural occurance. It may start to develop immediately once you are exposing typical carbon steel material to the environment. Therefore in order to control the corrosion rate to within acceptable level, you may need to apply corrosion prevention method. The problems of corrosion should be approached in the design stage and the selection of a protective coating is very important.
Corrosion prevention can be classified into 4 categories . Namely:
- A water soluble corrosion inhibitor reduces galvanic action by making the metal passive or by providing an insulating film on the anode, the cathode, or both .
- Are used to prevent the electrolyte from reaching the component surface. Protection is effective until the coating is penetrated, either by a pit, pore, crack, or by damage or wear. The substrate will then corrode preferentially to the coating (since it is anodic to the coating material), and corrosion products will lift off the coating and allow further attack.
- Which corrode preferentially to the substrate. If the coating is damaged or defective, it remains protective as it is the coating that suffers attack and not the substrate.
- Involves the reversal of electric current flow within the corrosion cell. Cathodic protection can reduce or eliminate corrosion by connecting a more active metal to a metal that must be protected . Cathodic protection simply involves supplying, from an external source, electrons to the metal to be protected, making it a cathode; the reaction is thus forced in the reverse (or reduction) direction .