General

• 1. General corrosion (uniform attack)

  • Relatively large area
  • takes over more exposed surface
  • measure by:weight loss, thickness reduction, rust formation & breakage
  • can be predicted
  • not safety concern- compared to localised corrosion

  Protection:

  • Weather resistant proper material
  • Inhibitors
  • Coatings/paint etc
  • Cathodic Protection
• 2.Galvanic Corrosion

  potential difference between 2 dissimilar metal

  electrically connected (current flows)

  decrease resistant of the two will corrode (anode)

  
  

  How to find corrosion properties:

  -use galvanic series

  • right - less stable/anodic
  • left - more stable/ cathodic

  Protection:

  • 2 metals that are close in galvanic series
  • Avoid small anode + large cathode
  • Thicker anode or easy replace
  • Insulate both metals
  • inhibitor
  • coating
  • sacrificial anode