Controlling factors in the protection of metals from corrosion

Summary

• 1. A more scientifically rational classification of the different methods of protection (against corrosion) is introduced, starting from their influence on: decreasing the degree of thermodynamic instability of the system, deceleration of the cathodic process, deceleration of the anodic process, or increasing the ohmic resistance of the system.

• 2. In the general case the effective methods of protection are those which affect the process which controls the basic corrosion process.

• 3. Simultaneous use of several protective methods with the same basic controlling factors increases their general effectiveness, but with different controlling factors the overall effectiveness may sometimes decrease.

• 4. Possible protective methods, which decrease the degree of thermodynamic instability, will always be able to decrease corrosion, but the effect of these methods will be less effective if the overall total retardation in the system is very large.