Corrosion Control

Corrosion Control


The various methods that can be used to protect a metallic system against corrosion can be widely divided into: Thermodynamic protection This type of protection is based on the requirement that the metals has a high positive value for the free energy change for conversion of the metal to a corrosion product in the exposed environment. Kinetic protection Corrosion rate of an actively corrosion metal is determined by the intersection of the kinetic curves that characterize the anodic and cathodic corrosion reactions. This type of protection is based on the principle that the corrosion rate can be reduced if either of these reaction can be changes such that the point of intersection is at a lower current density. eg.: cathodic protection Barrier protection The concept of barrier protection is to protect the metal from the environment by means of a barrier that resists penetration by aggressive environmental constituents. Typical forms include, anodic oxides, ceramic and inorganic coatings, inhibitors, organic coatings etc. Structural design Structures should be designed such that the length of time that a structure is wet with water is minimized. Environmental control This type of protection is limited to closed systems in which changes in the composition of the medium can be tolerated. The method depends of the removal of a constituent of the corrosion reaction from the medium, or in some cases adding a component to a the medium. Metallurgical design Use of the proper alloy for the environment against which protection is sought is the principle behind this form of corrosion protection.