It is generally understood that Corrosion means rust and is treated like an almost universal object of hatred. This word ‘Rust’ has been specifically reserved for iron corrosion. However, Not so many knows that corrosion is such a destructive process which affects almost all metals. Since iron is the first and most extensively used metal by man, there is a possibility that suffering of man due to serious corrosion problems to his precious metal ‘IRON’ must be the reason that this word ‘corrosion’ is mostly connected with iron.
Corrosion of metals remains a serious problem to this day. Solutions are also available. Items can be coated with paint which provide a barrier to attack from the surrounding seawater. However, coatings of such things are normally damaged during handling. It is therefore this may not be a solution to this long-term exposure. An alternate method regularly used in addition with skin coatings is use of Cathodic protection. In this method, the component which is likely to be corroded is fitted with anodes normally in the form of blocks of metallic alloys. Sacrificial corrosion of the anodes provides a form of electrical protection.
Why corrosion happens??
Corrosion can be defined as an electro-chemical reaction that involves metal/metals in particular. A chemical reaction and electrical properties does the entire thing, and finally results in the metal’s partial loss. One of the most familiar example for everyone (including me and you) is the presence of rust in our house hold metal stuffs like utensils.
Let us take an example of an iron-post placed in a football-ground. The rain has just stopped and the areas ‘1’ and ‘3’ of the iron-post are damp. In the presence of water (as a medium), there is a movement of electrons in the metallic structure from area 1 to area 3. Thus, in 1st area there is a loss of ‘Fe’ ions through water. Similarly, in 3rd area, just because of the availability of O2 (oxygen) and the accumulation of extra electrons there, the molecules of water combine to O2 and the extra electrons to form hydroxides.
The corrosion can be classified into two categories. These are :
- Oxidation Corrosion, and
- Galvanic Corrosion.