Corrosion Of Steel

Corrosion of Iron

Iron (or stigma) corrodes more quickly than most(prenominal) other(a) transition metallic elements and readily does so in the presence of both oxygen (in air) and pee to form an press out oxide. Rusting is speeded up in the presence of salt solution.

Rusting is Fe(s) + O2(g) + H2O(I) Þ Fe2O3 . x H2O(5) i.e., use up is hydrated adjure (III) oxide (the equation is not meant to be equilibrise and the amount of water x is variable, from dry to soggy). Rusting is oxidization because it involved put right gaining (Fe Þ Fe2O3) or iron atoms losing electrons (Fe - 3e- Þ Fe3+)

The rusting of iron is a major problem in its use as a structural material.

Iron and brand name (alloy of iron) are most easily protected by paint which provides a parapet between the metal and air/water. Moving parts on machines can be protected by a water repellent oil or grease layer.

This rusting can be prevented by connecting iron to a more reactive metal (e.g., zinc or magnesium). This is referred to as sacrificial protection or sacrificial corrosion, because the more reactive protecting metal is preferentially oxidised away, leaving the protected metal intact. Iron or steel can also be protected by mixing in other metals (e.g.



, chromium) to make non-rusting alloys called stainless steel. The chromium, wish aluminium, forms a protective oxide layer.

Coating iron or steel with a thin zinc layer is called galvanizing. The layer is produced by electrolytic deposition by making the iron/steel the negative cathode or dipping the iron/steel object in molten zinc. The zinc preferentially corrodes or oxidises to form a zinc oxide layer that doesnot flake off like iron oxide rust. Also, if the surface is scratched, the exposed zinc again corrodes before the iron and continues to protect it.

Steel cans are protected by comparatively unreacted tin and works well as long as the thin tin layer is complete.If you want to get a full essay, order it on our website: Orderessay



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