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Corrosion - Definition and examples of corrosion.


Definition of corrosion.

Corrosion is defined as the destructive attack and deterioration that occurs in a material as a result of chemical reactions that occurs between the material and the surrounding environment.

Commonly known corrosion as destructive phenomenon that suffers metals when it oxidize, but non-metallic materials such as plastics, glass or wood suffer an aging effect and destruction of the material if it is exposed to industrial environmental, acids or chemical agents or others medias capable to break or alter the internal structure of the material, eg glass corrodes in the presence of highly alkaline products, concrete corrodes in the presence of waters rich in sulfates, etc. ...

At the structural and mechanical level corrosion weakens the internal structure of the metal making it fragile and brittle, so that does not meet the requirements with which it was designed, can cause accidents in structures that require certain levels of security such as balconies, railings, stairs, structures of vehicles such as boats, planes, etc ...

At aesthetic level corrosion gives a negative aspect given in a feeling of neglect and aging and insecurity, do you enter in a plane that was completely rusted and corroded?

At the economic level corrosion on metals cause large monetary losses at worldwide, losses from stops factory production cause by corrosion in the accessories or elements that are part of industrial machinery, pipeline corrosion loss products in which leakage liquid or gaseous products that carry them...

A current study indicates that ¼ steel produced in worldwide, is apply to replace you exclusively corroded or oxidized structures.

Due the big problems (economics, technical and safety) that cause corrosion, it is vital and necessary to protect the metals from the corrosion phenomenon; that is the importance of paint as well as others methods such as galvanizing, anodizing, cathodic protection, etc. ..., as protective function against corrosion of metal surfaces.

Example of corrosion.

To understand the corrosion phenomenon in metals, we explain that with the corrosion that occurs in iron.

Iron is a metal that develop corrosion with the pass of time, a very pure iron surface and even from ordinary steel, smooth and clean, exposed to an atmosphere of very dry air (lower to 50% moisture), forms a very thin layer and oxide surface, this thin layer is very and compact adherence, which protects the rest of oxidation inside the metal (has a protective surface oxidation), provided no external chemical agent break that layer.

When the metal is exposed to an atmosphere of humid air, aggressive medias or high temperatures, the case is totally different, due the action of water and all liquids and gases that contains the media will produce the in the surface of a metal-oxide layer very porous and not adherence, this layer of oxides continues its course towards the interior metal, consuming and deteriorating the metal with high speed velocity.

The corrosion speed depends about the attacker agent that produces such corrosion; industrial environments, saline environments as well as certain chemical agents accelerate highly the corrosion phenomenon on metals.

The graph shows the extent and progress of corrosion of same metal exposed to different environments.

corrosion


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