Why Metals Corrode-What is a Corrosion Cell
Everybody is familiar with the results of the corrosion on metals which are observable as red-brown or green-blue rust (iron oxide). The actual process of corrosion is less noticeable and research still conducted today for better understanding of the mechanisms of corrosion and how to control it.
Metals in their engineered form are unstable products. What causes them to corrode is a consequence of their process there were subject to become useful engineered products. In order to produce metals, it is necessary to provide a large amount of energy to extract them from the natural occurring minerals and ores in blast furnaces and form them in steel mills. When these metals are exposed to their natural environments they release the energy that stored during their production and revert to their original form which is rust (iron oxide). The amount of energy required and stored in a metal or released by its corrosion varies between the different kinds. It is relative high for metals such magnesium, aluminum and iron, and relatively low for metals such as copper, silver and gold.
All corrosion of iron at normal atmospheric conditions is an electrochemical process. This means there is a creation of a direct electrical current DC, where is a transfer of electrons through a metallic conductor (the metal itself or other attached) and ions through an electrolyte (humidity, water) between two points of the metal with different potential (anode+ and cathode-). These certain conditions and elements are essential for corrosion to occur and are collectively referred to as the corrosion cell and include:
- Metallic pathway (or external conductor)
Protective coatings can control one of these elements-that of the electrolyte. Applying a tightly adhered continuous protective film over the surface of the metal and isolating those points with different potential (anode and cathode), we control the corrosion rate or eliminate it altogether. Working with a coatings professional you can identify the specific corrosion control needs of your infrastructure and select the appropriate coatings that will serve best your business.
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