Essay On Corrosion

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CORROSION It is the deterioration of materials by chemical interaction with their environment. For example, iron in the presence of moisture and air will return to its natural state, iron oxide or rust. Aluminum and magnesium form corrosion products that are white oxides or hydroxides. When a water solution containing soluble salts is present, corrosion of many alloys can occur easily at ambient temperatures. Corrosion can also occur in the absence of water but only at high temperatures, such as those found in gas turbine engines. However, the most common type of corrosion is electrochemical corrosion. CHEMISTRY OF CORROSION Almost all corrosion reactions behave as electro-chemical reaction. The losing and gaining of an electron by atoms create an oxidation and reduction reaction. At anodic site, where an oxidation reaction takes place, metallic element giving up an electron and become a positively charged ions. For example,…show more content…
It consists quantities of individual grains, each having a clearly defined boundary, which chemically differs from the host or metal within the grain. Usually the grain boundaries tend to corrode more easily to the metal within the grain. The presence of an electrolyte solution speeds up the growth of the corrosion on the grain boundaries. High strength aluminum alloys are susceptible to intergranular attack. CREVICE CORROSION: It is a form of attack that occur in any crevice location, where a small volume of stagnant solution present. Crevices are usually develop at gasket surfaces, lap joints, and under bolt or rivet heads. Crevice occurs due to an environmental differences between the local area and the larger environment. This type of corrosion can also occur when a surface is covered by foreign material. Welding, soldering and non-absorbent gaskets are used to minimize this type of
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