Although aluminium is a very reactive metal with a high affinity for oxygen, the metal is highly resistant to most environments and to a great variety of chemical agents.

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This resistance is due to the inert and protective character of the aluminium oxide film which forms on the metal surface. In most environments, the rate of corrosion of aluminium decreases rapidly with time. In only a few cases, e.g. caustic soda, does the corrosion rate approximate to the linear. Although the oxide film is extremely thin, between 50 and 100 Angstroms, it forms a protective barrier between the metal and the surrounding medium as soon as the metal comes into contact with an oxidising environment, such as water. The physical-chemical stability of the oxide film determines the corrosion resistance of the aluminium. This stability is dependent upon the pH value of the environment, since the oxide film is stable within the pH range of about 4 to 8. Below and above these values, acid dissolution yields Al3+ ions and the alkaline dissolution leads to the formation of Al(OH)4 ions.

What is the corrosion of aluminum?

Corrosion of Aluminum and Its Alloys: Forms of Corrosion. Abstract: Corrosion is the chemical reaction of a metal, in this case aluminum, with its environment, which leads to the deterioration of the properties of metals, aluminum in this case. Aluminum is a very reactive metal, but it is also a passive metal.

Is aluminum rust proof?

Aluminum corrodes but it does not rust. Rust refers only to iron and steel corrosion. Aluminum is actually very prone to corrosion. However, aluminum corrosion is aluminum oxide, a very hard material that actually protects the aluminum from further corrosion.

Is aluminum resistant to corrosion?

Aluminium corrosion resistance is very good in untreated aluminium. Untreated aluminium has very good corrosion resistance in most environments. This is primarily because aluminium spontaneously forms a thin but effective oxide layer that prevents further oxidation.

Corrosion is the chemical reaction of a metal, in this case aluminum, with its environment, which leads to the deterioration of the properties of metals, aluminum in this case. Aluminum is a very reactive metal, but it is also a passive metal. This contradictory nature is explainable because nascent aluminum reacts with oxygen or water and forms a coherent surface oxide which impedes further reaction of aluminum with the environment.

Corrosion is the chemical reaction of a metal, in this case aluminum, with its environment, which leads to the deterioration of the properties of metals, aluminum in this case. Aluminum is a very reactive metal, but it is also a passive metal. This contradictory nature is explainable because nascent aluminum reacts with oxygen or water and forms a coherent surface oxide which impedes further reaction of aluminum with the environment.

Aluminum is chemically very reactive. For example, powdered aluminum is used as rocket propellant for propulsion of the space shuttle’s solid fuel rockets. Additionally, the reaction of aluminum with water releases a tremendous amount of energy:

AI + 3H2O → AI(OH)3 + 3H2 ↑

Corrosion is the reaction of aluminum with water and the subsequent deterioration of its properties. Corrosion, by definition, is a slow process, requiring days or years to occur to a noticeable extent, as opposed to similar electrochemical reactions such as etching, brightening, or anodizing which occur in minutes or less.

Aluminum alloys may corrode via several different pathways. Recognizing the pathway or the forms of aluminum corrosion is an important step to determine the appropriate remedy for each probe.

Source :

http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=ktn&NM=187

http://www.aluminiumdesign.net/design-support/aluminium-corrosion-resistance/

http://www.alfed.org.uk/files/Fact%20sheets/2-aluminium-and-corrosion.pdf

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