Aluminum has become one of the most versatile structural materials because of its characteristics. Aluminum is light, and some aluminum alloys are stronger than steel structures. Under most conditions of use, aluminum has high corrosion resistance. It will not pollute adjacent surfaces with colored salts or discolor the materials in contact with it (such as textiles in the textile industry and solutions in chemical equipment). . It has good electrical and thermal conductivity, high heat and light reflectivity. Aluminum is easy to process into various shapes and easy to perform various surface treatments.
The density of aluminum is 2.7g/cm³, which is about 35% of steel and 30% of copper.
The tensile strength of industrial pure aluminum is about 100MPa, and its use as a structural material is somewhat limited. Cold working (such as cold rolling) of aluminum can double its strength. Adding a small amount of one or more other metals to aluminum, such as manganese, silicon, copper, magnesium or zinc, can greatly increase its strength with heat treatment. Like pure aluminum, cold working of aluminum alloy can also increase its strength. So far, aluminum alloys with a tensile strength of more than 700 MPa have been obtained.
When the surface of aluminum is exposed to the air, it will quickly form an invisible oxide film, so that the aluminum will no longer be oxidized. Unless it is exposed to a substance or environment that can destroy the protective layer of the oxide film, aluminum will not be corroded at all.
Aluminum is highly resistant to air corrosion, even in industrial gases that are corrosive to other metals. Aluminum is also resistant to corrosion by many acids. Alkali is one of the few substances that destroy the oxide film, so it has a corrosive effect on aluminum. Although the use of inhibitors can safely use aluminum in some weakly alkaline situations, in general, avoid direct contact of aluminum with alkaline substances.
