Aluminum is a metallic chemical element, symbol Al, atomic number 13, atomic weight 26.9815, belonging to group IIIA of the periodic system. Pure aluminum is soft and has little mechanical strength, but it can be alloyed with other elements to increase its strength and acquire various useful properties.
Aluminum alloys are light, strong, and easily formed for many metalworking processes. They are easy to assemble, cast or machine and accept a wide variety of finishes. Due to its physical, chemical and metallurgical properties, aluminum has become the most widely used non-ferrous metal.
What is aluminum?
Aluminum is the most abundant metallic element on earth, but it is never found in a free form in nature. It is widely distributed in plants and in almost all rocks, especially igneous rocks, which contain aluminum in the form of alumina silicate minerals. When these minerals dissolve, depending on chemical conditions, it is possible to precipitate aluminum in the form of mineral clays, aluminum hydroxides, or both. Under these conditions, bauxites are formed, which serve as a fundamental raw material in the production of aluminum.
Aluminum is stable in air and resistant to corrosion by sea water, many aqueous solutions and other chemical agents. This is due to the protection of the metal by an impenetrable layer of oxide. At greater than 99.95% purity, it resists attack by most acids, but dissolves in aqua regia. Its oxide layer dissolves in alkaline solutions and corrosion is rapid.
Aluminum is amphoteric and can react with mineral acids to form soluble salts with the evolution of hydrogen. Molten aluminum can have explosive reactions with water. Molten metal must not come into contact with wet tools or containers.
At high temperatures, it reduces many oxygen-containing compounds, especially metal oxides. These reactions are used in the manufacture of certain metals and alloys. Its application in construction represents the largest market in the aluminum industry. Thousands of houses use aluminum in doors, locks, windows, screens, nozzles and drainage channels.
In electrical applications, aluminum wires and cables are the main products. It is found in the home in the form of kitchen utensils, aluminum foil, tools, portable appliances, air conditioners, freezers, refrigerators, and in sports equipment such as skis and tennis rackets. There are hundreds of chemical applications of aluminum and its compounds. Powdered aluminum is used in paints, rocket fuel and explosives, and as a chemical reductant.
Where is it found?
Aluminum is also one of the most important products in industrial construction. Transportation is the second largest market. Many commercial and military aircraft are made almost entirely of aluminum.
In automobiles, aluminum appears in interiors and exteriors such as trim, grills, tires (rims), air conditioners, automatic transmissions, and some radiators, engine blocks, and body panels. It is also found in car bodies, rapid rail transportation, formed wheels for trucks, railcars, freight containers, and highway signs, lane dividers, and lighting.
In the aerospace industry, aluminum is also found in airplane engines, structures, decks, and landing gear and interiors; often about 80% of the aircraft’s weight is aluminum. The food packaging industry is a rapidly growing market.
In order to improve its properties, the thermal and mechanical treatments during its manufacture are chosen according to the expected performance. The implementation and transformation of aluminum benefit from all foundry methods. In addition, this metal can withstand a wide variety of surface treatments, such as anodizing and lacquering.
In addition, the addition of metals enables the various aluminum alloys to achieve mechanical strengths comparable to those of hardened steels, for a density which remains three times lower than that of steel.
How is it used in recycling?
Aluminum is 100% recyclable without altering its properties. In many countries, aluminum refiners are responsible for the recovery, crushing and remelting of aluminum from landfills, industrial and household waste. This secondary aluminum is mainly used in the manufacture of foundry parts for automobiles.
This high recycling rate makes it possible to eliminate pollution due to the aluminum production process, the most important being linked to the discharge of caustic red bauxite mud, not to mention the high electricity consumption necessary for the electrolysis of the aluminum.
What is its Effect on the Body?
This metal, useless to our body, nevertheless seems potentially dangerous for health. The toxic effects of aluminum seem to bear largely on the central nervous system and on bone tissue during exposure to very high doses. However, no study has been conducted on a population exposed to low doses: by ingestion of food products, drinking water and medicines; through the skin (cosmetics) or by contact (aluminum foil).
What are the advantages of aluminum?
Aluminum is a metal that has many advantages.
A lightweight material
Aluminum is very light, which allows for more aerial construction. It is for this reason that verandas and aluminum windows are much more openwork and elegant than PVC ones. The glass surface can be much larger thanks to this material, which is also a means of achieving significant savings. Aluminum indeed offers greater strength and rigidity than other materials, with a density of 2.7 g/ 3 cm.
An easy-to-work material
Malleable, aluminum is easy to forge, roll, extrude and transform into multiple shapes, due to its low melting temperature.
A durable material
Aluminum has the advantage of being fully recyclable, without loss of its properties, thanks to its infinite life cycle. In addition, its resistance to corrosion considerably reduces its maintenance and the use of chemicals. Indeed, a protective oxide layer naturally forms on the surface of aluminum when it comes into contact with air.
The most notable characteristic of aluminum is that it is a soft metal. Its resistance for use in construction often requires it to be combined with other metals, in particular copper and zinc. Of course, depending on the alloys used, the properties of aluminum will change.