Aluminum, an overview...
Aluminum is the most abundant metallic element in the Earth’s crust (about 8%) and is the third most common element after oxygen and silicon. Unlike copper or gold, aluminum cannot be found in nature in the pure state because of its high affinity with oxygen, being so always combined with another element like in alum (KAl(SO4)2∙12H2O) and in aluminum oxide (Al2O3). So, up to 1820, the aluminum was unknown as a metal.
In the 19th century the production process was so expensive and available quantities so small that aluminum was a precious metal ($1200/kg in 1852). Indeed, Napoleon III emperor of France had a baby rattle and some other small objects made of it, and a story tells that during a banquet the most honoured guests were given aluminum utensils, while the other guests were given gold utensils.
Presently, aluminum is the second largest used metal in the world, mainly due to its light weight, high strength and recyclability.
Aluminum is heavily used in the transportation industry because of its durability, strength and lightweight. Aluminum weight is one third of steel or cast iron. Taking into account increased thickness of the aluminum parts compared to steel, 1 kg of aluminum replaces 2 kg of steel, leading to lighter cars, trucks, etc… with reduced fuel consumption and CO2 generation.
Without aluminum the commercial aircraft industry would not have existed. The new A380 employs 66% of aluminum in the airframe, while a Boeing 747 contains 75 tons of aluminum.
The use of aluminum for the building of ships is increasing year by year. Today, single and multiple hull boats are made entirely of aluminum alloy. This kind of marine applications involve the largest usage of aluminum per produced object (400 ton) compared to a large, all aluminum car (1 ton).
The usage of aluminum is increasing in the military field too, where it is used as a substitute for the steel.
In building and construction aluminum find a wide variety of applications, and its use is steadily increasing. It can be used to manufacture structural elements, as in bridges (for example, the Corbin Bridge in Pennsylvania has been retrofitted with an extruded aluminum deck, which is lighter than the previous deck made of steel and timber, allowing the bridge to sustain 22 tons load compared to the previous 7 tons). Curtainwall made of extruded aluminum and glass are very attractive for the design of new buildings or retrofit of old ones. Windows made of extruded aluminum are attractive, energy-efficient (with thermal broken technology), and reliable. Domes for gymnasiums, schools, theme parks, storage facilities, multi-purpose arenas, industrial roof systems, and churches are made with aluminum because of its strength and low weight. Aluminum is one of the best material also in the roof construction, because of its strength against corrosion and, hence, weathering and influence of pollutants in the atmosphere. Low maintenance aluminum facades are used to cover old houses facades made with thin or wide wooden clapboard.
Aluminum find also wide use in the packaging industry, being produced in both rigid and foil forms. Rigid aluminum containers are used for beverage and food packaging. Aluminum cans account for all of the beverage can market, but only a small percentage of the food can market. Cans are 79 percent of aluminum packaging by weight. Foil packaging is used as a wrapping foil, as semi-rigid packages such as pie plates and frozen food trays, and as flexible packaging such as cigarette foil and candy wrappers.