In America is known as Aluminum, but IUPAC stated that its international name is Aluminium, although both spellings are considered correct, in research papers the IUPAC one is the prevalent. This chemical element represented by Al, is a non-magnetic metal, located in the boron group of the periodic table, with an atomic number of 13. Aluminium is also the third most common element found in the earth crust (It represents around 8 % of the former) being surpassed in abundance only by Oxygen and Silicate.

Aluminium is soft (2-4in the Mohs scale), ductile, malleable, has a silver-white color, has a low density compared to another metals (2700 kg/m³, whereas steel has 7850 kg/m³), it´s an excellent heat (80-230 W/(m·K)) and electrical conductor (between 35 and 38 m/(Ω mm²)), resist corrosion using a protective coat of oxide (phenomenon called passivation, which can be improved by anodizing), and can be recycled with a theoretical efficiency of 100 % without affecting its core mechanical properties.

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History and processing

In 1824 Hans Christian Ørsted (important figure in the establishment of electromagnetism) Danish physicist and chemist made the first successful attempt to synthetize Aluminum, using electrolysis in anhydrous Aluminium chloride (AlCl₃) with potassium amalgam, he reached several samples, with a lot of impurities, then he presented the samples of the metal in 1825, but left the research due to financial difficulties. By 1827 Friedrich Wöhler came to visit Ørsted to discuss the research, the Danish physicist told Wöhler he didn´t want to follow the research about aluminum extraction.

Wöhler could produce little pieces of Aluminium in 1845, but his processes couldn’t yield mass quantities, these lead to the Aluminium into the status of rare matel, being more expensive than silver, and gold. In 1886 Charles Hall (From U.S.) and French engineer Paul Heroult developed in parallel an inexpensive electrolysis process by which aluminum can be extracted from aluminum oxide in molten cryolite, and electrolysing the molten salt bath, this process is ruled by the following reaction:

Al₂O₃ + 3 C → 2 Al + 3 CO

The large amount of electricity required to power the electrolytic process limited the production of aluminum. Karl Josef Bayer (Australian Engineer) developed a process in 1888 by which alumina can be extracted from bauxite, the most important ore of aluminium. Both the Bayer and Hall-Herout processes are still used today to produce nearly all the world’s aluminum. The Hall–Héroult process was further improved in 1920 by a team led by Swedish chemist Carl Wilhelm Söderberg; this improvement greatly increased the world output of aluminium.

Theoretically Aluminium can be recycled with an efficiency of 100 %, this process can be accomplished by simply re-melting the metal, this way Aluminium can be obtained with only a fraction of the energy needed to extract the metal from natural ore, the energy input of Aluminum recycling is 5 % of the Bayer process.

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Aplications

Thanks to its properties and easy availability Aluminum can be used in a large array of fields, including but not limiting to: Packaging (cans, foil, tetrabriks), electrical transmission lines, transistors, street lighting, cooking utensils, musical instruments, carabiners, baseball bats, transportations (frames and outsides), coins, watches, etc. Two of the main processes that alow Aluminium its versatility are Anodizing, which allows a superficial oxide coating to the element, granting it an elavated resistance to corrosion; the other process is Extrusion, this one grants Aluminium a huge variety of shapes and sizes, with relative ease in making.

Construction

Even though the use of Aluminium in buildings dates to the 1920s, the first major structure to use it was the Empire State Building in 1930, with some of the interior structures and the spire being made of Aluminium. Later, in 1994, more than 5000 steel windows in of the Empire State were replaced with aluminum frames. (The former frames had deteriorated, allowing for frosting, water and air leakage.) Thanks to this change, the annual energy consumption of the building reduced at least a 15 %.

Due to its low specific weight Aluminum plates can easily half the weight of a steel one, with the same bearing capability, this result in Aluminium as a common material in the construction of skyscrapers, and other kind of buildings. Being used specially in the frames of translucent panes, these feature a low thermal conductivity, which reflects solar heat in summer, and retains heat inside in summer, thus reducing the air conditioner, or heating energy consumption, while letting in natural sunlight.

The Crystal Centre for Sustainable Urban Development was opened in London, in 2012. The building was designed with the application of Aluminium faces and the latest energy-saving construction techniques, and it received the top LEED (the Leadership in Energy and Environmental Design). Crystal Center consumes 46% less electricity and generates 65% less carbon dioxide than any other office building comparable in size.

"The Crystal" London Author: Robert Pittman for Flickr

Aircraft and Aerospace

Since the Wright brothers who used and Aluminium engine in their first flying biplane, this metal has been used in to fly across the earth and into the space, It has been used on Apollo spacecraft, the space shuttles and the International Space Station. Aluminum alloys excel in properties as mechanical stability, dampening, thermal management and reduced weight.

During WWII, the production of aluminum soared. More than half U.S. aircraft production was made primarily from aluminum. From there, alloys were used to construct early rockets, there were also several campaigns to encourage Americans to contribute with Aluminium for the war, In commercial airships, the modern standard is that 80 % of the aircraft is made of Aluminium; this is because of the weight-force ratio of the metal. For fuselage, supporting structures, and wings of commercial and military airships, Aluminium alloys are considered the standard best choice.

Julio Verne realized the potential use of Aluminium in his 1865 novel “Journey to the Moon”, when he described a Rocket made of Aluminum in great detail. For the space shuttle´s solid rocket booster, Aluminium was used as the primary propellant, due to its difficulty to ignite accidentally. The next generation of space exploration vehicle, Orion MPCV (Multi-Purpose Crew Vehicle, by NASA) will have a primary structure made of an Aluminium-Lithium alloy.

Aluminium Cans

Molson Coors Brewing Company began the use of aluminum cans in 1959, since then there has been an exponential growth in the numbers of drinks that use cans as a standard presentation, because they freeze rapidly, are easy to print on with endless designs, protect the integrity of the content, cans also are lightweight and easily stacked, which result in easy transport; They can be recyclable almost infinitely. The average can contains 70 percent recycled metal.

In the last 50 years, Aluminium cans manufacturers have lightened the design, originally cans weighted close to 85 grams, now they weigh less than 14 grams per unit. This package can be easily formed, doesn´t rust, and it´s resistant to corrosion. Thanks to their cylindrical shape and the yield strength of Aluminium, four six packs can support up to 2 tons.

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Sources and Further reading

• The Aluminum Association
• Aluminium
• Hall–Héroult process
• Bayer process
• All about Aluminium (Construction)
• Clinton Aluminum