Aluminium (Audio-IPA|En-uk-aluminium1.ogg|ˌæljʊˈmɪniəm, IPA|/ˌæljəˈmɪniəm/) or aluminum (Audio-IPA|En-uk-aluminum.ogg|/əˈluːmɪnəm/, see "spelling" below) is a silvery white and
ductilemember of the boron groupof chemical elements. It has the symbol Al; its atomic numberis 13. It is not soluble in water under normal circumstances.Aluminium is the most abundant metal in the Earth's crust, and the third most abundant element therein, after oxygenand silicon. It makes up about 8% by weight of the Earth’s solid surface. Aluminium is too reactive chemically to occur in nature as the free metal. Instead, it is found combined in over 270 different minerals. [cite web | publisher = Science is Fun | author = Bassam Z. Shakhashiri | url = http://scifun.chem.wisc.edu/chemweek/Aluminum/ALUMINUM.html | title = Chemical of the Week: Aluminum | accessdate = 2007-08-28] The chief source of aluminium is bauxite ore.
Aluminium is remarkable for its ability to resist
corrosion(due to the phenomenon of passivation) and its low density. Structural components made from aluminium and its alloys are vital to the aerospaceindustry and very important in other areas of transportation and building. Its reactive nature makes it useful as a catalyst or additive in chemical mixtures, including being used in ammonium nitrate explosivesto enhance blast power.
Aluminium is a soft, durable, lightweight,
malleable metalwith appearance ranging from silvery to dull grey, depending on the surface roughness. Aluminium is nonmagnetic and nonsparking. It is also insoluble in alcohol, though it can be soluble in water in certain forms. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa.I. J. Polmear, "Light Alloys", Arnold, 1995 ] Aluminium has about one-third the densityand stiffness of steel. It is ductile, and easily machined, cast, and extruded. Corrosionresistance can be excellent due to a thin surface layer of aluminium oxidethat forms when the metal is exposed to air, effectively preventing further oxidation. The strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is also often greatly reduced when many aqueous salts are present however, particularly in the presence of dissimilar metals.
Aluminium atoms are arranged in a
face-centered cubic(FCC) structure. Aluminium has a high stacking-fault energyof approximately 200 mJ/m². [G. E. Dieter, "Mechanical Metallurgy", McGraw-Hill, 1988]
Aluminium is one of the few metals that retain full silvery reflectance in finely powdered form, making it an important component of silver paints. Aluminium mirror finish has the highest reflectance of any metal in the 200–400 nm (UV) and the 3000–10000 nm (far IR) regions, while in the 400–700 nm visible range it is slightly outdone by
tinand silverand in the 700–3000 (near IR) by silver, gold, and copper.Fact|date=July 2007
Aluminium is a good thermal and
electrical conductor, by weight better than copper. Aluminium is capable of being a superconductor, with a superconducting critical temperature of 1.2 kelvinand a critical magnetic field of about 100 gauss. [cite journal|author= John F. Cochran and D. E. Mapother|title=Superconducting Transition in Aluminum |doi=10.1103/PhysRev.111.132| journal=Physical Review |volume=111 |issue=1 |pages=132–142| month=July| year=1958]
Aluminium has nine
isotopes, whose mass numbers range from 23 to 30. Only 27Al ( stable isotope) and 26Al (radioactive isotope, "t"1/2 = 7.2 × 105 y) occur naturally; however, 27Al has a natural abundance of 99.9+ %. 26Al is produced from argonin the atmosphere by spallationcaused by cosmic-ray protons. Aluminium isotopes have found practical application in dating marine sediments, manganese nodules, glacial ice, quartzin rock exposures, and meteorites. The ratio of 26Al to 10Be has been used to study the role of transport, deposition, sedimentstorage, burial times, and erosion on 105 to 106 year time scales. [ [http://www.onafarawayday.com/Radiogenic/Ch14/Ch14-6.htm Cosmogenic Isotopes and Aluminum] ] Cosmogenic26Al was first applied in studies of the Moonand meteorites. Meteoroid fragments, after departure from their parent bodies, are exposed to intense cosmic-ray bombardment during their travel through space, causing substantial 26Al production. After falling to Earth, atmospheric shielding protects the meteorite fragments from further 26Al production, and its decay can then be used to determine the meteorite's terrestrial age. Meteorite research has also shown that 26Al was relatively abundant at the time of formation of our planetary system. Most meteoriticists believe that the energy released by the decay of 26Al was responsible for the melting and differentiation of some asteroidsafter their formation 4.55 billion years ago. [Robert T. Dodd, "Thunderstones and Shooting Stars", pp. 89-90. ISBN 0-674-89137-6.]
Earth's crust, aluminium is the most abundant (8.13%) metallic element, and the third most abundant of all elements (after oxygen and silicon). However, because of its strong affinity to oxygen, it is almost never found in the elemental state; instead it is found in oxides or silicates. Feldspars, the most common group of minerals in the earth's crust, are aluminosilicates. Native aluminium metal can be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. [Citation | title = Aluminum Mineral Data | url = http://webmineral.com/data/Aluminum.shtml | accessdate = 2008-07-09]
Although aluminium is an extremely common and widespread element, the common aluminium minerals are not economic sources of the metal. Almost all metallic aluminium is produced from the
ore bauxite. Bauxite occurs as a weatheringproduct of low iron and silica bedrock in tropical climatic conditions. [Guilbert, John M. and Carles F. Park, "The Geology of Ore Deposits," Freeman, 1986, pp. 774-795 ISBN 0-7167-1456-6 ]
Production and refinement
Although aluminium is the most abundant metallic element in the Earth's crust (believed to be 7.5 to 8.1 percent), it is rare in its free form, occurring in oxygen-deficient environments such as
volcanicmud, and it was once considered a precious metalmore valuable than gold. Napoleon III, emperor of France, is reputed to have given a banquet where the most honoured guests were given aluminium utensils, while the other guests had to make do with gold. [cite journal | title = "Silver" from clay | author = S Venetski | journal = Metallurgist| volume = 13 | issue = 7 | pages = 451–453 |month=July | year=1969 | doi = 10.1007/BF00741130] [ChemMatters October 1990 Page 14] The Washington Monumentwas completed, with the 100 ounce (2.8 kg) aluminium capstone being put in place on December 6, 1884, in an elaborate dedication ceremony. It was the largest single piece of aluminium cast at the time. At that time, aluminium was more expensive than silver, gold, or platinum. Aluminium has been produced in commercial quantities for just over 100 years.
Aluminium is a strongly reactive metal that forms a high-energy chemical bond with oxygen. Compared to most other metals, it is difficult to extract from ore, such as
bauxite, due to the energy required to reduce aluminium oxide (Al2O3). For example, direct reduction with carbon, as is used to produce iron, is not chemically possible, since aluminium is a stronger reducing agent than carbon. Aluminium oxide has a melting point of about 2,000 °C. Therefore, it must be extracted by electrolysis. In this process, the aluminium oxide is dissolved in molten cryoliteand then reduced to the pure metal. The operational temperature of the reduction cells is around 950 to 980 °C. Cryolite is found as a mineral in Greenland, but in industrial use it has been replaced by a synthetic substance. Cryolite is a chemical compound of aluminium, sodium, and calcium fluorides: (Na3AlF6). The aluminium oxide (a white powder) is obtained by refining bauxite in the Bayer processof Karl Bayer. (Previously, the Deville processwas the predominant refining technology.)
The electrolytic process replaced the
Wöhler process, which involved the reduction of anhydrous aluminium chloride with potassium. Both of the electrodes used in the electrolysis of aluminium oxide are carbon. Once the refined alumina is dissolved in the electrolyte, its ions are free to move around. The reaction at the cathode(negative electrode) is:Al3+ + 3 e− → Al
Here the aluminium ion is being reduced (electrons are added). The aluminium metal then sinks to the bottom and is tapped off.
anode(positive electrode), oxygen is formed::2 O2− → O2 + 4 e−
This carbon anode is then oxidized by the oxygen, releasing carbon dioxide.:O2 + C → CO2The anodes in a reduction cell must therefore be replaced regularly, since they are consumed in the process.
Unlike the anodes, the cathodes are not oxidized because there is no oxygen present, as the carbon cathodes are protected by the liquid aluminium inside the cells. Nevertheless, cathodes do erode, mainly due to electrochemical processes and metal movement. After five to ten years, depending on the current used in the electrolysis, a cell has to be rebuilt because of cathode wear.
Aluminium electrolysis with the
Hall-Héroultprocess consumes a lot of energy, but alternative processes were always found to be less viable economically and/or ecologically. The worldwide average specific energy consumption is approximately 15±0.5 kilowatt-hours per kilogram of aluminium produced (52 to 56 MJ/kg). The most modern smelters achieve approximately 12.8 kW·h/kg (46.1 MJ/kg). (Compare this to the heat of reaction, 31 MJ/kg, and the Gibbs free energyof reaction, 29 MJ/kg.) Reduction line currents for older technologies are typically 100 to 200 kA; state-of-the-art smelters [cite web | publisher = AME Mineral Economics| author = | url = http://www.ame.com.au/smelters/al/smelters.htm| title = Aluminium Smelters| accessdate = 2008-04-17] operate at about 350 kA. Trials have been reported with 500 kA cells.
Recovery of the metal via
recyclinghas become an important facet of the aluminium industry. Recycling involves melting the scrap, a process that requires only five percent of the energy used to produce aluminium from ore. However, a significant part (up to 15% of input material) is lost as dross(ash-like oxide). [cite web | title = Benefits of Recycling | publisher = Ohio Department of Natural Resources | url = http://www.dnr.state.oh.us/recycling/awareness/facts/benefits.htm] Recycling was a low-profile activity until the late 1960s, when the growing use of aluminium beverage cans brought it to the public consciousness.
Electric power represents about 20% to 40% of the cost of producing aluminium, depending on the location of the smelter. Smelters tend to be situated where electric power is both plentiful and inexpensive, such as
South Africa, the South Islandof New Zealand, Australia, the People's Republic of China, the Middle East, Russia, Quebecand British Columbiain Canada, and Iceland.In 2005, the People's Republic of China was the top producer of aluminium with almost one-fifth world share, followed by Russia, Canada, and USA, reports the British Geological Survey.
Over the last 50 years, Australia has become a major producer of bauxite ore and a major producer and exporter of alumina. [cite web | publisher = Australian Aluminium Council | url = http://www.aluminium.org.au/Page.php?s=1005 | title = The Australian Industry | accessdate = 2007-08-11] Australia produced 62 million tonnes of bauxite in 2005. The Australian deposits have some refining problems, some being high in silica but have the advantage of being shallow and relatively easy to mine. [cite web | publisher = Australian Aluminium Council | url = http://www.aluminium.org.au/Page.php?s=1007 | title = Australian Bauxite | accessdate = 2007-08-11]
Oxidation state one
* AlH is produced when aluminium is heated in an atmosphere of
* Al2O is made by heating the normal oxide, Al2O3, with silicon at 1800 °C in a
* Al2S can be made by heating Al2S3 with aluminium shavings at 1300 °C in a vacuum. It quickly disproportionates to the starting materials. The selenide is made in a parallel manner.
*AlF, AlCl and AlBr exist in the gaseous phase when the tri-halide is heated with aluminium.Aluminium halides usually exist in the form AlX3.e.g. AlF3, AlCl3, AlBr3, AlI3 etc.
Oxidation state two
Aluminium monoxide, AlO, is present when aluminium powder burns in oxygen.
Oxidation state three
Fajans' rulesshow that the simple trivalent cation Al3+ is not expected to be found in anhydrous salts or binary compounds such as Al2O3. The hydroxide is a weak base and aluminium salts of weak acids, such as carbonate, can't be prepared. The salts of strong acids, such as nitrate, are stable and soluble in water, forming hydrates with at least six molecules of water of crystallization.
Aluminium hydride, (AlH3)n, can be produced from trimethylaluminiumand an excess of hydrogen. It burns explosively in air. It can also be prepared by the action of aluminium chloride on lithium hydridein ethersolution, but cannot be isolated free from the solvent.
Aluminium carbide, Al4C3 is made by heating a mixture of the elements above 1000 °C. The pale yellow crystals have a complex lattice structure, and react with water or dilute acids to give methane. The acetylide, Al2(C2)3, is made by passing acetyleneover heated aluminium.
Aluminium nitride, AlN, can be made from the elements at 800 °C. It is hydrolysed by water to form ammoniaand aluminium hydroxide.
Aluminium phosphide, AlP, is made similarly, and hydrolyses to give phosphine.
Aluminium oxide, Al2O3, occurs naturally as corundum, and can be made by burning aluminium in oxygen or by heating the hydroxide, nitrate or sulfate. As a gemstone, its hardness is only exceeded by diamond, boron nitride, and carborundum. It is almost insoluble in water.
Aluminium hydroxidemay be prepared as a gelatinous precipitate by adding ammonia to an aqueous solution of an aluminium salt. It is amphoteric, being both a very weak acid, and forming aluminates with alkalis. It exists in various crystalline forms.
Aluminium sulfide, Al2S3, may be prepared by passing hydrogen sulfideover aluminium powder. It is polymorphic.
Aluminium iodide, AlI3, is a dimerwith applications in organic synthesis.
Aluminium fluoride, AlF3, is made by treating the hydroxide with HF, or can be made from the elements. It consists of a giant molecule which sublimes without melting at 1291 °C. It is very inert. The other trihalides are dimeric, having a bridge-like structure.
* Aluminium fluoride/water complexes: When aluminium and fluoride are together in aqueous solution, they readily form complex ions such as AlF(H2O)5+2, AlF3(H2O)30, AlF6-3. Of these, AlF6-3 is the most stable. This is explained by the fact that aluminium and fluoride, which are both very compact ions, fit together just right to form the octahedral aluminium hexafluoride complex. When aluminium and fluoride are together in water in a 1:6 molar ratio, AlF6-3 is the most common form, even in rather low concentrations.
* Organo-metallic compounds of empirical formula AlR3 exist and, if not also giant molecules, are at least dimers or trimers. They have some uses in organic synthesis, for instance trimethylaluminium.
* Alumino-hydrides of the most electropositive elements are known, the most useful being
lithium aluminium hydride, Li [AlH4] . It decomposes into lithium hydride, aluminium and hydrogen when heated, and is hydrolysed by water. It has many uses in organic chemistry, particularly as a reducing agent. The aluminohalides have a similar structure.
Aluminium is the most widely used non-ferrous metal. [cite encyclopedia |year= |title = aluminum | encyclopedia=
Encyclopædia Britannica|publisher= |location= |url = http://www.britannica.com/eb/art-64454] Global production of aluminium in 2005 was 31.9 million tonnes. It exceeded that of any other metal except iron(837.5 million tonnes). [cite book | title = World Mineral Production: 2001 - 2005 | author = L E Hetherington, T J Brown, A J Benham, P A J Lusty, N E Idoine | year = 2007 | publisher = British Geological Survey | isbn = 978-0-85272-592-4 | format = available online | url = http://www.mineralsuk.com/britmin/wmp_2001_2005.pdf] Relatively pure aluminium is encountered only when corrosion resistance and/or workability is more important than strength or hardness. A thin layer of aluminium can be deposited onto a flat surface by physical vapor depositionor (very infrequently) chemical vapor depositionor other chemical means to form optical coatings and mirrors. When so deposited, a fresh, pure aluminium film serves as a good reflector (approximately 92%) of visible lightand an excellent reflector (as much as 98%) of medium and far infrared.
Pure aluminium has a low
tensile strength, but when combined with thermo-mechanical processing, aluminium alloys display a marked improvement in mechanical properties, especially when tempered. Aluminium alloys form vital components of aircraftand rockets as a result of their high strength-to-weight ratio. Aluminium readily forms alloys with many elements such as copper, zinc, magnesium, manganeseand silicon(e.g., duralumin). Today, almost all bulk metal materials that are referred to loosely as "aluminium," are actually alloys. For example, the common aluminium foils are alloys of 92% to 99% aluminium. [cite web | publisher = How Products are Made | author = L. S. Millberg | url = http://www.madehow.com/Volume-1/Aluminum-Foil.html | title = Aluminum Foil | accessdate = 2007-08-11]
Some of the many uses for aluminium metal are in:
* Transportation (
automobiles, aircraft, trucks, railway cars, marine vessels, bicycles etc.)
* Packaging (cans, foil, etc.)
* Water treatment
* Treatment against fish parasites such as "
* Construction (
windows, doors, siding, building wire, etc.)
Electrical transmission lines for power distribution
MKM steeland Alnicomagnets
* Super purity aluminium (SPA, 99.980% to 99.999% Al), used in electronics and CDs.
Heat sinks for electronic appliances such as transistors and CPUs.
* Substrate material of
metal-core copper clad laminatesused in high brightness LED lighting.
* Powdered aluminium is used in
paint, and in pyrotechnicssuch as solid rocketfuels and thermite.
* In the blades of prop
swords and knivesused in stage combat.
* Aluminium is widely used in watch production as it provides durability and resists tarnishing and corrosion. [ [http://watches.infoniac.com/index.php?page=post&id=62 Aluminum in Watchmaking] ]
* Aluminium ammonium sulfate ( [Al(NH4)] (SO4)2),
ammonium alumis used as a mordant, in water purification and sewage treatment, in paperproduction, as a food additive, and in leathertanning.
Aluminium acetateis a saltused in solution as an astringent.
Aluminium borate(Al2O3 B2O3) is used in the production of glassand ceramic.
Aluminium borohydride(Al(BH4)3) is used as an additive to jet fuel.
Aluminium chloride(AlCl3) is used: in paint manufacturing, in antiperspirants, in petroleum refiningand in the production of synthetic rubber.
Aluminium chlorohydrideis used as an antiperspirant and in the treatment of hyperhidrosis.
Aluminium fluorosilicate(Al2(SiF6)3) is used in the production of synthetic gemstones, glass and ceramic.
Aluminium hydroxide(Al(OH)3) is used: as an antacid, as a mordant, in waterpurification, in the manufacture of glass and ceramic and in the waterproofing of fabrics.
Aluminium oxide(Al2O3), alumina, is found naturally as corundum(rubies and sapphires), emery, and is used in glass making. Synthetic ruby and sapphire are used in lasers for the production of coherent light.
Aluminium phosphate(AlPO4) is used in the manufacture: of glass and ceramic, pulp and paper products, cosmetics, paints and varnishes and in making dental cement.
Aluminium sulfate(Al2(SO4)3) is used: in the manufacture of paper, as a mordant, in a fire extinguisher, in water purification and sewage treatment, as a food additive, in fireproofing, and in leather tanning.
* In many vaccines, certain aluminium salts serve as an immune adjuvant (immune response booster) to allow the protein in the vaccine to achieve sufficient potency as an immune stimulant.
Aluminium alloys in structural applications
Aluminium alloys with a wide range of properties are used in engineering structures. Alloy systems are classified by a number system (ANSI) or by names indicating their main alloying constituents (
The strength and durability of aluminium alloys vary widely, not only as a result of the components of the specific alloy, but also as a result of heat treatments and manufacturing processes. A lack of knowledge of these aspects has from time to time led to improperly designed structures and gained aluminium a bad reputation. (See main article)
One important structural limitation of aluminium alloys is their fatigue strength. Unlike steels, aluminium alloys have no well-defined
fatigue limit, meaning that fatigue failure will eventually occur under even very small cyclic loadings. This implies that engineers must assess these loads and design for a fixed life rather than an infinite life.
Another important property of aluminium alloys is their sensitivity to heat.Workshop procedures involving heating are complicated by the fact that aluminium, unlike steel, will melt without first glowing red. Forming operations where a
blow torchis used therefore requires some expertise, since no visual signs reveal how close the material is to melting. Aluminium alloys, like all structural alloys, also are subject to internal stresses following heating operations such as welding and casting. The problem with aluminium alloys in this regard is their low melting point, which make them more susceptible to distortions from thermally induced stress relief. Controlled stress relief can be done during manufacturing by heat-treating the parts in an oven, followed by gradual cooling -- in effect annealing the stresses.
The low melting point of aluminium alloys has not precluded their use in rocketry; even for use in constructing combustion chambers where gases can reach 3500 K. The Agena upper stage engine used a regeneratively cooled aluminium design for some parts of the nozzle, including the thermally critical throat region.
Compared to copper, aluminium has about 65% of the
electrical conductivityby volume, although 200% by weight. Traditionally copper is used as household wiring material. In the 1960s aluminium was considerably cheaper than copper, and so was introduced for household electrical wiring in the United States, even though many fixtures had not been designed to accept aluminium wire. However, in some cases the greater coefficient of thermal expansionof aluminium causes the wire to expand and contract relative to the dissimilar metal screwconnection, eventually loosening the connection. Also, pure aluminium has a tendency to "creep" under steady sustained pressure (to a greater degree as the temperature rises), again loosening the connection. Finally, Galvanic corrosionfrom the dissimilar metals increased the electrical resistance of the connection.
All of this resulted in overheated and loose connections, and this in turn resulted in fires. Builders then became wary of using the wire, and many jurisdictions outlawed its use in very small sizes in new construction. Eventually, newer fixtures were introduced with connections designed to avoid loosening and overheating. At first they were marked "Al/Cu", but they now bear a "CO/ALR" coding. In older assemblies, workers forestall the heating problem using a properly-done crimp of the aluminium wire to a short "
pigtail" of copper wire. Today, new alloys, designs, and methods are used for aluminium wiring in combination with aluminium terminations.
Ancient Greeks and Romans used aluminium salts as dyeing mordants and as astringents for dressing wounds;
alumis still used as a styptic. In 1761 Guyton de Morveausuggested calling the base alum "alumine." In 1808, Humphry Davyidentified the existence of a metal base of alum, which he at first termed "alumium" and later "aluminum" (see Etymology section, below).
Friedrich Wöhler is generally credited with isolating aluminium (
Latin"alumen", alum) in 1827 by mixing anhydrous aluminium chloridewith potassium. As the metal had first been produced two years earlier (in an impure form) by Danish physicist and chemist Hans Christian Ørsted, Ørsted can also be listed as its discoverer. [cite web | publisher = ChemicalElements.com | title = Periodic Table: Aluminum | url = http://www.chemicalelements.com/elements/al.html | author = Yinon Bentor | accessdate = 2007-08-11] Further, Pierre Berthierdiscovered aluminium in bauxite ore and successfully extracted it. [cite web | publisher = Today in Science History | title = Pierre Berthier | url = http://www.todayinsci.com/7/7_03.htm#Berthier | accessdate = 2007-08-11] Frenchman Henri Etienne Sainte-Claire Devilleimproved Wöhler's method in 1846, and described his improvements in a book in 1859, chief among these being the substitution of sodium for the considerably more expensive potassium.
(Note: The title of Deville's book is "De l'aluminium, ses propriétés, sa fabrication" (Paris, 1859). Deville likely also conceived the idea of the
electrolysisof aluminium oxide dissolved in cryolite; however, Charles Martin Hall and Paul Héroult might have developed the more practical process after Deville.)
Hall-Héroult processwas developed, aluminium was exceedingly difficult to extract from its various ores. This made pure aluminium more valuable than gold. Bars of aluminium were exhibited alongside the French crown jewelsat the Exposition Universelle of 1855, and Napoleon III was said to have reserved a set of aluminium dinner plates for his most honoured guests.
Aluminium was selected as the material to be used for the apex of the
Washington Monumentin 1884, a time when one ounce(30 grams) cost the daily wage of a common worker on the project; [cite journal | author = George J. Binczewski | title = The Point of a Monument: A History of the Aluminum Cap of the Washington Monument | journal = JOM | volume = 47 | issue = 11 | pages = 20–25 | year = 1995 | url = http://www.tms.org/pubs/journals/JOM/9511/Binczewski-9511.html] aluminium was about the same value as silver.
The Cowles companies supplied aluminium alloy in quantity in the
United Statesand Englandusing smelters like the furnace of Carl Wilhelm Siemensby 1886. [cite journal|title=Cowles' Aluminium Alloys|pages=13|month=January | year=1886|journal=The Manufacturer and Builder|location=New York|volume=18|issue=1|publisher=Western and Company, via Cornell University Library|url=http://moa.cit.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fmanu%2Fmanu0018%2F&tif=00019.TIF|accessdate=2007-10-27 and cite book|author=McMillan, Walter George|title=A Treatise on Electro-Metallurgy|publisher=Charles Griffin and Company, J.B. Lippincott Company, via Google Books scan of New York Public Library copy|location=London, Philadelphia|year=1891|url=http://books.google.com/books?id=DDAKAAAAIAAJ&pg=PA302|pages=302-305|accessdate=2007-10-26 and cite book|author=Sackett, William Edgar, John James Scannell and Mary Eleanor Watson|title=New Jersey's First Citizens|url=http://books.google.com/books?id=cNgDAAAAYAAJ&pg=PA103|publisher=J.J. Scannell via Google Books scan of New York Public Library copy|location=New Jersey|date=1917/1918|pages=103-105|accessdate=2007-10-25] Charles Martin Hallof Ohioin the U.S. and Paul Héroultof Franceindependently developed the Hall-Héroult electrolytic process that made extracting aluminium from minerals cheaper and is now the principal method used worldwide. The Hall-Heroult process cannot produce Super Purity Aluminium directly. Hall's process,US patent reference|number = 400664|y = 1889 | m=04|d=02|inventor= Charles Martin Hall|title=Process of Reducing Aluminium from its Fluoride Salts by Electrolysis] in 1888 with the financial backing of Alfred E. Hunt, started the Pittsburgh Reduction Company today known as Alcoa. Héroult's process was in production by 1889 in Switzerlandat Aluminium Industrie, now Alcan, and at British Aluminium, now Luxfer Groupand Alcoa, by 1896 in Scotland.cite book|author=Donald Holmes Wallace|title=Market Control in the Aluminum Industry|url=http://books.google.com/books?id=E-acdJWbo90C&pg=PA6|year=1977|origyear=1937|pages=6|isbn=0-4050-9786-7|publisher=Harvard University Press via Ayer Publishing via Google Books limited view|accessdate=2007-10-27]
By 1895 the metal was being used as a building material as far away as
Sydney, Australiain the dome of the Chief Secretary's Building.
Many navies use an aluminium
superstructurefor their vessels, however, the 1975 fire aboard USS Belknapthat gutted her aluminium superstructure, as well as observation of battle damage to British ships during the Falklands War, led to many navies switching to all steel superstructures. The Arleigh Burke classwas the first such U.S. ship, being constructed entirely of steel.
In April 2008 the price of aluminium was around $1.35/lb. [ [http://www.infomine.com/commodities/aluminum.asp Aluminum prices] ]
The earliest citation given in the
Oxford English Dictionaryfor any word used as a name for this element is "alumium", which British chemist and inventor Humphry Davyemployed in 1808 for the metal he was trying to isolate electrolytically from the mineral " alumina". The citation is from his journal "Philosophical Transactions": "Had I been so fortunate as..to have procured the metallic substances I was in search of, I should have proposed for them the names of silicium, alumium, zirconium, and glucium." ["alumium", "Oxford English Dictionary". Ed. J.A. Simpson and E.S.C. Weiner, second edition Oxford: Clarendon Press, 1989. OED Online Oxford University Press. Accessed 29 October 2006. Citation is listed as "1808 SIR H. DAVY in Phil. Trans. XCVIII. 353". The ellipsis in the quotation is as it appears in the "OED" citation. ]
By 1812, Davy had settled on "aluminum". He wrote in the journal "Chemical Philosophy": "As yet Aluminum has not been obtained in a perfectly free state." ["aluminum", "ibid". Citation is listed as "1812 SIR H. DAVY "Chem. Philos." I. 355"] But the same year, an anonymous contributor to the "
Quarterly Review," a British political-literary journal, objected to "aluminum" and proposed the name "aluminium", "for so we shall take the liberty of writing the word, in preference to aluminum, which has a less classical sound." ["aluminium", "ibid". Citation is listed as "1812 "Q. Rev." VIII. 72"]
The "-ium" suffix had the advantage of conforming to the precedent set in other newly discovered elements of the time: potassium, sodium, magnesium, calcium, and
strontium(all of which Davy had isolated himself). Nevertheless, "-um" spellings for elements were not unknown at the time, as for example platinum, known to Europeans since the sixteenth century, molybdenum, discovered in 1778, and tantalum, discovered in 1802.
Americans adopted "-ium" to fit the standard form of the periodic table of elements, for most of the nineteenth century, with "aluminium" appearing in Webster's Dictionary of 1828. In 1892, however, Charles Martin Hall used the "-um" spelling in an advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the "-ium" spelling in all the patents he filed between 1886 and 1903. [cite web | author = Peter Meiers | publisher = The History of Fluorine, Fluoride and Fluoridation | title = Manufacture of Aluminum | url =http://www.fluoride-history.de/p-aluminum.htm] It has consequently been suggested that the spelling reflects an easier to pronounce word with one fewer syllable, or that the spelling on the flier was a mistake. Hall's domination of production of the metal ensured that the spelling "aluminum" became the standard in North America; the "Webster Unabridged Dictionary" of 1913, though, continued to use the "-ium" version.
In 1926, the
American Chemical Societyofficially decided to use "aluminum" in its publications; American dictionaries typically label the spelling "aluminium" as a British variant.
In the UK and other countries using British spelling, only "aluminium" is used. In the United States, the spelling "aluminium" is largely unknown, and the spelling "aluminum" predominates. [Greenwood&Earnshaw] [John Bremner, "Words on Words: A Dictionary for Writers and Others Who Care about Words", page 22–23. ISBN 0-231-04493-3] The
Canadian Oxford Dictionaryprefers "aluminum", whereas the Australian Macquarie Dictionaryprefers "aluminium". The spelling in virtually all other languages is analogous to the "-ium" ending.
International Union of Pure and Applied Chemistry(IUPAC) adopted "aluminium" as the standard international name for the element in 1990, but three years later recognized "aluminum" as an acceptable variant. Hence their periodic table includes both, but places "aluminium" first. [ [http://www.iupac.org/reports/periodic_table/index.html IUPAC Periodic Table of the Elements] ] IUPAC officially prefers the use of "aluminium" in its internal publications, although several IUPAC publications use the spelling "aluminum". [ [http://www.iupac.org/general/search.php?restrict=publications&query=aluminum&submit=Search IUPAC Web site publication search for 'aluminum'] ]
Aluminium's use in some antiperspirants and food additives is controversial. Aluminium in food may be absorbed more than aluminium from water.cite journal |author=Yokel RA, Hicks CL, Florence RL |title=Aluminum bioavailability from basic sodium aluminum phosphate, an approved food additive emulsifying agent, incorporated in cheese |journal=Food and chemical toxicology |volume=46 |issue=6 |pages=2261–6 |year=2008 |month=June |pmid=18436363 |doi=10.1016/j.fct.2008.03.004 |url=http://linkinghub.elsevier.com/retrieve/pii/S0278-6915(08)00134-8] Some researchers have expressed concerns that the aluminium in antiperspirants may increase the risk of breast cancer,cite journal |author=Exley C, Charles LM, Barr L, Martin C, Polwart A, Darbre PD |title=Aluminium in human breast tissue |journal=J. Inorg. Biochem. |volume=101 |issue=9 |pages=1344–6 |year=2007 |month=September |pmid=17629949 |doi=10.1016/j.jinorgbio.2007.06.005 |url=] and aluminium has been implicated as a factor in
Alzheimer's disease.cite journal |author=Ferreira PC, Piai Kde A, Takayanagui AM, Segura-Muñoz SI |title=Aluminum as a risk factor for Alzheimer's disease |journal=Rev Lat Am Enfermagem |volume=16 |issue=1 |pages=151–7 |year=2008 |pmid=18392545 |doi= |url=http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-11692008000100023&lng=en&nrm=iso&tlng=en]
The toxicity of aluminium can be traced to increased deposition in bone and the central nervous system, particularly in the presence of reduced renal function. Because aluminium competes with calcium for absorption, increased amounts of dietary aluminium may contribute to the reduced skeletal mineralization (osteopenia) observed in preterm infants and infants with growth retardation. Full-term infants with normal renal function do not seem to be at substantial risk from aluminium toxicity from soy protein-based formulas.Aluminium can cause
neurotoxicityin very high doses which can alter the function of the blood-brain barrier. [cite journal | author = Banks, W.A. | coauthors = Kastin, A.J. | year = 1989 | title = Aluminum-induced neurotoxicity: alterations in membrane function at the blood-brain barrier | journal = Neurosci Biobehav Rev | volume = 13 | issue = 1 | pages = 47–53 | doi = 10.1016/S0149-7634(89)80051-X] It is one of the few abundant elements that have no known function in living cells. A small percentage of people are allergic to it — they experience contact dermatitis: an itchy rashfrom using stypticor antiperspirantproducts, digestive disorders and inability to absorb nutrients from eating food cooked in aluminium pans, and vomitingand other symptoms of poisoningfrom ingesting such products as Amphojel, and Maalox(antacids). Such allergies are extremely rare though, in other people aluminium is not considered as toxic as heavy metals, but there is evidence of some toxicity if it is consumed in excessive amounts. The use of aluminium cookware, popular because of its corrosionresistance and good heat conduction, has not been shown to lead to aluminium toxicity in general. Excessive consumption of antacids containing aluminium compounds and excessive use of aluminium-containing antiperspirants are more likely causes of toxicity. Also, studies have shown that consumption of citric acid with aluminium significantly increases aluminium absorption, [cite journal| title=Dietary citric acid enhances absorption of aluminum in antacids| author = Slanina, P. | coauthors = Frech, W.; Ekstrom, L. G.; Loof, L.; Slorach, S.; and Cedergren, A. | journal = Clinical Chemistry | volume = 32 | pages = 539–541 | date = 1986 | publisher = American Association for Clinical Chemistry |url=http://www.clinchem.org/cgi/content/abstract/32/3/539 | accessdate = 2008-10-09] and maltolhas been shown to increase the accumulation of aluminium in nervous and osseus tissue (http://www.ncbi.nlm.nih.gov/pubmed/8445293). Furthermore, aluminium increases estrogen-related gene expressionin human breast cancercells grown in the laboratory. [ [http://www3.interscience.wiley.com/cgi-bin/abstract/112438172/ABSTRACT Metalloestrogens: an emerging class of inorganic xenoestrogens with potential to add to the oestrogenic burden of the human breast] J Appl Toxicol. 2006 May-Jun;26(3):191-7] These salts' estrogen-like effects have led to their classification as a metalloestrogen.
It has been suggested that aluminium is a cause of
Alzheimer's disease, as some brain plaques have been found to contain the metal. Research in this area has been inconclusive; aluminium accumulation may be a consequence of the Alzheimer's damage, not the cause. In any event, if there is any toxicity of aluminium it must be via a very specific mechanism, since total human exposure to the element in the form of naturally occurring clay in soil and dust is enormously large over a lifetime. [cite web | publisher = National Institute of Environmental Health Sciences | title = Alzheimer's Disease and Aluminum |month=October | year=2005 | url = http://www.niehs.nih.gov/external/faq/aluminum.htm] [cite news | author = Michael Hopkin | title = Death of Alzheimer victim linked to aluminium pollution| publisher = news @ nature.com | doi = 10.1038/news060417-10 | date = 21 April 2006]
Mercury applied to the surface of an
aluminium alloycan damage the protective oxide surface film by forming a Mercury-aluminium amalgam. This may cause further corrosion and weakening of the structure. For this reason, mercury thermometers are not allowed on many airliners, as aluminium is used in many aircraft structures.
A mixture of powdered aluminium and Fe2O3 is known as
thermite, and burns with a high energy output to form Fe and Al2O3. Thermite can be produced inadvertently during grinding operations, but the high ignition temperaturemakes incidents unlikely in most workshop environments.
Effect on plants
Aluminium is primary among the factors that reduce plant growth on acid soils. Although it is generally harmless to plant growth in pH-neutral soils, the concentration in acid soils of toxic Al3+
cations increases and disturbs root growth and function. Wheat's adaptationto allow aluminium tolerance is such that the aluminium induces a release of organic compounds that bind to the harmful aluminium cations. Sorghumis believed to have the same tolerance mechanism. The first gene for aluminium tolerance has been identified in wheat. A group in the U.S. Department of Agriculture showed that sorghum's aluminium tolerance is controlled by a single gene, as for wheat. This is not the case in all plants.
Aluminium in Africa
Institute for the History of Aluminium (IHA)
List of countries by aluminium production
Aluminium industry in Russia
* [http://www.webelements.com/webelements/elements/text/Al/index.html WebElements.com – Aluminium]
* [http://electrochem.cwru.edu/ed/encycl/art-a01-al-prod.htm Electrolytic production]
* [http://www.indexmundi.com/en/commodities/minerals/aluminum/aluminum_table12.html World production of primary aluminium, by country]
* [http://www.world-aluminium.org/About+Aluminium/Story+of/In+history History of Aluminium (from the website of the International Aluminium Institute)]
* [http://www.emedicine.com/med/topic113.htm Emedicine - Aluminium]
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