116-710: Centigon Security Group , formerly Carat Security Group is a large, privately held manufacturer of mobile armor . Based in Lamballe , France, the Group is the result of several mergers, including the purchase of Centigon by industry rival, Carat Duchatelet. One of the world's leading commercial armored vehicle providers, it operates six factories worldwide, employs a labor force of 800, and produces 1,400 armored vehicles annually. Among its subsidiaries' products are armored limousines for heads of states, armored sedans and SUVs, specialized vehicles for transporting cash, ballistic glass, and
232-491: A precipitate of aluminium hydroxide , Al(OH) 3 , forms. This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Increasing the pH even further leads to the hydroxide dissolving again as aluminate , [Al(H 2 O) 2 (OH) 4 ] , is formed. Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. This behavior of Al(OH) 3
348-515: A "less classical sound". This name persisted: although the -um spelling was occasionally used in Britain, the American scientific language used -ium from the start. Most scientists throughout the world used -ium in the 19th century; and it was entrenched in several other European languages, such as French , German , and Dutch . In 1828, an American lexicographer, Noah Webster , entered only
464-492: A Swedish chemist, Jöns Jacob Berzelius , in which the name aluminium is given to the element that would be synthesized from alum. (Another article in the same journal issue also refers to the metal whose oxide is the basis of sapphire , i.e. the same metal, as to aluminium .) A January 1811 summary of one of Davy's lectures at the Royal Society mentioned the name aluminium as a possibility. The next year, Davy published
580-546: A chemistry textbook in which he used the spelling aluminum . Both spellings have coexisted since. Their usage is currently regional: aluminum dominates in the United States and Canada; aluminium is prevalent in the rest of the English-speaking world. In 1812, British scientist Thomas Young wrote an anonymous review of Davy's book, in which he proposed the name aluminium instead of aluminum , which he thought had
696-403: A fixed thickness of armour plate, a projectile striking at an angle must penetrate more armour than one impacting perpendicularly . An angled surface also increases the chance of deflecting a projectile. This can be seen on v-hull designs, which direct the force of an Improvised explosive device or landmine away from the crew compartment, increasing crew survivability . Beginning during
812-551: A hammer, an axe, etc. The plastic provides little in the way of bullet-resistance. The glass, which is much harder than plastic, flattens the bullet and thereby prevents penetration. This type of bullet-resistant glass is usually 70–75 mm (2.8–3.0 in) thick. Bullet-resistant glass constructed of laminated glass layers is built from glass sheets bonded together with polyvinyl butyral , polyurethane or ethylene-vinyl acetate . This type of bullet-resistant glass has been in regular use on combat vehicles since World War II ; it
928-490: A layer two inches thick and backed by half an inch of steel . Plastic armour was highly effective at stopping armour piercing bullets because the hard granite particles would deflect the bullet, which would then lodge between plastic armour and the steel backing plate. Plastic armour could be applied by pouring it into a cavity formed by the steel backing plate and a temporary wooden form. Some main battle tank (MBT) armour utilises polymers, for example polyurethane as used in
1044-441: A probable cause for it being soft with a low melting point and low electrical resistivity . Aluminium metal has an appearance ranging from silvery white to dull gray depending on its surface roughness . Aluminium mirrors are the most reflective of all metal mirrors for near ultraviolet and far infrared light. It is also one of the most reflective for light in the visible spectrum, nearly on par with silver in this respect, and
1160-683: A process termed passivation . Because of its general resistance to corrosion, aluminium is one of the few metals that retains silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium is not attacked by oxidizing acids because of its passivation. This allows aluminium to be used to store reagents such as nitric acid , concentrated sulfuric acid , and some organic acids. In hot concentrated hydrochloric acid , aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates —protective passivation under these conditions
1276-525: A refractory material, and in ceramics , as well as being the starting material for the electrolytic production of aluminium. Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. The two main oxide-hydroxides, AlO(OH), are boehmite and diaspore . There are three main trihydroxides: bayerite , gibbsite , and nordstrandite , which differ in their crystalline structure ( polymorphs ). Many other intermediate and related structures are also known. Most are produced from ores by
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#17331058431271392-450: A shaped-charge warhead hits, the explosive detonates and pushes the steel plates into the warhead, disrupting the flow of the charge's liquid metal penetrator (usually copper at around 500 degrees Celsius; it can be made to flow like water by sufficient pressure). Traditional "light" ERA is less effective against kinetic penetrators. "Heavy" reactive armour, however, offers better protection. The only example currently in widespread service
1508-669: A sort of armour in the form of an aramid composite kevlar bandage around the fan casing or debris containment walls built into the casing of their gas turbine engines to prevent injuries or airframe damage should the fan, compressor, or turbine blades break free. The design and purpose of the vehicle determines the amount of armour plating carried, as the plating is often very heavy and excessive amounts of armour restrict mobility. In order to decrease this problem, some new materials ( nanomaterials ) and material compositions are being researched which include buckypaper , and aluminium foam armour plates. Rolled homogeneous armour
1624-474: A stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Such an electron configuration is shared with the other well-characterized members of its group, boron , gallium , indium , and thallium ; it is also expected for nihonium . Aluminium can surrender its three outermost electrons in many chemical reactions (see below ). The electronegativity of aluminium
1740-698: A trade show in Shanghai; presenting two Carat Duchatelet armored limousines. In 2014 Carat and Centigon parted again. Vehicle armour Military vehicles are commonly armoured (or armored; see spelling differences ) to withstand the impact of shrapnel , bullets , shells , rockets , and missiles , protecting the personnel inside from enemy fire. Such vehicles include armoured fighting vehicles like tanks , aircraft , and ships . Civilian vehicles may also be armoured. These vehicles include cars used by officials (e.g., presidential limousines ), reporters and others in conflict zones or where violent crime
1856-548: A type of Reactive armour . These elements are often a laminate consisting of two hard plates (usually high hardness steel) with some low density interlayer material between them. Upon impact, the interlayer swells and moves the plates, disrupting heat 'jets' and possibly degrading kinetic energy projectiles. Behind these elements will be some backing element designed to stop the degraded jet or projectile element, which may be of high hardness steel, or some composite of steel and ceramic or possibly uranium. Soviet main battle tanks from
1972-768: A variety of vehicles and equipment for the defense industry . In addition to offering feature-loaded premium transportation CSG also produces simpler, cheaper, less protected "no frills" vehicles aimed at a growing customer base in Africa and the Middle East. Its Black Scorpion Fast Attack Vehicle developed for this niche market was introduced at the Eurosatory 2010 [1] international exhibition of land security and defense vehicles in Paris. In April 2011, Carat made its first appearance in China, with
2088-815: A variety of wet processes using acid and base. Heating the hydroxides leads to formation of corundum. These materials are of central importance to the production of aluminium and are themselves extremely useful. Some mixed oxide phases are also very useful, such as spinel (MgAl 2 O 4 ), Na-β-alumina (NaAl 11 O 17 ), and tricalcium aluminate (Ca 3 Al 2 O 6 , an important mineral phase in Portland cement ). The only stable chalcogenides under normal conditions are aluminium sulfide (Al 2 S 3 ), selenide (Al 2 Se 3 ), and telluride (Al 2 Te 3 ). All three are prepared by direct reaction of their elements at about 1,000 °C (1,800 °F) and quickly hydrolyze completely in water to yield aluminium hydroxide and
2204-567: A way of purifying bauxite to yield alumina, now known as the Bayer process , in 1889. Modern production of aluminium is based on the Bayer and Hall–Héroult processes. As large-scale production caused aluminium prices to drop, the metal became widely used in jewelry, eyeglass frames, optical instruments, tableware, and foil , and other everyday items in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided
2320-477: A way that each tank component functions as added back-up armour to protect the crew. Outer armour is modular and enables quickly replacing damaged parts. For efficiency, the heaviest armour on an armoured fighting vehicle (AFV) is placed on its front. Tank tactics require the vehicle to always face the likely direction of enemy fire as much as possible, even in defence or withdrawal operations. Sloping and curving armour can both increase its protection. Given
2436-404: A whole, spaced armour can provide significantly increased protection while saving weight. The analogous Whipple shield uses the principle of spaced armour to protect spacecraft from the impacts of very fast micrometeoroids . The impact with the first wall melts or breaks up the incoming particle, causing fragments to be spread over a wider area when striking the subsequent walls. Sloped armour
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#17331058431272552-434: Is Al. Al was present in the early Solar System with abundance of 0.005% relative to Al but its half-life of 728,000 years is too short for any original nuclei to survive; Al is therefore extinct . Unlike for Al, hydrogen burning is the primary source of Al, with the nuclide emerging after a nucleus of Mg catches a free proton. However, the trace quantities of Al that do exist are the most common gamma ray emitter in
2668-407: Is paramagnetic and thus essentially unaffected by static magnetic fields. The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of eddy currents . Aluminium combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has
2784-429: Is small and highly charged ; as such, it has more polarizing power , and bonds formed by aluminium have a more covalent character. The strong affinity of aluminium for oxygen leads to the common occurrence of its oxides in nature. Aluminium is found on Earth primarily in rocks in the crust , where it is the third-most abundant element , after oxygen and silicon , rather than in the mantle , and virtually never as
2900-483: Is 1.61 (Pauling scale). A free aluminium atom has a radius of 143 pm . With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure , aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; hence aluminium (at these conditions)
3016-421: Is Russian Kontakt-5 . Explosive reactive armour poses a threat to friendly troops near the vehicle. Non-explosive reactive armour is an advanced spaced armour which uses materials which change their geometry so as to increase protection under the stress of impact. Active protection systems use a sensor to detect an incoming projectile and explosively launch a counter-projectile into its path. Slat armour
3132-399: Is a chemical element ; it has symbol Al and atomic number 13. Aluminium has a density lower than that of other common metals , about one-third that of steel . It has a great affinity towards oxygen , forming a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver , both in its color and in its great ability to reflect light. It
3248-785: Is a concern, such as personal armour and military aviation . Some notable examples of its use include the USAF A-10 Thunderbolt II and the Soviet/Russian-built Sukhoi Su-25 ground-attack aircraft, utilising a bathtub-shaped titanium enclosure for the pilot, as well as the Soviet/Russian Mil Mi-24 attack helicopter. Because of its high density, depleted uranium can also be used in tank armour, sandwiched between sheets of steel armour plate. For instance, some late-production M1A1HA and M1A2 Abrams tanks built after 1998 have DU reinforcement as part of
3364-420: Is a layer of armour-plating outside the hull (watercraft) of warships, typically on battleships , battlecruisers , cruisers and some aircraft carriers . Typically, the belt covers from the deck down someway below the waterline of the ship. If built within the hull, rather than forming the outer hull, it can be fitted at an inclined angle to improve the protection. When struck by a shell or torpedo ,
3480-416: Is a material with the appearance and light-transmitting behaviour of standard glass, which offers varying degrees of protection from small arms fire. The polycarbonate layer, usually consisting of products such as Armormax, Makroclear , Cyrolon, Lexan or Tuffak, is often sandwiched between layers of regular glass. The use of plastic in the laminate provides impact-resistance, such as physical assault with
3596-548: Is a metal. This crystal system is shared by many other metals, such as lead and copper ; the size of a unit cell of aluminium is comparable to that of those other metals. The system, however, is not shared by the other members of its group: boron has ionization energies too high to allow metallization, thallium has a hexagonal close-packed structure, and gallium and indium have unusual structures that are not close-packed like those of aluminium and thallium. The few electrons that are available for metallic bonding in aluminium are
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3712-515: 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. Aluminium also occurs in the minerals beryl , cryolite , garnet , spinel , and turquoise . Impurities in Al 2 O 3 , such as chromium and iron , yield the gemstones ruby and sapphire , respectively. Native aluminium metal
3828-405: Is also easily machined and cast . Aluminium is an excellent thermal and electrical conductor , having around 60% the conductivity of copper , both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity , with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss (10 milliteslas ). It
3944-456: Is armour that is mounted at a non-vertical and non-horizontal angle, typically on tanks and other armoured fighting vehicles. For a given normal to the surface of the armour, its plate thickness, increasing armour slope improves the armour's level of protection by increasing the thickness measured on a horizontal plane, while for a given area density of the armour the protection can be either increased or reduced by other sloping effects, depending on
4060-618: Is at ground. If an incoming HEAT jet penetrates the outer shell and forms a bridge between the shells, the electrical energy discharges through the jet, disrupting it. Trials have so far been extremely promising, and it is hoped that improved systems could protect against KE penetrators. The developers of the Future Rapid Effect System (FRES) series of armoured vehicles are considering this technology. Aluminium Aluminium (or aluminum in North American English )
4176-487: Is common. Civilian armoured cars are also routinely used by security firms to carry money or valuables to reduce the risk of highway robbery or the hijacking of the cargo. Armour may also be used in vehicles to protect from threats other than a deliberate attack. Some spacecraft are equipped with specialised armour to protect them against impacts from micrometeoroids or fragments of space debris . Modern aircraft powered by jet engines usually have them fitted with
4292-404: Is designed to protect against anti-tank rocket and missile attacks, where the warhead is a shaped charge . The slats are spaced so that the warhead is either partially deformed before detonating, or the fuzing mechanism is damaged, thereby preventing detonation entirely. As shaped charges rely on very specific structure to create a jet of hot metal, any disruption to this structure greatly reduces
4408-546: Is extremely rare and can only be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. Native aluminium has been reported in cold seeps in the northeastern continental slope of the South China Sea . It is possible that these deposits resulted from bacterial reduction of tetrahydroxoaluminate Al(OH) 4 . Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of
4524-536: Is greatly reduced by aqueous salts, particularly in the presence of dissimilar metals. Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (Al 2 S 3 ), and the aluminium halides (AlX 3 ). It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table. The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in
4640-492: Is in fact more basic than that of gallium. Aluminium also bears minor similarities to the metalloid boron in the same group: AlX 3 compounds are valence isoelectronic to BX 3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts . Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including
4756-470: Is low in comparison with many other metals. All other isotopes of aluminium are radioactive . The most stable of these is Al : while it was present along with stable Al in the interstellar medium from which the Solar System formed, having been produced by stellar nucleosynthesis as well, its half-life is only 717,000 years and therefore a detectable amount has not survived since the formation of
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4872-500: Is negligible. Aqua regia also dissolves aluminium. Aluminium is corroded by dissolved chlorides , such as common sodium chloride , which is why household plumbing is never made from aluminium. The oxide layer on aluminium is also destroyed by contact with mercury due to amalgamation or with salts of some electropositive metals. As such, the strongest aluminium alloys are less corrosion-resistant due to galvanic reactions with alloyed copper , and aluminium's corrosion resistance
4988-515: Is not as important. It is a polymer with the formula (AlH 3 ) n , in contrast to the corresponding boron hydride that is a dimer with the formula (BH 3 ) 2 . Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). It is the twelfth most abundant of all elements and third most abundant among the elements that have odd atomic numbers, after hydrogen and nitrogen. The only stable isotope of aluminium, Al,
5104-614: Is produced loses its coherence before reaching the main armour and impacting over a broader area. Sometimes the interior surfaces of these hollow cavities are sloped, presenting angles to the anticipated path of the shaped charge's jet in order to further dissipate its power. Taken to the extreme, relatively thin armour plates, metal mesh, or slatted plates , much lighter than fully protective armour, can be attached as side skirts or turret skirts to provide additional protection against such weapons. This can be seen in middle and late-World War II German tanks , as well as many modern AFVs . Taken as
5220-416: Is quite soft and lacking in strength. In most applications various aluminium alloys are used instead because of their higher strength and hardness. The yield strength of pure aluminium is 7–11 MPa , while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium is ductile , with a percent elongation of 50-70%, and malleable allowing it to be easily drawn and extruded . It
5336-435: Is soft, nonmagnetic , and ductile . It has one stable isotope, Al, which is highly abundant, making aluminium the twelfth-most common element in the universe. The radioactivity of Al leads to it being used in radiometric dating . Chemically, aluminium is a post-transition metal in the boron group ; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state . The aluminium cation Al
5452-403: Is strong, hard, and tough (does not shatter when struck with a fast, hard blow). Steel with these characteristics are produced by processing cast steel billets of appropriate size and then rolling them into plates of required thickness. Rolling and forging (hammering the steel when it is red hot) irons out the grain structure in the steel, removing imperfections which would reduce the strength of
5568-422: Is surrounded by six fluorine atoms in a distorted octahedral arrangement, with each fluorine atom being shared between the corners of two octahedra. Such {AlF 6 } units also exist in complex fluorides such as cryolite , Na 3 AlF 6 . AlF 3 melts at 1,290 °C (2,354 °F) and is made by reaction of aluminium oxide with hydrogen fluoride gas at 700 °C (1,300 °F). With heavier halides,
5684-547: Is termed amphoterism and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. One effect of this is that aluminium salts with weak acids are hydrolyzed in water to the aquated hydroxide and the corresponding nonmetal hydride: for example, aluminium sulfide yields hydrogen sulfide . However, some salts like aluminium carbonate exist in aqueous solution but are unstable as such; and only incomplete hydrolysis takes place for salts with strong acids, such as
5800-416: Is that of the preceding noble gas , whereas those of its heavier congeners gallium , indium , thallium , and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Hence, the inner electrons of aluminium shield the valence electrons almost completely, unlike those of aluminium's heavier congeners. As such, aluminium is the most electropositive metal in its group, and its hydroxide
5916-433: Is the eighteenth most abundant nucleus in the universe. It is created almost entirely after fusion of carbon in massive stars that will later become Type II supernovas : this fusion creates Mg, which upon capturing free protons and neutrons, becomes aluminium. Some smaller quantities of Al are created in hydrogen burning shells of evolved stars, where Mg can capture free protons. Essentially all aluminium now in existence
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#17331058431276032-570: Is the fact that sloping armour is a more efficient way of covering the necessary equipment since it encloses less volume with less material. The sharpest angles are usually seen on the frontal glacis plate, both as it is the hull side most likely to be hit and because there is more room to slope in the longitudinal direction of a vehicle. Explosive reactive armour , initially developed by German researcher Manfred Held while working in Israel, uses layers of high explosive sandwiched between steel plates. When
6148-455: Is typically about 100–120 mm (3.9–4.7 in) thick and is usually extremely heavy. Newer materials are being developed. One such, aluminium oxynitride , is much lighter but at US$ 10–15 per square inch is much more costly. Ceramic 's precise mechanism for defeating HEAT was uncovered in the 1980s. High speed photography showed that the ceramic material shatters as the HEAT round penetrates,
6264-480: The Cold War , many AFVs have spall liners inside of the armour, designed to protect crew and equipment inside from fragmentation (spalling) released from the impact of enemy shells, especially high-explosive squash head warheads. Spall liners are made of aramids ( Kevlar , Twaron ), UHMWPE ( Dyneema , Spectra Shield ), or similar materials. Appliqué armour, or add-on armour, consists of extra plates mounted onto
6380-455: The Friedel–Crafts reactions . Aluminium trichloride has major industrial uses involving this reaction, such as in the manufacture of anthraquinones and styrene ; it is also often used as the precursor for many other aluminium compounds and as a reagent for converting nonmetal fluorides into the corresponding chlorides (a transhalogenation reaction ). Aluminium forms one stable oxide with
6496-466: The London Metal Exchange , the oldest industrial metal exchange in the world, in 1978. The output continued to grow: the annual production of aluminium exceeded 50,000,000 metric tons in 2013. The real price for aluminium declined from $ 14,000 per metric ton in 1900 to $ 2,340 in 1948 (in 1998 United States dollars). Extraction and processing costs were lowered over technological progress and
6612-760: The T-64 onward utilised composite armour which often consisted of some low density filler between relatively thick steel plates or castings, for example Combination K . For example, the T-64 turret had a layer of ceramic balls and aluminum sandwiched between layers of cast steel armour, whilst some models of the T-72 features a glass filler called "Kvartz". The tank glacis was often a sandwich of steel and some low density filler, either textolite (a fibreglass reinforced polymer) or ceramic plates. Later T-80 and T-72 turrets contained NERA elements, similar to those discussed above. Belt armour
6728-467: The aluminum spelling in his American Dictionary of the English Language . In the 1830s, the -um spelling gained usage in the United States; by the 1860s, it had become the more common spelling there outside science. In 1892, Hall used the -um spelling in his advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the -ium spelling in all
6844-423: The chemical formula Al 2 O 3 , commonly called alumina . It can be found in nature in the mineral corundum , α-alumina; there is also a γ-alumina phase. Its crystalline form, corundum, is very hard ( Mohs hardness 9), has a high melting point of 2,045 °C (3,713 °F), has very low volatility, is chemically inert, and a good electrical insulator, it is often used in abrasives (such as toothpaste), as
6960-634: The free metal . It is obtained industrially by mining bauxite , a sedimentary rock rich in aluminium minerals. The discovery of aluminium was announced in 1825 by Danish physicist Hans Christian Ørsted . The first industrial production of aluminium was initiated by French chemist Henri Étienne Sainte-Claire Deville in 1856. Aluminium became much more available to the public with the Hall–Héroult process developed independently by French engineer Paul Héroult and American engineer Charles Martin Hall in 1886, and
7076-542: The interstellar gas ; if the original Al were still present, gamma ray maps of the Milky Way would be brighter. Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass). Aluminium occurs in greater proportion in the Earth's crust than in the universe at large. This is because aluminium easily forms the oxide and becomes bound into rocks and stays in the Earth's crust , while less reactive metals sink to
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#17331058431277192-477: The "BDD" appliqué armour applied to modernized T-62 and T-55 . Bulletproof glass is a colloquial term for glass that is particularly resistant to being penetrated when struck by bullets . The industry generally refers to it as bullet-resistant glass or transparent armour . Bullet-resistant glass is usually constructed using a strong but transparent material such as polycarbonate thermoplastic or by using layers of laminated glass . The desired result
7308-570: The "bathtub" for its shape. In addition, the windscreens of larger aircraft are generally made of impact-resistant, laminated materials , even on civilian craft, to prevent damage from bird strikes or other debris. The most heavily armoured vehicles today are the main battle tanks , which are the spearhead of the ground forces, and are designed to withstand anti-tank guided missiles , kinetic energy penetrators , high-explosive anti-tank weapons, NBC threats and in some tanks even steep-trajectory shells. The Israeli Merkava tanks were designed in
7424-516: The 5th century BCE. The ancients are known to have used alum as a dyeing mordant and for city defense. After the Crusades , alum, an indispensable good in the European fabric industry, was a subject of international commerce; it was imported to Europe from the eastern Mediterranean until the mid-15th century. The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum
7540-472: The Al–Zn–Mg class. Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. A fine powder of aluminium reacts explosively on contact with liquid oxygen ; under normal conditions, however, aluminium forms a thin oxide layer (~5 nm at room temperature) that protects the metal from further corrosion by oxygen, water, or dilute acid,
7656-682: The Americans. Moreover, there was the Killdozer incident , with the modified bulldozer being armoured with steel and concrete composite, which proved to be highly resistant to small arms. Armour with two or more plates spaced a distance apart, called spaced armour, has been in use since the First World War , where it was used on the Schneider CA1 and Saint-Chamond tanks. Spaced armour can be advantageous in several situations. For example, it can reduce
7772-418: The United States dollar, and alumina prices. The BRIC countries' combined share in primary production and primary consumption grew substantially in the first decade of the 21st century. China is accumulating an especially large share of the world's production thanks to an abundance of resources, cheap energy, and governmental stimuli; it also increased its consumption share from 2% in 1972 to 40% in 2010. In
7888-462: The United States, Western Europe, and Japan, most aluminium was consumed in transportation, engineering, construction, and packaging. In 2021, prices for industrial metals such as aluminium have soared to near-record levels as energy shortages in China drive up costs for electricity. The names aluminium and aluminum are derived from the word alumine , an obsolete term for alumina , the primary naturally occurring oxide of aluminium . Alumine
8004-578: The aluminium atoms have tetrahedral four-coordination and the other half have trigonal bipyramidal five-coordination. Four pnictides – aluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. They are all III-V semiconductors isoelectronic to silicon and germanium , all of which but AlN have the zinc blende structure. All four can be made by high-temperature (and possibly high-pressure) direct reaction of their component elements. Aluminium alloys well with most other metals (with
8120-472: The armour materials used and the qualities of the projectile hitting it. The increased protection caused by increasing the slope while keeping the plate thickness constant, is due to a proportional increase of area density and thus mass, and thus offers no weight benefit. Therefore, the other possible effects of sloping, such as deflection, deforming and ricochet of a projectile, have been the reasons to apply sloped armour in armoured vehicles design. Another motive
8236-481: The armour plating in the front of the hull and the front of the turret, and there is a program to upgrade the rest (see Chobham armour ). Plastic metal was a type of vehicle armour originally developed for merchant ships by the British Admiralty in 1940. The original composition was described as 50% clean granite of half-inch size, 43% of limestone mineral, and 7% of bitumen . It was typically applied in
8352-411: The belt armour is designed to prevent penetration, by either being too thick for the warhead to penetrate, or sloped to a degree that would deflect either projectile. Often, the main belt armour was supplemented with a torpedo bulkhead spaced several metres behind the main belt, designed to maintain the ship's watertight integrity even if the main belt were penetrated. The air-space between the belt and
8468-436: The characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al is a small and highly charged cation, it is strongly polarizing and bonding in aluminium compounds tends towards covalency ; this behavior is similar to that of beryllium (Be ), and the two display an example of a diagonal relationship . The underlying core under aluminium's valence shell
8584-419: The coordination numbers are lower. The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium trichloride (AlCl 3 ) has a layered polymeric structure below its melting point of 192.4 °C (378 °F) but transforms on melting to Al 2 Cl 6 dimers. At higher temperatures those increasingly dissociate into trigonal planar AlCl 3 monomers similar to
8700-428: The core. In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass ) and the third most abundant of all elements (after oxygen and silicon). A large number of silicates in the Earth's crust contain aluminium. In contrast, the Earth's mantle is only 2.38% aluminium by mass. Aluminium also occurs in seawater at a concentration of 2 μg/kg. Because of its strong affinity for oxygen, aluminium
8816-474: The decay of Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago. The remaining isotopes of aluminium, with mass numbers ranging from 21 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. An aluminium atom has 13 electrons, arranged in an electron configuration of [ Ne ] 3s 3p , with three electrons beyond
8932-413: The effectiveness of kinetic energy penetrators because the interaction with each plate can cause the round to tumble, deflect, deform, or disintegrate. This effect can be enhanced when the armour is sloped . Spaced armour can also offer increased protection against HEAT projectiles. This occurs because the shaped charge warhead can detonate prematurely (at the first surface), so that the metal jet that
9048-564: The effectiveness of the warhead. Slat armour can be defeated by tandem-charge designs such as the RPG-27 and RPG-29 . Electric armour is a recent development in the United Kingdom by the Defence Science and Technology Laboratory . A vehicle is fitted with two thin shells, separated by insulating material. The outer shell holds an enormous electric charge , while the inner shell
9164-399: The environment, no living organism is known to metabolize aluminium salts , but this aluminium is well tolerated by plants and animals. Because of the abundance of these salts, the potential for a biological role for them is of interest, and studies are ongoing. Of aluminium isotopes, only Al is stable. This situation is common for elements with an odd atomic number. It is
9280-478: The exception of most alkali metals and group 13 metals) and over 150 intermetallics with other metals are known. Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing . Bonding in them is predominantly metallic and the crystal structure primarily depends on efficiency of packing. There are few compounds with lower oxidation states. A few aluminium(I) compounds exist: AlF, AlCl, AlBr, and AlI exist in
9396-520: The fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. The only lighter metals are the metals of groups 1 and 2 , which apart from beryllium and magnesium are too reactive for structural use (and beryllium is very toxic). Aluminium is not as strong or stiff as steel, but the low density makes up for this in the aerospace industry and for many other applications where light weight and relatively high strength are crucial. Pure aluminium
9512-730: The gas phase after explosion and in stellar absorption spectra. More thoroughly investigated are compounds of the formula R 4 Al 2 which contain an Al–Al bond and where R is a large organic ligand . A variety of compounds of empirical formula AlR 3 and AlR 1.5 Cl 1.5 exist. The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. Pr , Bu , Me 3 CCH 2 ); for example, triisobutylaluminium exists as an equilibrium mixture of
9628-453: The gaseous phase when the respective trihalide is heated with aluminium, and at cryogenic temperatures. A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine , Al 4 I 4 (NEt 3 ) 4 . Al 2 O and Al 2 S also exist but are very unstable. Very simple aluminium(II) compounds are invoked or observed in the reactions of Al metal with oxidants. For example, aluminium monoxide , AlO, has been detected in
9744-646: The halides, nitrate , and sulfate . For similar reasons, anhydrous aluminium salts cannot be made by heating their "hydrates": hydrated aluminium chloride is in fact not AlCl 3 ·6H 2 O but [Al(H 2 O) 6 ]Cl 3 , and the Al–O bonds are so strong that heating is not sufficient to break them and form Al–Cl bonds instead: All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF 3 ) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation . Each aluminium atom
9860-494: The highly energetic fragments destroying the geometry of the metal jet generated by the hollow charge , greatly diminishing the penetration. Ceramic layers can also be used as part of composite armour solutions. The high hardness of some ceramic materials serves as a disruptor that shatters and spreads the kinetic energy of projectiles. Composite armour is armour consisting of layers of two or more materials with significantly different physical properties; steel and ceramics are
9976-671: The hull also adds buoyancy . Several wartime vessels had belt armour that was thinner or shallower than was desirable, to speed production and conserve resources. Deck armour on aircraft carriers is usually at the flight deck level, but on some early carriers was at the hangar deck . (See armoured flight deck .) Armour plating is not common on aircraft, which generally rely on their speed and maneuverability to avoid attacks from enemy aircraft and ground fire, rather than trying to resist impacts. Additionally, any armour capable of stopping large-calibre anti-aircraft fire or missile fragments would result in an unacceptable weight penalty. So, only
10092-521: The hull or turret of an AFV. The plates can be made of any material and are designed to be retrofitted to an AFV to withstand weapons that can penetrate the original armour of the vehicle. An advantage of appliqué armour is the possibility to tailor a vehicle's protection level to a specific threat scenario. Vehicle armour is sometimes improvised in the midst of an armed conflict by vehicle crews or individual units. In World War II , British, Canadian and Polish tank crews welded spare strips of tank track to
10208-759: The hulls of their Sherman tanks. U.S. tank crews often added sand bags in the hull and turrets on Sherman tanks, often in an elaborate cage made of girders. Some Sherman tanks were up-armoured in the field with glacis plates and other armour cut from knocked-out tanks to create Improvised Jumbos , named after the heavily armoured M4A3E2 assault tank. In the Vietnam War , U.S. " gun trucks " were armoured with sandbags and locally fabricated steel armour plate. More recently, U.S. troops in Iraq armoured Humvees and various military transport vehicles with scrap materials: this came to be known as " hillbilly armour " or "haji armour" by
10324-433: The low-pressure polymerization of ethene and propene . There are also some heterocyclic and cluster organoaluminium compounds involving Al–N bonds. The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH 4 ), which is used as a reducing agent in organic chemistry . It can be produced from lithium hydride and aluminium trichloride . The simplest hydride, aluminium hydride or alane,
10440-508: The mass production of aluminium led to its extensive use in industry and everyday life. In the First and Second World Wars, aluminium was a crucial strategic resource for aviation . In 1954, aluminium became the most produced non-ferrous metal , surpassing copper . In the 21st century, most aluminium was consumed in transportation, engineering, construction, and packaging in the United States, Western Europe, and Japan. Despite its prevalence in
10556-529: The metal remained rare; its cost exceeded that of gold. The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Deville had discovered that aluminium trichloride could be reduced by sodium, which was more convenient and less expensive than potassium, which Wöhler had used. Even then, aluminium was still not of great purity and produced aluminium differed in properties by sample. Because of its electricity-conducting capacity, aluminium
10672-628: The metal to be isolated from alum was alumium , which Davy suggested in an 1808 article on his electrochemical research, published in Philosophical Transactions of the Royal Society . It appeared that the name was created from the English word alum and the Latin suffix -ium ; but it was customary then to give elements names originating in Latin, so this name was not adopted universally. This name
10788-465: The metal with many uses at the time. During World War I , major governments demanded large shipments of aluminium for light strong airframes; during World War II , demand by major governments for aviation was even higher. By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. In 1954, production of aluminium surpassed that of copper , historically second in production only to iron, making it
10904-486: The metal. Almost all metallic aluminium is produced from the ore bauxite (AlO x (OH) 3–2 x ). Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. In 2017, most bauxite was mined in Australia, China, Guinea, and India. The history of aluminium has been shaped by usage of alum . The first written record of alum, made by Greek historian Herodotus , dates back to
11020-485: The monomer and dimer. These dimers, such as trimethylaluminium (Al 2 Me 6 ), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. They are hard acids and react readily with ligands, forming adducts. In industry, they are mostly used in alkene insertion reactions, as discovered by Karl Ziegler , most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in
11136-654: The most common types of material in composite armour. Composite armour was initially developed in the 1940s, although it did not enter service until much later and the early examples are often ignored in the face of newer armour such as Chobham armour . Composite armour's effectiveness depends on its composition and may be effective against kinetic energy penetrators as well as shaped charge munitions ; heavy metals are sometimes included specifically for protection from kinetic energy penetrators. Composite armour used on modern Western and Israeli main battle tanks largely consists of non-explosive reactive armour (NERA) elements -
11252-506: The most produced non-ferrous metal . During the mid-20th century, aluminium emerged as a civil engineering material, with building applications in both basic construction and interior finish work, and increasingly being used in military engineering, for both airplanes and land armor vehicle engines. Earth's first artificial satellite , launched in 1957, consisted of two separate aluminium semi-spheres joined and all subsequent space vehicles have used aluminium to some extent. The aluminium can
11368-599: The next decade, the -um spelling dominated American usage. In 1925, the American Chemical Society adopted this spelling. The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990. In 1993, they recognized aluminum as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry also acknowledges this spelling. IUPAC official publications use
11484-429: The only primordial aluminium isotope, i.e. the only one that has existed on Earth in its current form since the formation of the planet. It is therefore a mononuclidic element and its standard atomic weight is virtually the same as that of the isotope. This makes aluminium very useful in nuclear magnetic resonance (NMR), as its single stable isotope has a high NMR sensitivity. The standard atomic weight of aluminium
11600-407: The oxidation state 3+. The coordination number of such compounds varies, but generally Al is either six- or four-coordinate. Almost all compounds of aluminium(III) are colorless. In aqueous solution, Al exists as the hexaaqua cation [Al(H 2 O) 6 ] , which has an approximate K a of 10 . Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until
11716-460: The patents he filed between 1886 and 1903. It is unknown whether this spelling was introduced by mistake or intentionally, but Hall preferred aluminum since its introduction because it resembled platinum , the name of a prestigious metal. By 1890, both spellings had been common in the United States, the -ium spelling being slightly more common; by 1895, the situation had reversed; by 1900, aluminum had become twice as common as aluminium ; in
11832-404: The planet. However, minute traces of Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons. The ratio of Al to Be has been used for radiodating of geological processes over 10 to 10 year time scales, in particular transport, deposition, sediment storage, burial times, and erosion. Most meteorite scientists believe that the energy released by
11948-423: The respective hydrogen chalcogenide . As aluminium is a small atom relative to these chalcogens, these have four-coordinate tetrahedral aluminium with various polymorphs having structures related to wurtzite , with two-thirds of the possible metal sites occupied either in an orderly (α) or random (β) fashion; the sulfide also has a γ form related to γ-alumina, and an unusual high-temperature hexagonal form where half
12064-485: The scale of the economies. However, the need to exploit lower-grade poorer quality deposits and the use of fast increasing input costs (above all, energy) increased the net cost of aluminium; the real price began to grow in the 1970s with the rise of energy cost. Production moved from the industrialized countries to countries where production was cheaper. Production costs in the late 20th century changed because of advances in technology, lower energy prices, exchange rates of
12180-468: The steel. Rolling also elongates the grain structure in the steel to form long lines, which enable the stress the steel is placed under when loaded to flow throughout the metal, and not be concentrated in one area. Aluminium is used when light weight is a necessity. It is most commonly used on APCs and armoured cars . While certainly not the strongest metal, it is cheap, lightweight, and tough enough that it can serve as easy armour. Wrought iron
12296-408: The structure of BCl 3 . Aluminium tribromide and aluminium triiodide form Al 2 X 6 dimers in all three phases and hence do not show such significant changes of properties upon phase change. These materials are prepared by treating aluminium with the halogen. The aluminium trihalides form many addition compounds or complexes; their Lewis acidic nature makes them useful as catalysts for
12412-536: The two therefore look similar. Aluminium is also good at reflecting solar radiation , although prolonged exposure to sunlight in air adds wear to the surface of the metal; this may be prevented if aluminium is anodized , which adds a protective layer of oxide on the surface. The density of aluminium is 2.70 g/cm , about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness. Aluminium's low density compared to most other metals arises from
12528-615: The vital parts of an aircraft, such as the ejection seat and engines, are usually armoured. This is one area where titanium is used extensively as armour plating. For example, in the American Fairchild Republic A-10 Thunderbolt II and the Soviet-built Sukhoi Su-25 ground attack aircraft, as well as the Mil Mi-24 Hind ground-attack helicopter, the pilot sits in a titanium enclosure known as
12644-461: Was a salt of an earth of alum. In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. In 1754, German chemist Andreas Sigismund Marggraf synthesized alumina by boiling clay in sulfuric acid and subsequently adding potash . Attempts to produce aluminium date back to 1760. The first successful attempt, however,
12760-485: Was borrowed from French, which in turn derived it from alumen , the classical Latin name for alum , the mineral from which it was collected. The Latin word alumen stems from the Proto-Indo-European root *alu- meaning "bitter" or "beer". British chemist Humphry Davy , who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. The first name proposed for
12876-422: Was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted . He reacted anhydrous aluminium chloride with potassium amalgam , yielding a lump of metal looking similar to tin. He presented his results and demonstrated a sample of the new metal in 1825. In 1827, German chemist Friedrich Wöhler repeated Ørsted's experiments but did not identify any aluminium. (The reason for this inconsistency
12992-492: Was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. The English name alum does not come directly from Latin, whereas alumine / alumina obviously comes from the Latin word alumen (upon declension , alumen changes to alumin- ). One example was Essai sur la Nomenclature chimique (July 1811), written in French by
13108-418: Was invented in 1956 and employed as a storage for drinks in 1958. Throughout the 20th century, the production of aluminium rose rapidly: while the world production of aluminium in 1900 was 6,800 metric tons, the annual production first exceeded 100,000 metric tons in 1916; 1,000,000 tons in 1941; 10,000,000 tons in 1971. In the 1970s, the increased demand for aluminium made it an exchange commodity; it entered
13224-433: Was only discovered in 1921.) He conducted a similar experiment in the same year by mixing anhydrous aluminium chloride with potassium and produced a powder of aluminium. In 1845, he was able to produce small pieces of the metal and described some physical properties of this metal. For many years thereafter, Wöhler was credited as the discoverer of aluminium. As Wöhler's method could not yield great quantities of aluminium,
13340-571: Was used as the cap of the Washington Monument , completed in 1885. The tallest building in the world at the time, the non-corroding metal cap was intended to serve as a lightning rod peak. The first industrial large-scale production method was independently developed in 1886 by French engineer Paul Héroult and American engineer Charles Martin Hall ; it is now known as the Hall–Héroult process . The Hall–Héroult process converts alumina into metal. Austrian chemist Carl Joseph Bayer discovered
13456-529: Was used on ironclad warships . Early European iron armour consisted of 10 to 12.5 cm of wrought iron backed by up to one metre of solid wood . It has since been replaced by steel due to steel being significantly stronger. Titanium has almost twice the density of aluminium, but can have a yield strength similar to high strength steels, giving it a high specific strength . It also has a high specific resilience and specific toughness. So, despite being more expensive, it finds an application in areas where weight
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