Aluminium bronze
Overview
 
Aluminium bronze is a type of bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...

 in which aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 is the main alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

ing metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 added to copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, in contrast to standard bronze (copper and tin) or brass (copper and zinc) . A variety of aluminium bronzes of differing compositions have found industrial use, with most ranging from 5% to 11% aluminium by weight, the remaining mass being copper; other alloying agents such as iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, and silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 are also sometimes added to aluminium bronzes.
The following table lists the most common standard aluminium bronze wrought alloy compositions, by ISO 428
ISO 428
ISO 428 was an International Organization for Standardization standard fully entitled "Wrought Copper-Aluminium Alloys -- Chemical Composition And Forms of Wrought Products", specifying the allowable compositions of various copper-aluminum alloy specifications...

 designations.
Encyclopedia
Aluminium bronze is a type of bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...

 in which aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 is the main alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

ing metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 added to copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, in contrast to standard bronze (copper and tin) or brass (copper and zinc) . A variety of aluminium bronzes of differing compositions have found industrial use, with most ranging from 5% to 11% aluminium by weight, the remaining mass being copper; other alloying agents such as iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, and silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 are also sometimes added to aluminium bronzes.

Compositions

The following table lists the most common standard aluminium bronze wrought alloy compositions, by ISO 428
ISO 428
ISO 428 was an International Organization for Standardization standard fully entitled "Wrought Copper-Aluminium Alloys -- Chemical Composition And Forms of Wrought Products", specifying the allowable compositions of various copper-aluminum alloy specifications...

 designations. The percentages show the proportional composition of the alloy by weight. Copper is the remainder by weight and is not listed:
Alloy Aluminium Iron Nickel Manganese Zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

Arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

CuAl5 4.0% - 6.5% 0.5% max 0.8% max 0.5% max 0.5% max 0.4% max
CuAl8 7.0% - 9.0% 0.5% max 0.8% max 0.5% max 0.5% max
CuAl8Fe3 6.5% - 8.5% 1.5% - 3.5% 1.0% max 0.8% max 0.5% max
CuAl9Mn2 8.0% - 10.0% 1.5% max 0.8% max 1.5% - 3.0% 0.5% max
CuAl10Fe3 8.5% - 11.0% 2.0% - 4.0% 1.0% max 2.0% max 0.5% max
CuAl10Fe5Ni5 8.5% - 11.5% 2.0% - 6.0% 4.0% - 6.0% 2.0% max 0.5% max

Material properties

Aluminium bronzes are most valued for their higher strength and corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...

 resistance as compared to other bronze alloys. These alloys are tarnish
Tarnish
Tarnish is a thin layer of corrosion that forms over copper, brass, silver, aluminum, and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in the air. For example, silver needs hydrogen sulfide to tarnish; it...

-resistant and show low rates of corrosion in atmospheric
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

 conditions, low oxidation rates at high temperatures, and low reactivity with sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

ous compounds and other exhaust
Exhaust gas
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack or propelling nozzle.It often disperses...

 products of combustion
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...

. They are also resistant to corrosion in sea water. Aluminium bronzes' resistance to corrosion rests in the aluminium component of the alloys, which reacts with atmospheric oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 to form a thin, tough
Tough
Tough may refer to:* Toughness, the resistance to fracture of a material when stressed* Machismo, prominently exhibited or excessive masculinity* Emotional resiliencePeople:* Allen Tough , Canadian academic* Dave Tough , jazz drummer...

 surface layer of alumina (aluminium oxide) which acts as a barrier to corrosion of the copper-rich alloy. The addition of tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

 can improve corrosion resistance.

Another notable property of aluminium bronzes are their biostatic effects. The copper component of the alloy prevents colonization by marine organisms including algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

, lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...

s, barnacle
Barnacle
A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...

s, and mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...

s, and therefore can be preferable to stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....

 or other non-cupric alloys in applications where such colonization would be unwanted.

Aluminium bronzes tend to have a golden color.

Applications

Aluminium bronzes are most commonly used in applications where their resistance to corrosion makes them preferable to other engineering materials. These applications include plain bearing
Plain bearing
A plain bearing, also known as a plane bearing or a friction bearing is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore the journal slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole...

s and landing gear
Landing Gear
Landing Gear is Devin the Dude's fifth studio album. It was released on October 7, 2008. It was his first studio album since signing with the label Razor & Tie. It features a high-profile guest appearance from Snoop Dogg. As of October 30, 2008, the album has sold 18,906 copies.-Track...

 components on aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

, engine
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...

 components (especially for seagoing ships), underwater fastenings in naval architecture
Naval architecture
Naval architecture is an engineering discipline dealing with the design, construction, maintenance and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation and calculations during all stages of the life of a...

, and ship propeller
Propeller
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

s. Aluminum bronze is also used to fulfill the ATEX directive
ATEX directive
The ATEX directive consists of two EU directives describing what equipment and work environment is allowed in an environment with an explosive atmosphere...

 for Zones 1, 2, 21, and 22. The attractive gold-toned coloration of aluminium bronzes has also led to their use in jewelry.

Aluminium bronzes are in the highest demand from the following industries and areas:
  • General sea water-related service
  • Water supply
    Water supply
    Water supply is the provision of water by public utilities, commercial organisations, community endeavours or by individuals, usually via a system of pumps and pipes...

  • Oil
    Oil
    An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....

     and petrochemical
    Petrochemical
    Petrochemicals are chemical products derived from petroleum. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as corn or sugar cane....

     industries (i.e. tools for use in non-sparking
    Ember
    Embers are the glowing, hot coals made of greatly heated wood, coal, or other carbon-based material that remain after, or sometimes precede a fire. Embers can glow very hot, sometimes as hot as the fire which created them...

     environments)
  • Specialized anti-corrosive applications
  • Certain structural retrofit building applications


Aluminium bronze can be welded
Welding
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

 using the MIG welding technique with an aluminium bronze core and pure argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

 gas.

Aluminium bronze is used to replace gold for the casting of dental crowns. The alloys used are chemically inert and have the appearance of gold.

Alloys similar to aluminium bronze are used in making coins, for example the one and two dollar coins of Australian
Coins of the Australian dollar
Coins of the Australian dollar were introduced on 14 February 1966, although they did not at that time include a one-dollar coin. The dollar was equivalent in value to 10 shillings in the former currency .- Regular coinage :...

 and New Zealand
Coins of the New Zealand dollar
This article concerns the coins of the New Zealand dollar.- Pre-dollar :Prior to 10 July 1967, the New Zealand pound, using the £sd system, was the currency of New Zealand. Coins of the pound tend to follow the size, weight, and composition of their British counterparts...

 currency produced by the Royal Australian Mint
Royal Australian Mint
The Royal Australian Mint is situated in the Australian federal capital city of Canberra, in the suburb of Deakin.Before the opening of the mint, Australian coins were struck at branches of the Royal Mint - the Sydney Mint, Melbourne Mint and Perth Mint. The Royal Australian Mint holds a place in...

, some Mexican coins
Mexican peso
The peso is the currency of Mexico. Modern peso and dollar currencies have a common origin in the 15th–19th century Spanish dollar, most continuing to use its sign, "$". The Mexican peso is the 12th most traded currency in the world, the third most traded in the Americas, and by far the most...

 and the Nordic gold
Nordic gold
Nordic gold is the alloy from which the middle three denominations of euro coins, 50 cent, 20 cent, and 10 cent coins are made. It has also been in use for a number of years in other countries, most notably in the Swedish 10-krona coin...

 used for some Euro coins
Euro coins
There are eight euro coin denominations, ranging from one cent to two euros . The coins first came into use in 2002. They have a common reverse, portraying a map of Europe, but each country in the eurozone has its own design on the obverse, which means that each coin has a variety of different...

. The Canadian 2 dollar coin, produced by the Royal Canadian Mint
Royal Canadian Mint
The Royal Canadian Mint produces all of Canada's circulation coins, and manufactures circulation coins on behalf of other nations. The Mint also designs and manufactures: precious and base metal collector coins; gold, silver, palladium, and platinum bullion coins; medals, as well as medallions and...

and circulated since 1996, is a bi-metallic piece with an outer ring of nickel and an inner circle of aluminum bronze composed of 92% copper, 6% aluminum, and 2% nickel.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK