 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Aluminium bronze" – news ·newspapers ·books ·scholar ·JSTOR(July 2010) (Learn how and when to remove this message) |
_(8729765938).jpg)
Aluminium bronze is a type ofbronze in whichaluminium is the mainalloyingmetal added tocopper, in contrast to standard bronze (copper andtin) orbrass (copper andzinc). 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 asiron,nickel,manganese, andsilicon are also sometimes added to aluminium bronzes.
The following table lists the most common standard aluminium bronze wrought alloy compositions, by ISO 428 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 | Arsenic |
|---|---|---|---|---|---|---|
| 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. |
Aluminium bronzes are most valued for their higher strength andcorrosion resistance as compared to other bronze alloys. These alloys aretarnish-resistant and show low rates of corrosion inatmospheric conditions, lowoxidation rates at high temperatures, and low reactivity withsulfurous compounds and otherexhaust products ofcombustion. They are also resistant to corrosion insea water. Aluminium bronzes' resistance to corrosion results from the aluminium in the alloys, which reacts with atmosphericoxygen to form a thin, tough surface layer ofalumina (aluminium oxide) which acts as a barrier to corrosion of the copper-rich alloy. The addition oftin can improve corrosion resistance.[1]
Another notable property of aluminium bronzes are theirbiostatic effects. The copper component of the alloy prevents colonization by marine organisms includingalgae,lichens,barnacles, andmussels, and therefore can be preferable tostainless steel or other non-cupric alloys in applications where such colonization would be unwanted.
Aluminium bronzes tend to have a golden color.
Aluminium bronzes are most commonly used in applications where their resistance to corrosion makes them preferable to other engineering materials. These applications includeplain bearings andlanding gear components onaircraft,guitar strings, valve components,engine components (especially for seagoing ships), underwater fastenings innaval architecture, and shippropellers.[2] Aluminium bronze is also used to fulfil theATEX directive for Zones 1, 2, 21, and 22. The attractive gold-toned coloration of aluminium bronzes has also led to their use injewellery.
Aluminium bronzes are in the highest demand from the following industries and areas:
Aluminium bronze can bewelded using theMIG welding technique with an aluminium bronze core and pureargon gas.
Aluminium bronze is used to replace gold for the casting ofdental crowns. The alloys used are chemically inert and have the appearance of gold.
The Doehler Die Casting Co. of Toledo, Ohio were known for the production of Brastil, a high tensile corrosion resistant bronze alloy.[3][4]
Italy pioneered the use for coinage of an aluminium-bronze alloy calledbronzital (literally "Italian bronze") in its 5- and 10-centesimi from 1939. Its alloy was finalized in 1967 to 92% copper, 6% aluminium, and 2% nickel,[5] and was since used in the 20, 200 and 500Italian Lira coins until 2001. Bronzital has since been used for theAustralian andNew Zealand 1- and 2-dollar coins, the pre-2009Mexican 20- and 50-centavo coins, the inner cores of the bi-metallic Mexican 1-, 2- and 5-peso coins, the pre-2017Philippine 10-peso coin, theCanadian 2 dollar coin (a.k.a. the 'toonie'), and the outer rings of the Mexican 10-, 20-, 50- and 100-peso coins.
Nordic Gold, composed of 89% copper, 5% aluminium, 5% zinc, and 1% tin, is a more recently developed aluminium-bronze alloy for coinage. It was first used for the Swedish10-kronor coin in 1991, and became widespread after the introduction of Nordic gold 10, 20 and 50-centEuro coins in 2002.
Aluminium bronze is used in marine applications due to its excellent corrosion resistance in seawater.[6][7] It is found in marine hardware likepropellers, pumps, and valves, as well as in shipbuilding components and hull fittings.[8] For its non-magnetic properties, it is also used in naval vessels, particularly insonar equipment.[9]
Media related toAluminium bronze at Wikimedia Commons