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Bronze is an
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
consisting primarily of
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
, commonly with about 12–12.5%
tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
and often with the addition of other metals (including
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
,
manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
,
nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
, or
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
) and sometimes non-metals, such as
phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
, or
metalloids A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are ...
such as
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but ...
or
silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...
. These additions produce a range of alloys that may be harder than copper alone, or have other useful properties, such as
strength Strength may refer to: Physical strength *Physical strength, as in people or animals * Hysterical strength, extreme strength occurring when people are in life-and-death situations *Superhuman strength, great physical strength far above human c ...
,
ductility Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...
, or
machinability Machinability is the ease with which a metal can be cut (machined) permitting the removal of the material with a satisfactory finish at low cost.Degarmo, p. 542. Materials with good machinability (free machining materials) require little power to c ...
. The
archaeological period The names for archaeological periods in the list of archaeological periods vary enormously from region to region. This is a list of the main divisions by continent and region. Dating also varies considerably and those given are broad approximations ...
in which bronze was the hardest metal in widespread use is known as the
Bronze Age The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second pri ...
. The beginning of the Bronze Age in western
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
and India is conventionally dated to the mid-4th
millennium A millennium (plural millennia or millenniums) is a period of one thousand years, sometimes called a kiloannum (ka), or kiloyear (ky). Normally, the word is used specifically for periods of a thousand years that begin at the starting point (ini ...
BCE (~3500 BCE), and to the early 2nd millennium BCE in China; elsewhere it gradually spread across regions. The Bronze Age was followed by the
Iron Age The Iron Age is the final epoch of the three-age division of the prehistory and protohistory of humanity. It was preceded by the Stone Age (Paleolithic, Mesolithic, Neolithic) and the Bronze Age (Chalcolithic). The concept has been mostly appl ...
starting from about 1300 BCE and reaching most of Eurasia by about 500 BCE, although bronze continued to be much more widely used than it is in modern times. Because historical artworks were often made of
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...
es (copper and zinc) and bronzes with different compositions, modern museum and scholarly descriptions of older artworks increasingly use the generalized term "
copper alloy Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both of t ...
" instead.


Etymology

The word ''bronze'' (1730–1740) is borrowed from
Middle French Middle French (french: moyen français) is a historical division of the French language that covers the period from the 14th to the 16th century. It is a period of transition during which: * the French language became clearly distinguished from t ...
(1511), itself borrowed from Italian 'bell metal, brass' (13th century, transcribed in
Medieval Latin Medieval Latin was the form of Literary Latin used in Roman Catholic Western Europe during the Middle Ages. In this region it served as the primary written language, though local languages were also written to varying degrees. Latin functioned ...
as ) from either: * , back-formation from
Byzantine Greek Medieval Greek (also known as Middle Greek, Byzantine Greek, or Romaic) is the stage of the Greek language between the end of classical antiquity in the 5th–6th centuries and the end of the Middle Ages, conventionally dated to the Ottoman co ...
(, 11th century), perhaps from (, '
Brindisi Brindisi ( , ) ; la, Brundisium; grc, Βρεντέσιον, translit=Brentésion; cms, Brunda), group=pron is a city in the region of Apulia in southern Italy, the capital of the province of Brindisi, on the coast of the Adriatic Sea. Histo ...
', reputed for its bronze; or originally: * in its earliest form from
Old Persian Old Persian is one of the two directly attested Old Iranian languages (the other being Avestan language, Avestan) and is the ancestor of Middle Persian (the language of Sasanian Empire). Like other Old Iranian languages, it was known to its native ...
, (, 'brass', modern ) and () 'copper', from which also came
Georgian Georgian may refer to: Common meanings * Anything related to, or originating from Georgia (country) ** Georgians, an indigenous Caucasian ethnic group ** Georgian language, a Kartvelian language spoken by Georgians **Georgian scripts, three scrip ...
( ), Turkish ''pirinç,'' and
Armenian Armenian may refer to: * Something of, from, or related to Armenia, a country in the South Caucasus region of Eurasia * Armenians, the national people of Armenia, or people of Armenian descent ** Armenian Diaspora, Armenian communities across the ...
(), also meaning 'bronze'.


History

The discovery of bronze enabled people to create metal objects that were harder and more durable than previously possible. Bronze
tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates ba ...
s,
weapon A weapon, arm or armament is any implement or device that can be used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime, law enforcement, s ...
s,
armor Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or fr ...
, and
building material Building material is material used for construction. Many naturally occurring substances, such as clay, rock (geology), rocks, sand, wood, and even twigs and leaves, have been used to construct buildings. Apart from naturally occurring materia ...
s such as decorative tiles were harder and more durable than their stone and copper ("
Chalcolithic The Copper Age, also called the Chalcolithic (; from grc-gre, χαλκός ''khalkós'', "copper" and  ''líthos'', "stone") or (A)eneolithic (from Latin '' aeneus'' "of copper"), is an archaeological period characterized by regular ...
") predecessors. Initially, bronze was made out of copper and
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but ...
, forming
arsenic bronze Arsenical bronze is an alloy in which arsenic, as opposed to or in addition to tin or other constituent metals, is combined with copper to make bronze. The use of arsenic with copper, either as the secondary constituent or with another component ...
, or from naturally or artificially mixed ores of copper and arsenic. The earliest artifacts so far known come from the
Iranian plateau The Iranian plateau or Persian plateau is a geological feature in Western Asia, Central Asia, and South Asia. It comprises part of the Eurasian Plate and is wedged between the Arabian Plate and the Indian Plate; situated between the Zagros ...
, in the 5th millennium BCE, and are smelted from native arsenical copper and copper-arsenides, such as
algodonite Algodonite is a copper arsenide mineral with formula: Cu6As. It is a gray white metallic mineral crystallizing in the hexagonal system. It has a Mohs hardness of 4 and a specific gravity of 8.38 - 8.72. It was first described in 1857 from the Alg ...
and
domeykite Domeykite is a copper arsenide mineral, Cu3As. It crystallizes in the isometric system, although crystals are very rare. It typically forms as irregular masses or botryoidal forms. It is an opaque, white to gray (weathers brassy) metallic minera ...
. The earliest tin-copper-alloy artifact has been dated to c. 4650 BCE, in a
Vinča culture The Vinča culture (), also known as Turdaș culture or Turdaș–Vinča culture, is a Neolithic archaeological culture of Southeast Europe, dated to the period 5700–4500 BC or 5300–4700/4500 BC.. Named for its type site, Vinča-Belo Brdo ...
site in Pločnik (
Serbia Serbia (, ; Serbian language, Serbian: , , ), officially the Republic of Serbia (Serbian language, Serbian: , , ), is a landlocked country in Southeast Europe, Southeastern and Central Europe, situated at the crossroads of the Pannonian Bas ...
), and believed to have been smelted from a natural tin-copper ore, stannite. Other early examples date to the late
4th millennium BCE The 4th millennium BC spanned the years 4000 BC to 3001 BC. Some of the major changes in human culture during this time included the beginning of the Bronze Age and the invention of writing, which played a major role in starting recorded history. ...
in
Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
,
Susa Susa ( ; Middle elx, 𒀸𒋗𒊺𒂗, translit=Šušen; Middle and Neo- elx, 𒋢𒋢𒌦, translit=Šušun; Neo-Elamite and Achaemenid elx, 𒀸𒋗𒐼𒀭, translit=Šušán; Achaemenid elx, 𒀸𒋗𒐼, translit=Šušá; fa, شوش ...
(Iran) and some ancient sites in China, Luristan (Iran),
Tepe Sialk Tepe Sialk ( fa, تپه سیلک) is a large ancient archeological site (a ''tepe'', "hill, tell (archaeology), tell") in a suburb of the city of Kashan, Isfahan Province, in central Iran, close to Fin Garden. The culture that inhabited this area ...
(Iran),
Mundigak Mundigak ( ps, منډیګک) is an archaeological site in Kandahar province in Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at ...
(Afghanistan), and
Mesopotamia Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the F ...
(Iraq). Tin bronze was superior to arsenic bronze in that the alloying process could be more easily controlled, and the resulting alloy was stronger and easier to cast. Also, unlike arsenic, metallic tin and fumes from tin refining are not toxic.
Tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
became the major non-copper ingredient of bronze in the late 3rd millennium BCE.
Ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...
s of copper and the far rarer tin are not often found together (exceptions include
Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...
in the United Kingdom, one ancient site in Thailand and one in Iran), so serious bronze work has always involved trade.
Tin sources and trade in ancient times Tin is an essential metal in the creation of tin- bronzes, and its acquisition was an important part of ancient cultures from the Bronze Age onward. Its use began in the Middle East and the Balkans around 3000 BC. Tin is a relatively rare element ...
had a major influence on the development of cultures. In Europe, a major source of tin was the British deposits of ore in
Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...
, which were traded as far as
Phoenicia Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their histor ...
in the eastern
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...
. In many parts of the world, large hoards of bronze artifacts are found, suggesting that bronze also represented a store of value and an indicator of social status. In Europe, large hoards of bronze tools, typically socketed axes (illustrated above), are found, which mostly show no signs of wear. With
Chinese ritual bronze Sets and individual examples of ritual bronzes survive from when they were made mainly during the Chinese Bronze Age. Ritual bronzes create quite an impression both due to their sophistication of design and manufacturing process, but also bec ...
s, which are documented in the inscriptions they carry and from other sources, the case is clear. These were made in enormous quantities for elite burials, and also used by the living for ritual offerings.


Transition to iron

Though bronze is generally harder than
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag Inclusion (mineral), inclusions (up to 2% by weight), which give it a ...
, with
Vickers hardness The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers test is often easier to use than other hardness t ...
of 60–258 vs. 30–80, the
Bronze Age The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second pri ...
gave way to the
Iron Age The Iron Age is the final epoch of the three-age division of the prehistory and protohistory of humanity. It was preceded by the Stone Age (Paleolithic, Mesolithic, Neolithic) and the Bronze Age (Chalcolithic). The concept has been mostly appl ...
after a serious disruption of the tin trade: the population migrations of around 1200–1100 BCE reduced the shipping of tin around the Mediterranean and from Britain, limiting supplies and raising prices. As the art of working in iron improved, iron became cheaper and improved in quality. As cultures advanced from hand-wrought iron to machine-forged iron (typically made with
trip hammer A trip hammer, also known as a tilt hammer or helve hammer, is a massive powered hammer. Traditional uses of trip hammers include pounding, decorticating and polishing of grain in agriculture. In mining, trip hammers were used for crushing meta ...
s powered by water), blacksmiths learned how to make
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
. Steel is stronger than bronze and holds a sharper edge longer. Bronze was still used during the Iron Age, and has continued in use for many purposes to the modern day.


Composition

There are many different bronze alloys, but typically modern bronze is 88%
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
and 12% tin. ''Alpha bronze'' consists of the alpha
solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word ...
of tin in copper. Alpha bronze alloys of 4–5% tin are used to make coins, springs,
turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...
s and blades. Historical "bronzes" are highly variable in composition, as most metalworkers probably used whatever scrap was on hand; the metal of the 12th-century English
Gloucester Candlestick The Gloucester Candlestick is an elaborately decorated English Romanesque gilt-bronze candlestick, now in the Victoria and Albert Museum in London. It was made for Gloucester Cathedral between 1104 and 1113, and is one of the outstanding surviv ...
is bronze containing a mixture of copper, zinc, tin, lead, nickel, iron, antimony, arsenic and an unusually large amount of silver – between 22.5% in the base and 5.76% in the pan below the candle. The proportions of this mixture suggest that the candlestick was made from a hoard of old coins. The 13th-century
Benin Bronzes The Benin Bronzes are a group of several thousand metal plaques and sculptures that decorated the royal palace of the Kingdom of Benin, in what is now Edo State, Nigeria. Collectively, the objects form the best examples of Benin art and were cre ...
are in fact brass, and the 12th-century Romanesque Baptismal font at St Bartholomew's Church, Liège is described as both bronze and
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...
. In the Bronze Age, two forms of bronze were commonly used: "classic bronze", about 10% tin, was used in casting; and "mild bronze", about 6% tin, was hammered from ingots to make sheets. Bladed weapons were mostly cast from classic bronze, while helmets and armor were hammered from mild bronze. Commercial bronze (90% copper and 10% zinc) and architectural bronze (57% copper, 3%
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
, 40% zinc) are more properly regarded as brass alloys because they contain
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
as the main alloying ingredient. They are commonly used in architectural applications. Plastic bronze contains a significant quantity of lead, which makes for improved plasticity possibly used by the ancient Greeks in their ship construction. has a composition of Si: 2.80–3.80%, Mn: 0.50–1.30%, Fe: 0.80% max., Zn: 1.50% max., Pb: 0.05% max., Cu: balance. Other bronze alloys include
aluminium bronze Aluminium bronze is a type of bronze in which aluminium is the main alloying metal added to copper, in contrast to standard bronze (copper and tin) or brass (copper and zinc). A variety of aluminium bronzes of differing compositions have found in ...
,
phosphor bronze Phosphor bronze is a member of the family of copper alloys. It is composed of copper that is alloyed with 0.5–11% of tin and 0.01–0.35% phosphorus, and may contain other elements to confer specific properties (e.g. lead at 0.5–3.0% to form ...
, manganese bronze,
bell metal Bell metal or bell bronze is an alloy used for making bells and related instruments, such as cymbals. It is a form of bronze with a higher tin content, usually in approximately a 4:1 ratio of copper to tin (typically, 78% copper, 22% tin by mas ...
,
arsenical bronze Arsenical bronze is an alloy in which arsenic, as opposed to or in addition to tin or other constituent metals, is combined with copper to make bronze. The use of arsenic with copper, either as the secondary constituent or with another component s ...
,
speculum metal Speculum metal is a mixture of around two-thirds copper and one-third tin, making a white brittle alloy that can be polished to make a highly reflective surface. It was used historically to make different kinds of mirrors from personal grooming a ...
and
cymbal alloys Cymbals are made from four main alloys, all of them copper-based. These are: bell bronze, malleable bronze, brass, and nickel silver. Bell bronze Bell bronze, also known as '' bell metal'', is the traditional alloy used for fine cymbals, many ...
.


Properties

Bronzes are typically ductile alloys, considerably less
brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Bre ...
than cast iron. Typically bronze oxidizes only superficially; once a copper oxide (eventually becoming copper carbonate) layer is formed, the underlying metal is protected from further corrosion. This can be seen on statues from the Hellenistic period. However, if copper chlorides are formed, a corrosion-mode called "
bronze disease Bronze disease is an irreversible and nearly inexorable corrosion process that occurs when chlorides come into contact with bronze or other copper-bearing alloys. It can occur as both a dark green coating, or as a much lighter whitish fuzzy or ...
" will eventually completely destroy it. Copper-based
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
s have lower
melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
s than steel or iron and are more readily produced from their constituent metals. They are generally about 10 percent denser than steel, although alloys using
aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
or
silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...
may be slightly less dense. Bronze is a better conductor of heat and electricity than most steels. The cost of copper-base alloys is generally higher than that of steels but lower than that of
nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
-base alloys. Copper and its alloys have a huge variety of uses that reflect their versatile physical, mechanical, and
chemical properties A chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity.William L. Masterton, Cecile N. Hurley ...
. Some common examples are the high
electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...
of pure copper, low-friction properties of bearing bronze (bronze that has a high lead content— 6–8%), resonant qualities of bell bronze (20% tin, 80% copper), and resistance to corrosion by
seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
of several bronze alloys. The melting point of bronze varies depending on the ratio of the alloy components and is about . Bronze is usually nonmagnetic, but certain alloys containing iron or nickel may have magnetic properties.


Uses

Bronze, or bronze-like alloys and mixtures, were used for coins over a longer period. Bronze was especially suitable for use in boat and ship fittings prior to the wide employment of
stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...
owing to its combination of toughness and resistance to salt water corrosion. Bronze is still commonly used in ship propellers and submerged bearings. In the 20th century, silicon was introduced as the primary alloying element, creating an alloy with wide application in industry and the major form used in contemporary
statuary A statue is a free-standing sculpture in which the realistic, full-length figures of persons or animals are carved or cast in a durable material such as wood, metal or stone. Typical statues are life-sized or close to life-size; a sculpture t ...
. Sculptors may prefer silicon bronze because of the ready availability of silicon bronze brazing rod, which allows color-matched repair of defects in castings. Aluminum is also used for the structural metal aluminum bronze. Bronze parts are tough and typically used for bearings, clips,
electrical connector Components of an electrical circuit are electrically connected if an electric current can run between them through an electrical conductor. An electrical connector is an electromechanical device used to create an electrical connection between ...
s and springs. Bronze also has low
friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of t ...
against dissimilar metals, making it important for
cannon A cannon is a large- caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder ...
s prior to modern tolerancing, where iron cannonballs would otherwise stick in the barrel. It is still widely used today for springs, bearings, bushings, automobile transmission pilot bearings, and similar fittings, and is particularly common in the bearings of small
electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...
s. Phosphor bronze is particularly suited to precision-grade bearings and springs. It is also used in
guitar The guitar is a fretted musical instrument that typically has six strings. It is usually held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected stri ...
and
piano The piano is a stringed keyboard instrument in which the strings are struck by wooden hammers that are coated with a softer material (modern hammers are covered with dense wool felt; some early pianos used leather). It is played using a keyboa ...
strings. Unlike steel, bronze struck against a hard surface will not generate sparks, so it (along with
beryllium copper Beryllium copper (BeCu), also known as copper beryllium (CuBe), beryllium bronze, and spring copper, is a copper alloy with 0.5–3% beryllium but can contain other elements as well. Beryllium copper combines high strength with non- magnetic an ...
) is used to make
hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as w ...
s,
mallet A mallet is a tool used for imparting force on another object, often made of rubber or sometimes wood, that is smaller than a maul or beetle, and usually has a relatively large head. The term is descriptive of the overall size and proport ...
s,
wrench A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning. In the UK, Ireland, Australia, and New Zealan ...
es and other durable tools to be used in explosive atmospheres or in the presence of flammable vapors. Bronze is used to make
bronze wool Bronze wool is a bundle of very fine bronze filaments , used in finishing and repair work to polish wood or metal objects. Niemeyer, Shirley (1994). "NF94-139 Preservation of Metal Items". Historical Materials from University of Nebraska-Lincoln E ...
for woodworking applications where
steel wool Steel wool, also known as iron wool, wire wool or wire sponge, is a bundle of very fine and flexible sharp-edged steel filaments. It was described as a new product in 1896.''Iron Age'', Vol. LVII, p.871, cited by ''Journal of the Iron and Steel ...
would discolor oak. Phosphor bronze is used for ships' propellers, musical instruments, and electrical contacts. Plain bearing#Bronze, Bearings are often made of bronze for its friction properties. It can be impregnated with oil to make the proprietary Oilite and similar material for bearings. Aluminum bronze is hard and wear-resistant, and is used for bearings and machine tool ways.


Sculptures

Bronze is widely used for casting bronze sculptures. Common bronze alloys have the unusual and desirable property of expanding slightly just before they set, thus filling the finest details of a mould. Then, as the bronze cools, it shrinks a little, making it easier to separate from the mould. The Assyrian king Sennacherib (704–681 BCE) claims to have been the first to cast monumental bronze statues (of up to 30 tonnes) using two-part moulds instead of the Lost-wax casting, lost-wax method. Bronze statues were regarded as the highest form of sculpture in Ancient Greek art, though survivals are few, as bronze was a valuable material in short supply in the Late Antique and medieval periods. Many of the most famous Greek bronze sculptures are known through Roman copies in marble, which were more likely to survive. In India, bronze sculptures from the Kushana (Chausa hoard) and Gupta periods (Brahma from Mirpur-Khas, Akota Hoard, Sultanganj Buddha) and later periods (Hansi Hoard) have been found. Indian Hindu artisans from the period of the Chola dynasty, Chola empire in Tamil Nadu used bronze to create intricate statues via the lost-wax casting method with ornate detailing depicting the deities of Hinduism. The art form survives to this day, with many silpis, craftsmen, working in the areas of Swamimalai and Chennai. In antiquity other cultures also produced works of High culture, high art using bronze. For example: in Africa, the Benin Bronzes, bronze heads of the Benin Empire, Kingdom of Benin; in Europe, Grecian bronzes typically of figures from Greek mythology; in east Asia, Chinese ritual bronzes of the Shang dynasty, Shang and Zhou dynasty—more often ceremonial vessels but including some figurine examples. Bronze continues into modern times as one of the materials of choice for monumental statuary. File:Dancing girl of Mohenjo-daro.jpg, The ''Dancing Girl (sculpture), Dancing Girl'', an Indus Valley civilisation, Harappan artwork; 2400–1900 BCE; bronze; height: 10.8 cm; National Museum, New Delhi, National Museum (New Delhi, India) File:商青銅鼎-Ritual Tripod Cauldron (Ding) MET DP164965.jpg, Chinese ritual bronzes, Ritual tripod cauldron (Ding (vessel), ding); circa 13th century BCE; bronze: height with handles: 25.4 cm; Metropolitan Museum of Art (New York City) Kushite Pharaoh MET DT8840.jpg, Ancient Egyptian art, Ancient Egyptian statuette of a Kingdom of Kush, Kushite pharaoh; 713–664 BCE; bronze, precious-metal leaf; height: 7.6 cm, width: 3.2 cm, depth: 3.6 cm; Metropolitan Museum of Art File:Bronze tripod base for a thymiaterion (incense burner) MET DP21045.jpg, Etruscan civilization, Etruscan tripod base for a thymiaterion (incense burner); 475-450 BCE; bronze; height: 11 cm; Metropolitan Museum of Art File:God of Cape Artemision 01.JPG, The ''Artemision Bronze''; 460-450 BCE; bronze; height: 2.1 m; National Archaeological Museum, Athens, National Archaeological Museum (Athens) File:Egypt, Greco-Roman Period, probably Ptolemaic Dynasty - Statuette of Isis and Horus - 1940.613 - Cleveland Museum of Art.tif, Ancient Egyptian statuette of Isis and Horus; 305–30 BCE; solid cast of bronze; 4.8 × 10.3 cm; Cleveland Museum of Art (Cleveland, Ohio, US) Bronze statue of Eros sleeping MET DP123903.jpg, Ancient Greek art, Ancient Greek statue of Eros sleeping; 3rd–2nd century BCE; bronze; 41.9 × 35.6 × 85.2 cm; Metropolitan Museum of Art Buddha Offering Protection MET DP-15581-036.jpg, Gupta Empire, Gupta sculpture of Buddha offering protection; late 6th–early 7th century; copper alloy; height: 47 cm, width: 15.6 cm, diameter: 14.3 cm; from India (probably Bihar); Metropolitan Museum of Art File:Caldron MET cdi49-69-6s3.jpg, French or South Netherlandish Medieval caldron; 13th or 14th century; bronze and wrought iron; height: 37.5 cm, diameter: 34.3 cm; Metropolitan Museum of Art File:Pair of firedogs (chenets) MET DP170900.jpg, Pair of French Rococo firedogs (chenets); circa 1750; gilt bronze; dimensions of the first: 52.7 x 48.3 x 26.7 cm, of the second: 45.1 x 49.1 x 24.8 cm; Metropolitan Museum of Art File:Mantel clock (pendule de chiminée) MET DT6546.jpg, French Neoclassicism, Neoclassical mantel clock (pendule de cheminée); 1757–1760; gilded and patinated bronze, oak veneered with ebony, white enamel with black numerals, and other materials; 48.3 × 69.9 × 27.9 cm; Metropolitan Museum of Art File:Pair of firedogs MET DT8904.jpg, Pair of French Chinoiserie firedogs; 1760–1770; gilt bronze; height (each): 41.9 cm; Metropolitan Museum of Art File:Pair of vases MET DP170824.jpg, Pair of Chinese vases with French Rococo mounts; the vases: early 18th century, the mounts: 1760–70; hard-paste porcelain with gilt-bronze mounts; 32.4 x 16.5 x 12.4 cm; Metropolitan Museum of Art File:Mantel clock ("Pendule Uranie") MET DP346441.jpg, French Neoclassical mantel clock ("Pendule Uranie"); 1764–1770; case: patinated bronze and gilded bronze, Dial: white enamel, movement: brass and steel; 71.1 × 52.1 × 26.7 cm; Metropolitan Museum of Art File:Pair of mounted vases (vase à monter) MET DP102639.jpg, Pair of mounted vases (vase à monter); 1765–70; soft-paste porcelain and French gilt bronze; 28.9 x 17.1 cm; Metropolitan Museum of Art File:Winter MET DP162240.jpg, ''Winter''; by Jean-Antoine Houdon; 1787; bronze; 143.5 x 39.1 x 50.5 cm, height of the pedestal: 86.4 cm; Metropolitan Museum of Art


Mirrors

Before it became possible to produce glass with acceptably flat surfaces, bronze was a standard material for mirrors. Bronze was used for this purpose in many parts of the world, probably based on independent discoveries. Bronze mirrors survive from the Egyptian Middle Kingdom of Egypt, Middle Kingdom (2040–1750 BCE), and China from at least c. 550 BCE. In Europe, the Etruscans were making bronze mirrors in the sixth century BCE, and Ancient Greece, Greek and Ancient Rome, Roman mirrors followed the same pattern. Although other materials such as
speculum metal Speculum metal is a mixture of around two-thirds copper and one-third tin, making a white brittle alloy that can be polished to make a highly reflective surface. It was used historically to make different kinds of mirrors from personal grooming a ...
had come into use, and Western glass mirrors had largely taken over, bronze mirrors were still being made in Japan and elsewhere in the eighteenth century, and are still made on a small scale in Kerala, India.


Musical instruments

Bronze is the preferred metal for bell (instrument), bells in the form of a high tin bronze alloy known as
bell metal Bell metal or bell bronze is an alloy used for making bells and related instruments, such as cymbals. It is a form of bronze with a higher tin content, usually in approximately a 4:1 ratio of copper to tin (typically, 78% copper, 22% tin by mas ...
, which is typically about 23% tin. Nearly all professional cymbals are made from bronze, which gives a desirable balance of durability and timbre. Several types of bronze are used, commonly B20 (bronze), B20 bronze, which is roughly 20% tin, 80% copper, with traces of silver, or the tougher B8 bronze made from 8% tin and 92% copper. As the tin content in a bell or cymbal rises, the timbre drops. Bronze is also used for the windings of steel and nylon strings of various String instrument, stringed instruments such as the double bass, piano, harpsichord, and guitar. Bronze strings are commonly reserved on pianoforte for the lower pitch tones, as they possess a superior sustain quality to that of high-tensile steel. Bronzes of various metallurgical properties are widely used in struck idiophones around the world, notably bells, singing bowls, gongs, cymbals, and other idiophones from Asia. Examples include Tibetan singing bowls, temple bells of many sizes and shapes, Javanese people, Javanese gamelan, and other bronze musical instruments. The earliest bronze archeological finds in Indonesia date from 1–2 BCE, including flat plates probably suspended and struck by a wooden or bone mallet. Ancient bronze drums from Thailand and Vietnam date back 2,000 years. Bronze bells from Thailand and Cambodia date back to 3,600 BCE. Some companies are now making saxophones from phosphor bronze (3.5 to 10% tin and up to 1% phosphorus content). Bell bronze/B20 is used to make the tone rings of many professional model banjos. The tone ring is a heavy (usually ) folded or arched metal ring attached to a thick wood rim, over which a skin, or most often, a plastic membrane (or head) is stretched – it is the bell bronze that gives the banjo a crisp powerful lower register and clear bell-like treble register.


Biblical references

There are over 125 references to bronze (‘nehoshet’), which appears to be the Hebrew word used for copper and any of its alloys. However, the Old Testament era Hebrews are not thought to have had the capability to manufacture zinc (needed to make brass) and so it is likely that 'nehoshet’ refers to copper and its alloys with tin, now called bronze. In the King James Version, there is no use of the word 'bronze' and ‘nehoshet’ was translated as 'brass'. Modern translations use 'bronze'. Bronze (nehoshet) was used widely in the Tabernacle for items such as the bronze altar (Exodus Ch.27), bronze laver (Exodus Ch.30), utensils, and mirror (Exodus Ch.38). It was mentioned in the account of Moses holding up a bronze snake on a pole in Numbers Ch.21. In First Kings, it is mentioned that Hiram Abiff, Hiram was very skilled in working with bronze, and he made many furnishings for Solomon's Temple including pillars, capitals, stands, wheels, bowls, and plates, some of which were highly decorative (see I King 7:13-47). Bronze was also widely used as battle armor and helmet, as in the battle of David and Goliath in I Samuel 17:5-6;38 (also see II Chron. 12:10).


Coins and medals

Bronze has also been used in coins; most "copper" coins are actually bronze, with about 4 percent tin and 1 percent zinc. As with coins, bronze has been used in the manufacture of various types of medals for centuries, and "bronze medals" are known in contemporary times for being awarded for third place in sporting competitions and other events. The term is now often used for third place even when no actual bronze medal is awarded. The usage in part arose from the trio of gold, silver and bronze to represent the first three Ages of Man in Greek mythology: the Golden Age, when men lived among the gods; the Silver age, where youth lasted a hundred years; and the Greek Heroic Age, Bronze Age, the era of heroes. It was first adopted for a sports event at the 1904 Summer Olympics. At the 1896 event, silver was awarded to winners and bronze to runners-up, while at 1900 other prizes were given rather than medals. Bronze is the normal material for the related form of the plaquette, normally a rectangular work of art with a scene in relief, for a collectors' market.


See also


References


External links

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Bronze bells


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Viking Bronze – Ancient and Early Medieval bronze casting
{{Authority control Bronze, Copper alloys Tin alloys