Bronze

Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals (such as phosphorus) or metalloids (such as arsenic or silicon).

This is done (at least in part) to prevent database searches from failing merely because of errors or disagreements in the naming of historic copper alloys.

Bronze tools, weapons, armor, and building materials such as decorative tiles were harder and more durable than their stone and copper ("Chalcolithic") predecessors.

[6] The earliest known arsenic-copper-alloy artifacts come from a Yahya Culture (Period V 3800-3400 BCE) site, at Tal-i-Iblis on the Iranian plateau, and were smelted from native arsenical copper and copper-arsenides, such as algodonite and domeykite.

[7][8] The earliest tin-copper-alloy artifact has been dated to c. 4650 BCE, in a Vinča culture site in Pločnik (Serbia), and believed to have been smelted from a natural tin-copper ore, stannite.

[11] Ores of copper and the far rarer tin are not often found together (exceptions include Cornwall in the United Kingdom, one ancient site in Thailand and one in Iran), so serious bronze work has always involved trade with other regions.

In Europe, a major source of tin was the British deposits of ore in Cornwall, which were traded as far as Phoenicia in the eastern Mediterranean.

In Europe, large hoards of bronze tools, typically socketed axes (illustrated above), are found, which mostly show no signs of wear.

Though bronze, whose Vickers hardness is 60–258, is generally harder than wrought iron, with a hardness of 30–80,[12] the Bronze Age gave way to the Iron Age after a serious disruption of the tin trade: the population migrations of around 1200–1100 BCE reduced the shipment of tin around the Mediterranean and from Britain, limiting supplies and raising prices.

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 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.

Copper-based alloys have lower melting points than steel or iron and are more readily produced from their constituent metals.

Bronze was especially suitable for use in boat and ship fittings prior to the wide employment of stainless steel owing to its combination of toughness and resistance to salt water corrosion.

Bronze also has low friction against dissimilar metals, making it important for cannons prior to modern tolerancing, where iron cannonballs would otherwise stick in the barrel.

Unlike steel, bronze struck against a hard surface will not generate sparks, so it (along with beryllium copper) is used to make hammers, mallets, wrenches and other durable tools to be used in explosive atmospheres or in the presence of flammable vapors.

[24] The Doehler Die Casting Co. of Toledo, Ohio were known for the production of Brastil, a high tensile corrosion resistant bronze alloy.

[25][26] The Seagram Building on New York City's Park Avenue is the "iconic glass box sheathed in bronze, designed by Mies van der Rohe.

[27] Mies van der Rohe achieved the crisp edges that were custom-made with specific detailing by General Bronze[28] and "even the screws that hold in the fixed glass-plate windows were made of brass.

Common bronze alloys have the unusual and desirable property of expanding slightly just before they set, thus filling the finest details of a mould.

[30] 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 method.

[32] Indian Hindu artisans from the period of the 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 material used for the fountain, known as statuary bronze, is a quaternary alloy made of copper, zinc, tin, and lead, and traditionally golden brown in color.

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.

Examples include Tibetan singing bowls, temple bells of many sizes and shapes, 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.

[43] The tone ring is a heavy (usually 3 lb; 1.4 kg) 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.

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.