Bronze

It is used for screws and wires. The initials BSA could stand for:. It is somewhat stronger than copper and it has equivalent ductility. UK Boarding Schools Association. Commercial bronze is 90% copper and 10% tin. Business Software Alliance. Alpha bronze alloys of 4-5% tin are used to make coins, springs, turbines and blades. Bulgarian Studies Association.

Alpha bronze consists of the alpha solid solution of tin in copper. Building Societies Association. Bronze is typically 60% copper and 40% tin. Brookhaven Science Associates. Phosphor bronze is particularly suited to precision-grade bearings and springs. Broadcasting Standards Authority. Bronze is still widely used today for springs, bearings, bushings and similar roles, and is particularly common in the bearings on small electric motors. British Surfing Association.

Bronze also has very little metal-on-metal friction, which made it invaluable for the building of cannon where iron cannonballs would otherwise stick in the barrel. British Stammering Association. Common bronze alloys often have the unusual and very desirable property of expanding slightly just before they set, thus filling in the finest details of a mould. British Sociological Association. Bronze is the most popular metal for top-quality bells and cymbals, and also for cast metal sculpture (see bronze sculpture). British Society of Audiology. Aluminium is also used for the structural metal Aluminium bronze. British Social Attitudes.

In the twentieth 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. British Snowboarding Association. Some common examples are the high electrical conductivity of pure copper, the excellent deep-drawing qualities of cartridge case brass, the low-friction properties of bearing bronze, the resonant qualities of bell bronze, and the resistance to corrosion by sea water by several bronze alloys. British School at Athens. Copper and its alloys have a huge variety of uses that reflect their versatile physical, mechanical, and chemical properties. Boy Scouts of America. The cost of copper-base alloys is generally higher than that of steels but lower than that of nickel-base alloys. Bovine serum albumin.

Bronzes also conduct heat and electricity better than most steels. Botanical Society of America. Bronzes resist corrosion (especially seawater corrosion) and metal fatigue better than steel. Boston Society of Architects. Bronzes are softer and weaker than steel, and more elastic, though bronze springs are less stiff (and so storing less energy) for the same bulk. Body surface area. They are generally about 10 percent heavier than steel, although alloys using aluminium or silicon may be slightly less dense. Blackwell Science Asia.

Copper-based alloys have lower melting points than steel and are more readily produced from their constituent metals. Birmingham Small Arms Company. Steel, of course, has wondrous properties that bronze cannot compete with. Basic Skills Agency. It is considerably less brittle than iron and has a lower casting temperature. Bank Secrecy Act. While it develops a patina, it does not otherwise oxidize into nothingness.

Excluding steel from the discussion, bronze is superior to iron in nearly every application. As ironworking improved, iron became both cheaper and stronger, eclipsing bronze in Europe by the early to mid-Middle Ages. Bronze was still used during the Iron Age, but for many purposes the weaker iron was sufficiently strong. But the Bronze Age gave way to the Iron Age, perhaps because the shipping of tin around the Mediterranean (or maybe from Britain) became more limited during the major population migrations around 1200 – 1100 BC, which dramatically limited supplies and raised prices [1].

Bronze was stronger than the era's iron; quality steels were not available until thousands of years later. The earliest tin-alloy bronzes date to the late 4th millennium BC in Susa (Iran) and some ancient sites in Luristan (Iran) and Mesopotamia (Iraq). For Europe, the major site for tin was Britain. The archaeologists suspect a serious disruption of the tin-trade led to the development of the Iron Age.

Serious bronze has always involved trade. While copper and tin can natually co-occur, the two ores are rarely found together (an ancient site in Thailand does prove they can co-occur). In early use, the natural impurity arsenic created a superior natural alloy; this is termed arsenical bronze, which Ötzi's axe is made of. First used in the Bronze Age, it made tools, weapons and armor harder or more durable than their stone and copper ("Chalcolithic") predecessors.

. (See table below). Bronze is the usual English term for a broad range of copper alloys, usually with tin as the main additive, but other elements may be the main additive (e.g., phosphor, manganese, aluminum, silicon).