Bronze Alloys

Bronze is a metal alloy primarily consisting of copper and tin as main additive. Bronze alloy is hard and brittle, in ancient days they are very significant, that the Bronze Age was named after the metal. Initially copper and arsenic was used with bronze to form arsenic bronze, but later tin was used. As comparative, tin bronze was good than arsenic bronze in that alloying process, it could more easily controlled, because as tin was available as metal and the alloy was stronger and easier to cast and tin is not toxic.

Composition

There are different bronze alloys but modern bronze is 88% copper and 12% tin. For making coins, springs, turbines and blades; alpha bronze alloys of 4-5% tin are used. The 12^th century metal is, bronze containing a mixture of copper, Zinc, lead, nickel, iron, antimony, arsenic, large amount of silver between 22.5% in the base and 5.76% below the candle in the pan.  Commercial bronze consist of 90% copper and 10% zinc and Architectural bronze consist of 57% copper, 3% lead and 40% Zinc, they are regarded as brass alloys; because they contain zinc is the main alloying element. Bismuth bronze is the bronze alloy consist of 52% copper, 30% nickel, 12% zinc, 5% lead, 1% bismuth, these are make use in mirrors because they use to hold good polish and sometimes used as reflectors. Aluminium bronze, phosphor bronze, manganese bronze, bell metal, arsenical bronze are included in other bronze alloys.

Properties

When compared with iron bronze is considerably less brittle. Steel and alloy have higher melting point than copper based alloy, and copper based alloy are readily produced from constituent metals, and they are 10% heavier than steel. Bronze is softer and weaker than steel, for e.g. bronze springs , which is less stiff and store less energy for the same bulk. It is corrosion prevention, especially seawater corrosion and metal fatigue more than steel and also better conductor of heat and electricity. The melting point of bronze is about 950⁰c and varies depending on the actual ratio of alloy components.

Uses

Bronze was well suited for use in boat and ship fittings, and it is still widely used in ship propellers and submerged bearing due to its resistant to corrosion. Aluminium is also used for the structural metal aluminium bronze. Bronze parts are very tough and are used for bearings, clips, electrical connectors and springs. It is mostly used in the cast bronze sculpture.

Questions:

• Explain bronze alloy?
• In modern bronze _% of copper and _ % tin is present?