什麼是青銅

通常爲銅和錫的合金。早在西元前3000年（參閱Bronze Age）就已製造出青銅，現仍廣泛使用。約自西元前1000年起，在工具和武器中以鐵代替青銅，這是因爲鐵較銅和錫豐富。青銅的熔點較低，較易鑄造。青銅也較純鐵堅硬，也遠比它耐腐蝕。鍾銅的特性在於受敲擊時能發出宏亮的聲音，它是一種含錫量較高（20～25%）的青銅。雕塑青銅的含錫量不到10%，還加有鋅和鉛的混合物，從工藝上看是一種黃銅。磷青銅鑄錠的含磷量少於1%，鑄件只含微量，特別適用於作泵的柱塞、閥和套。在機械工業中也使用錳青銅，它含有少量錫或甚至不含錫，但含有大量鋅和可達4.5%的錳。鋁青銅含有高達16%的鋁和少量其他金屬如鐵或鎳，特別堅硬和耐腐蝕；可鑄造或鍛造成管件、泵、齒輪、船用螺旋槳和渦輪葉片。很多「銅幣」實際上是用青銅鑄造的，其典型成分是約4%的錫和1%的鋅。

bronze

Alloy traditionally composed of copper and tin. Bronze was first made before 3000 BC (see Bronze Age) and is still widely used, though iron often replaced bronze in tools and weapons after about 1000 BC because of iron's abundance compared to copper and tin. Bronze is harder than copper, more readily melted, and easier to cast. It is also harder than iron and far more resistant to corrosion. Bell metal (which produces pleasing sounds when struck) is bronze with 20-25% tin content. Statuary bronze, with less than 10% tin and an admixture of zinc and lead, is technically a brass. The addition of less than 1% phosphorus improves the hardness and strength of bronze; that formulation is used for pump plungers, valves, and bushings. Also useful in mechanical engineering are manganese bronzes, with little or no tin but considerable amounts of zinc and up to 4.5% manganese. Aluminum bronzes, containing up to 16% aluminum and small amounts of other metals such as iron or nickel, are especially strong and corrosion-resistant; they are cast or wrought into pipe fittings, pumps, gears, ship propellers, and turbine blades. Most “copper” coins are actually bronze, typically with about 4% tin and 1% zinc.