空中英语教室:20110223 MP3在线课程 ALUMINUM DOES IT ALL

时间 : 2013-12-20 09:36来源 : VOA官网 收听下载次数 :
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ALUMINUM DOES IT ALL

You'll be amazed at what this silvery metal can do!

Ask your friends to name some things made with aluminum. Chances are they'll mention common items like cooking foil or soda cans. But do they know that aluminum was once so rare it was considered a precious m etal?

Before the late 19th century, aluminum was rarely found in its pure form. But in 1886, American Charles Martin Hall and Frenchman Paul-Louis-Toussaint Heroult both made a discovery. They found an inexpensive way to separate aluminum from other minerals using electricity. Thanks to Hall and Heroult, aluminum became easier to process. It has since become the second most-used metal in the world after iron.

Prized for its many uses, aluminum can be combined with other metals to create alloys with unique features. Depending on which metal is added, aluminum can be made stronger or more flexible.

By far, aluminum's most attractive feature is its light weight. Pure aluminum is roughly one-third the weight of steel. That means aluminum can be used to make items that are light and durable. Uses range from car parts to power cables.

Aluminum may be less expensive than it once was, but it remains as valuable as ever!

万用金属:铝

这种银色金属的功能令人惊奇!

请朋友说几样铝制品, 他们很可能都会提到如铝箔纸或汽水罐等常见物品。 但他们可知道,铝一度也曾是非常稀有的贵金属!

十九世纪末以前,很少发现纯铝, 但在一八八六年,美国人查尔斯·马丁·霍尔与法国人保罗-路易-土桑·埃鲁都有了新发现。两人找到低价的方法,利用电把铝从其他矿物中析出。拜霍尔跟埃鲁之赐,铝变得更容易制造, 从此成为继铁之后世上第二个最广泛使用的金属。

铝因用途广而备受重视,并可与其他金属结合成具有独特性质的合金。视所融合的金属而定,铝可以变得更强韧或更具弹性。

至今,铝最吸引人的特色就是重量轻盈。与钢相较,纯铝的重量约只有钢的三分之一, 因此铝可用来制作轻巧耐用的物品, 从汽车零件到电缆线皆可。

铝或许要比从前便宜许多,但珍贵却一如以往!

 

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