机械专业英语.doc

U1 Types of Materials 材料的类型 Materials may be grouped in several ways. Scientists often classify materials by their state: solid, liquid, or gas. They also separate them anic (once living) and anic (never living) materials. 材料可以按多种方法分类。科学家常根据状态将材料分为:固体、液体或气体。他们也把材料分为有机材料( 曾经有生命的) 和无机材料( 从未有生命的)。 For industrial purposes, materials are divided into engineering materials or nonengineering materials. Engineering materials are those used in manufacture and e parts of products. 就工业效用而言,材料被分为工程材料和非工程材料。那些用于加工制造并成为产品组成部分的就是工程材料。 Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not e part of the product. 非工程材料则是化学品、燃料、润滑剂以及其它用于加工制造过程但不成为产品组成部分的材料。 Engineering materials may be further subdivided into: ① Metal ② Ceramics ③ Composite ④ Polymers, etc. 工程材料还能进一步细分为: ①金属材料②陶瓷材料③复合材料④聚合材料,等等。? Metals and Metal Alloys 金属和金属合金 Metals are elements that generally have good electrical and thermal conductivity. Many metals have high strength, high stiffness, and have good ductility. 金属就是通常具有良好导电性和导热性的元素。许多金属具有高强度、高硬度以及良好的延展性。 Some metals, such as iron, cobalt and nickel, are ic. At low temperatures, some metals and pounds e superconductors. 某些金属能被磁化, 例如铁、钴和镍。在极低的温度下, 某些金属和金属化合物能转变成超导体。 What is the difference between an alloy and a pure metal? Pure metals are elements e from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans. 合金与纯金属的区别是什么?纯金属是在元素周期表中占据特定位置的元素。例如电线中的铜和制造烹饪箔及饮料罐的铝。 Alloys contain more than one metallic element. Their properties can be changed by changing the elements present in the alloy. Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium; and gold jewelry which usually contains an alloy of gold and nickel. 合金包含不止一种金属元素。合金的性质能通过改变其中存在的元素而改变。金属合金的例子有:不锈钢是一种铁、镍、铬的合金,以及金饰品通常含有金镍合金。 Why are metals and alloys used? Many metals and alloys have high densities and ar