All products that come out of industry consist of at least one and often many types of materials.

工业生产的一切产品至少都是用一种,经常是许多种材料制成的。

属类：产品说明书-机械产品说明-

The most obvious example is the automobile. A car contains a wide variety of materials, ranging from glass to steel to rubber, plus numerous other metals and plastics.

最明显的例子便是汽车。生产一辆汽车需用大量不同的材料,包括玻璃、钢材、橡胶,以及许多其他的金属和塑料。

属类：产品说明书-机械产品说明-

The number of materials, which are available to the engineer in industry, is almost infinite.

工程师能够用于工业的材料种类几乎是无限的。

属类：产品说明书-机械产品说明-

The various compositions of steel alone run into the thousands.

光钢材一类,其不同方式的合成种类就有成千上万。

属类：产品说明书-机械产品说明-

It has been said that there are more than 10,000 varieties of glass, and the numbers of plastics are equally great.

据说玻璃有一万多种,塑料的种类与玻璃的种类相当。

属类：产品说明书-机械产品说明-

In addition, several hundred new varieties of materials appear on the market each month.

另外,每月都有几百种新型材料上市。

属类：产品说明书-机械产品说明-

The property of a material originates from the internal structure of that material. This is analogous to saying that the operation of a TV set depends on the components and circuits within that set.

一种材料的性能来自其内部结构。这好比说,一台电视机的运行依赖于电视机内部的零件和电路。

属类：产品说明书-机械产品说明-

The internal structures of materials involve atoms, and the way atoms are associated with their neighbors into crystals, molecules, and microstructures.

材料的内部结构涉及到由原子和原子之间的相互关联而形成的晶体、分子和微结构。

属类：产品说明书-机械产品说明-

It is convenient to divide materials into three main types: metals, plastics or polymers and ceramics.

为方便起见,材料分为三大类:金属,塑料或聚合物和陶瓷。

属类：产品说明书-机械产品说明-

Characteristically, metals are opaque, ductile, and good conductors of heat and electricity.

从特点来看,金属不透明,有韧性,是热和电的良导体。

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Plastics (or polymers), which usually contain light elements, and therefore have relatively low density, are generally insulators, and are flexible and formable at relatively low temperatures.

塑料(聚合物)通常包含轻元素,因而密度较低,一般为绝缘体,并能在较低温度下弯折和成形。

属类：产品说明书-机械产品说明-

Ceramics, which contain compounds of both metallic and nonmetallic elements, are usually relatively resistant to severe mechanical, thermal, and chemical conditions.

陶瓷是由金属和非金属元素的化合物构成,通常能抗恶劣的机械、温度和化学环境。

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Metals are divided into ferrous and non-ferrous metals. The former contain iron and the latter do not contain iron.

金属分为黑色金属和有色金属。前者含铁,后者不含铁。

属类：产品说明书-机械产品说明-

Certain elements can improve the properties of steer and are therefore added to it. For example, chromium may be included to resist corrosion and tungsten to increase hardness.

某些元素加进钢里能够改善钢的性能。例如:加铬后能耐腐蚀;加钨后可增加硬度。

属类：产品说明书-机械产品说明-

Aluminum, copper, and the alloys, bronze and brass, are common non-ferrous metals.

铝、铜、合金、黄铜等是常用的有色金属。

属类：产品说明书-机械产品说明-

Plastics and ceramics are non-metals; however, plastics may be machined like metals.

塑料和陶瓷是非金属。然而,塑料可象金属一样进行加工。

属类：产品说明书-机械产品说明-

Plastics are classified into two types-thermoplastics and thermosets.

塑料分成两类:热塑塑料和热固塑料。

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Thermoplastics can be shaped and reshaped by heat and pressure but thermosets cannot be reshaped because they undergo chemical changes as they harden.

热塑塑料可通过加热和加压成形和再成形,而热固塑料却由于在硬化过程中发生了化学变化而不能再成形。

属类：产品说明书-机械产品说明-

Ceramics are often employed by engineers when materials which can withstand high temperatures are needed.

工程师在需用耐高温材料时常常选用陶瓷。

属类：产品说明书-机械产品说明-

In selecting a material, the primary concern of engineers is to match the material properties to the service requirements of the component.

在选用某种材料时,工程师主要关心的是该材料的性能要满足构件的工作要求。

属类：产品说明书-机械产品说明-