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1、Solid materials have been conveniently grouped into three basic classifications: metals, ceramics, and polymers. This scheme is based primarily on chemical makeup and atomic structure, and most materials fall into one distinct grouping or another, although there are some intermediates. In addition,
2、there are three other groups of important engineering materialscomposites, semiconductors, and biomaterials. 译文：固体材料被便利的分为三个基本的类型：金属，陶瓷和聚合物。这个分类是首先基 于化学组成和原子结构来分的，大多数材料落在明显的一个类别里面，尽管有许多中间品。 除此之外， 有三类其他重要的工程材料复合材料，半导体材料和生物材料。 Composites consist of combinations of two or more different materials, wher
3、eas semiconductors are utilized because of their unusual electrical characteristics; biomaterials are implanted into the human body. A brief explanation of the material types and representative characteristics is offered next. 译文：复合材料由两种或者两种以上不同的材料组成，然而半导体由于它们非同寻常的电 学性质而得到使用；生物材料被移植进入人类的身体中。关于材料类型和他
4、们特殊的特征 的一个简单的解释将在后面给出。 METALS Metallic materials are normally combinations of metallic elements. They have large numbers of nonlocalized electrons; that is, these electrons are not bound to particular atoms. Many properties of metals are directly able to these electrons. be bound to 被约束于。 。 be attri
5、bute to 归属于。 。归因于。 。 译文：金属材料通常由金属元素组成。它们有大量无规则运动的电子。也就是说，这些电 子不是被约束于某个特定的原子。金属的许多性质直接归属这些不规则运动的电子。 Metals are extremely good conductors of electricity and heat and are not transparent to visible light; a polished metal surface has a lustrous appearance. Furthermore, metals are quite strong, yet defo
6、rmable, which accounts for their extensive use in structural applications. 科技英语在讲述科学真理的时候通常用主动语态。如： Metals are extremely good conductors of electricity Deformable ？ 译文：金属是十分好的电和热的导体，它们对可见光不透明；一个抛光的金属表面有光辉 的外表。除此之外，金属是十分硬的，也是可变形的，这个性质解释了它们广泛使用在结 构方面的应用。 CERAMICS Ceramics are compounds between metalli
7、c and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. The wide range of materials that falls within this classification includes ceramics that are composed of clay minerals, cement, and glass. that 引导的定语从句 译文：陶瓷是介于金属和非金属元素之间的化合物；它们通常是氧化物，氮化物和碳化物。 落在这个分类种类中的宽的材料范围包括陶瓷，它
8、们由粘土矿物，水泥和玻璃组成。 These materials are typically insulative to the passage of electricity and heat, and are more resistant to high temperatures and harsh environments than metals and polymers. With regard to mechanical behavior, ceramics are hard but very brittle.more. Than. with regard to.译文：这些材料是典型的电
9、和热的绝缘体，并且它们比金属和聚合物更加耐高温和耐苛刻 的环境。至于机械性能，陶瓷是硬的但是却很脆。 POLYMERS Polymers include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements; furthermore, they have very large molecular structures. These mate
10、rials typically have low densities and may be extremely flexible. 译文：聚合物包括常见的塑料和橡胶材料。它们中的大多数是有机化合物，这些化合物是 以化学的方法把碳、氢和其他非金属元素组合而成。因此，它们有非常大的分子结构。这 些材料通常有低的密度并且可能十分柔软。 COMPOSITES A number of composite materials have been engineered that consist of more than one material type. Fiberglass is a familiar
11、example, in which glass fibers are embedded within a polymeric material. more than 译文：许多复合材料被作用工程使用，它们由至少一种类型的材料组成。玻璃丝是一个熟 悉的例子，玻璃纤维被埋入聚合物材料中。 A composite is designed to display a combination of the best characteristics of each of the component materials. Fiberglass acquires strength from the glass
12、and flexibility from the polymer. Many of the recent material developments have involved composite materials. 译文：为了联合显示每一种组分材料最好的特性，一种复合材料被设计出来。玻璃丝从玻 璃中获得强度并且从聚合物中获得柔软性。最近发展中的绝大多数材料包含了复合材料。 SEMICONDUCTORS Semiconductors have electrical properties that are intermediate between the electrical conducto
13、rs and insulators. Furthermore, the electrical characteristics of these materials are extremely sensitive to the presence of minute concentrations of impurity atoms, which concentrations may be controlled over very small spatial regions.be sensitive to 对敏感的 译文：半导体有电的性质，它们是介于电导体和绝缘体之间的中间物。除此之外，这些材 料的
14、电学性质对微量杂质原子的存在十分敏感，杂质原子浓度可能只是在一个十分小的区 域内可以控制。 The semiconductors have made possible the advent of integrated circuitry that has totally revolutionized the electronics and computer industries (not to mention our lives) over the past two decades. 译文：这些半导体使得集成电路的出现变得可能，在过去 20 多年间，这些集成电路革新了 电子装置和计算机工业（更
15、不用说我们的生活） 。 BIOMATERIALS Biomaterials are employed in components implanted into the human body for replacement of diseased or damaged body parts. These materials must not produce toxic substances and must be compatible with body tissues (i.e., must not cause adverse biological reactions). 译文：生物材料被应用
16、于移植进入人类身体以取代病变的或者损坏的身体部件。这些材料 不能产生有毒物质而且必须同人身体器官要相容（比如，不能导致相反的生物反应） 。All of the above materialsmetals, ceramics, polymers, composites, and semiconductorsmay be used as biomaterials. For example, some of the biomaterials such as CF/C (carbon fibers/carbon) and CF/PS (polysulfone) are utilized in artificial hip replacements. 译文：所有以上材料金属，陶瓷，聚合物，复合材料和半导体材料可能用作生物材料。 比如，如 CF/C 和 CF/PS（聚砜）这些生物材料被用作人工肾的取代物。 ADVANCED MATERIALS Materials that are utilized in h
