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1、材料科学与工程-专业英语-Unit-Classification-of-Materials译文 作者： 日期：11 Classification of Materials（材料分类）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
2、into one distinct grouping or another, although there are some intermediates. In addition, 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
3、，半导体材料和生物材料。Composites consist of combinations of two or more different materials, whereas 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
4、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。关于材料类型和他们特殊的特征的一个简单的解释将在后面给出。Metallic materials are normally combinations of metallic elements. They have large numbers of nonlocalized electrons; that is, these electrons are not bound to particularatoms. Many properties o
5、f metals are directly able to these electrons.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
6、 quite strong, yet deformable, which accounts for their extensive use in structural applications.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 are compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbi
7、des. The wide range of materials that falls within this classification includes ceramics that are composed of clay minerals, cement, and glass.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,
8、 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.译文：这些材料是典型的电和热的绝缘体，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 include the familiar plastic and rubber materials. Many of them a
9、re organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements; furthermore, they have very large molecular structures. These materials 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
10、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。A number of composite materials have been engineered that consist of more than one material type. Fiberglass is a familiar example, in which glass fibers are embedded within a polymeric material.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 desi
11、gned to display a combination of the best characteristics of each of the component materials. Fiberglass acquires strength from the glass 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
12、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 have electrical properties that are intermediate between the electrical conductors and insulators. Furthermore, the electrical characteristics of these materials are extremely sensitive to the presence of minute concentrations of impurity atoms, which concent
13、rations may be controlled over very small spatial regions.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。Biomaterials are employed in components implanted into the human body for replacement of diseased or damaged body parts. These materials must not produce tox
14、ic 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）。Materials that are utilized in high-technology (or high-tech) applications are sometimes termed advanced materials.
15、By high technology we mean a device or product that operates or functions using relatively intricate and sophisticated principles; examples include electronic equipment , computers, fiberoptic systems, spacecraft, aircraft, and military rocketry.译文：用在高科技中的材料有时被称作先进材料。借助于高科技，我们预定一个装置或者产品，这些产品用相对复杂和熟练的原理运转或者起作用；这些例子包括电子设备，计算机，光纤系统，宇宙飞船，航天飞机和军事火箭。In spite of the tremendous progress that has been made in the discipline of materials science and engineering within
