專業(yè)外語英語加漢語Unit2classification_of_material

1、.Unit2 Classification of Materials材料的分類 Basic Classifications and Engineering Materials基本分類、工程材料Solid materials have been conveniently grouped into three basic classifications： metals，ceramics and polymers固體材料便利的被分為三個基本類型:金屬、陶瓷和聚合物.This scheme is based primarily on chemical makeup and atomic structu

2、re, and most materials fall into one distinct grouping or another， although there are some intermediates. 這個方案,是主要基于化學結構和原子的結構,和大多數(shù)材料屬于一個或另一個截然不同的分組,雖然有一些中間體。In addition，there are three other groups of important engineering materials-composites， semiconductor， and biomaterials除此之外,還有其他三組重要的工程材料- - -

3、 - - - -復合材料、半導體、生物材料等。 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 brief explanation of the material types and representative characteris

4、tics is offered next復合材料由兩種或者兩種以上不同的材料組成，然而半導體由于它們非同尋常的電學性質而得到使用；生物材料被移植進入人類的身體中。關于材料類型和他們特殊的特征的一個簡單的解釋將在后面給出。 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 p

5、roperties of metals are directly attributable to these electrons金屬材料通常由金屬元素組成。它們有大量無規(guī)則運動的電子。也就是說，這些電子不是被約束于某個特定的原子。金屬的許多性質直接歸屬這些不規(guī)則運動的電子。 Metals are extremely good conductors of electricity and heat，and are not transparent to visible light：a polished metal surface has a lustrous appearance Furthermo

6、re， metals are quite strong，yet deformable， which accounts for their extensive use in structural applications金屬是十分好的電和熱的導體，它們對可見光不透明；一個拋光的金屬表面有光輝的外表。除此之外，金屬是十分硬的，也是可變形的，這個性質解釋了它們廣泛使用在結構方面的應用。 Ceramics： Ceramics are compounds between metallic and nonmetallic elements： they are most frequently oxides,

7、 nitrides，and carbidesThe wide range of materials that falls within this classification includes ceramics that are composed of clay minerals， cement， and glass. 陶瓷是介于金屬和非金屬元素之間的化合物；它們通常是氧化物，氮化物和碳化物。落在這個分類種類中的寬的材料范圍包括陶瓷，它們由粘土礦物，水泥和玻璃組成。 These materials are typically insulative to the passage of elect

8、ricity and heat， and are more resistant to high temperatures and harsh environments than metals and polymersWith regard to mechanical behavior，ceramics are hard but very brittle這些材料是典型的電和熱的絕緣體，并且它們比金屬和聚合物更加耐高溫和耐苛刻的環(huán)境。至于機械性能，陶瓷是硬的但是卻很脆。 Polymers：Polymers include the familiar plastic and rubber materi

9、als Many of them are organic compounds that are chemically based on carbon，hydrogen， and other nonmetallic elements； furthermore，they have very large molecular structuresThese materials typically have low densities and may be extremely flexible聚合物包括常見的塑料和橡膠材料。它們中的大多數(shù)是有機化合物，這些化合物是以化學的方法把碳、氫和其他非金屬元素組合

10、而成。因此，它們有非常大的分子結構。這些材料通常有低的密度并且可能十分柔軟。 Composites： A number of composite materials have been engineered that consist of more than one material typeFiberglass is a familiar example，in which glass fibers are embedded within a polymeric material. 許多復合材料被作用工程使用，它們由至少一種類型的材料組成。玻璃絲是一個熟悉的例子，玻璃纖維被埋入聚合物材料中A

11、composite is designed 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為了聯(lián)合顯示每一種組分材料最好的特性，一種復合材料被設計出來。玻璃絲從玻璃中獲

12、得強度并且從聚合物中獲得柔軟性。最近發(fā)展中的絕大多數(shù)材料包含了復合材料 Semiconductors： 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 impur

13、ity atoms，which concentrations may be controlled over very small spatial regions半導體有電的性質，它們是介于電導體和絕緣體之間的中間物。除此之外，這些材料的電學性質對微量雜質原子的存在十分敏感，雜質原子濃度可能只是在一個十分小的區(qū)域內可以控制。The semiconductors have made possible the advent of integrated circuitry that has totally revolutionized the electronics and computer indu

14、stries over the past two decades這些半導體使得集成電路的出現(xiàn)變得可能，在過去20多年間，這些集成電路革新了電子裝置和計算機工業(yè)（更不用說我們的生活）。 Biomaterials: Biomaterials are employed in components implanted into the human body for replacement of diseased or damaged body partsThese materials must not produce toxic substances and must be compatible wi

15、th body tissue(iemust not cause adverse biological reactions)生物材料被應用于移植進入人類身體以取代病變的或者損壞的身體部件。這些材料不能產生有毒物質而且必須同人身體器官要相容（比如，不能導致相反的生物反應）。All of the above materials-metals，ceramics，polymers，composites and semiconductors-may be used as biomaterialsFor example，some of the biomaterials such as CFC(carbon

16、fiberscarbon)and CFPS (polysulfone) are utilized in artificial hip replacements所有以上材料金屬，陶瓷，聚合物，復合材料和半導體材料可能用作生物材料。比如，如CF/C和CF/PS（聚砜）這些生物材料被用作人工關節(jié)的取代物。Advanced Materials Materials that are utilized in high-technology (or high-tech) applications are sometimes termed advanced materialsBy high technolog

17、y we mean a device or product that operates or functions using relatively intricate and sophisticated principles；examples include electronic equipment(VCRs，CD players，etc)，computers，fiberoptic systems，spacecraft，aircraft，and military rocketry用在高科技中的材料有時被稱作先進材料。借助于高科技，我們預定一個裝置或者產品，這些產品用相對復雜和熟練的原理運轉或者

18、起作用；這些例子包括電子設備（ VCRs, CD 播放器），計算機，光纖系統(tǒng)，宇宙飛船，航天飛機和軍事火箭。These advanced materials are typically either traditional materials whose properties have been enhanced or newly developed，highperformance materialsFurthermore，they may be of all material types(egmetals，ceramics，polymers)，and are normally relativ

19、ely expensive這些高級材料或是典型的傳統(tǒng)材料，它們的性質被提高，最近開發(fā)出來的，高性能材料。除此之外，它們可能是所有材料類型（比如，金屬、陶瓷和聚合物），通常相對較貴。Modern Materials Needs In spite of the tremendous progress that has been made in the discipline of materials science and engineering within the past few years，there still remain technological challenges，includi

20、ng the development of even more sophisticated and specialized materials，as well as consideration of the environmental impact of materials productionSome comment is appropriate relative to these issues so as to round out this perspective在過去幾年內，盡管材料科學與工程的規(guī)律取得了巨大的進步，仍然有一些技術挑戰(zhàn)，包括開發(fā)更加熟練的專業(yè)化的材料，還有考慮材料生產對環(huán)

21、境導致的影響。針對這個問題，一些評論是十分相關的。 Nuclear energy holds some promise，but the solutions to the many problems that remain will necessarily involve materials from fuels to containment structures and facilities for the disposal of radioactive waste核能還是非常有前途的，但是許多需要解決的問題仍然存在，從燃料到保護結構以及放置這些放射性廢料的裝置材料都是有必要改善的。 Sign

22、ificant quantities of energy are involved in transportationReducing the weight of transportation vehicles(automobiles，aircraft，trains，etc)，as well as increasing engine operating temperatures，will enhance fuel efficiencyNew high strength，lowdensity structural materials remain to be developed，as well

23、as materials that have highertemperature capabilities，for use in engine components相當數(shù)量的能源用在交通上。減少交通工具（汽車，飛機，火車等）的重量，和提高引擎操作溫度，將提高燃料的使用效率。新的高強，低密度結構材料仍在發(fā)展，用作引擎部位能耐高溫材料也在發(fā)展中。Furthermore，there is a recognized need to find new，economical sources of energy，and to use the present resources more efficientl

24、yMaterials will undoubtedly play a significant role in these developments除此之外，尋找新的、經濟的能源資源，并且更加有效的使用目前現(xiàn)存的資源是公認為必須的。材料將毫無疑問的在這些發(fā)展過程中扮演重要的角色。For example，the direct conversion of solar energy into electrical energy uses silicon materialsTo ensure a viable technology，materials that are highly efficient

25、in this conversion process yet less costly must be developed比如，用硅材料把太陽能直接轉化為電能。為了保證技術的可行，在這個轉化過程中的高效但不貴的材料必須被發(fā)展。Additionally，environmental quality depends on our ability to control air and water pollutionPollution control techniques employ various materials In addition, materials Processing and refi

26、nement methods need to be improved so that they produce less environmental degradation，that is，less pollution and less despoilage of the landscape from mining of raw materials除此之外，環(huán)境質量取決于我們控制大氣和水污染的能力。污染控制技術使用了各種材料。再者，材料加工和精制的方法需要改善以便它們產生很少的環(huán)境退化，也就是說，在材料加工過程中，帶來更少的污染和更少的對自然環(huán)境的破壞 Also， in some materi

27、als manufacturing processes，toxic substances are Produced，and the ecological impact of their disposal must be considered. 也，在一些材料生產過程中，有毒物質產生了，并且它們的處置對生態(tài)產生的影響必須加以考慮。Many materials that we use are derived from resources that are nonrenewable，that is not capable of being regeneratedThese include polymers， for which the prime raw material