武汉理工大学研究生--材料科技英语-课文翻译(2)

PLASTICS

Organic polymers constitute the third group of important industrial materials. These are all based onthe chemistry of carbon and they contain large macromolecules. These materials are easy to fabricate,are good insulators, are light and have good corrosion resistance. However, their strength is low andtheir high temperature resistance is poor. As these materials are light, inert and easy to fabricate theyare used extensively in the transport industry for vehicles. They have good fabricability and insulatingproperties hence they are used in electrical industry. Because of their inert characteristics they are alsoused in the chemical industry. Organic polymers are primarily synthetic organic compounds. Some likerubber are natural products.

有机聚合物构成了第三类重要工业材料。它们都是基于碳元素的化学成分，且它们含有大的高分子。这类材料易于制造，绝缘体良好，质轻且具有良好的耐腐蚀性。然而，它们的强度低，耐高温性差。由于这类材料质轻，具有惰性且容易制造，因此它们广泛用于车辆的运输业。而它们具有良好的可制造性和绝缘性，因此它们也用于电气工业中。由于它们的惰性特性，它们也被用于化学工业。有机聚合物主要是人工合成的有机化合物，也有些是天然产物，比如橡胶。

Plastic materials display properties that are unique when compared to other materials and havecontributed greatly to quality of our everyday life. Plastics, properly applied, will perform functions ata cost that other materials cannot match. Many natural plastics exist, such as rubber, asphalt, and

cellulose. Plastics are used in our clothing, housing, automobiles, aircraft, packaging, electronics, signs,recreation items, and medical implants to name but a few of their many applications.

与其他材料相比，塑料材料显示出独特的性能，大大有助于我们的日常生活质量。适当的应用塑料，它将以其他材料无法比拟的价格履行职能。有许多天然塑料存在，如橡胶、沥青和纤维素。塑料用于我们的服装，住房，汽车，飞机，包装，电子，标牌，娱乐用品和医疗植入物，这只列举了许多应用中的一些。

Occasionally plastics are still improperly used and draw negative comments. The thousands ofsuccessful applications that contribute to the quality of our life are seldom noticed and are taken forgranted. Remember, MATERIALS DON'T FAIL, DESIGNS DO.

塑料偶尔也有使用不当的地方，并招致了负面评论。成千上万有助于提高我们生活质量的成功应用很少被人注意，这被视为理所当然。记住，材料不会错，但设计会出错。

Plastics encompass a large and varied group of materials consisting of different combinations orformulations of carbon, oxygen, hydrogen, nitrogen and other organic and inorganic elements. Mostplastics are solid in finished form; however, at some stage of their existence, they are liquid and may beformed into various shapes. The forming is usually done through the application, either singly ortogether, of heat and pressure. There are over fifty different, unique families of plastics in commercialuse today and each family may have dozens of variations.

塑料包括由碳，氧，氢，氮和其他有机和无机元素的不同组合或配方组成的一类大的且多样

化的材料。大多数塑料是成品的固体; 然而，在它们存在的某个阶段它们是液体的并且可以形成各种形状。塑料通常通过热、压力或它们的组合来成型。如今，有超过五十种不同的独特的塑料种类在商业中应用，每个种类的塑料可能有几十种变体。

Optical fibers

Optical fibers, used to transmit light, are gaining wide acceptance in the communications fieldbecause they can be produced from the plentiful silica sand to replace heavier, bulkier, and moreexpensive copper and aluminum conductors. Optical fibers of glass and plastic have been used formany years in the medical profession and by engineers as inspection tubes. Flexible fibers on probes探针 or endoscopes 内窥镜 are inserted into the human body or into a motor and attached to atelevision system or magnifying lens to allow viewing of these otherwise inaccessible places.

用于传输光的光纤在通信领域得到广泛的认可，因为它们可以由含量丰富的硅砂生产，以取代更重，体积更大，更昂贵的铜和铝导体。玻璃和塑料的光纤已经在医疗行业和被工程师用作检查管使用了多年。探针或内窥镜上的柔性纤维插入到人体或电动机中，并连接到电视系统或放大镜，以允许这些不可接近的位置可以观察。

A signal optical fiber the size of a hair has the potential to transmit several thousand voice signals,compared to the fewer than 50 voice signals that can be carried on a copper wire of the same size. Forthis reason, telephone, television, computer, and other communications systems are moving to thesmaller coaxial 同轴的 fiber-optics cable to replace copper-stranded cables. Photons ofelectromagnetic radiation (light) replace electrons in signal transmission through these transparentoptical fibers. This has increased the speed, the distance, and the amount of information (density)beyond all imagination. Cladding of fiber-optic cables with a transparent covering 包层, whose indexof refraction is lower than that of the fiber, prevents leakage of light. Because of the quality of the olderfibers in transmitting signals, it is necessary to boost 推进 the signal every 50km using repeaterstations 中继站.

与相同尺寸的铜线上携带的少于50个声信号相比，信号光纤具有发送几千个声信号的潜力。因此，电话，电视，计算机和其他通信系统正在向较小的同轴光纤电缆转移以取代铜绞线。电磁辐射的光子（光）通过这些透明光纤代替信号传输中的电子。这超出所有想象的增加了运输速度，距离和信息量（密度）。具有透明覆盖层的光纤电缆包层，其折射率低于光纤的折射率，防止了光的泄漏。由于传输信号中较旧的光纤存在质量问题，因此有必要每50km使用中继站将信号提升。

With the use of laser light and thinner cable (10μm in diameter), litter energy is lost and boostingstations are seldom needed. Present-day technology limits the laser transmission of data overfiber-optic cable to some 50 mi using numerous lasers to keep the signals stable. This represents a datacapacity of about 40 gigabits per second with the cable’s capacity of 10 Tbits/s.

随着激光和更薄的电缆（直径为10μm）的使用，能量损失较少，增压站很少需要。当今技术限制数据在光纤上的激光传输在大约50mi，因此使用许多激光器来保持信号的稳定。这

表示电缆容量为10Tbits/s，其数据容量为40Gbits/s。

Glass

Glass when newly formed, with a perfect surface, is very strong about five times as strong as steel.This may seem strange, but theoretically glass should be very strong because of the nature of itsinteratomic bonds. In practice, the strength is very much less than the theoretical value. One of the maincauses of this loss of strength is the presence of surface defects, such as those caused by chemicalcorrosion or mechanical abrasion. These flaws can be very small but because glass is rigid they act toconcentrate any applied stress over only a few interatomic bonds at the apex of the crack. Under theseconditions the strong bonds break and fracture occurs. Once started it has a high probability ofspreading right across the material because there are no internal grain boundaries to stop it. Thus, apiece of glass will often shatter suddenly when subject to a stress.

新形成的玻璃，具有完美的表面，强度是钢的五倍。这似乎看起来很奇怪，但理论上玻璃应该是非常强的，这是因为它的原子间键的性质的缘故。实际上，其强度远远低于理论值。这种强度损失的主要原因之一是存在表面缺陷，例如由化学腐蚀或机械磨损引起的缺陷。这些缺陷可能非常小，但是由于玻璃是刚性的，它们的作用是将任何施加的应力集中在裂缝顶点的仅仅几个原子间的作用力上。在这些条件下，强键断裂导致玻璃出现破裂。一旦开始，由于没有内部晶粒边界阻止它，所以它很可能在材料之间传播。因此，当受到压力时，一片玻璃将经常会突然破碎。

This concept of stress is also important in cooling the glass during the manufacturing process. Ifthe glass is cooled too rapidly it does not have time to release stresses set up within it during coolingthese are \occurspontaneously, or when a tiny flaw is produced on the surface. In order to avoid these internal stresses,glass articles are subjected to a controlled heat treatment after manufacture, a process known asannealing. The temperature is raised to that which will allow internal stresses to be relaxed by flowwithin the glass (but not so high that the article will deform) and held there for an appropriate time. It isthen slowly reduced to a point well below the transformation range and afterwards more rapidly toroom temperature.

这种应力概念在制造过程中对玻璃的冷却也很重要。如果玻璃冷却太快，则在冷却过程中没有时间释放在其内部施加的应力，这些“冷冻”可能导致玻璃在变成固态时破碎。这可能是自发发生的，或者当表面产生微小的缺陷时发生。为了避免这些内应力，玻璃制品在制造之后受到可控的热处理，这个过程称为退火。温度升高到允许内部应力通过玻璃内的流动而松弛的温度（但不会使得物品变形）并将其保持在适当的时间。然后将其缓慢降至远低于转化范围的温度，随后更快地降至室温。

Glass is in widespread use largely due to the production of glass compositions that are transparentto visible wavelengths of light. In contrast, polycrystalline materials do not in general transmit visiblelight. The individual crystallites may be transparent, but their facets (grain boundaries) reflect or scatterlight resulting in diffuse reflection. Glass does not contain the internal subdivisions associated withgrain boundaries in polycrystals and hence does not scatter light in the same manner as apolycrystalline material. The glass surface is often smooth since during glass

formation the moleculesof the supercooled liquid are not forced to dispose in rigid crystal geometries and can follow surfacetension, which imposes a microscopically smooth surface. These properties, which give glass itsclearness, can be retained even if glass is partially light-absorbing.

玻璃的广泛使用主要由于生产的玻璃成分对可见光波长是可透过的。相比之下，多晶材料通常不透射可见光。单晶可以是透明的，但它们的面（晶界）反射或散射光导致漫射。玻璃不包含与多晶体中的晶界相关的内部细分，因此不以与多晶材料相同的方式散射光。玻璃表面通常是平滑的，因为在玻璃形成期间，过冷液体的分子不被强制地以刚性晶体几何形状分布，并且可以遵循表面张力，这使其强制形成微观平滑的表面。即使玻璃部分吸光，这些赋予玻璃清晰度的性质也能保留。

The refractive index depends upon the wavelength of light, the density, temperature, thermalhistory, stress, and composition of the glass. The change of index with wavelengths called dispersion. Itis because of this change that the various colours are dispersed by a prism. Glasses of higher refractiveindex have greater dispersion, the higher the index, the more the dispersion tends to increase withdecreasing wavelength.

折射率取决于光的波长，玻璃的密度，温度，热历史，所受应力和组成。折射率随波长变化称为色散。正是由于这种变化，各种颜色被棱镜分散。折射率较高的玻璃具有较大的色散，折射率越高，随着波长的减小，色散倾向程度增加。

Elastic and plastic deformation

Two of the most important properties of metals for manufacturing purposes are elastic deformationand plastic deformation. Stress is the material’s resistance to the applied load or force. When metals areplaced under tensile, torsion, or compression stress, a slight elongation or compression takes place inthe crystal lattice. This movement is called strain. Elastic deformation is not permanent. As soon as thestress is removed, the structure returns to its former shape. Also, this elongation or compression in onedirection will produce an opposite change at 90 degrees to that force. That is, a piece of metal willbecome thinner if it is stretched lengthwise. This ratio of movement at right angles to the applied forceis called Poisson’s ratio.

用于制造业的金属的两个最重要的特性是弹性变形和塑性变形。应力是材料对施加的载荷或力的抵抗力。当金属处于拉伸，扭转或压缩应力下时，晶格中会发生轻微的伸长或压缩。这种运动被称为应变。弹性形变不是永久性的。一旦应力消除，其结构就恢复到原来的形状。而且，一个方向上的这种伸长或压缩将产生与该力成90度相反的变化。这个与所施加的力成直角运动的比例，叫做泊松比。

Plastic deformation is one of the most useful characteristics of metals. Forging, drawing, forming,extruding, rolling, stamping, and pressing all involve plastic deformation. Plastic deformation in metalscan take place only at a stress or load higher than the elastic limit. As the applied load is increased, theatoms must slide over each other to produce a permanent change in shape or break the atomic bonds,resulting in total rupture.

塑性变形是金属最有用的特征之一。锻造，拉丝，成型，挤压，轧制，冲压和压制都涉及塑性变形。金属中的塑性变形只能在高于弹性极限的应力或负荷下进行。当施加的载荷增加时，原子一定彼此滑动以产生永久形变或破坏原子键，导致完全破裂。

Friction Materials

Graphite and carbonaceous raw materials are used as friction modifiers for balancing cohesive andadhesive frictional forces. These materials cushion friction particles to optimize stopping performanceand pedal feel. They also offer lubrication against the brake drum, or rotor, thermal conductivity todissipate heat during heavy braking, and offers increased strength properties to retain friction materialintegrity. Superior Graphite offers a number of solutions to meet the demanding rigors of frictionmaterial applications. The FormulaFX? line of materials has been designed to offer high purity,consistent particle size distributions, and unique physical characteristics needed for general and highperformance formulations.

石墨和碳质原料用作润滑剂，以平衡粘性和粘着摩擦力。这些材料缓冲摩擦颗粒以优化制动性能和踏板感觉。它们还为制动鼓或转子提供润滑，导热，以便在重型制动过程中散热，并提升强度特性以保持摩擦材料的完整性。优良的石墨提供了许多解决方法，来满足摩擦材料应用中的严格要求。FormulaFX?系列材料的设计旨在提供高纯度，粒度分布一致，以及普通和高性能配方所需的独特物理特性。

Magnetic property of materials

Diamagnetic materials are solids composed of atoms with completely filled electron shells, so theinteraction is nil. Some examples and copper (Cu), silver(Ag), gold(Au), and organic polymers.

反磁性材料是由核外电子是饱和状态的原子组成的固体，因此相互作用为零。比如：铜（Cu），银（Ag），金（Au）和有机聚合物。

Paramagnetic materials contain unpaired electrons in their inner shells that form atomic dipolesthat are free to rotate with an external field, producing some interaction and rendering a relativepermeabilityμslightly greater than 1. Like diamagnetic materials, paramagnetic materials onlyexhibit magnetism when in the presence of an external magnetic field. Some examples of paramagneticmaterials are the metals aluminum (Al), chromium (Cr), and titanium (Ti).

顺磁性材料在内部壳层中含有未配对的电子，形成原子偶极子，可以自由地与外部磁场旋转，产生一些相互作用，并使相对磁导率μ略大于1。像反磁材料一样，顺磁材料只有在存在外部磁场时才表现出磁性。如金属铝（Al），铬（Cr）和钛（Ti）都是顺磁材料。

Ferromagnetism is present in some metallic materials that possess a permanent magnetic moment.Iron (Fe), cobalt (Co), nickel (Ni), and some metal alloys exhibit ferromagnetism. The magneticbehavior can be increased in magnitude by strong magnetic fields. The explanation of this type ofbehavior uses the word domain, which is a tiny region about 1 mm in length or width. Each domainacts like a tiny magnet with a north pole and a south pole and is the result of the electronic structure ofindividual atoms. These regions are visible using powerful electron microscopes. If the magneticmaterial is demagnetized (B=0), as in heating, the domains are arranged in a random fashion. Thesedomains are capable of rotating as well as changing size.

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