材料科学与工程专业外语翻译 12章
材料科学与工程专业英语第三版-翻译以及答案
UNIT 1一、材料根深蒂固于我们生活的程度可能远远的超过了我们的想象，交通、装修、制衣、通信、娱乐（recreation）和食品生产，事实上（virtually），我们生活中的方方面面或多或少受到了材料的影响。
历史上，社会的发展和进步和生产材料的能力以及操纵材料来实现他们的需求密切（intimately）相关，事实上，早期的文明就是通过材料发展的能力来命名的（石器时代、青铜时代、铁器时代）。
二、早期的人类仅仅使用（access）了非常有限数量的材料，比如自然的石头、木头、粘土（clay）、兽皮等等。
随着时间的发展，通过使用技术来生产获得的材料比自然的材料具有更加优秀的性能。
这些性材料包括了陶瓷（pottery）以及各种各样的金属，而且他们还发现通过添加其他物质和改变加热温度可以改变材料的性能。
此时，材料的应用（utilization）完全就是一个选择的过程，也就是说，在一系列有限的材料中，根据材料的优点来选择最合适的材料，直到最近的时间内，科学家才理解了材料的基本结构以及它们的性能的关系。
在过去的100年间对这些知识的获得，使对材料性质的研究变得非常时髦起来。
因此，为了满足我们现代而且复杂的社会，成千上万具有不同性质的材料被研发出来，包括了金属、塑料、玻璃和纤维。
三、由于很多新的技术的发展，使我们获得了合适的材料并且使得我们的存在变得更为舒适。
对一种材料性质的理解的进步往往是技术的发展的先兆，例如：如果没有合适并且没有不昂贵的钢材，或者没有其他可以替代（substitute）的东西，汽车就不可能被生产，在现代、复杂的（sophisticated）电子设备依赖于半导体（semiconducting）材料四、有时，将材料科学与工程划分为材料科学和材料工程这两个副学科（subdiscipline）是非常有用的，严格的来说，材料科学是研究材料的性能以及结构的关系，与此相反，材料工程则是基于材料结构和性能的关系，来设计和生产具有预定性能的材料，基于预期的性能。
材料科学与工程专业英语第三版-翻译以及答案.
UNIT 1一、材料根深蒂固于我们生活的程度可能进进的超过了我们的想象,交通、装修、制衣、通信、娱乐(recreation和食品生产,事实上(virtually,我们生活中的方方面面或多或少受到了材料的影响。
历史上,社会的发展和迚步和生产材料的能力以及操纵材料杢实现他们的需求密切(intimately相关,事实上,早期的文明就是通过材料发展的能力杢命名的(石器时代、青铜时代、铁器时代。
二、早期的人类仅仅使用(access了非常有限数量的材料,比如自然的石头、木头、粘土(clay、兽皮等等。
随着时间的发展,通过使用技术杢生产获得的材料比自然的材料具有更加优秀的性能。
这些性材料包拪了陶瓷(pottery以及各种各样的金属,而且他们还发现通过添加其他物质和改变加热温度可以改变材料的性能。
此时,材料的应用(utilization完全就是一个选择的过程,也就是说,在一系列有限的材料中,根据材料的优点杢选择最合适的材料,直到最近的时间内,科学家才理解了材料的基本结构以及它们的性能的关系。
在过去的100年间对这些知识的获得,使对材料性质的研究变得非常时髦起杢。
因此,为了满足我们现代而且复杂的社会,成千上万具有不同性质的材料被研发出杢,包拪了金属、塑料、玻璃和纤维。
三、由于很多新的技术的发展,使我们获得了合适的材料幵且使得我们的存在变得更为舒适。
对一种材料性质的理解的迚步往往是技术的发展的先兆,例如:如果没有合适幵且没有不昂贵的钢材,或者没有其他可以替代(substitute的东西,汽车就不可能被生产,在现代、复杂的(sophisticated电子设备依赖于半导体(semiconducting材料四、有时,将材料科学与工程划分为材料科学和材料工程这两个副学科(subdiscipline是非常有用的,严栺的杢说,材料科学是研究材料的性能以及结构的关系,与此相反,材料工程则是基于材料结构和性能的关系,杢设计和生产具有预定性能的材料,基于预期的性能。
材料科学与工程专业英语课文翻译(1,2,3,10).
United 1 材料科学与工程材料在我们的文化中比我们认识到的还要根深蒂固。
如交通、房子、衣物,通讯、娱乐和食物的生产,实际上,我们日常生活中的每一部分都或多或少地受到材料的影响。
历史上社会的发展、先进与那些能满足社会需要的材料的生产及操作能力密切相关。
实际上,早期的文明就以材料的发展程度来命名,如石器时代,铜器时代。
早期人们能得到的只有一些很有限的天然材料,如石头、木材、粘土等。
渐渐地,他们通过技术来生产优于自然材料的新材料,这些新材料包括陶器和金属。
进一步地,人们发现材料的性质可以通过加热或加入其他物质来改变。
在这点上,材料的应用完全是一个选择的过程。
也就是说,在一系列非常有限的材料中,根据材料的优点选择一种最适合某种应用的材料。
直到最近,科学家才终于了解材料的结构要素与其特性之间的关系。
这个大约是过去的60 年中获得的认识使得材料的性质研究成为时髦。
因此,成千上万的材料通过其特殊的性质得以发展来满足我们现代及复杂的社会需要。
很多使我们生活舒适的技术的发展与适宜材料的获得密切相关。
一种材料的先进程度通常是一种技术进步的先兆。
比如,没有便宜的钢制品或其他替代品就没有汽车。
在现代,复杂的电子器件取决于所谓的半导体零件.材料科学与工程有时把材料科学与工程细分成材料科学和材料工程学科是有用的。
严格地说,材料科学涉及材料到研究材料的结构和性质的关系。
相反,材料工程是根据材料的结构和性质的关系来设计或操纵材料的结构以求制造出一系列可预定的性质。
从功能方面来说,材料科学家的作用是发展或合成新的材料,而材料工程师是利用已有的材料创造新的产品或体系,和/或发展材料加工新技术。
多数材料专业的本科毕业生被同时训练成材料科学家和材料工程师。
“structure”一词是个模糊的术语值得解释。
简单地说,材料的结构通常与其内在成分的排列有关。
原子内的结构包括介于单个原子间的电子和原子核的相互作用。
在原子水平上,结构包括原子或分子与其他相关的原子或分子的组织。
材料科学与工程_专业英语_Uni...
材料科学与工程_专业英语_Uni...Unit 3 Structure-Property Relationships of MaterialsToday’s materials can be classified as metals and alloys, as polymers or plastics, as ceramics, or as composites; composites, most of which are man-made, actually are combinations of different materials.译文：当今的材料可以分为金属和合金，聚合物或者塑料，陶瓷或复合材料；复合材料，它们大多数是人造的，实际上是不同材料组合而成。
A pplica tion of these m ateria ls de pe nd on their pr ope rties; theref ore, w e ne ed to know w hat pr operties are re quired by the a pplica tion and to be a ble to re late those s pecifica tion to the m aterial.译文：这些材料的应用取决于它们的性质；因此，根据应用的场合，我们需要知道什么样的性质是必需的，我们需要能够把这些详细说明同材料联系起来。
For exam ple, a la dder m ust w ithsta nd a des ign loa d, the w eight of a pe rs on us ing the la dde r. H ow ever, the m ateria l property that ca n be m easured is s tre ngth, w hich is af f ecte d by the loa d a nd desig n dim ension. S tre ngth values m us t theref ore be applie d to dete rm ine d the la dde r dim ensions to e ns ure saf e us e. Therefore, in ge ne ral, the s truc tures of m etallic m aterials have ef fects on the ir prope rties.译文：比如，一个梯子必须能经受住设计的载荷，也就是使用这个梯子的人的重量。
材料科学与工程专业(第四版)英语翻译(1
材料科学与工程专业(第四版)英语翻译(1篇一：材料科学与工程专业英语第二版课文翻译(1,2,3,10)United 1 材料科学与工程材料在我们的文化中比我们认识到的还要根深蒂固。
如交通、房子、衣物，通讯、娱乐和食物的生产，实际上，我们日常生活中的每一部分都或多或少地受到材料的影响。
历史上社会的发展、先进与那些能满足社会需要的材料的生产及操作能力密切相关。
实际上，早期的文明就以材料的发展程度来命名，如石器时代，铜器时代。
早期人们能得到的只有一些很有限的天然材料，如石头、木材、粘土等。
渐渐地，他们通过技术来生产优于自然材料的新材料，这些新材料包括陶器和金属。
进一步地，人们发现材料的性质可以通过加热或加入其他物质来改变。
在这点上，材料的应用完全是一个选择的过程。
也就是说，在一系列非常有限的材料中，根据材料的优点选择一种最适合某种应用的材料。
直到最近，科学家才终于了解材料的结构要素与其特性之间的关系。
这个大约是过去的 60 年中获得的认识使得材料的性质研究成为时髦。
因此，成千上万的材料通过其特殊的性质得以发展来满足我们现代及复杂的社会需要。
很多使我们生活舒适的技术的发展与适宜材料的获得密切相关。
一种材料的先进程度通常是一种技术进步的先兆。
比如，没有便宜的钢制品或其他替代品就没有汽车。
在现代，复杂的电子器件取决于所谓的半导体零件.材料科学与工程有时把材料科学与工程细分成材料科学和材料工程学科是有用的。
严格地说，材料科学涉及材料到研究材料的结构和性质的关系。
相反，材料工程是根据材料的结构和性质的关系来设计或操纵材料的结构以求制造出一系列可预定的性质。
从功能方面来说，材料科学家的作用是发展或合成新的材料，而材料工程师是利用已有的材料创造新的产品或体系，和/或发展材料加工新技术。
多数材料专业的本科毕业生被同时训练成材料科学家和材料工程师。
“structure”一词是个模糊的术语值得解释。
简单地说，材料的结构通常与其内在成分的排列有关。
材材料科学与工程专业英语
2.6 semiconductorFollowing the discussion of intrinsic ,elemental semiconductors we note that the fermi function indicates that the number of charge carriers increases exponentially with temperature. This effect so dominates the conductivity of semiconductors that conductivity also follows an exponential increase with temperature(an example of an arrhenius equation ).This increase is in sharp contrast to the behavior of metals.We consider the effect of impurities in extrinsic,elemental semiconductors.Doping a group IV a material(such as Si) with a group V a impurity (such as P)produces an n-type semiconductor in which negative charge carriers(conduction electrons)dominate.The “extea”electron from the group V A addition produces a donor level in the energy band structure of the semiconductor.As with instrinsic semiconductors,extrinsic semiconduction exhibits arrhenius behavior.in n-type material, the temperature span between the regions of extrinsic and insrinsic behavior is called the exhaustion range .A p-type semiconductor is produced by doping a group IV a material with a group III a impurity(such as Al).The group III A element has a “missing” electron producing anacceptor level in the band stucture and leading to formation of positive charge carriers (electron holes). The region between extrinsic and instrinsic behavior for p-type semiconductors is called the saturation range . Hall effect measurements can distinguish between n-type and p-type conduction.Compound semiconductors usually have an MX composition with an average of four valence electrons per atom .The III-V and II-VI compounds are the common examples .amorphous semiconductors are the non-crystalline materials with semiconducting behavior.Elemental and compound material are both found in this category .To appreciate the applications of semiconductors,we review a few decades.the solid state rectifier (or diode) contains a single p-n junction .Current flows readily when this junction is forward biased but is almost completely choked off when reverse biased.the transistor is a device consisting of a pair of nearby pn junctions.The net result is a solid state amplifier. Replacing vacuum tubes with solid state elements such as these produced substantial miniaturization of electrical circuits.Further miniaturization has resulted by the production of microcircuis consisting of precise parrerns of n-type and p-type regions ona single crystal chip.The major electrical properties needed to specify an intrinsic semiconductor are band gap,electron mobility,hole mobility,and conduction electron density (=electron hole density ) at room temperature.For extrinsic semiconductors,one needs to specify either the donor level (for n-type material) or the acceptor level (for p-type material).2.7 compositesOne category of structural engineering material is that of composites .These materials involve some combination of two or more components from the “fundamental” materal types .A key philosophy in selecting composite materials is that they provide the “best of both worlds”that is ,attrative properties from each component. A classic example is fiberglass.The strength of small diameter glass fibers is combined with the ductility of the polymetric matrix.The combination of these two components provides a product superior to either component alone .Many composites,such as fiberglass,involve combinations that cross over the boundaries of different kinds of materials. Others,such as concrete,involve different component from within a single material type.In general,we shall use a fairly narrowdefinition of composites.We shall consider only thode material thata combine different components on the microscopic(rather than macroscopic )scale .We shall noot include multiphase alloys and ceramics ,which are the result of routine processing.Similarly,the microcircuits be discussed later are not include because each component retains its distinctive character in these material systems. In spite of these restrictions,we shall find this category to include a tremendously diverse collection of materials,from the common to some of most sophisticated.We shall consider three categories of composites mateials. Conveninently ,these categories are demonstrated by three of our most common structural material ,fiberglass ,wood,and concrete .Fiberglass(or glass fiber reinforced polymer ) is an excellent example of a human made fiber reinforced composite.The glass-polymer system is just one of many important example .The fiber reinforcement is generally found in one of three primary configutations: aligned in a single direction ,randomly chopped,or woven in a fabric that is laminated with the matrix.Wood is a stuctural analog of fiberglass ,that is ,a natural fiber reinforced composite.The fibers of wood are elongated,biological cells. The matrixcorresponds to lignin and hemicellulose deposits.concrete is our best example of an aggregate composite, in which particles rather than fibers reinforce amatrix common concrete is rock and sand in a calcium aluminosilicate (cement)matrix.While concrete has been a construction material for centuries ,these are numerous c composites developed in recent decades that use a similar particulate reinforcement concept.The concept of property averaging is central to understanding the utility of composite material.an important example is the elastic modulus of a composite .The modulus is a sensitive function of the gemetry of the reinforcing component.similarly important is the srength of the interface betweeen the reinforcing component and the matrix .We sahll concentrate on these mechanical properties of composites in regard for their wide use as structural materials.So caaled “advanced”composites have provided some unusually attractive features,such as high strrenth to weight ratios.Some care is required in citing these properties,as they can be highly directional in nature.2.6there are numerous uses of piezoelectrics. for instance, plates cut from a single crystal can exhibit a specific natural resonance frequency(i.e., the frequency of an electromagneticwave that causes it to vibrate mechanically at the same frequency); these can be used as a frequency standard in highly stable crystal controlled clocks and in fixed frequency communications devices. other resonant applications include selective wave filters and transducers(e.g., for ultrasonic cleaning and drilling) and non-resonant devices(e.g., accelerometers, pressure gauges, microphone pickups) are dominated by ceramic piezoelectrics.2.7.3 fiberglass was a convenient and familiar example of fiber reinforced composites. Similarly ,concrete is an excellent example of an aggregate composite. As with wood,this common construction material is used in staggering quantities. The weight of concrete used annually exceeds that of all metals combined.For concrete, the term “aggregate” refers to a combination of sand(fine aggregate) and gravel(coarse aggregate). This component of concrete is a “natual” material in the same sense as wood. Ordinarily ,these materials are chosen for their relatively high density and strength. A table of aggregate compositions would be complex and largely meaningless. In general, aggregate materials are geological silicates chosen from locally available deposits. As such, these materials arecomplex and relatively impure examples of the crystalline silicates. Igneous rocks are common examples. “igneous” means solidified from a molten state. For quickly cooled igneous rocks ,some fraction of the resulting material may be non-crystalline, corresponding to the glassy silicates. The relative particle sizes of sand and gravel are measured(and controlled) by passing these materials through standard screens(or sieves). The reason for a combination of fine and coarse aggregate in a given concrete mix is that the space is more efficiently filled by a range of particle sizes. The combination of fine and coarse aggregate accounts for 60 to 75 percent of the total volume of the final concrete.Modern concrete uses portland cement,which is a calcium aluminosilicate. There are five common types of portland cement. They vary in the relative concentrations of four calcium containing minerals. The matrix is formed by the addition of water to the appropriate cement powder. The particle sizes for the cement powers are relatively small compared to the finest of the aggregates. Variation in cement particle size can strongly affect the rate at which the cement hydrates. As one might expect from inspecting the complex compositions of portland cement, the chemistry of the hydration process isequally complex.In ploymer technology, we noted several “additives” which provided certain desirable features to the end product. In cement technology , there are a numble of admixtures,which are additions providing certain features. Any component of concrete other than aggregate,cement,or water is, by definition ,an admixture. One of the admixtures is an “air entrainer” which reminds us that air can be thought of as a fourth component of concrete. The air entrainer admixture increases the concentration of entrapped air bubbles, usually for the purpose of workability(during forming) and increased resistance to freeze thaw cycles.Why concrete is an important engineering material, a large numble of other composite systems are based on particle reinforcement. Particulate composites refer specifically to systems with relatively large size dispersed particles(at least several micrometers in diameter),and the particles are in relatively high concentration(greater than 25 and frequently between 60 and 90) of small diameter oxide particles. The oxide particles strengthen the metal by serving as obstacles to dislocation motion.2.7.2 like so many accomplishments of human beings, those fiberreinforced composites imitate nature. Common wood is such a composite, which serves as an excellent structural material. In fact, the weight of wood used each year in the Uited Sates exceeds the combined total for steel and concrete. We find two categories , softwoods and hardwoods. These are relative terms, although softwoods generally have lower strengths. The fundamental difference between the categories is their seasonal nature. Softwoods are “evergreens” with needlelike leaves and exposed seeds. Hardwoods are deciduous( i.e., lose their leaves annually)with covered seeds( i.e.,nuts)The microstructure of wood illustrates its commonality with the human-made composites. The dominant feature of the microstructure is the large number of tubelike cells oriented vertically. These longgitudinal cells are aligned with the vertical axis of the tree. There are some radial cells perpendicular to the longitudinal ones. As the name implies, the radial cells extend from the center of the tree trunk out radically toward the surface. The longitudinal cells carry sap and other fluids critical to the growth process. Early seaon cells are of larger diameter than later season cells. This growth pattern leads to the characteristic “ring structure”which indicates the tree’s age. The radial cells store foodfor the growing tree. The cell walls are composed of cellulose. The strength of the cells in the longitudinal direction is a function of fiber alignment in that direction. The cells are held together by a matrix of lignin and hemicellulose. Lignin is a phenol propane network ploymer, and hemicellulose is ploymeric cellulose with a relatively low degree of ploymerization.Related to this ,the dimensions as well as the proper ties of wood vary significantly with atmospheric moisture levels. Care will be required in specifying the atmospheric conditions for which mechanical property data apply.2.7.1 let us begin by concentrating on fiberglass, or glass fiber reinforced ploymer. This is a classic example of a modern composite system. A typical fracture surface of a composite shows fibers embedded in the ploymeric matrix, such fibers may have different composition since each is the result of substantial development that has led to optimal suitability for specific applications. For example, the most generally used glass fiber composition is E glass, in which E stands for its especially low electrical conductivity and its attractiveness as a dielectric. Its popularity in structural composites is related to the chemical durability of the borosilicatecomposition. We should note that optimal strengh is achieved by the aligned, continuous fiber reinforcement. In other words, the strength is highly anisotropic.The fiber reinforced composites include some of the most sophisticated materials developed by man for some of the most demanding engineering applications. Important examples include boron reinforced aluminum, graphite epoxy, and al reinforced aluminum. Metal fibers are frequently small diameter wires. Especially high strength reinforcement come from “whiskers” which are small, single crystal fibers that can be grown with a nearly perfect crystalline structure. Unfortunately , whiskers cannot be grown as continuous filaments in the manner of glass fibers or metal wires.2.5polymerpolymers are chemical compounds that consist of long,chainlike molecules made up of multiple repeatinf units.The term polyner was coined in 1832 by the Swedish chemist Jins Jacob Berzelius from the Greek pols,or "many" and meros,or "parts."Polymers are also referred to as macromolecules,or "gaint molecules"-a term introduced by the German chemist Hermann Staudinger in 1992.Some gaint molecules occur maturally.Proteins ,for example ,are natural polymers of amino acids that make up muchof the structural material of animals;and the polymers deoxyribonucleic acid(DNA) and ribonucleic acid(RNA) are liner strands of nucleotides that define the genetic make up of living organisms.Other examples of natural polmers are silk ,wool.natural rubber,cellulose ,and shellac.There materials have been known and exploited since ancient times.Indeed,people in what is now Switzerland cultivates flax,a source of polymeric cellulose fibres,during the Neolithic Period,or New Stone Age,some 10 000 years ,while other ancients collected proteinaceous wool fibers from sheep and silk fibers from silkworms.About five millennia ago,tanners produced leather through the cross linking of proteins by gallic acid forming the basis of the oldest industry in continuous production.Even embalming,the art for which ancient Egypt is famous is based on the condensation and cross linking of proteins with form aldehyde.Early developments in polymer technology,taking place in the 19th century,involved the conversion of natural polymers to more useful products-for example,the conversion of cellulose,obtained from cotton or wood,into celluloid,one of the first plastic.Before the 1930s only a small number of synthetically produced polymers were availablecommercially,but after that period and especially after World War II,synthetic compounds came to dominance.Derived principally from the refining of petroleum and natural gas,synthetic polymers are made into the plastics,rubbers,man-made fibres,adhesives,and surface coatings that have become so ubiquitous in modern life.As an important materials,the polymers are available in a wide variety of commercial forms:fibers,thin films and sheets,foams and in bulk.A common synonym for polymers is "plastic",a name derived from the deformability associated with the fabrication of most polymeric products.To some critics,"plastic" is a synonym for modern culture.Accurate or not,it represents the impact that this complex family of engineering materials has had on our society.Polymers are distinguished from our previous types of materials by chemistry.Metal,ceramics.and glasses are inorganic materials.The polymers discussed here are organic.The student should not be concerned about a lack of background in organic chenistry.This passage is intended to provide any of the fundamentals of organic chemistry needed to appreciate the unique nature of polymeric materials.We begin our discussion of polymers by investigating polymerization,theprocess by which long chain or network molecules are made from relatively small organic molecules.The structural features of the resulting polymers are rather unique compared to the inorganic materials.Ingeneral,the ,elting point and rigidity of polymers increase with the extent of plymerization and with the complexity of the molecular structure.We shall find that polymers fall into one of two main categories.Thermoplastic polymers are materials that become less rigid upon heating,and thermosetting polymers become more rigid upon heating.For both categories,it is important to appreciate the roles played by additives,which provide important features such as color and resistance to combustion.As with ceramics and glasses,we shall discuss important mechanical and optical properties of polymers.Mechanically,polymers exhibit behavior associated with their long chain molecular structure.Examples include viscoelastic and elastomeric deformation .Optical properties such as transparency and color,so important in ceramic technology,are also significant in the selection of polymers.2.5.1 PolymerizationThe term polymer simply means "many mers" where mer is thebuilding block of the long chain or network molecule.There are two distinct ways in which a poly merization reaction can take place.Chain growth(also known as addition polymerization)involves a rapid "chain reaction" of chemically activated monomers.Step growth(also known as condensation polymerization)involves individual chemical reactions between pairs of reactive monomers and is a much slower process.In either case,the critical feature of a monomer,which permits it to join with similar molecules and form a polymer,is the presence of reactive sites,that is double bonds(chain growth) or reactive functional groups (step geowth).Each covalent bond is a pair of electrins shared between adjacent atoms.The double bond is two such pairs.The chain growth reaction converts the double bond in the monomer to a single bond in the mer.The remaining two electrons become parts of the single bonds joining adjacent mers.2.5.2 Thermal Plastic PolymersThermoplastic polymers become soft and deformable upon heating.This is characteristic of linear polymeric molecules.The high temperature plasticity is due to the ability of the molecules to slide past one another.This is anotherexample of a thermally activated,or Arrhenius process.In this sence ,thermoplastic materials are similar to metals that gain ductility at high temperatures.The key distinction between thermoplastics and metals is what we mean by "high" temperatures.The secondary bonding,which must be overcome to deform thermoplastics,may allow substantial deformation around 100,whereas metallic bonding generally restricts creep deformation to temperature closer to 1000 in typical alloys.It should be noted that,as with metals,the ductility of thermoplastic polymers is lost upon cooling.2.5.3 Thermal Setting PolymersThermosetting polymers are the opposite of the thermoplastics.They become hard and rigid upon heating.Unlike thermoplastic polymers,this phenomenon is not lost upon cooling.This is characteristic of network molecular structures formed by the step growth mechanism.The chemical reaction "steps" are enhanced by higher temperatures and are irreversible,that is,the polymerization remains upon cooling.In fabricating thermosetting products,they can be removed from the mold at the fabrication temperature (typically 200 to 300).By contrast,thermoplastics must be cooled in themokd to prevent distortion.It might also be noted that network copolymers can be formed similar to be the block and graft copolymers.The network copolymer will result from polymerization of a combination of more than one species of polyfunctional monomers.2.5.4 AdditivesCopolymers and blends were discussed above as analogs of metallic alloys.There are aeveral other alloylike additives that traditionally have been used in polymer technology to provide specific characteristics to the polymers .A plasticizer is added to soften a polymer.This addition is essentially blending with a low molecular weight (approximately 300 amu) polymer.A filler ,on the other hand .is added to strengthen a polymer primarily by restricting chain mobility.it also provides dimensional stability and reduced cost.Relatively inert materials are used.Examples include shortchanger cellulose (and organic filler) and asbestos (and inorganic filler).Roughly one third of the typical automobile tire is a filler (i.e.,carbon black).Reinforcements such as glass fibers are also categorized as additives but produce suchfundamentally different materials (e.g.,fiberglass) that they are properly discussed later on composites.Stabilizers are additives used to reduce polymer degradtion.They represent a complex set of materials because of the large variety of degradation mechanisms(oxidation,thermal,and ultraviolet).As an example,polyisoprene can absorb up to 15% oxygen at room temperature with its elastic properties being destoryed by the first 1%.Natural rubber latex contains complex phenol groups that retard the room temperature oxidation reactions.However,these naturally occurring antioxidants are not effective at elevated temperatures.Therefore ,additional stabilizers(e.g.,other phenols,amines,sulphur compounds,etc.)are added to rubber intended for tire applications.Flame retardant are added to reduce the inherent combustibility of certain polymers such as bustion is simply the reaction of a hydrocarbon with oxygen accompanied by substantial heat evolution.Many polymeric hydrocarbons exhibit combustibility.Others,such as polyvinylchloride(PVC),donot.The resistance of PVC to combustion appears to come from the evolution of the chlorine atoms from the polymeric chaim.These halogens hinder the process of combustion by terminating free radical chain reactions.Additives that provide this function for halogen free polymers include chlorine,bromine,and phosphorus containing reactants.Colorant are additions to provide color to a polymer where appearance is a factor in materials selection.Two types of colorants are used,pigments and dyes.A pigment is an insoluble,colored material added in powered form.Typical examples are crystalline ceramics such as titanium oxide and aluminum silicate,although organic pigments are availble.Dyes are soluble,organic colorants that can provide transparent colors.2.5.5 Viscoelastic DeformationAt relatively low temperature,polymers are rigid solids and deform elastically.At relatively high temperatures,they are liquidlike and deform viscously.The boundary between elastic and viscous behavior is again known as the glass transition temperature,Tg.However,the variation in polymer deformation with temperature is not demonstrated in the sameway.For glassws,the variation in viscosity was plotted against temperature.For polymers,the modulus of elasticity is plotted instead of viscosity.There is a drastic and complicated drop in modulis with temperature for a typical,commercial thermoplastic with approxinately 50% crystallinity.THe magnitude of the drop is illustrated by the use of a logarithmic scale for modulus.At "low" temperatures (well below Tg),a rigid modulus occurs corresponding to mechanical behavior reminiscent of metals and ceramics.However,the substantial component of secondary bonding in the polymers cause the modulus for these materials to be substantially lower than the ones found for metals and ceramics,which were fully bonded by primary chemical bonds (metallic,ionic,and covalent).In the glass transition temperature (Tg) range,the modulus drops precipitously and the mechanical behavior is leathery.The polymer can be extensively deformed and slowly returns to itTys original shape upon stress removal.Just above Tg,a rubbery plateau is observed.In this region,extensive deformation is possible with rapid spring back to the original shape when stress is removed.These last two regions(leathery and rubbery) extend our understanding of elastic deformation.Sometimes the elastic deformation meant a relatively small strain directlyproporyional to applied stress.For polymers,extensive,non-linear deformationcan be fully recovered and is ,by definition,elastic.This concept will be explored shortly when we discuss elastomers,those polymers with predominant rubbery region.2.5.6 ElastomersTypical linear polymers exhibits a rubbery deformation region.For certain polymers known as elastomers,the rubbery plateau is pronounced and establishes the normal room temperature behavior of these materials.(For these materials,the glass transition temperature is below room temperture.)This subgroup of thermoplastic polymers includes the natural and synthetic rubbers (such as polyisoprene).These materials provide a dramatic example of the uncoiling of a linear polymer.As a practical matter,the complete uncoiling of the molecule is not achieved,but huge elastic strains do occur.The stress-strain curve for the elastic deformation of an elastomer shows dramatic contrast to the stress-strain curve for a common metal.In that case,the elastic modulus was constant throughout the elastic region (stress was directly proportional to strain).While the clastic modulus (slope of thestress-strain curve) increases with increasing strain.For low strains,the modulus is low corresponding to the small forces needed to overcome secondary bonding and to uncoil the molecules.For high strains,the modulus rises sharply,indicating the greater force needed to stretch the primary bonds along themolecular "backbone".In both region,however,there is a significant componrnt of secondary bonding involved in the deformation mechanism,and the moduli are much lower than those for common metals and ceramics.Tabulated values of moduli for elastomers are generally for the low strain region in which the materials are primarily used.Finally,it is important to emphasize that we are talking about elastic or temporary deformation.The uncoiled polymer molecules of an elastomer recoil to their original length upon removal of stress.2.5.7 Stress RelaxationFor metals and ceramics,we found creep deformation to be an important phenomenon at high temperatures (greater than one half the absolute melting point).A similar phenomenon,termed stress relaxation,occurs in polymers.This is perhaps moresignificant to polymers.Because of their loe melting points,stress relaxation can occur at room temperature.A familar example is the rubber band,understress for a long period of time,which does not snap back to its original size upon stress removal.2.4（88）Chemical substitutions in the BaTio3 structure can alter a number of ferro electric properties.For example,BaTio3 exhibits a large peak in dielectric constant near the Curie point-a property that is undesirable for stable capactior applications.This problem may be addressed by the substitution of lead (**) for (**),which increases the Curie point;by the substitutionof strontium,which lowers the Curie point;or by substituting Ba with calcium,which broadens the temperature range at which the peak occurs.Barium titanate can be produced by mixing and firing barium carbonate and titanium dioxide,but liquid-mix techniques are increasingly used in order to achieve better mixing,precise control of the barium titanium ratio,high purity,and submicrometre particle size.Processing of the resulting powder varies according to whether the capacitor isto be of the disk or multilayer type.Disks are dry pressed or punched from tape and then fired at temperatures between 1250 and 1350.Silver-paste screen printed electrodes are bonded to the surfaces at 750.Leads are soldered to the electrodes,and the disks are epoxy coated or wax impregnated for encapsulation.The capacitance of cermic disk capacitors can be increased by using thinner capacitors;unfortunately,fragility result.Multilayer capacitors overcome this problem by interleaving dielectric and electrode layers.The electrode layers are usually palladium or a palladium-silver alloy.These metals have a melting point that is higher than the sintering temperature of the ceramic,allowing the two materials to be cofired.By connecting alternate layers in paralled,large capacitance can be realized with the MLC.The dielectric layers are processed by tape casting or doctor blading and then yer thickness as small as 5 micrometres have been achieved.Finished "build" of dielectric and electrode layers are then diced into cubes and cofired.MLCs have the advantages of small size,low cost ,and good mounting on circuit boards.They are increasingly used in palce of disk capacitors in most electronic circuitry.Where monolithic units are still。
材料科学与工程专业英语翻译
材料科学与工程专业英语翻译Unit1：交叉学科 interdiscipline介电常数 dielectric constant 固体性质 solid materials热容 heat capacity 力学性质 mechanical property电磁辐射electro-magnetic radiation材料加工processing of materials 弹性模量（模数）elastic coefficient1.直到最近，科学家才终于了解材料的结构要素与其特性之间的关系。
It was not until relatively recent times that scientists came to understand the relationship between the structural elements of materials and their properties .2.材料工程学主要解决材料的制造问题和材料的应用问题。
Material engineering mainly to solve the problem and create material application.3.材料的加工过程不但决定了材料的结构，同时决定了材料的特征和性能。
Materials processing process is not only to de structure and decided that the material characteristic and performance.4.材料的力学性能与其所受外力或负荷而导致的形变有关。
Material mechanical properties with the extemal force or in de deformation of the load.Unit2：先进材料 advanced material陶瓷材料 ceramic material粘土矿物 clay minerals高性能材料high performance material 合金 metal alloys移植 implant to玻璃纤维 glass fiber 碳纳米管 carbon nanotub1、金属元素有许多有利电子，金属材料的许多性质可直接归功于这些电子。
材料科学与工程第四版部分翻译
P2Material science is the investigation of the relationship among processing, structure, properties, and performance of materials.材料科学是研究材料的加工，组织性能和功能之间关系的学科（材料与工程之间的关系可以用图一的四面体来表示）P2The discipline of materials science involves investigating the relationships that exist between the structures and properties of materials.材料科学是研究材料的结构和性能之间的关系的学科In contrast, materials engineering is, on the basis of these structure-property correlations, designing or engineering the structure of a material to produce a predetermined set of properties. 而材料加工是在材料组织和性能关系的基础上，对材料的组织进行设计，以获得一系列预定的性能P5 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 concentrations may be controlled over very small spatial regions. The semiconductors have made possible the advent of integrated circuitry that has totally revolutionized the electronics and computer industries.半导体有介于电导体和绝缘体之间的性能。
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热性能指的是材料受热时的响应，研究材料的热性能是非常重要的。
通常情况下，固体以热的形式吸收能量，它的温度和尺寸都会增加。
如果存在温度梯度能量就会传输到工件上温度更低的区域，最终工件会熔化。
在使用实际应用中，热容，热膨胀和导热性通常是很关键的。
本章的目的就是描述先前从未接触过的重要的材料热性能。
特别的，我们讨论热膨胀，热容和导热性对材料的综合影响。
和以往一样，我们着重强调在这些性能和原子组成结构的关系。
最后，我们描述材料的热传导机理和热应力。
当材料被加热的时候，固体中原子的平均热能就会增加。
大约一半的能量用于增加原子的势能，另一半用于增加原子的平动能和振动能。
原子的振动产生振动波束也叫做声子会沿着固体传播。
由于能量是量子化的，只需通过改变原子的数量就能改变声波的能量。
因此声子的能量是量子化的并与振动原子的波长有关，在公式中是代表振动频率。
我们将会看到原子的振动对于理解材料的热性能的物理机理是非常重要的。
绝倒多数材料在加热时会膨胀，冷却时会收缩。
线性热膨胀系数是表征材料随温度的变化而膨胀或收缩的参数。
线性热膨胀系数通过公式来定义。
公式中热应变是由温度的变化引起的。
我们知道原子得到热能，其振动就会加剧。
由于键能曲线是不均匀的，相邻原子之间的平均间距会随着温度的增加而增加。
除了长度改变外，人们也会对固体体积随温度变化而变化感兴趣。
通过义体积热膨胀系数，我们能得到下面这个方程。
其中是初始体积，是由温度变化所引起的材料体积的变化。
对于各向同性的固体而言，体积热膨胀系数和线性热膨胀系数的关系是。
然而我们也应该意识到并不是所有材料都是各向同性的。
讨论到现在我们也许会得到错误的结论的图像是温度的函数，这个图像是通过给予的斜度产生的一条直。
图9.1中展示了来自这种行为的某些误差展示了一些的突然变化，这一温度变化与二氧化硅的晶体结构有关。
该临界温度是材料发生多晶体相变时的温度。
然而，即使对于单晶材料，也能经常观察到来自应变随温度变化而变化行为的误差。
就像图9.1b中那样许多陶瓷中也有不恒定值。
我们也该注意到熔融的石英在图中展示的整个温度范围内值接近零。
因此，我们应该知道方程9-1只是在相对较小的温度范围内才成立，在选用手册中的值进行计算的时候必须注意这个问题。
根据原子键合的特点，合理的归纳几种不同类别的材料的值是可能的。
例如，由于热塑性塑料聚合体链之间缺乏主价键连接，这些材料就表现出相对较高的值。
相反，网状聚合体在未拉伸状态下的值较小。
晶体材料中，金属具有最大的膨胀系数值。
然而，这些值通常低于绝大多数聚合体材料的值。
许多陶瓷晶体比金属晶体更松散。
因此，一些原子的振动就能够在没有膨胀的情况下发生。
所以，通常情况下，陶瓷晶体有比金属晶体更低的值。
非晶体结构的陶瓷材料的值变化范围很大。
玻璃的膨胀行为是一个与其成分和热过程有关的复杂函数。
材料的热容C是一摩尔的材料升高一度所需要吸收的热量。
数学表达式为C=。
在这个公式中dQ是让材料升高dt的温度所需要的热量。
为了大体上获得理论上的热容值不需得到表达式dq\dt的值。
经典的热力学计算表明一个原来在温度t下的固体状态所获得的三维方向的热能通过下式给出。
Q=。
在这里k表示波尔斯曼常数，na表示阿伏伽德罗常数。
通过关于温度的微分我们发现。
这里R是气体常数，其值为8.1314。
公式9-6就是有名的。
公式。
这个简化的表达式是在等体积上加热的。
此外，在等式9-6中的热容是指C，并且另一种是热量在常压下被加到固体上。
相应的热容c就会变大，因为固体体积在常压下变大需要额外的热量。
Cv和Cp的不同是，随着温度的升高并且只有在接近晶体固体融化或者在无定形固体在玻璃态转化的时候是重要的。
单位质量的热熔叫做材料的比热。
我们用大写字母C表示比热，用小写字母c表示热熔。
恒压下比热的数值Cp是通过实验数值给出的。
与热熔类似，Cv和Cp的不同可以被忽略。
通过实验数值我们能够得到比热Cp和理论估计值Cv之间可以通过下式计算。
注意的是热熔和比热都是物质固有的性质。
相似的非固有的性质叫做热电容，Csh，通过固有的性质Cv和材料的质量M相乘得到。
这里p是材料的密度，V是体积。
热容是指让物质升高一摄氏度所必须的热量。
热电容是一个应用中的设计参数，其中温度变化相对于时间的速率dT\dt是很重要的。
如果其他的变量都是常数，一个系统中温度转化的最大速率反比与热电容。
此外，当需要温度快速变化时，低Cth的材料更好。
例如，多空的陶瓷耐火材料比同种材料的固体砖块材料在填充熔炉是更合适，因为他们的低的热电容允许更快的冷却和加热速率。
通过实验我们知道多空材料能够有更好的保热性。
在设计集成电路时的一个问题是在耗能电子元件中电阻的加热会造成温度的升高。
当电流通过元件，热量耗散。
Q可以通过下式计算。
这里Q是以焦耳为单位的。
I是以安培为单位的，R是电阻以欧姆为单位。
这个过程产生的热量可能是很大的。
如果热量不能够被耗能元件临近的散热元件通过物质带走，它能够引起元件温度的升高和相应的性能的下降。
尽管炊具都能用金属制造出来，但是许多金属器皿仍然有用木头或塑料做的手把。
为什么要进行这种设计上的修改呢？当你握着厚厚的金属手把拿起一个被加热一段时间的很重的盘子的时候，你就知道答案了——金属手把变得很烫了。
相反，塑料手把并不会把热量从热源传到你手上，所以即使盘子变热了手把仍然是冷的。
在这个部分，我们将会解释原子结构与材料热传导能力之间的关系。
由于温度梯度引起的热能通过固体物质传导类似于由于浓度梯度引起的原子扩散。
热传导的方向是从高温区向低温区（即温度梯度降低的方向），描述一种材料的热传导能力的参数是热导率。
温度梯度和热导率K之间的关系类似于5.4部分的扩散方程考虑到图9.2中展示的热流问题，温度梯度和热导率K之间相关的方程是……。
在方程中是单位时间内面积为A的平面所传导的热量。
K的单位是或。
方程9—10表明单位时间单位面积内的热流正比于温度梯度，并且比例常数是热导率。
热能传过一种材料可以通过两种机制晶体震动（声子）或者是自由电子的运动。
因此，最简单的模型是K=Kp+Ke,Kp代表声子的作用，Ke代表电子的作用。
这两种机制的相对重要性主要取决于材料的电子键合结构。
当材料中部分价键填充的时候，热传导主要取决于自由电子的运动。
小键长材料例如半导体中，两种机制的作用都很显著，然而大键长材料例如金刚石主要是声子机制。
方程9-2表明在稳态条件下唯一影响热传导的与材料有关的参数是热导率。
然而在非稳态条件下，情况就变得稍微复杂一些。
不加推导引出的决定方程是值。
在方程中，Dth是称为热扩散系数的材料性能。
毫无疑问，这个与时间无关的热传导方程等同于第5章提到的与时间无关的扩散方程。
Dth可以定义为更加基本由K和Cp决定的热参数。
在方程中是材料的密度。
使用前面的两个方程的时候，Dth的单位是。
注意这些单位与扩散系数D的单位相同。
由于高的Dth值意味着当温度急剧变化的时候材料能够迅速作出响应，因此在工程实践中，在温度梯度非常重要的场合热扩散也许是最重要的设计指标。
在前面部分介绍的热容的作用是什么呢？方程9-13表明Dth确实含有Cth的概念，因此影响材料单位质量热容的决定因素是非常重要的。
对于快速的热传导，重要的不仅是低的热容还有高的热导率。
你有过从洗碗机中取出过热的杯子并倒上冷饮料使玻璃杯破碎？你有过把吃剩的东西放在玻璃盘子里面存放在冰箱并把盘子直接放在热火炉上使盘子破裂吗？这是两个由热应力引起的材料失效的例子。
当靠近熔炉的冷却水管出现裂缝并把冷却水喷到熔炉内衬的时候，由热应力引起的材料失效在工业生产中也许会发生。
在这部分我们描述热应力形成的机理并讨论如何选择材料以减少由热应力引起的材料失效。
对于有着非零α值的材料，温度的改变会引起材料空间尺寸的改变叫做热应变。
在特定的情况下热应变会反过来产生一个热应力，当这个热应力达到较大的量级的时候便会引起材料的失效。
考虑到在图9-3中展示的情况。
在这个图的a部分，一根不收约束的原长为L。
的长条状材料伸长量为*L=···。
在这个图的b部分，相同长度的长条状材料被约束住以致不能够伸长当温度升高*T的时候。
为了使长条状材料上总的应变为零，热应变必须通过一个相反方向的机械应变m来平衡，这个机械应变有相同的数值但是方向相反。
用数学表示为···。
在这种特殊的情况下我们可以得到···和如果应变是足够的小以致于变形是弹性的，我们就可以发现···。
另外一种形式的热饮发的应力发生在当两种有着不同热膨胀系数的材料被紧固在一起时。
这种情形在图9-4中展示出来。
孤立的A和B将会分别发生大小为···和···的热应变。
然而当快速的连在一起，A的应变将会和B的应变相等。
因此，必须有一个额外的机械应变在两个棒材上发生···通过假设弹性变形和在接口处用一个力平衡，这个等式可以用来决定每一个棒材的热变形。
这种形式的热应力通常发生在两种复合的材料中。
例如，层状的电子设备将会因为热应力的不协调而失效。
印刷电路板，还有集成电路，是由导电的金属和不导电的陶瓷或聚合物组成的几层。
不同金属的热膨胀系数不同，导致力的产生在织构处，并且会进一步发展在使用过程中。
应变的数值可以用下式估算···。
由于错位引起的力可能引起电路板翘曲或层与层间失去胶合。
相似的影响也会在其他的异种材料结合和材料中出现。
需要注意的是当系数吻合的时候没有压力会产生。
微应力也会在单相多晶材料中产生由于晶体的各向异性。
这个问题在陶瓷中尤为严重。
作为最后一个产生热应变的机制，考虑到9-5中展示的那样。
这种情况下，一个热的固体被用冷水喷洒。
如果表面裂纹出现，潜在的脆性失效就将存在。
这种现象叫做热冲击。
几种材料性能有助于抵抗热冲击失效。
首先，由于热应力的值与···成比例，小的···数值将会帮助最小化这个问题。
其次，热应力的根源是式样厚度方向的温度梯度。
因此，梯度的数值与式样的热应变成反比关系，比较大的K值是好的。
第三，材料失效当断裂应力，通过···定义的，超过极限。
因此，在候选材料中选择材料应用并且这种场合抵抗热冲击的能力是相当重要的，那么就必须选择有着最高···比例的材料。
十二章在决定材料的加工和其可能的实际应用的时候，材料的机械性能，包括强度，刚度和延展性都是非常重要的。
许多材料服役的时候，都要承受力或者是载荷的作用。