第一篇：机械工程英语翻译

Part2

Unit 12

Nanomaterial and Micro-machine

纳米材料和微型机器

Nanomaterial

纳米材料

Nanomaterials and nanotechnolology have become a magic word in modern society.纳米材料和纳米技术已成为现代社会一个具有魔幻色彩的词汇。Nanomaterials represent today’s frontier in the development of novel advanced materials and present great promises and opportunities for a new generation of materials with improved and tailorable properties for applications in sensors, optoelectronics, energy storage, separation and catalysis.纳米材料代表了当今新型先进材料发展的前沿，为具有各种改良的、能按照人们各种要求进行“定制”的性能的新一代材料，在传感器、光电子学、储能、分离和催化剂技术等方面提供了广阔的应用前景。So nanomaterials are considered as a great potential in the 21th century

because of their special properties in many fields such as optics, electronics, magnetic, mechanics, and chemistry.因此纳米材料被视为21世纪具有巨大的潜力的一种材料，因为在很多领域如光学、电子学、磁学、力学和化学他们的特殊性质。

These uinque properties are attractive for various high performance applications.这些特殊的性质对于各种不同高性能的应用程序 来说具有很大的吸引力。

Exampeples include wear-resistant surfaces, low temperature sinterable high-strength ceramics, and magnetic nanocomposites.例如耐磨的表层以及在低温环境下 具有高张力的陶瓷和磁力纳米复合材料。

Nanostructured materials present great promises and opportunities for a new generation of materials of materials with improved and marvelous properties.纳米结构的材料为新一代具有改良的非凡的性能的材料提供了广阔的前景。

It is appropriate to begin with a brief introduction to the history of the subject.在这里简单介绍一下纳米材料的历史。

Scientific work on this subject can be traced back over 100 years.在这方面的科学研究可以追溯得到100多年以前。

In 1861 the British chemist Thomas Graham coined the term “colloid” to describe a solution contion containing 1 to 100 nm diameter particles in suspension.在1961年，英国化学家格雷姆首次用“胶体”这个术语来描述一种含有直径为1~100nm的微小悬浮颗粒的溶液。

Around the turn of century, such famous scientists as Rayleigh, Maxwell, and Einstein studied colloids.大约在20世纪末20世纪初的时候，一些有名的科学家如雷利,麦克斯韦和爱因斯坦开始研究胶体。

In 1930 the Langmuir-Blodgett method for developing monolayer films was developed.1930年，单分子薄膜的狼缪尔布罗杰特方法形成。

By 1960 Uyeda had used electron microscopy and diffraction to study inpidual particles.到1960年Uyeda 已经用电子显微镜检查法以及衍射来研究单个粒子。At about the same time, arc, plasma, and chemical flame furnaces were employed to produce submicron particles.几乎是同一时间 电弧，单离子体和化学反射炉已经用于生产亚微米粒子了。

Magnetic alloy particles for use in magnetic tapes were produced in 1970.1970年磁力合金粒子已经运用于磁带中了。

By1980, studies were made on clusters containing fewer than 100 atoms.到1980年，已有很多人开始对含有不到100个原子的原子团进行了研究。In1985,a team led by Smalley and Kroto found spectroscopic evidence that C60 clusters were unusually stable.在1985年，一个由斯莫利和克罗托领导的科研小组通过光谱分析证实了C60原子团具有不同寻常的稳定性。

In1991, Lijima reported studies of graphitic carbon tube filaments.1991年，Lijima 也报道了有关石墨碳管状丝材的研究情况。

Research on nanomaterials has been stimulated by their technological applications.关于纳米材料的研究是在他们的技术的应用引起的。

The first technological uses of these materials were as catalysts and pigments.这些纳米材料的第一次技术使用是催化剂和天然色素运用。

The large surface area to volume ratio increases the chemical activity.大面积的体积比增加到化学活动上。

Because of this increased activity, there are significant cost advantages in fabricating catalysts from nanomaterials.正因为这些增加的研究，从纳米材料上制造催化剂才有了巨大的成本优势。

The properties of some single-phase materials can be improved by preparing them as nanostructurs.一些单相的材料的性能还可以通过纳米结构来优化。

For example, the sintering temperature can be decreased and the plasticity increased on single-phase, structural ceramics by reducing the grain size to several nanometers.例如，降低燃烧温度，把颗粒大小缩小几个纳米，可以单相的提升建筑陶瓷的可塑性。

Multiphase nanostructured materials have displayed novel behavior resulting from the small size of the inpidual phases.由单个颗粒的小型体积，多相的纳米结构材料已经展示了非比寻常的性质。

In microelectronics, the need for faster switching times and ever larger integration has motivated considerable effort to reduce the size of electronic components.在微电子学中，对快速转换时间和更大规模的集成电路的需要在减小电子元件尺寸的工作起到了很大的作用

Increasing the component density increased the difficulty of satisfying cooling requirements and reduces the allowable amount of energy released on switching between states.而增加器件密度又会增加必须满足冷却条件以及减少开关状态转换是所允许的最大能量释放的难度。

It would be ideal if the switching occurred with the motion of a single electron.在单电子的移动时开关是最理想的状态。

One kind of single-electron device is based on the change in the Coulombic energy（库伦能）when an electron is added or removed from a particle.当从一个粒子中增加或较少一个电子的时候，一种单电子装置是以库伦能的变化为基础的。

For a nanoparticle this energy change can be large enough that adding a single electron will effectively block the flow of other electrons.对于纳米粒子来说，这个能量的变化因增加单个电子有效的限制其他电子的流动而充分。

In addition to technology, nanomaterials are also interesting systems for basic scientific investigations.除了技术，纳米材料的基本科学调查也是有趣的系统。For example , small particles display deviations偏差 from bulk 体积solid behavior such as reductions in the melting temperature and changes(usually reductions)in the lattice parameter.（网状参数）

例如微粒材料和块状材料会呈现出不同的性能，比如其熔点降低和晶格参数变小。

The changes in the lattice parameter observed for metal and semiconductor particles result from the effect of the surface stress, while the reduction in the melting temperature results from the effect of the surface free energy.金属和半导体粒子观察来的晶状参数变化是来自于表面的压力，而熔点的降低是来自于表层的自由能的作用。

By studying the size dependence of the properties of particles, it is possible to find the critical length scales at which particles behave essentially as bulk matter.通过研究微粒性能的数量相关性，有可能发现微粒像块状材料性能的临界尺度。

Generally, the physical properties of a nanoparticle approach bulk values for particles containing more than a fen hundred atoms.一般说来，纳米粒子如果达到包含有几百个原子的大小时，其物理性能就会接近块体材料。

New techniques have been developed recently that have permitted researchers to produce larger quantities of other nanomaterials.发展的新技术已经被研究学者用于发掘纳米材料的更多的性能了。Each fabrication technique has its own set of advantages and disadvantages.每项制造技术都有其优缺点。

Chemical techniques are very versatile in that they can be applied to nearly all materials(ceramics, semiconductors, and metals)and can usually produce a large amount of materials.化学技术是通用的，它可以运用到陶瓷，半导体以及金属等所有种材料中，还可以用来生产大量的其他材料。

A difficulty with chemical processing is the need to find the proper chemical reactions and processing conditions for each material.化学处理的困难是需要找到合适每种材料的化学反应以及反应条件。

The ability to characterize nanomaterials has been increased greatly by the invention of the scanning tunneling microscope(STM)and other proximal probes such as the atomic force microscope(AFM), the magnetic force microscope, and the optical near-field microscope.因为扫描隧道电子显微镜以及源自显微镜和磁力显微镜等类似仪器的发明，人们对纳米的特点的认知能力又大大增强了。STM has been used to carefully place atoms on surfaces to write bits using a small number of atoms.STM

（扫描隧道电子显微镜）技术一般用来将少量的单个原子小心地“搬运”到某些材料得的表面来书写二进制数码。

It has also been employed to construct a circular arrangement of metal atoms on an insulating surface and hence a nano-scale electronic component is fabricated.它还可以用来在绝缘表面将金属原子摆放成一个环状图形，从而制造出纳米尺寸的电子器件。

Other new instruments and improvements of existing instruments are increasingly becoming important tools for characterizing surface of films, biological materials, and nanomatirials.其他新的工具和现有工具的改善已经成为显现薄膜表层，生物材料以及纳米材料的主要手段。

The development of nanoindentors and the improved ability to interpret resulting from nanoindentation measurements have increased our ability to study the mechanical properties of nanostructured materials.纳米材料的发展以及改良的纳米技术的测量能力的展现增强了我们去研究纳米结构材料的性能的能力。

Improved high-resolution electron microscopes and modeling of the electron microscope images have improved our knowledge of the structure of the particles and the interphase region between particles in consolidated nanomaterials.改良的高分辨率的电子显微镜以及 电子显微镜图像的模型提高了我们对粒子的结构以及在加固的纳米材料的分裂区间的认识。

Micro-machine 微型机器 Introduction 介绍

From the beginning, mankind seems instinctively to have desired large machines and small machines.从一开始，人类似乎就本能地有一种想制造“大机器”和“小机器”的愿望。

That is , “large” and “small” in comparison with human －scale.这里的所谓“大”和“小”是相对人类本身的尺寸而言的。

Machines larger than human are powerful allies in the battle against the fury of nature;smaller machines are loyal partners that do whatever they are told.比人体大的机器将称成为人类同暴虐无情的自然界作斗争的得力帮手，而那些小机器则只能乖乖听从人类的命令，让干什么就干什么。

If we compare the facility and technology of manufacturing larger machines, common sense tells us that the smaller machines are easier to make.如果我们将生产大型机器的设备和技术相比，常识告诉我们小型机器更容易制造。

Nevertheless, throughout the history of technology, larger machines have always stood out.尽管如此，整个技术的历史，较大型机器一直很突出。

The size of the restored models of the water-mill invented by Vitruvius in the Roman Era, the windmill of the Middle Ages,and the steam engine invented by Watt is overwhelming.维特鲁维在罗马时代发明恢复模型尺寸大小的水车，中世纪的风车，和瓦特发明的蒸汽机是势不可挡的。

On the other hand, smaller machines in history of technology are mostly tools.另一方面，小型机器的科技历史大部分是工具。

If smaller machines are easier to make, a variety of such machines existed，but until modern times ,no significant small machines existed except for guns and clocks.如果小型机器相对容易制造，那么会存在一系列这样的机器，但直到现代，没有重要的小机器存在除了枪和闹钟外。

This fact may imply that smaller machines were actually more difficult to make.这样的事实可能暗示较小机器事实上是更难制造。

Of course, this does not mean simply that it was difficult to make a small machine;it means that it was difficult to invent a small machine that would be significant to human beings.当然，这并不简单意味着制造一个小机器是很困难的；而是意味着创造一个小机器是困难的，那将对人类是重要的。

Some people might say that mankind may not have wanted smaller machines.一些人可能会说人类可能不需要较小型机器。

This theory, however, does not explain the recent popularity of palm-size mechatronics products.然而，这一理论并不能解释最近流行的手掌大小的机电一体化产品。

The absence of small machines in history may be due to the extreme difficulty in manufacturing small precision parts.历史上小机器的缺乏可能是由于制造高精度小部件极度困难。The dream of the ultimate small machine, or micro-machine, was first depicted in detail about 30 years ago in the 1966 movie “Fantastic Voyage.”

最终的小机器或微型的梦想，首次被描述在详细介绍30年前在1966年的“奇妙的航行”科幻电影中。

At the time, the study of micro-machining of semiconductors had already begun.那时候，半导体的微细加工的研究已经开始。

Therefore, manufacturing minute mechanisms through micro-machining of semiconductors would have been possible.然而，通过半导体的微加工制造分钟的机制是有可能的。

There was, however, a wait of over 20 years before the introduction of electrostatic motors and gears made by semiconductor micro-machining.然而，有等待超过20年引进的半导体微细加工制成的静电马达和齿轮。

Why didn’t the study of micro-machining and the dream of micro-machines meet earlier?

为什么不把微加工的研究和微型机械的梦想早一点接触呢? A possible reason for this is as follows.一个可能的原因如下。

In addition to micro-machining, the development of micro-machines requires a number of technologies including materials, instrumentation, control, energy, information processing, and design.此外微加工，微型机器的发展需要许多科技技术包括物材、仪器仪表、控制、能源、信息处理和设计。

Before micro-machine research and development can be started, all of these technologies must reach a certain level.在微型机器研究和发展开始前，所有这些技术必须达到一定水平。In other words, the overall technological level, as a whole, must reach a certain critical point, but it hadn’t reached that point 40 years ago.换句话说，整体技术水平，作为一个整体，必须达到一定的临界点，但在40年以前是达不到这一点。

Approximately 20 years after “Fantastic Voyage ,”the technology level for micro-machines finally reached a critical point.大约在科幻电影《奇妙的航行》上映后20年，微型机械的技术终于达到一个相当水平。

Micro-motors and micro-gears made by semiconductor micromachining were introduced at about that time, triggering the research on development of micro-machines.用半导体加工技术制造出的微型电动机和微型齿轮机构开始在那时候出现，从而刺激了微型机械的研究和发展。

Micromachines as Gentle Machine 微电机作为温和的机器

The most unique feature of a micro-machine is , of course, its small size.Utilizing its tiny dimensions , a micro-machine can perform tasks in a revolutionary way that would be impossible for conventional machines.当然，它的体积小的微型机器的最独特的功能。利用其微小的尺寸，微机器可以一种革命性的方式，执行传统的机器不可能的任务。That is , micro-machines do not affect the object or the environment as much as conventional machines do.也就是说，相比传统机器，微型机器可以尽可能多的不影响它的对象或环境。

Micro-machines perform their tasks gently.This is a fundamental difference between micro-machines and conventional machines.微型机器可以柔和的执行他们的任务。这是微型机器和常规机器之间的根本区别。

The medical field holds the highest expectations for benefits from this feature of micro-machines.在医疗领域拥有最高期望得益于微型机器的特点。

Diagnosis and treatment will change drastically from conventional methods, and “Fantastic Voyage” may no longer be a fantasy.诊断和治疗将从传统方法上发生急剧变化，同时“神奇之旅”可能不再是一个幻想。

If a micro-machine can gently enter a human body to treat illnesses, humans will be freed from painful surgery and uncomfortable gastro-camera testing.如果一个微型机器可以轻轻地进入人体，以治疗疾病，人类将摆脱痛苦的手术和不舒服的胃肠相机测试。

Furthermore, if micro-machines can halt the trend of ever-increasing size in medical equipment, it could slow the excess growth and complexity of medical technology, contributing to the solving of serious problems with high medical costs for citizens.此外，如果微型机器可以控制医疗设备日益增加大尺寸，它可能会放缓医疗技术过剩的增长和复杂性，从而促使公民高额的医疗费用问题得到解决。

Micro-electronics and mechatronics 微型电子和机电一体化

The concept of micro-machines and related technologies is still not adequately unified, as these are still at the development stage.微型机器和相关技术的概念，还没有充分统一，因为这是仍处于发展阶段。

The micro-machines and related technologies are currently referred to by a variety of different terms.目前，微型机器及其相关技术涉及许多不同术语。

In the United States, the accepted them is “Micro Electro Mechanical Systems”(MEMS);in Europe, the term “Microsystems Technology”(MST)is common, while the term “micro-engineering” is sometimes used in Britain.在美国，“微机电系统”（MEMS）是被接受的，在欧洲通常叫“微系统技术”（MST）而在英国它被称作“微型工程”。Meanwhile in Australia “Micro-machine”.与此同时它在澳大利亚被称作“微型机器”。

The most common term if it is translated into English is "micro-machine” in Japan.最常见到术语，在日本它如果被翻译成英文是“微型机器”。

However “Micro-robot” and “Micro-mechanism are also available case by case.但是“微型机器人”和微观机制“也是到处可见的。

The evolution of machines and micromachines 机器和微型机器的发展

Many researchers see micro-machines as the ultimate in mechatronics , developed out of machine systems.许多研究人员把微型机器看作是机电一体化最终开发的系统。Ever since the Industrial Revolution, machine systems have grown larger and larger in the course of their evolution.自从工业革命以来，机器系统在其演化过程中已经越来越大。Only very recently has evolution in the opposite direction begun, with the appearance of mechatronics.最近机电一体化的外观次啊开始在反方向的演变。

Devices such as video cameras, tape recorders, portable telephones, portable copiers which at one time were too large to put one’s arms around , now fit on the palm of one’s hand.设备，如摄像机，录音机，便携式电话，便携式复印机，曾经太大以至于拿起来就是身边的武器，现在适合放在也个人的手上。

Miniaturization through mechatronics has resulted mainly from the development of electronic controls and control software for machine systems, but the changes to the structural parts of machine systems have been minor compared to those in the control systems.机械电子技术的发展带来的结构微型化主要是机械系统中电子控制技术和控制软件发展的结果。但机械系统结构部件的发展变化与控制系统的技术发展还是无法相比。

The next target in miniaturization of machine systems is miniaturization of the structural parts left untouched by present mechatronics.机械系统微型化的下一个目标是当前电子技术尚未触及到的结构部件的微型化。

These are the micro-machines which are seen as the ultimate in mechatronics.这就是所谓被视为机械电子学终极发展目标的微型机械

Seen in this light, the aim of micro-machines can be expressed as follows: 由此看来，微型机器的目的，可以表示如下

“Micro-machines are autonomous machines which can be put on a fingertip, composed of parts the smallest sized of which is a few dozen micrometers.”

微型机器是可以放在指尖上的自动机器，它的组成部分最小的尺寸是几十微米。

That is, since micro-machines which can be put on a fingertip have to perform operations in spaces inaccessible to humans, they are required to be autonomous and capable of assessing situations independently, as are intelligent robots.也就是说，既然要小到可以放在指尖上的微型机械完成那些由于空间位置限制人类而无法实行的操作，这些微型机械就应该具有”自治“能力，也就是说它们就像那些智能机器人一样，可以多所处的工作环境独，立做出判断。

To achieve this kind of functionality, a large number of parts must be assembled in a confined space.要实现这种功能，大量的部件必须组装在一个密闭空间内。

This factor determines the size of the smallest parts, and given the resolution of micro-machining systems, a target size of several dozen micrometers should be achievable.这个因素决定了组成部分的最小尺寸，由于微加工系统的解决，目标在几十微米大小是可以实现。

第二篇：机械工程英语翻译

Unit1

1、What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table.Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans.合金与纯金属的区别是什么？纯金属是在元素周期表中占据特定位置的元素。例如电线中的铜和制造烹饪箔及饮料罐的铝。

Alloys contain more than one metallic element.Their properties can be changed by changing the elements present in the alloy.Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium;and gold jewelry which usually contains an alloy of gold and nickel.合金包含不止一种金属元素。合金的性质能通过改变其中存在的元素而改变。金属合金的例子有：不锈钢是一种铁、镍、铬的合金，以及金饰品通常含有金镍合金。

2、Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio.为什么要使用金属和合金？许多金属和合金具有高密度，因此被用在需要较高质量体积比的场合。

Some metal alloys,such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy.Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金属合金，例如铝基合金，其密度低，可用于航空航天以节约燃料。许多合金还具有高断裂韧性，这意味着它们能经得起冲击并且是耐用的。

3、The atomic bonding of metals also affects their properties.In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere.Since electrons conduct heat and electricity, metals make good cooking pans and electrical wires.金属的原子连结对它们的特性也有影响。在金属内部，原子的外层阶电子由所有原子共享并能到处自由移动。由于电子能导热和导电，所以用金属可以制造好的烹饪锅和电线。

It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal.No photons pass through.因为这些阶电子吸收到达金属的光子，所以透过金属不可能看得见。没有光子能通过金属.4、Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.陶瓷和玻璃的特性高熔点、低密度、高强度、高刚度、高硬度、高耐磨性和抗腐蚀性是陶瓷和玻璃的一些有用特性。

Many ceramics are good electrical and thermal insulators.Some ceramics have special properties: some ceramics are magnetic materials;some are piezoelectric materials;and a few special ceramics are superconductors at very low temperatures.Ceramics and glasses have one major drawback: they are brittle.许多陶瓷都是电和热的良绝缘体。某些陶瓷还具有一些特殊性能：有些是磁性材料，有些是压电材料，还有些特殊陶瓷在极低温度下是超导体。陶瓷和玻璃都有一个主要的缺点：它们容易破碎。

5、An optical fiber contains three layers: a core made of highly pure glass with a high refractive index for the light to travel, a middle layer of glass with a lower refractive index known as the cladding which protects the core glass from scratches and other surface imperfections, and an out polymer jacket to protect the fiber from damage.光导纤维有三层：核心由高折射指数高纯光传输玻璃制成，中间层为低折射指数玻璃，是保护核心玻璃表面不被擦伤和完整性不被破坏的所谓覆层，外层是聚合物护套，用于保护光导纤维不受损。

In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light.为了使核心玻璃有比覆层大的折射指数，在其中掺入微小的、可控数量的能减缓光速而不会吸收光线的杂质或搀杂剂。

Because the refractive index of the core glass is greater than that of the cladding, light traveling in the core glass will remain in the core glass due to total internal reflection as long as the light strikes the core/cladding interface at an angle greater than the critical angle.由于核心玻璃的折射指数比覆层大，只要在全内反射过程中光线照射核心/覆层分界面的角度比临界角大，在核心玻璃中传送的光线将仍保留在核心玻璃中。The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.全内反射现象与核心玻璃的高纯度一样，使光线几乎无强度损耗传递长距离成为可能。Unit7

1、The importance of machining processes can be emphasised by the fact that every product we use in our daily life has undergone this process either directly or indirectly.机加工过程的重要性可通过日常生活使用的每件产品都直接或间接经历这一过程的事实来强调。(1)In USA, more than $100 billions are spent annually on machining and related operations.(2)A large majority(above 80%)of all the machine tools used in the manufacturing industry have undergone metal cutting.(3)An estimate showed that about 10 to 15% of all the metal produced in USA was converted into chips.(1)在美国，每年花在机加工及其相关作业上的费用都多于千亿美元

(2)用于制造业的全部机床中的大多数(多于80%)都经历过金属切削。(3)有估计显示美国生产的所有金属中约10到15%转变成了切屑。

2、Chip Formation 切屑的形成

Metal cutting process is a very complex process.Fig.7.2 shows the basic material removal operation schematically.金属切削过程是一个很复杂的过程。图7.2用图的形式显示了基本材料去除作业。The metal in front of the tool rake face gets immediately compressed, first elastically and then plastically.This zone is traditionally called shear zone in view of fact that the material in the final form would be removed by shear from the parent metal.在刀具前倾面前的金属直接受到压缩，首先弹性变形然后塑性变形。考虑到最终形状中的材料是通过剪切从母体金属去除的，此区域传统上称为剪切区。The actual separation of the metal starts as a yielding or fracture, depending upon the cutting conditions, starting from the cutting tool tip.Then the deformed metal(called chip)flows over the tool(rake)face.金属的实际分离始于屈服或断裂(视切削条件而定)，从切削刀尖开始。然后变形金属(称为切屑)流过刀具(前倾)面。

If the friction between the tool rake face and the underside of the chip(deformed material)is considerable, then the chip gets further deformed, which is termed as secondary deformation.The chip after sliding over the tool rake face is lifted away from the tool, and the resultant curvature of the chip is termed as chip curl.如果刀具前倾面与切屑(变形金属)底面之间的摩擦相当大，那么切屑进一步变形，这也叫做二次变形。滑过刀具前倾面的切屑被提升离开刀具，切屑弯曲的结果被称为切屑卷。

3、Discontinuous Chip.The segmented chip separates into short pieces, which may or may not adhere to each other.Severe distortion of the metal occurs adjacent to the face, resulting in a crack that runs ahead of the tool.间断切屑：分段的切屑分散成小碎片，既可能相互附着也可能不相互附着。在靠近切削面处发生金属的剧烈变形，导致在运动刀具前方金属层产生裂缝。Eventually, the shear stress across the chip becomes equal to the shear strength of the material, resulting in fracture and separation.With this type of chip, there is little relative movement of the chip along the tool face, Fig.7.3a.最后，横过切屑的剪切应力与材料的剪切强度相等，造成断裂和分离。生成这类切屑时，切屑沿刀具面几乎没有相对运动，见图7.3a。

4、Cutting Fluids 切削液

The functions of cutting fluids(which are often erroneously called coolants)are: • To cool the tool and workpiece • To reduce the friction • To protect the work against rusting • To improve the surface finish • To prevent the formation of built-up edge • To wash away the chips from the cutting zone 切削液(经常误称为冷却液)的功能如下：

• 冷却刀具和工件 • 减少摩擦 • 保护工件不生锈 • 改善表面光洁度

• 防止切屑瘤的形成 • 从切削区冲掉切屑

However, the prime function of a cutting fluid in a metal cutting operation is to control the total heat.This can be done by dissipating the heat generated as well as reducing it.The mechanisms by which a cutting fluid performs these functions are: cooling action and lubricating action.然而，在金属切削作业中切削液的主要功能是控制总热量。这可通过既散发又减少所产生的热量来达到。切削液实现这些功能的机理是：冷却作用和润滑作用

5、Lubricating action.The best improvement in cutting performance can be achieved by the lubricating action since this reduces the heat generated, thus reducing the energy input to the metal cutting operation.润滑作用：切削作业的最大改善可通过润滑作用来达到，由于它减少了热量的产生因而减少了金属切削作业的能量输入。

However, if the cutting fluid is to be effective, it must reach the chip tool interface.But it is not easy to visualize how it is accomplished in the case of a continuous turning with a single point turning tool, specially when the chip-tool contact pressure is as high as 70 MPa.可是，如果要使切削液起作用就必须让它到达切屑刀具接触界面。但如何在采用单尖刀具连续车削的场合尤其是切屑-刀具接触压力高达70MPa时实现并非易事。

Merchant thought that minute asperities existed at the chip-tool interface and the fluid was drawn into the interface by the capillary action of the interlocking network of these surface asperities.Merchant认为：在切屑与刀具接触界面上存在微小的粗粒，切削液通过这些表面的微小粗粒组成连锁的网络的毛细管被吸入到切屑与刀具的接触界面上。

第八单元

1、Grinding is a manufacturing process that involves the removal of metal by employing a rotating abrasive wheel.The latter simulates a milling cutter with an extremely large number of miniature cutting edges.磨削是通过采用旋转磨轮去除金属的制造工艺。磨轮用非常大量的微型切削刃模仿铣刀进行切削。

Generally, grinding is considered to be a finishing process that is usually used for obtaining high-dimensional accuracy and better surface finish.Grinding can be performed on flat, cylindrical, or even internal surfaces by employing specialized machine tools, which are referred to as grinding machines.一般而言，磨削被认为是一种通常用于获得高尺寸精度和较好表面光洁度的精加工作业。磨削通过采用被称为磨床的特殊机床能在平面、圆柱面甚至内表面上进行。

Obviously, grinding machines differ in construction as well as capabilities, and the type to be employed is determined mainly by the geometrical shape and nature of the surface to be ground, e.g., cylindrical surfaces are ground on cylindrical grinding machines.显然，磨床根据结构和功能的不同有所区别，使用何种形式的磨床主要取决于被磨削表面的几何形状和物理性质。例如，圆柱面在外圆磨床上磨削。

2、Internal grinding.Internal grinding is employed for grinding relatively short holes, as shown in Fig.8.3.The workpiece is held in a chuck or a special fixture.Both the grinding wheel and the workpiece rotate during the operation and feed is applied in the longitudinal direction.内表面磨削：内表面磨削用于相对较短的孔，如图8.3所示。工件安装在卡盘或特殊夹具上。作业时砂轮和工件都回转并且采用纵向进给。

Any desired depth of cut can be obtained by the cross feed of the grinding wheel.A variation from this type is planetary internal grinding, which is recommended for heavy workpieces that cannot be held in chucks.通过砂轮的横向进给能得到任意所需的切削深度。这种方法的一个变体是行星式内表面磨削，当工件较重不能用卡盘固定时推荐使用。

In that case, the grinding wheel not only spins around its own axis but also rotates around the centerline of the hole that is being ground.在这种情况下，砂轮不但绕自身轴线回转，同时还绕被磨削孔的中心线旋转。

3、Grinding Wheels 砂轮

Grinding wheels are composed of abrasive grains having similar size and a binder.The actual grinding process is performed by the abrasive grains.Pores between the grains within the binder enable the grains to act as separate single-point cutting tools.砂轮由具有相近尺寸的磨料颗粒和粘合剂组成。实际磨削作业由磨粒完成。在粘合剂中磨粒之间的孔隙使磨粒能象独立的单刃切削刀具一样工作。These pores also provide space for the generated chips, thus preventing the wheel from clogging.In addition, pores assist the easy flow of coolants to enable efficient and prompt removal of the heat generated during the grinding process.这些孔隙同时还为产生的切屑提供空间以防砂轮堵塞。另外孔隙帮助冷却液容易流动，从而使在磨削作业中产生的热量能有效而迅速地散发。

Grinding wheels are identified based on their shape and size, kind of abrasive, grain size, binder, grade(hardness), and structure.砂轮根据它们的形状和尺寸、磨料的类型、磨粒的大小、粘合剂、等级(硬度)和结构组织来分类

4、The grade of the bond.The grade of the bond is actually an indication of the resistance of the bond to pulling off the abrasive grains from the grinding wheel.Generally, wheels having hard grades are used for grinding soft materials and vice versa.粘结体的等级：粘结体的等级实际上是其抵抗将磨粒从砂轮上拉脱的指标。一般而言，具有较硬等级的砂轮用于磨削较软材料，反之亦然。

If a hard-grade wheel were to be used for grinding a hard material, the dull grains would not be pulled off from the bond quickly enough, thus impeding the self-dressing process of the surface of the wheel and finally resulting in clogging of the wheel and burns on the ground surface.如果较硬等级的砂轮用于磨削较硬材料，磨钝的磨粒将不能足够快地脱离粘结体，这会妨碍砂轮表面的自修复，最终导致砂轮的堵塞并在被磨表面留下灼斑。In fact, the cutting properties of all grinding wheels must be restored periodically by dressing with a cemented carbide roller or a diamond tool to give the wheel the exact desired shape and remove all worn abrasive grains.实际上，所有砂轮的磨削性能都必须定期地通过使用硬质合金滚轮或金刚石修整器修整而被恢复，以求很准确地把砂轮加工成要求的形状，并去除已磨钝的磨粒。第十一单元

1、The Lathe and Its Construction 车床及其结构

A lathe is a machine tool used primarily for producing surfaces of revolution and flat edges.车床是主要用于生成旋转表面和平整边缘的机床。

Based on their purpose, construction, number of tools that can simultaneously be mounted, and degree of automation, lathes-or, more accurately, lathe-type machine tools can be classified as follows: 根据它们的使用目的、结构、能同时被安装刀具的数量和自动化的程度，车床—或更确切地说是车床类的机床，可以被分成以下几类：

(1)Engine lathes(2)Toolroom lathes(3)Turret lathes(4)Vertical turning and boring mills(5)Automatic lathes(6)Special-purpose lathes(1)普通车床(2)万能车床(3)转塔车床(4)立式车床(5)自动车床(6)特殊车床

2、The carriage.The main function of the carriage is mounting of the cutting tools and generating longitudinal and/or cross feeds.It is actually an H-shaped block that slides on the lathe bed between the head stock and tail stock while being guided by the V-shaped guide ways of the bed.大拖板：大拖板的主要功能是安装刀具和产生纵向和/或横向进给。它实际上是一由车床床身V形导轨引导的、能在车床床身主轴箱和尾架之间滑动的H形滑块。

The carriage can be moved either manually or mechanically by means of the apron and either the feed rod or the lead screw.大拖板能手动或者通过溜板箱和光杆(进给杆)或丝杆(引导螺杆)机动。

3、Turning tools.Turning tools can be either finishing or rough turning tools.Rough turning tools have small nose radii and are employed when deep cuts are made.车削刀具：车削刀具可以是精车刀具或粗车刀具。粗车刀具刀尖半径较小，用于深切削。

On the other hand, finishing tools have larger nose radii and are used for obtaining the final required dimensions with good surface finish by making slight depths of cut.Rough turning tools can be right-hand or left-hand types, depending upon the direction of feed.They can have straight,bent, or offset shanks.而精车刀具刀尖半径较大，用于通过微量进刀深度来获得具有较好表面光洁度的最终所需尺寸。粗车刀具按其进给方向可以是右手型的或是左手型的。它们可以有直的、弯的或偏置的刀杆。

4、Cylindrical turning.Cylindrical turning is the simplest and the most common of all lathe operations.A single full turn of the workpiece generates a circle whose center falls on the lathe axis;this motion is then reproduced numerous times as a result of the axial feed motion of the tool.圆柱面车削：圆柱面车削是所有车床操作中最简单也是最普通的。工件旋转一整圈产生一个圆心落在车床主轴上的圆；由于刀具的轴向进给运动这种动作重复许多次。

The resulting machining marks are, therefore, a helix having a very small pitch, which is equal to the feed.Consequently, the machined surface is always cylindrical.所以，由此产生的机加工痕迹是一条具有很小节距的螺旋线，该节距等于进给。因此机加工表面始终是圆柱形的。

The axial feed is provided by the carriage or the compound rest, either manually or automatically, whereas the depth of cut is controlled by the cross slide.轴向进给通过大拖板或复式刀架手动或自动提供，然而切削深度则由横向滑板控制。

In roughing cuts, it is recommended that large depths of cuts(up to 0.25in.or 6mm, depending upon the workpiece material)and smaller feeds would be used.On the other hand, very fine feeds, smaller depths of cut(less than 0.05in, or 0.4mm), and high cutting speeds are preferred for finishing cuts.粗车中，推荐使用较大切削深度(根据工件材料可达0.25英寸或6毫米)和较小进给。另一方面，精车则最好采用很小的进给、较小的切削深度(小于0.05英寸或0.4毫米)和较高的切削速度。第十二单元

1、Drilling and Drills 钻削和钻头

Drilling involves producing through or blind holes in a work piece by forcing a tool, which rotates around its axis, against the work piece.钻削就是通过迫使绕自身轴线旋转的切削刀具进入工件而在其上生成通孔或盲孔。

Consequently, the range of cutting from that axis of rotation is equal to the radius of the required hole.In practice, two symmetrical cutting edges that rotate about the same axis are employed.因此，从旋转轴线开始的切削范围等于所需孔的半径。实际上，使用的是两条围绕相同轴线旋转的对称切削刃。

2、Each of the cutting edges of a milling cutter acts as an inpidual single-point cutter when it engages with the workpiece metal.Therefore, each of those cutting edges has appropriate rake and relief angles.在铣刀切削工件金属时，铣刀的每条切削刃都象一单独的单刃刀具一样作用。所以每条切削刃都适当的前后角。

Since only a few of the cutting edges are engaged with the workpiece at a time, heavy cuts can be taken without adversely affecting the tool life.In fact, the permissible cutting speeds and feeds for milling are three to four times higher than those for turning or drilling.由于同一时间只有部分切削刃切削工件，因此可以在对刀具寿命没有不利影响的情况下承担重型切削。事实上，铣削允许的切削速度和进给比车削或钻削高三到四倍。

Moreover, the quality of the surfaces machined by milling is generally superior to the quality of surfaces machined by turning, shaping, or drilling.此外，由铣削加工的表面质量通常优于车削、刨削或钻削加工的表面质量。A wide variety of milling cutters is available in industry.This, together with the fact that a milling machine is a very versatile machine tool, makes the milling machine the backbone of a machining workshop.工业上可采用的铣刀类型众多。连同铣床是极通用机床的事实，使得铣床成为机加工车间的支柱。第十四单元

1、Dimensioning 标注尺寸

The design of a machine includes many factors other than those of determining the loads and stresses and selecting the proper materials.机械设计除了计算载荷和应力、选择合适的材料外，还包括许多其它因素。Before construction or manufacture can begin, it is necessary to have complete assembly and detail drawings to convey all necessary information to the shop men.The designer frequently is called upon to check the drawings before they are sent to the shop.Much experience and familiarity with manufacturing processes are needed before one can become conversant with all phases of production drawings.在建造或制造开始前，完成装配图和零件图以把必要信息传达给车间工人是必须的。在送往车间前设计者常常被召集来检查图纸。而在精通生产图纸的所有情况之前，需要有许多经验并熟悉制造工艺。

2、The development of production processes for large-volume manufacture at low cost has been largely dependent upon interchangeability of component parts.Thus the designer must determine both the proper tolerances for the inpidual parts, and the correct amount of clearance or interference to permit assembly with the mating parts.大规模低成本制造生产工艺的发展很大程度取决于组成零件的互换性。因此设计者必须确定单个零件的合适公差以及配合零件装配允许的正确间隙或过盈量。The manner of placing tolerances on drawings depends somewhat on the kind of product or type of manufacturing process.If the tolerance on a dimension is not specifically stated, the drawing should contain a blanket note which gives the value of the tolerance for such dimensions.在图纸上标注公差的方法相当程度上依赖于产品的性质或制造工艺的类型。如果尺寸公差没有特别注明，图纸应该包含一个给出这些尺寸公差值的普遍适用注释。

However, some companies do not use blanket notes on the supposition that if each dimension is considered inpidually, wider tolerances than those called for in the note could probably be specified.In any event it is very important that a drawing be free from ambiguities and be subject only to a single interpretation.然而有些公司不采用普遍适用注释，假定每个尺寸是单独被考虑的，可能会规定出比注释中要求的更宽的公差。在任何情况下图纸不模棱两可并只服从于单一的解释是十分重要的。

3、There should be no more dimensions than are absolutely necessary, and no feature should be located by more than one dimension in any direction.除绝对需要的尺寸外，不应该有更多的尺寸；而在任意方向上，只能在一个尺寸上标注特性要求。

It may be necessary occasionally to give an auxiliary dimension for reference, possibly for inspection.When this is so, the dimension should be enclosed in a bracket and marked for reference.Such dimensions are not governed by general tolerances.偶尔也可能为了检查而必须给出供参考的辅助尺寸。在这种情况下，尺寸应该用括号括起来，以便参考。这样的尺寸不受通用公差控制。Unit15

1、Ultrasonic machining,elecron-beam machining,plasma-jet machining ,and laser machining are all examples of these new processes.Another modern process is chemical etching ,which,unlike the others,was developed primarily for producing complex integral shapes in soft materials,namely ,aluminum alloys ,for the aircraft industry.1超声加工，电子束加工，等离子射流加工，激光加工等就是特种加工工艺的代表。另一种现代加工方法是化学蚀刻法，与其他方法不同，它原来是为用软材料即铝合金、为飞机工业生产形状复杂的整体零件而开发的。

2、The term electrical maching may be applied to a group of processes that employ an electric current or discharge to remove material.Removal of material though an electric current or discharge eliminates the inefficient conversion of electrical power to mechanical power characteristic of conventional machining and metal-deformation processes电加工这一术语适用于使用电流或放电以去除材料的一组加工方法。虽然电流或放电消除了电能的效率，消除了传统机械加工和金属变形过程中的电功率的低效率的转换

The elimination of the mechanical stage also overcomes one difficulty inherent in conventional machining ,namely ,the increase in tool forces and tool wear encountered when machining the harder metals and alloys used in modern engineering practice 在机械加工阶段也克服了传统加工方法存在的困难，即，在现代工程实践中加工较难的金属和合金时切削力和道具磨损的增加。

3、The erosive action of electric sparks has long been known.Two recent discoveries,however,have made spark-cutting practical.A DC spark causes greater erosion of the electrode connected to the positive pole of the power supply——very important，if tool wear is to be minimized and the work erosion rate maximized.The second important discovery is that the rate of erosion by the spark is greatly increased if it is made to take place in a liquid rather than air.It must be noted that if a spark is permitted to last to long ,it will degenerate into a stationary arc which is not suitable for machining.电火花的侵蚀作用早已公知的。然而，最近的两项发现是电火花加工能实际使用。直流电火花使在与电源正极相连的电极处产生较大的蚀除，如果要使刀具磨损最小而使工件蚀除率最大的话，这一点是非常重要的。第二个重要的发现是如果电火花的蚀除发生在液体而不是空气中那么它的蚀除率会大大提高。必须指出的是,如果一个火花被允许长时间持续,它将退化为一个不适合用于加工的稳定电弧。V unit16

1、laser beam machining(LBM)utilises the energy from the coherent light beams called laser(light amplification by stimulated emission of radiation).The basic principle utilised in LBM is that under proper conditions light energy of a particular frequency is used to stimulate the electrons in an atom to emit additional light with exactly the same characteristics of the original light source.激光加工利用称为激光的相干光束的能量(光受激辐射放大器)。激光加工的基本原理是在一定条件下采用特定频率的光激发原子中的电子，是其发射特征与原光源完全相同的光 Part2 第一单元

1、The modern digital computer is an electronic machine that can perform mathematical and logical calculations and data processing functions in accordance with a predetermined program of instructions.The computer itself is referred to as hardware, whereas the various programs are referred to as software.现在数字计算机是一部能够根据预定的程序来完成数字和逻辑运算以及数据处理功能的电子设备，计算机本身称为硬件，而各种各样的程序称为软件。In a network,all computers are connected and communicated with each other according to some kinds of enacted regulations or agreement ,which are called the “network protocols “.the main function of network protocols is realizing the orderly transmission or acceptance of information.The most common protocol which is being used is Transport Control Protocol /Internet Protocol(TCP/IP).Among many system models illustrating network protocols in the world ,the ISO/OSI network model enacted by International Standardization Organization has pided the whole system into seven layers ,each layer has its own name and function respectively.在网络中所有的计算机都根据一些准则和协议进行连接和通信，规则和协议称为网络协议。网络协议的主要功能是实现信息的有序传递或接受。最常用的协议是传输控制协议/互联网协议（TCP / IP）。在世界上许多系统模型，说明网络协议由国际标准化组织制定的ISO / OSI网络模型将整个系统分为七层,每一层分别有自己的名称和功能

2、the widest area network in the world is Internet.it is one kind of wide area virtual networks,which uses TCP/IP protocol and interconnects more than tens of million computers around the world into a gigantic network system互联网是世界上最宽广的区域网，它是一种大范围的虚拟网络，利用TCP / IP协议，使世界各地数以百万的电脑变成一个庞大的网络系统。

Each computer of internet has its sole address in the world ,thus its application can overcome the limitation of continents,countries and areas ,and make up a virtual space in which every person can receive the latest news and enjoy the fastest service even when he is in the most remote area of the world.互联网上的每台计算机都有唯一的地址，因此它的应用可以克服大陆、国家和地区,的限制，并组成一个虚拟的空间。每个人都可以获得的最新消息和享受最快的服务即使他是在世界最偏远的地区。today more and more computers and devices are connected with internet system,more and more service and information can be offered by the utlization of internet,and it has become an important base for information super highway structure plan in many countries one of fastest growing +课本99页蓝体字

今天,越来越多的电脑和设备被互联网系统连接，越来越多的服务和信息被互联网的使用所提供，在许多国家信息高速公路结构计划已成为一项重要的基础研究。互联网发展最快的领域之一是万维网的应用，在互联网中，各种信息，如文本、图像、声音和许多其他多媒体文件，可以通过超文本链接功能共同观看和导航。with the rapid development of information and electronics technology ,internet is developing by an incredibly speed and it has become an indispensable component of human‘s civilization随着信息和电子技术的快速发展，互联网以一个令人难以置信的速度发展，它已成为人类文明的不可或缺的组成部分。unit11课本173页

第三篇：机械工程英语翻译

• Types of Materials

材料的类型

Materials may be grouped in several ways.Scientists often classify materials by their state: solid, liquid, or gas.They also separate them into organic(once living)and inorganic(never living)materials.材料可以按多种方法分类。科学家常根据状态将材料分为：固体、液体或气体。他们也把材料分为有机材料(曾经有生命的)和无机材料(从未有生命的)。

For industrial purposes, materials are pided into engineering materials or nonengineering materials.Engineering materials are those used in manufacture and become parts of products.就工业效用而言，材料被分为工程材料和非工程材料。那些用于加工制造并成为产品组成部分的就是工程材料。

Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product.非工程材料则是化学品、燃料、润滑剂以及其它用于加工制造过程但不成为产品组成部分的材料。

Engineering materials may be further subpided into: ①Metal ②Ceramics ③Composite ④Polymers, etc.工程材料还能进一步细分为：①金属材料②陶瓷材料③复合材料 ④聚合材料，等等。

• Metals and Metal Alloys

金属和金属合金

Metals are elements that generally have good electrical and thermal conductivity.Many metals have high strength, high stiffness, and have good ductility.金属就是通常具有良好导电性和导热性的元素。许多金属具有高强度、高硬度以及良好的延展性。

Some metals, such as iron, cobalt and nickel, are magnetic.At low temperatures, some metals and intermetallic compounds become superconductors.某些金属能被磁化，例如铁、钴和镍。在极低的温度下，某些金属和金属化合物能转变成超导体。

What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table.Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans.合金与纯金属的区别是什么？纯金属是在元素周期表中占据特定位置的元素。例如电线中的铜和制造烹饪箔及饮料罐的铝。

Alloys contain more than one metallic element.Their properties can be changed by changing the elements present in the alloy.Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium;and gold jewelry which usually contains an alloy of gold and nickel.合金包含不止一种金属元素。合金的性质能通过改变其中存在的元素而改变。金属合金的例子有：不锈钢是一种铁、镍、铬的合金，以及金饰品通常含有金镍合金。

Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio.为什么要使用金属和合金？许多金属和合金具有高密度，因此被用在需要较高质量体积比的场合。

Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy.Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金属合金，例如铝基合金，其密度低，可用于航空航天以节约燃料。许多合金还具有高断裂韧性，这意味着它们能经得起冲击并且是耐用的。

What are some important properties of metals?

Density is defined as a material’s mass pided by its volume.Most metals have relatively high densities, especially compared to polymers.金属有哪些重要特性？

密度定义为材料的质量与其体积之比。大多数金属密度相对较高，尤其是和聚合物相比较而言。

Materials with high densities often contain atoms with high atomic numbers, such as gold or lead.However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low weight.高密度材料通常由较大原子序数原子构成，例如金和铅。然而，诸如铝和镁之类的一些金属则具有低密度，并被用于既需要金属特性又要求重量轻的场合。

Fracture toughness can be described as a material’s ability to avoid fracture, especially when a flaw is introduced.Metals can generally contain nicks and dents without weakening very much, and are impact resistant.A football player counts on this when he trusts that his facemask won’t shatter.断裂韧性可以描述为材料防止断裂特别是出现缺陷时不断裂的能力。金属一般能在有缺口和凹痕的情况下不显著削弱，并且能抵抗冲击。橄榄球运动员据此相信他的面罩不会裂成碎片。

Plastic deformation is the ability of bend or deform before breaking.As engineers, we usually design materials so that they don’t deform under normal conditions.You don’t want your car to lean to the east after a strong west wind.塑性变形就是在断裂前弯曲或变形的能力。作为工程师，设计时通常要使材料在正常条件下不变形。没有人愿意一阵强烈的西风过后自己的汽车向东倾斜。

However, sometimes we can take advantage of plastic deformation.The crumple zones in a car absorb energy by undergoing plastic deformation before they break.然而，有时我们也能利用塑性变形。汽车上压皱的区域在它们断裂前通过经历塑性变形来吸收能量。

The atomic bonding of metals also affects their properties.In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere.Since electrons conduct heat and electricity, metals make good cooking pans and electrical wires.金属的原子连结对它们的特性也有影响。在金属内部，原子的外层阶电子由所有原子共享并能到处自由移动。由于电子能导热和导电，所以用金属可以制造好的烹饪锅和电线。

It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal.No photons pass through.因为这些阶电子吸收到达金属的光子，所以透过金属不可能看得见。没有光子能通过金属。

Alloys are compounds consisting of more than one metal.Adding other metals can affect the density, strength, fracture toughness, plastic deformation, electrical conductivity and environmental degradation.合金是由一种以上金属组成的混合物。加一些其它金属能影响密度、强度、断裂韧性、塑性变形、导电性以及环境侵蚀。

For example, adding a small amount of iron to aluminum will make it stronger.Also, adding some chromium to steel will slow the rusting process, but will make it more brittle.例如，往铝里加少量铁可使其更强。同样，在钢里加一些铬能减缓它的生锈过程，但也将使它更脆。

• Ceramics and Glasses 陶瓷和玻璃

A ceramic is often broadly defined as any inorganic nonmetallic material． By this definition, ceramic materials would also include glasses;however, many materials scientists add the stipulation that “ceramic” must also be crystalline.陶瓷通常被概括地定义为无机的非金属材料。照此定义，陶瓷材料也应包括玻璃；然而许多材料科学家添加了“陶瓷”必须同时是晶体物组成的约定。

A glass is an inorganic nonmetallic material that does not have a crystalline structure.Such materials are said to be amorphous.玻璃是没有晶体状结构的无机非金属材料。这种材料被称为非结晶质材料。Properties of Ceramics and Glasses

Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.陶瓷和玻璃的特性

高熔点、低密度、高强度、高刚度、高硬度、高耐磨性和抗腐蚀性是陶瓷和玻璃的一些有用特性。

Many ceramics are good electrical and thermal insulators.Some ceramics have special properties: some ceramics are magnetic materials;some are piezoelectric materials;and a few special ceramics are superconductors at very low temperatures.Ceramics and glasses have one major drawback: they are brittle.许多陶瓷都是电和热的良绝缘体。某些陶瓷还具有一些特殊性能：有些是磁性材料，有些是压电材料，还有些特殊陶瓷在极低温度下是超导体。陶瓷和玻璃都有一个主要的缺点：它们容易破碎。

Ceramics are not typic