材料专业英语翻译

Unit1

Advanced Engineering Materials

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 divided 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 subdivided 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 divided 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着削弱，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 typically formed from the melt. This is because most ceramics will crack extensively . form a powder) upon cooling from the liquid state.

陶瓷一般不是由熔化形成的。因为大多数陶瓷在从液态冷却时将会完全破碎(即形成粉末)。

Hence, all the simple and efficient manufacturing techniques used for glass production such as casting and blowing, which involve the molten state, cannot be used for

the production of crystalline ceramics. Instead, “sintering” or “firing” is the process typically used.

因此，所有用于玻璃生产的简单有效的—诸如浇铸和吹制这些涉及熔化的技术都不能用于由晶体物组成的陶瓷的生产。作为替代，一般采用“烧结”或“焙烧”工艺。

In sintering, ceramic powders are processed into compacted shapes and then heated to temperatures just below the melting point. At such temperatures, the powders react

internally to remove porosity and fully dense articles can be obtained.

在烧结过程中，陶瓷粉末先挤压成型然后加热到略低于熔点温度。在这样的温度下，粉末内部起反应去除孔隙并得到十分致密的物品。

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。

Composites 复合材料

Composites are formed from two or more types of materials. Examples include polymer/ceramic and metal/ceramic composites. Composites are used because overall

properties of the composites are superior to those of the individual components.

复合材料由两种或更多材料构成。例子有聚合物/陶瓷和金属/陶瓷复合材料。之所以使用复合材料是因为其全面性能优于组成部分单独的性能。

For example: polymer/ceramic composites have a greater modulus than the polymer component, but aren’t as brittle as ceramics.

Two types of composites are: fiber-reinforced composites and particle-reinforced composites.

例如：聚合物/陶瓷复合材料具有比聚合物成分更大的模量，但又不像陶瓷那样易碎。

复合材料有两种：纤维加强型复合材料和微粒加强型复合材料。

Fiber-reinforced Composites

Reinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers. Fibers increase the

modulus of the matrix material.

纤维加强型复合材料

加强纤维可以是金属、陶瓷、玻璃或是已变成石墨的被称为碳纤维的聚合物。纤维能加强基材的模量。

The strong covalent bonds along the fiber’s length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken

or moved.

沿着纤维长度有很强结合力的共价结合在这个方向上给予复合材料很高的模量，因为要损坏或拉伸纤维就必须破坏或移除这种结合。

Fibers are difficult to process into composites, making fiber-reinforced composites relatively expensive.

把纤维放入复合材料较困难，这使得制造纤维加强型复合材料相对昂贵。

Fiber-reinforced composites are used in some of the most advanced, and therefore most expensive sports equipment, such as a time-trial racing bicycle frame which

consists of carbon fibers in a thermoset polymer matrix.

纤维加强型复合材料用于某些最先进也是最昂贵的运动设备，例如计时赛竞赛用自行车骨架就是用含碳纤维的热固塑料基材制成的。

Body parts of race cars and some automobiles are composites made of glass fibers (or fiberglass) in a thermoset matrix.

竞赛用汽车和某些机动车的车体部件是由含玻璃纤维(或玻璃丝)的热固塑料基材制成的。

Fibers have a very high modulus along their axis, but have a low modulus perpendicular to their axis. Fiber composite manufacturers often rotate layers of

fibers to avoid directional variations in the modulus.

纤维在沿着其轴向有很高的模量，但垂直于其轴向的模量却较低。纤维复合材料的制造者往往旋转纤维层以防模量产生方向变化。

Particle-reinforced composites

Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as aluminum, and amorphous materials,

including polymers and carbon black.

微粒加强型复合材料

用于加强的微粒包含了陶瓷和玻璃之类的矿物微粒，铝之类的金属微粒以及包括聚合物和碳黑的非结晶质微粒。

Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix. An example of

particle-reinforced composites is an automobile tire which has carbon black particles in a matrix of polyisobutylene elastomeric polymer.

微粒用于增加基材的模量、减少基材的渗透性和延展性。微粒加强型复合材料的一个例子是机动车胎，它就是在聚异丁烯人造橡胶聚合物基材中加入了碳黑微粒。

Polymers 聚合材料

A polymer has a repeating structure, usually based on a carbon backbone. The repeating structure results in large chainlike molecules. Polymers are useful

because they are lightweight, corrosion resistant, easy to process at low temperatures and generally inexpensive.

聚合物具有一般是基于碳链的重复结构。这种重复结构产生链状大分子。由于重量轻、耐腐蚀、容易在较低温度下加工并且通常较便宜，聚合物是很有用的。

Some important characteristics of polymers include their size (or molecular weight), softening and melting points, crystallinity, and structure. The

mechanical properties of polymers generally include low strength and high toughness. Their strength is often improved using reinforced composite structures.

聚合材料具有一些重要特性，包括尺寸(或分子量)、软化及熔化点、结晶度和结构。聚合材料的机械性能一般表现为低强度和高韧性。它们的强度通常可采用加强复合结构来改善。

Important Characteristics of Polymers

Size. Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/mol—that can be more than 2,000 repeating units depending on

the polymer structure!

聚合材料的重要特性

尺寸：单个聚合物分子一般分子量为10,000到1,000,000g/mol之间，具体取决于聚合物的结构—这可以比2,000个重复单元还多。

The mechanical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights.

聚合物的分子量极大地影响其机械性能，分子量越大，工程性能也越好。

Thermal transitions. The softening point (glass transition temperature) and the melting point of a polymer will determine which it will be suitable for

applications. These temperatures usually determine the upper limit for which a polymer can be used.

热转换性：聚合物的软化点(玻璃状转化温度)和熔化点决定了它是否适合应用。这些温度通常决定聚合物能否使用的上限。

For example, many industrially important polymers have glass transition temperatures near the boiling point of water (100℃, 212℉), and they are most useful for room

temperature applications. Some specially engineered polymers can withstand temperatures as high as 300℃(572℉).

例如，许多工业上的重要聚合物其玻璃状转化温度接近水的沸点(100℃, 212℉)，它们被广泛用于室温下。而某些特别制造的聚合物能经受住高达300℃(572℉)的温度。

Crystallinity. Polymers can be crystalline or amorphous, but they usually have a combination of crystalline and amorphous structures (semi-crystalline).

结晶度：聚合物可以是晶体状的或非结晶质的，但它们通常是晶体状和非结晶质结构的结合物(半晶体)。

Interchain interactions. The polymer chains can be free to slide past one another (thermo-plastic) or they can be connected to each other with crosslinks

(thermoset or elastomer). Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable.

原子链间的相互作用：聚合物的原子链可以自由地彼此滑动(热可塑性)或通过交键互相连接(热固性或弹性)。热可塑性材料可以重新形成和循环使用，而热固性与弹性材料则是不能再

使用的。

Intrachain structure. The chemical structure of the chains also has a tremendous effect on the properties. Depending on the structure the polymer may be

hydrophilic or hydrophobic (likes or hates water), stiff or flexible, crystalline or amorphous, reactive or unreactive.

链内结构：原子链的化学结构对性能也有很大影响。根据各自的结构不同，聚合物可以是亲水的或憎水的(喜欢或讨厌水)、硬的或软的、晶体状的或非结晶质的、易起反应的或不易起

反应的。

Unit 2

Heat Treatment of Matels

The understanding of heat treatment is embraced by the broader study of metallurgy. Metallurgy is the physics, chemistry, and engineering related to metals

from ore extraction to the final product.

对热处理的理解包含于对冶金学较广泛的研究。冶金学是物理学、化学和涉及金属从矿石提炼到最后产物的工程学。

Heat treatment is the operation of heating and cooling a metal in its solid state to change its physical properties. According to the procedure used, steel can be

hardened to resist cutting action and abrasion, or it can be softened to permit machining.

热处理是将金属在固态加热和冷却以改变其物理性能的操作。按所采用的步骤，钢可以通过硬化来抵抗切削和磨损，也可以通过软化来允许机加工。

With the proper heat treatment internal stresses may be removed, grain size reduced, toughness increased, or a hard surface produced on a ductile interior. The

analysis of the steel must be known because small percentages of certain elements, notably carbon, greatly affect the physical properties.

使用合适的热处理可以去除内应力、细化晶粒、增加韧性或在柔软材料上覆盖坚硬的表面。因为某些元素(尤其是碳)的微小百分比极大地影响物理性能，所以必须知道对钢的分析。

Alloy steel owe their properties to the presence of one or more elements other than carbon, namely nickel, chromium, manganese, molybdenum, tungsten, silicon,

vanadium, and copper. Because of their improved physical properties they are used commercially in many ways not possible with carbon steels.

合金钢的性质取决于其所含有的除碳以外的一种或多种元素，如镍、铬、锰、钼、钨、硅、钒和铜。由于合金钢改善的物理性能，它们被大量使用在许多碳钢不适用的地方。

The following discussion applies principally to the heat treatment of ordinary commercial steels known as plain carbon steels. With this process the rate of

cooling is the controlling factor, rapid cooling from above the critical range results in hard structure, whereas very slow cooling produces the opposite effect.

下列讨论主要针对被称为普通碳钢的工业用钢而言。热处理时冷却速率是控制

要素，从高于临界温度快速冷却导致坚硬的组织结构，而缓慢冷却则产生相反效果。

A Simplified Iron-carbon Diagram

简化铁碳状态图

If we focus only on the materials normally known as steels, a simplified diagram is often used.

如果只把注意力集中于一般所说的钢上，经常要用到简化铁碳状态图。

Those portions of the iron-carbon diagram near the delta region and those above 2% carbon content are of little importance to the engineer and are deleted. A simplified diagram, such as the one in focuses on the eutectoid region and is quite useful in understanding the properties and processing of steel.

铁碳状态图中靠近三角区和含碳量高于2%的那些部分对工程师而言不重要，因此将它

们删除。如图所示的简化铁碳状态图将焦点集中在共析区，这对理解钢的性能和处理是

十分有用的。

The key transition described in this diagram is the decomposition of single-phase austenite(γ) to the two-phase ferrite plus carbide structure as temperature drops.

在此图中描述的关键转变是单相奥氏体(γ) 随着温度下降分解成两相铁素体

加渗碳体组织结构。

Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved

through heat treatment.

控制这一由于奥氏体和铁素体的碳溶解性完全不同而产生的反应，使得通过热处理能获

得很大范围的特性。

upper temperatures, only austenite is present, the % carbon being dissolved in solid solution with the iron. When the steel cools to 727℃(1341℉), several changes

occur simultaneously.

为了理解这些过程，考虑含碳量为%的共析钢，沿着图的x-x’线慢慢冷却。在

较高温度时，只存在奥氏体，%的碳溶解在铁里形成固溶体。当钢冷却到727℃ (1341℉)时，将同时发生若干变化。

The iron wants to change from the FCC austenite structure to the BCC ferrite structure, but the ferrite can only contain % carbon in solid solution.

铁需要从面心立方体奥氏体结构转变为体心立方体铁素体结构，但是铁素体只

能容纳固溶体状态的%的碳。

The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C. In essence, the net reaction at the eutectoid is austenite %C→ferrite

%C+cementite %C.

被析出的碳与金属化合物Fe3C形成富碳的渗碳体。本质上，共析体的基本反应是奥氏体%的碳→铁素体%的碳+渗碳体%的碳。

Since this chemical separation of the carbon component occurs entirely in the solid state, the resulting structure is a fine mechanical mixture of

ferrite and

cementite. Specimens prepared by polishing and etching in a weak solution of nitric acid and alcohol reveal the lamellar structure of alternating plates that forms on slow cooling.

由于这种碳成分的化学分离完全发生在固态中，产生的组织结构是一种细致的铁素体与渗碳体的机械混合物。通过打磨并在弱硝酸酒精溶液中蚀刻制备的样本显示出由缓慢冷却形成的交互层状的薄片结构。

This structure is composed of two distinct phases, but has its own set of characteristic properties and goes by the name pearlite, because of its resemblance to mother- of- pearl at low magnification.

这种结构由两种截然不同的状态组成，但它本身具有一系列特性，且因与低倍数放大时的珠母层有类同之处而被称为珠光体。

Steels having less than the eutectoid amount of carbon (less than %) are known as hypo-eutectoid steels. Consider now the transformation of such a

含碳量少于共析体(低于%)的钢称为亚共析钢。现在来看这种材料沿着图中y-y’线冷却的转变情况。

At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are ferrite and austenite. Tie-line and level-law

calculations show that low-carbon ferrite nucleates and grows, leaving the remaining austenite richer in carbon.

在较高温度时，这种材料全部是奥氏体，但随着冷却就进入到铁素体和奥氏体稳定状态的区域。由截线及杠杆定律分析可知，低碳铁素体成核并长大，剩下含碳量高的奥氏体。At 727℃(1341℉), the austenite is of eutectoid composition % carbon) and further cooling transforms the remaining austenite to pearlite. The resulting structure is a mixture of primary or pro-eutectoid ferrite (ferrite that formed above the eutectoid reaction) and regions of pearlite.

在727℃(1341℉)时，奥氏体为共析组成(含碳量%)，再冷却剩余的奥氏体就转化为珠光体。作为结果的组织结构是初步的共析铁素体(在共析反应前的铁素体)和部分珠光体的混合物。

Hypereutectoid steels are steels that contain greater than the eutectoid amount of carbon. When such steel cools, as shown in z-z’ of the process is similar to the hypo-eutectoid case, except that the primary or pro-eutectoid phase is now cementite instead of ferrite.

过共析钢是含碳量大于共析量的钢。当这种钢冷却时，就像图的z-z’线所示，除了初步的共析状态用渗碳体取代铁素体外，其余类似亚共析钢的情况。

As the carbon-rich phase forms, the remaining austenite decreases in carbon content, reaching the eutectoid composition at 727℃(1341℉). As before, any remaining austenite transforms to pearlite upon slow cooling through this temperature.

随着富碳部分的形成，剩余奥氏体含碳量减少，在727℃(1341℉)时达到共析组织。就像以前说的一样，当缓慢冷却到这温度时所有剩余奥氏体转化为珠光体。

It should be remembered that the transitions that have been described by the phase diagrams are for equilibrium conditions, which can be approximated

by slow cooling. With slow heating, these transitions occur in the reverse manner.

应该记住由状态图描述的这种转化只适合于通过缓慢冷却的近似平衡条件。如果缓慢加热，则以相反的方式发生这种转化。

However, when alloys are cooled rapidly, entirely different results may be obtained, because sufficient time is not provided for the normal phase reactions to occur, in such cases, the phase diagram is no longer a useful tool for engineering analysis.

然而，当快速冷却合金时，可能得到完全不同的结果。因为没有足够的时间让正常的状态反应发生，在这种情况下对工程分析而言状态图不再是有用的工具。

Hardening 淬火

Hardening is the process of heating a piece of steel to a temperature within or above its critical range and then cooling it rapidly.

淬火就是把钢件加热到或超过它的临界温度范围，然后使其快速冷却的过程。

If the carbon content of the steel is known, the proper temperature to which the steel should be heated may be obtained by reference to the iron-iron carbide phase diagram. However, if the composition of the steel is unknown, a little preliminary experimentation may be necessary to determine the range.

如果钢的含碳量已知，钢件合适的加热温度可参考铁碳合金状态图得到。然而当钢的成分不知道时，则需做一些预备试验来确定其温度范围。

A good procedure to follow is to heat-quench a number of small specimens of the steel at various temperatures and observe the result, either by hardness testing or by microscopic examination. When the correct temperature is obtained, there will be a marked change in hardness and other properties.

要遵循的合适步骤是将这种钢的一些小试件加热到不同的温度后淬火，再通过硬度试验或显微镜检查观测结果。一旦获得正确的温度，硬度和其它性能都将有明显的变化。

In any heat-treating operation the rate of heating is important. Heat flows from the exterior to the interior of steel at a definite rate. If the steel is heated too fast, the outside becomes hotter than the interior and uniform structure cannot be obtained.

在任何热处理作业中，加热的速率都是重要的。热量以一定的速率从钢的外部传导到内部。如果钢被加热得太快，其外部比内部热就不能得到均匀的组织结构。

If a piece is irregular in shape, a slow rate is all the more essential to eliminate warping and cracking. The heavier the section, the longer must be the heating time to achieve uniform results.

如果工件形状不规则，为了消除翘曲和开裂最根本的是加热速率要缓慢。截面越厚，加热的时间就要越长才能达到均匀的结果。

Even after the correct temperature has been reached, the piece should be held at that temperature for a sufficient period of time to permit its thickest section to attain a uniform temperature.

即使加热到正确的温度后，工件也应在此温度下保持足够时间以让其最厚截面达到相同温度。

The hardness obtained from a given treatment depends on the quenching rate, the carbon content, and the work size. In alloy steels the kind and amount of alloying element influences only the hardenability (the ability of the

workpiece to be hardened to depths) of the steel and does not affect the hardness except in unhardened or partially hardened steels.

通过给定的热处理所得到的硬度取决于淬火速率、含碳量和工件尺寸。除了非淬硬钢或部分淬硬钢外，合金钢中合金元素的种类及含量仅影响钢的淬透性(工件被硬化到深层的能力)而

不影响硬度。

Steel with low carbon content will not respond appreciably to hardening treatment. As the carbon content in steel increases up to around %, the possible hardness obtainable also increases.

含碳量低的钢对淬火处理没有明显的反应。随着钢的含碳量增加到大约%，可能得到的硬度也增加。

Above this point the hardness can be increased only slightly, because steels above the eutectoid point are made up entirely of pearlite and cementite in the annealed state. Pearlite responds best to heat-treating operations; and steel composed mostly of pearlite can be transformed into a hard steel.

高于此点，由于超过共析点钢完全由珠光体和退火状态的渗碳体组成，硬度增加并不多。珠光体对热处理作业响应最好；基本由珠光体组成的钢能转化成硬质钢。

As the size of parts to be hardened increases, the surface hardness decreases somewhat even though all other conditions have remained the same. There is a limit to the rate of heat flow through steel.

即使所有其它条件保持不变，随着要淬火的零件尺寸的增加其表面硬度也会有所下降。热量在钢中的传导速率是有限的。

No matter how cool the quenching medium may be, if the heat inside a large piece cannot escape faster than a certain critical rate, there is a definite limit to the inside hardness. However, brine or water quenching is capable of rapidly bringing the surface of the quenched part to its own temperature and maintaining it at or close to this temperature.

无论淬火介质怎么冷，如果在大工件中的热量不能比特定的临界速率更快散发，那它内部硬度就会受到明确限制。然而盐水或水淬火能够将被淬零件的表面迅速冷却至本身温度并将其保持或接近此温度。

Under these circumstances there would always be some finite depth of surface hardening regardless of size. This is not true in oil quenching, when the surface temperature may be high during the critical stages of quenching.

在这种情况下不管零件尺寸如何，其表面总归有一定深度被硬化。但油淬情况就不是如此，因为油淬时在淬火临界阶段零件表面的温度可能仍然很高。

Tempering 回火

Steel that has been hardened by rapid quenching is brittle and not suitable for most uses. By tempering or drawing, the hardness and brittleness may be reduced to the desired point for service conditions．

快速淬火硬化的钢是硬而易碎的，不适合大多数场合使用。通过回火，硬度和脆性可以降低到使用条件所需要的程度。

As these properties are reduced there is also a decrease in tensile strength and an increase in the ductility and toughness of the steel. The operation consists of reheating quench-hardened steel to some temperature below the

critical range followed by any rate of cooling.

随着这些性能的降低，拉伸强度也降低而钢的延展性和韧性则会提高。回火作业包括将淬硬钢重新加热到低于临界范围的某一温度然后以任意速率冷却。

Although this process softens steel, it differs considerably from annealing in that the process lends itself to close control of the physical properties and in most cases does not soften the steel to the extent that annealing would. The final structure obtained from tempering a fully hardened steel is called tempered martensite.

虽然这过程使钢软化，但它与退火是大不相同的，因为回火适合于严格控制物理性能并在大多数情况下不会把钢软化到退火那种程度。回火完全淬硬钢得到的最终组织结构被称为回火马氏体

Tempering is possible because of the instability of the martensite, the principal constituent of hardened steel. Low-temperature draws, from 300℉ to 400℉ (150℃~205℃), do not cause much decrease in hardness and are used principally to relieve internal strains.

由于马氏体这一淬硬钢主要成分的不稳定性，使得回火成为可能。低温回火，300℉到400℉(150℃~205℃)，不会引起硬度下降很多，主要用于减少内部应变。

As the tempering temperatures are increased, the breakdown of the martensite takes place at a faster rate, and at about 600℉(315℃) the change to a structure called tempered martensite is very rapid. The tempering operation may be described as one of precipitation and agglomeration or coalescence of cementite.

随着回火温度的提高，马氏体以较快的速率分解，并在大约600℉(315℃)迅速转变为被称为回火马氏体的结构。回火作业可以描述为渗碳体析出和凝聚或聚结的过程。

A substantial precipitation of cementite begins at 600℉(315℃), which produces a decrease in hardness. Increasing the temperature causes coalescence of the carbides with continued decrease in hardness.

渗碳体的大量析出开始于600℉(315℃)，这使硬度下降。温度的上升会使碳化物聚结而硬度继续降低。

In the process of tempering, some consideration should be given to time as well as to temperature. Although most of the softening action occurs in the first few minutes after the temperature is reached, there is some additional reduction in hardness if the temperature is maintained for a prolonged time.

在回火过程中，不但要考虑温度而且要考虑时间。虽然大多数软化作用发生在达到所需温度后的最初几分钟，但如果此温度维持一段延长时间，仍会有些额外的硬度下降。

Usual practice is to heat the steel to the desired temperature and hold it there only long enough to have it uniformly heated.

通常的做法是将钢加热到所需温度并且仅保温到正好使其均匀受热。

Two special processes using interrupted quenching are a form of tempering. In both, the hardened steel is quenched in a salt bath held at a selected lower temperature before being allowed to cool. These processes, known as austempering and martempering, result in products having certain desirable physical properties.

两种采用中断淬火的特殊工艺也是回火的形式。这两种工艺中，淬硬钢在其被

允许冷却前先在一选定的较低温度盐浴淬火。这两种分别被称为奥氏体回火和马氏体回

火的工艺，能使产品具有特定所需的物理性能。

Annealing 退火

The primary purpose of annealing is to soften hard steel so that it may be machined or cold worked.

退火的主要目的是使坚硬的钢软化以便机加工或冷作。

This is usually accomplished by heating the steel too slightly above the critical temperature, holding it there until the temperature of the piece is uniform

throughout, and then cooling at a slowly controlled rate so that the temperature of the surface and that of the center of the piece are approximately the same. 通常是非常缓慢地将钢加热到临界温度以上，并将其在此温度下保持到工件全部均匀受热，然后以受控的速率慢慢地冷却，这样使得工件表面和内部的温度近似相同。

This process is known as full annealing because it wipes out all trace of previous structure, refines the crystalline structure, and softens the metal. Annealing also relieves internal stresses previously set up in the metal.

这过程被称为完全退火，因为它去除了以前组织结构的所有痕迹、细化晶粒并软化金属。退火也释放了先前在金属中的内应力。

The temperature to which a given steel should be heated in annealing depends on its composition; for carbon steels it can be obtained readily from the partial iron-iron carbide equilibrium diagram. When the annealing temperature has been reached, the steel should be held there until it is uniform throughout.

给定的钢其退火温度取决于它的成分；对碳钢而言可容易地从局部的铁碳合金

平衡图得到。达到退火温度后，钢应当保持在此温度等到全部均匀受热。

This usually takes about 45min for each inch(25mm) of thickness of the largest section. For maximum softness and ductility the cooling rate should be very slow, such s allowing the parts to cool down with the furnace. The higher the carbon content, the slower this rate must be.

加热时间一般以工件的最大截面厚度计每英寸(25mm )大约需45min。为了得到最大柔

软性和延展性冷却速率应该很慢，比如让零件与炉子一起冷下来。含碳量越高，冷却的

速率必须越慢。

The heating rate should be consistent with the size and uniformity of sections, so that the entire part is brought up to temperature as uniformly as possible. 加热的速率也应与截面的尺寸及均匀程度相协调，这样才能使整个零件尽可能均匀地加热。

Normalizing and Spheroidizing

正火和球化

The process of normalizing consists of heating the steel about 50℉ to 100℉ (10℃~40℃) above the upper critical range and cooling in still air to room

temperature.

正火处理包括先将钢加热到高于上临界区50℉到100℉(10℃~40℃)然后在静

止的空气中冷却到室温。

This process is principally used with low- and medium-carbon steels as well as alloy steels to make the grain structure more uniform, to relieve internal stresses, or o achieve desired results in physical properties. Most commercial steels are normalized after being rolled or cast.

退火主要用于低碳钢、中碳钢及合金钢，使晶粒结构更均匀、释放内应力或获得所需的物理特性。大多数商业钢材在轧制或铸造后都要退火。

Spheroidizing is the process of producing a structure in which the cementite is in a spheroidal distribution. If steel is heated slowly to a temperature just elow the critical range and held there for a prolonged period of time, this structure will be obtained.

球化是使渗碳体产生成类似球状分布结构的工艺。如果把钢缓慢加热到恰好低于临界温度并且保持较长一段时间，就能得到这种组织结构。

The globular structure obtained gives improved machinability to the steel. This treatment is particularly useful for hypereutectoid steels that must be machined.

所获得的球状结构改善了钢的可切削性。此处理方法对必须机加工的过共析钢特别有用。

Surface Hardening

表面硬化

Carburizing渗碳

The oldest known method of producing a hard surface on steel is case hardening or carburizing. Iron at temperatures close to and above its critical temperature as an affinity for carbon.

最早的硬化钢表面的方法是表面淬火或渗碳。铁在靠近并高于其临界温度时对碳具有亲合力。

The carbon is absorbed into the metal to form a solid solution with iron and converts the outer surface into high-carbon steel. The carbon is gradually diffused to the

interior of the part. The depth of the case depends on the time and temperature of the treatment.

碳被吸收进金属与铁形成固溶体使外表面转变成高碳钢。碳逐渐扩散到零件内部。渗碳层的深度取决于热处理的时间和温度。

Pack carburizing consists of placing the parts to be treated in a closed container with some carbonaceous material such as charcoal or coke. It is a long process and sed to produce fairly thick cases of from to in.~ in depth. 固体渗碳的方法是将要处理的零件与木炭或焦炭这些含碳的材料一起放入密闭容器。这是一个较长的过程，用于产生深度为到英寸~这么厚的硬化层。

Steel for carburizing is usually a low-carbon steel of about % carbon that would not in itself responds appreciably to heat treatment. In the course of the rocess the outer layer is converted into high-carbon steel with a content ranging from % to % carbon.

用于渗碳的一般是含碳量约为%、本身不太适合热处理的低碳钢。在处理过程中外层转化为含碳量从%到%的高碳钢。

A steel with varying carbon content and, consequently, different

critical temperatures requires a special heat treatment.

含碳量变化的钢具有不同的临界温度，因此需要特殊的热处理。

Because there is some grain growth in the steel during the prolonged carburizing treatment, the work should be heated to the critical temperature of the core and then ooled, thus refining the core structure. The steel should then be reheated to a point above the transformation range of the case and quenched to produce a hard, fine tructure.

由于在较长的渗碳过程中钢内部会有些晶粒生长，所以工件应该加热到核心部分的临界温度再冷却以细化核心部分的组织结构。然后重新加热到高于外层转变温度再淬火以生成坚硬、细致的组织结构。

The lower heat-treating temperature of the case results from the fact that hypereutectoid steels are normally austenitized for hardening just above the lower critical point. A third tempering treatment may be used to reduce strains.

由于恰好高于低临界温度通常使过共析钢奥氏体化而硬化，所以对外层采用较低的热处理温度。第三次回火处理可用于减少应变。

Carbonitriding

Carbonitriding, sometimes known as dry cyaniding or nicarbing, is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen. 碳氮共渗

碳氮共渗，有时也称为干法氰化或渗碳氮化，是一种表面硬化工艺。通过把钢放在高于临界温度的气体中，让它吸收碳和氮。

Any carbon-rich gas with ammonia can be used. The wear-resistant case produced ranges from to inch~ in thickness. An advantage of carbonitriding is that the hardenability of the case is significantly increased when nitrogen is added, permitting the use of low-cost steels.

可以使用任何富碳气体加氨气，能生成厚度从到英寸~ 的耐磨外层。碳氮共渗的优点之一是加入氮后外层的淬透性极大增加，为使用低价钢提供条件。

Cyaniding

Cyaniding, or liquid carbonitriding as it is sometimes called, is also a process that combines the absorption of carbon and nitrogen to obtain surface Srdness in low-carbon steels that do not respond to ordinary heat treatment. 氰化

氰化，有时称为液体碳氮共渗，也是一种结合了吸收碳和氮来获得表面硬度的工艺，它主要用于不适合通常热处理的低碳钢。

The part to be case hardened is immersed in a bath of fused sodium cyanide salts at a temperature slightly above the Ac1 range, the duration of soaking depending on the depth of the case. The part is then quenched in water or oil to obtain a hard surface.

需表面硬化的零件浸没在略高于Ac1温度熔化的氰化钠盐溶液中，浸泡的持续时间取决于硬化层的深度。然后将零件在水或油中淬火。

Case depths of to . ~ may be readily obtained by this process. Cyaniding is used principally for the treatment of small parts.

通过这样处理可以容易地获得到英寸~的硬化深度。氰化主要用于处理小零件。

Nitriding

Nitriding is somewhat similar to ordinary case hardening, but it uses a different material and treatment to create the hard surface constituents. 渗氮

渗氮有些类似普通表面硬化，但它采用不同的材料和处理方法来产生坚硬表面成分。

In this process the metal is heated to a temperature of around 950℉(510℃) and held there for a period of time in contact with ammonia gas. Nitrogen from the gas is

introduced into the steel, forming very hard nitrides that are finely dispersed through the surface metal.

这种工艺中金属加热到约950℉(510℃)，然后与氨气接触一段时间。氨气中的氮进入钢内，形成细微分布于金属表面又十分坚固的氮化物。

Nitrogen has greater hardening ability with certain elements than with others, hence, special nitriding alloy steels have been developed.

氮与某些元素的硬化能力比其它元素大，因此开发了专用的渗氮合金钢。Aluminum in the range of 1% to % has proved to be especially suitable in steel, in that it combines with the gas to form a very stable and hard constituent. The Tmperature of heating ranges from 925℉ to 1,050℉(495℃~565℃).

在钢中含铝1%到%被证明特别合适，它能与氨气结合形成很稳定坚固的成分。其加热温度范围为925℉到1,050℉ (495℃~565℃)。

Liquid nitriding utilizes molten cyanide salts and, as in gas nitriding, the temperature is held below the transformation range. Liquid nitriding adds more nitrogen and less carbon than either cyaniding or carburizing in cyanide baths.

液体渗氮利用熔化的氰化物盐，就像气体渗氮，温度保持在低于转化范围内。液体渗氮时在氰化物溶液中加入比氰化及渗碳都较多的氮和较少的碳。

Case thickness of to .~ is obtained, whereas for gas nitriding the case may be as thick as in.. In general the uses of the two-nitriding processes are similar.

液体渗氮可以获得厚度为到英寸 ~的硬化层，然而气体渗氮则能获得厚英寸的硬化层。一般而言两种渗氮方法的用途是类似的。

Nitriding develops extreme hardness in the surface of steel. This hardness ranges from 900 to 1,100 Brinell, which is considerably higher than that obtained by ordinary case hardening.

渗氮在钢表面获得远远超出正常标准的硬度。其硬度范围为900到1,100布氏硬度，这远高于普通表面硬化所获得的硬度。

Nitriding steels, by virtue of their alloying content, are stronger than ordinary steels and respond readily to heat treatment. It is recommended that these steels be machined and heat-treated before nitriding, because there is no scale or further work necessary after this process.

由于渗氮钢的合金比例，它们比普通钢更强，也容易热处理。建议对这种钢在渗氮前先机加工和热处理，因为渗氮后没有剥落并不需要更多的加工。

Fortunately, the interior structure and properties are not affected appreciably by the nitriding treatment and, because no quenching is necessary, there is

little tendency to warp, develop cracks, or change condition in any way. The surface effectively resists corrosive action of water, saltwater spray, alkalies, crude oil, and natural gas.

值得庆幸的是由于渗氮处理一点都不影响内部结构和性能，也无需淬火，所以几乎没有任何产生翘曲、裂缝及变化条件的趋势。这种表面能有效地抵御水、盐雾、碱、原油和天然气的腐蚀反应。

Unit 3

Casting Processes

Casting is a manufacturing process in which molten metal is poured or injected and allowed to solidify in a suitably shaped mold cavity. During or after cooling, the cast part is removed from the mold and then processed for delivery.

铸造是一种将熔化的金属倒入或注入合适的铸模腔并且在其中固化的制造工艺。在冷却期间或冷却后，把铸件从铸模中取出，然后进行交付。

Casting processes and cast-material technologies vary from simple to highly complex. Material and process selection depends on the part’s complexity and function, the product’s quality specif ications, and the projected cost level.

铸造工艺和铸造材料技术从简单到高度复杂变化很大。材料和工艺的选择取决于零件的复杂性和功能、产品的质量要求以及成本预算水平。

Castings are parts that are made close to their final dimensions by a casting process. With a history dating back 6,000 years, the various casting processes are in a state of continuous refinement and evolution as technological advances are being made.

通过铸造加工，铸件可以做成很接近它们的最终尺寸。回溯6,000年历史，各种各样的铸造工艺就如同科技进步一样处于一个不断改进和发展的状态。

Sand Casting 砂型铸造

Sand casting is used to make large parts (typically iron, but also bronze, brass, aluminum). Molten metal is poured into a mold cavity formed out of sand (natural or synthetic).

砂型铸造用于制造大型零件(具有代表性是铁，除此之外还有青铜、黄铜和铝)。

将熔化的金属倒入由型砂(天然的或人造的)做成铸模腔。

The processes of sand casting are discussed in this section, including patterns, sprues and runners, design considerations, and casting allowance.

本节讨论砂型铸造工艺，包括型模、浇注口、浇道、设计考虑因素及铸造余量。

The cavity in the sand is formed by using a pattern (an approximate duplicate of the real part), which are typically made out of wood, sometimes metal. The cavity is contained in an aggregate housed in a box called the flask.

砂型里的型腔是采用型模(真实零件的近似复制品)构成的，型模一般为木制，有时也用金属制造。型腔整个包含在一个被放入称为砂箱的箱子里的组合体内。

Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages. Cores are placed in the cavity to form holes of the desired shapes. Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold.

砂芯是插入铸模的砂型，用于生成诸如孔或内通道之类的内部特征。砂芯安放在型腔里

形成所需形状的孔洞。砂芯座是加在型模、砂芯或铸模上的特定区域，用来在铸模内部定位和支撑砂芯

。

A riser is an extra void created in the mold to contain excessive molten material. The purpose of this is to feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting. 冒口是在铸模内部增加的额外空间，用于容纳过多的熔化金属。其目的是当熔化金属凝固和收缩时往型腔里补充熔化金属，从而防止在主铸件中产生孔隙。

在典型砂型铸造的两箱铸模中，上半部分(包括型模顶半部、砂箱和砂芯)称为上型箱，下半部分称为下型箱，见图所示。分型线或分型面是分离上下型箱的线或面。

The drag is first filled partially with sand, and the core print, the cores, and the gating system are placed near the parting line. The cope is then assembled to the drag, and the sand is poured on the cope half, covering the pattern, core and the gating system.

首先往下型箱里部分地填入型砂和砂芯座、砂芯，并在靠近分型线处放置浇注系统。然后将上型箱与下型箱装配在一起，再把型砂倒入上型箱盖住型模、砂芯和浇注系统。

The sand is compacted by vibration and mechanical means. Next, the cope is removed from the drag, and the pattern is carefully removed. The object is to remove the pattern without breaking the mold cavity.

型砂通过振动和机械方法压实。然后从下型箱上撤掉上型箱，小心翼翼地取出型模。其目的是取出型模而不破坏型腔。

This is facilitated by designing a draft, a slight angular offset from the vertical to the vertical surfaces of the pattern. This is usually a minimum of .), whichever is greater. The rougher the surface of the pattern, the more the draft to be provided.

通过设计拔模斜度—型模垂直相交表面的微小角度偏移量—来使取出型模变得容易。拔模斜度最小一般为.)，只能比此大。型模表面越粗糙，则拔模斜度应越大。

The molten material is poured into the pouring cup, which is part of the gating system that supplies the molten material to the mold cavity.

熔化的金属从浇注杯注入型腔，浇注杯是浇注系统向型腔提供熔化金属的部分。The vertical part of the gating system connected to the pouring cup is the sprue, and the horizontal portion is called the runners and finally to the multiple points where it is introduced to the mold cavity called the gates.

将浇注系统的垂直部分与浇注杯连接的是浇注口，浇注系统的水平部分称为浇道，最后到多点把熔化金属导入型腔的称为闸道。

Additionally there are extensions to the gating system called vents that provide the path for the built-up gases and the displaced air to vent to the atmosphere. 除此之外，还有称为排放口的浇注系统延长段，它为合成气体和置换空气排放到大气提供通道。

The cavity is usually made oversize to allow for the metal contraction as it cools down to room temperature. This is achieved by making the pattern oversize. To account for shrinking, the pattern must be made oversize by these factors on the average. These are linear factors and apply in each direction.

型腔通常大于所需尺寸以允许在金属冷却到室温时收缩。这通过把型模做得大

于所需尺寸来达到。为解决收缩效应，一般而言型模做得比所需尺寸大，必须考虑线性因素并作用于各个方向。

These shrinkage allowances are only approximate, because the exact allowance is determined by the shape and size of the casting. In addition, different parts of the casting might require different shrinkage allowances.

收缩余量仅仅是近似的，因为准确的余量是由铸件的形状和尺寸决定的。另外，铸件的不同部分也可能需要不同的收缩余量。

Sand castings generally have a rough surface sometimes with surface impurities, and surface variations. A machining (finish) allowance is made for this type of defect.

砂型铸件一般表面粗糙，有时还带有表面杂质和表面变异。对这类缺陷采用机加工(最后一道工序)的余量。

1. Patterns are made. These will be the shape used to form the cavity in the sand.

一般而言，砂型铸造作业的典型阶段包括(如图所示)：

1. 制作型模。做成用于在型砂中形成型腔的形状。

2. Cores may also be made at this time. These cores are made of bonded sand that will be broken out of the cast part after it is complete.

3. Sand is mulled (mixed) thoroughly with additives such as bentonite to increase bonding and overall strength.

2. 同时还要制作砂芯。这些砂芯用粘结砂做成，等铸件完成后将被打碎取出。

3. 型砂与膨润土之类的添加剂充分地混合以增强连接及整体强度。

4. Sand is formed about the patterns, and gates, runners, risers, vents and pouring cups are added as needed. A compaction stage is typically used to ensure good coverage and solid molds.

4. 型砂在型模周围成形，并根据需要安放闸道、浇道、冒口、排放口和浇注杯等。通常要采取压紧步骤来保证良好的覆盖和坚固的铸型。

Cores may also be added to make concave or internal features for the cast part. Alignment pins may also be used for mating the molds later. Chills may be added to cool large masses faster.

安放砂芯来制成铸件的凹形结构或内部特征。为了以后铸模匹配还要用到定位销。对大质量铸件可能需要加入冷却物来使其较快冷却。

5. The patterns are removed, and the molds may be put through a baking stage to increase strength.

6. Mold halves are mated and prepared for pouring metal.

5. 取走型模，将铸模烘焙以增加强度。

6. 匹配上下铸模，做好浇铸金属的准备。

7. Metal is preheated in a furnace or crucible until is above the liquidus temperature in a suitable range (we don’t want the metal solidifying before the pour is complete). The exact temperature may be closely controlled depending upon the application.

7. 金属在熔炉或坩埚中预热到高于液化温度的一个合适范围内(不希望金属在浇铸完成前凝固)。确切的温度要根据应用场合严格控制。

Degassing, and other treatment processes may be done at this time, such as removal of impurities . slag). Some portion of this metal may be remelted scrap

金属材料专业英语(带音标)

金属材料专业英语 材料科学 材料科学定义 [m???'] 加工性能 .[?θ] 强度 & .[k?'r????n] &['?] .[ '?r?'b?l?t?] 抗腐蚀及耐用金属特性 , & 抗敏感及环境保护[?'l??] 化学元素'?] 元素的原子序数 原子及固体物质 原子的组织图['k?] 周期表[?'?]. 周期的；定期的 原子键结合 金属与合金['?l?i, ?'l?i] & 铁及非铁金属['?s]. [化]亚铁的；铁的，含铁的金属的特性 晶体结构['?l]n. 水晶；结晶，晶体；水晶饰品 . 水晶的；透明的，清澈的 , & 晶体结构，定向格子及单位晶格['l?]n. 格子；格架；晶格 . 使成格子状

X – X线结晶分析法[,?n?'?l] 金属结晶格子 点阵常数 's 米勒指数 金相及相律 固熔体 置换固熔体[?:??n?l] 间隙固熔体[?'??l]n. 填隙原子；节间 . 间质的；空隙的；填隙的 金属间化合物[?'t?]['k?, k?m']. 混合；合成；和解妥协；搀合 . 妥协；和解 n. 化合物；复合词；混合物 . 复合的；混合的 转变 转变点 磁性转变[m?ɡ'] 同素转变[m?ɡ']. [化]同素异形的 热平衡['θ??l]. 热的，热量的 n. 上升暖气流. 热的，热量的['?m] 自由度 临界温度

共晶[:']n. 共熔合金 . 共熔的；容易溶解的 [’] 包晶温度 包晶反应 包晶合金 亚共晶体[?']n. 低级低共熔体. 亚共晶的 过共晶体 金属塑性[?:'??n]n. 变形 滑动面 畸变['t?:??n] 硬化 退火 回复柔软 再结晶[?'??n] & 金属材料的性能及试验化学性能['?p?] 物理性能 磁性['m?ɡ?m] & 比电阻 & 比重 比热

翻译资料英语

FINANCIAL INNOV ATION Like other industries, the financial industry is in business to earn profits by selling its products. If a soap company perceives that there is a need in the marketplace for a laundry detergent with fabric softener, it develops a product to fit the need .Similarly, in order to maximize their profits, financial institutions develop new products to satisfy their own needs as well as those of their customers; in other words, innovation-which can be extremely beneficial to the economy-is driven by the desire to get (or stay) rich. This view of the innovation process leads to the following simple analysis: A chance in the financial institutions for innovations that are likely to be profitable. Starting in the 1960s, individuals and financial institutions operating in financial markets were confronted with drastic changes in the economic environment: Inflation and interest rates climbed sharply and became hard to predict, a situation that changed demand conditions in financial markets. Computer technology advanced rapidly, which changed supply conditions. In addition, financial regulations became especially inconvenient. Banking institution discovers many old ways of doing business being able to not have earned money again; they provide the masses finance with service and financial products sale neither well. Many financial intermediary is discovered they have no way to raise having arrived at a fund, but these self that will not a suspense of business right away with original tradition finance implement. For existing under new economy environment, research and development puts up banking institution be obliged to being able to satisfy customer need moreover the new product being able to gain a profit of and serving, this process is called financial engineering. In their case, necessity was the mother of innovation. Our discussion of why financial innovation occurs suggests that there are three basic types of financial innovations: Escapism to responding to needing condition change, to the small advantages supplying with condition change and to controlling. We have had one now understandable that banking institution is innovative for instance the cause institutions, let’s look at examples of how financial institutions in their search for profits have produced financial innovations of the three basic types. 1

三级英语翻译(精品收藏)

三年级上册英语第一单元《Ｈｅｌｌｏ》课文翻译人教（新版) Hellｏ! I'm Zoｏm。您好！我是祖姆. Hｅllo，I'ｍ Mｉke。你好，我是迈克。?Hi， I'm Wu yifａn．你好,我是吴一凡.?Ｈi！ My nａme＇s Zｉp. 你好！我的名字是次波。?Gｏodby ｅ! 再见！ Bｙe， Miss Whitｅ！再见，怀特小姐! Helｌｏ,I’mＣhen Jie。嗨,你好，我叫陈洁.?Wｈa ｔ’s your ｎａme？你叫什么名字? My name’sＳarah. 我叫莎拉. Ｈeｌｌo,Ｉ＇m Miss Whｉｔｅ. 你好，我是怀特小姐。 Hello，I'ｍ Wu ｙiｆan. 你好,我是吴一凡。 Hｉ,I’ｍ Sａrah。你好！我是莎拉。 Helｌo， I'ｍ Lｉu Xin．你好！我是刘欣。?Hi， Ｉ’m John．嗨，我是约翰.?I havｅ a ruler. 我有一把尺子。 I have a rulｅr. Me toｏ ! 我有一支尺子.我也是！?I hａｖe a penｃil。Ｍe tｏo ! 我有一支铅笔。我也是!?Ｉｈａvｅａ crayon. Mｅｔoｏ！我有一支蜡笔。我也是!?I ｈave an eraser． Me tｏo！我有一块橡皮。我

也是！?Helｌo，I’m Mike。你好，我是迈克.?Wｈ at's ｙｏur ｎamｅ? 你叫什么名字？ My name’s Jｏhn. 我是约翰.?Gｏoｄｂye！再见！?Ｂye， Mｉsｓ White ！再见，怀特小姐! Whaｔ＇ｓ your name? 你叫什么名字？?Mｙｎ ame's Ｌilｙ．我的名字是莉莉。 Oh， no！哦,不！?Zoｏm!yoｕｒｂａg！祖姆！你的包！?Open your ｐenｃｉｌｂｏx. 打开你的铅笔盒。Shｏｗ me ｙｏur ｐen。让我看看你的钢笔。 Cｌose yｏuｒ bｏｏk. 把书合上. Carry your bag。携带你的包。?Ｈeｌlo! 您好！?Ｈi!Ｗｈo＇s tｈｅre? 你好！谁在那里？ Gueｓs！猜！?Arｅ you Ｔutｕ？你是图图？?Ｎo! 不! Ｈａｈa! I＇m Zip! 哈哈!我是次波！ Hi，Ｚip！ My name’s Zｏoｍ。嗨，次波！我的名字是祖姆。 Ｌet'ｓｐlaｙ！ Ok? 让我们玩！好吗??Great! 太好了！ 三年级上册英语第二单元《Ｃoloｕｒs》课文翻译人教

专业英语课文翻译

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。在更大的结构领域上，其包括大的原子团，这些原子团通常聚集在一起，称为“微观”结构，意思是可以使用某种显微镜直接观察得到的结构。最后，结构单元可以通过肉眼看到的称为宏观结构。 “Property”一词的概念值得详细阐述。在使用中，所有材料对外部的刺激都表现出某种反应。比如，材料受到力作用会引起形变，或者抛光金属表面会反射光。材料的特征取决于其对外部刺激的反应程度。通常，材料的性质与其形状及大小无关。实际上，所有固体材料的重要性质可以概括分为六类：机械、电学、热学、磁学、光学和腐蚀性。对于每一种性质，其都有一种对特定刺激引起反应的能 力。如机械性能与施加压力引起的形变有关，包括弹性和强度。对于电性能，如电导性和介电系数，特定的刺激物是电场。固体的热学行为则可用热容和热导率来表示。磁学性质

材料英语翻译

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材料科学与工程专业英语1（18单元课后翻译答案）- 目睹了我们的生活通过发生在医药、电信和交通运输行业的革命得到了重塑。8 .世界上80%的人口缺乏安全饮用水，近40%的人口没有卫生设施。9 .材料和社会是相互联系的，我们应该看到微型企业研究议程和影响人类状况的社会问题之间的密切关系，这是合理的。从化学角度来看，金属是一种容易失去电子形成正离子的元素，正离子与其他金原子形成金属键。2.金属键的无方向性被认为是金属延展性的主要原因。3.只有当原子间的键断裂时，带有共价键的晶体才会变形，导致晶体断裂。4.合金，尤其是那些满足更高应用要求的合金，如喷气发动机，可能含有十多种元素。5.离域电子电子结构碱土金属化学电池核电荷电导率。金属有时被描述为被离域电子云包围的正离子晶格。7 .金属通常具有优异的导电性和导热性、高密度和在应力下变形而不裂开的能力。8 .合金是两种或多种元素在固溶体中的混合物，其中主要成分是金属。9 .将不同比例的金属结合在一起作为 超级合金的发展严重依赖于化学和加工创新，主要由航空和能源行业推动。2.抗蠕变性主要取决于晶体结构中位错速度的减缓。3.高温合金加工技术的发展大大提高了高温合金的工作温度。4.单晶高温合金是采用改进的定向凝固技术形成的，因此材料中没有晶界。5.面心立方晶体结构涡轮入口温度金属材料相稳定性核反应堆纳米粒子的合成。超级合金通常具有悬浮面心立方晶体结构。7 .在需要高温强度和腐蚀/氧化的地方使用超级合金 电阻。8 .超级合金广泛用于航空潜艇、核反应堆和军用电动机。9 .

在高温下，气态明矾腐蚀过程本质上是一个电化学过程，具有与电池相同的基本特性。2.从矿物中提取金属所需的能量问题与随后的腐蚀和能量释放直接相关。3.当电子与中和的正离子(如电解质中的氢离子)反应时，阴极的电子必须平衡。4.保护膜电路自由电子转移金属阳离子阳极反应5。一些金属如金和银可以 在地球上以天然金属状态存在，它们几乎不容易腐蚀。6 .氧化是从原子中剥离电子的过程，当电子被加到原子中时，就会发生还原。7 .如果表面变湿，腐蚀可能通过阳极和阴极之间的表面水层中的离子交换发生。8 .腐蚀通常根据腐蚀的外观进行分类 我们必须观察(研究)这些特性，看它们如何与我们期望的陶瓷成分相匹配。2.在高于玻璃化转变温度的高温下，玻璃不再具有脆性行为，而是显示出粘性液体。3.它们表现出优异的机械性能、抗腐蚀/抗氧化性能或电、光或磁性能。人们普遍认为，先进陶瓷的发展只是在最近100年，而传统的粘土基陶瓷已经使用了25000多年。5.玻璃转变温度离子共价键热膨胀应力分布系数玻璃光纤材料科学与工程固体氧化物燃料电池电子显微镜。被归类为陶瓷的金刚石的热导率是所有已知材料中最高的。7 .陶瓷的压缩强度比拉伸强度大，而金属的拉伸强度和压缩强度相当。8 .陶瓷的韧性通常较低，尽管将其结合在复合材料中可以显著提高其韧性 提高这一性能。9 .陶瓷产品的功能取决于它们的化学成分和微观结构，这决定了它们的合适性。材料科学和工程领域通常是根据四个主要方面——合成和加工、结构和组成、性能和性能——之间的相互关

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材料科学与工程专业英语第三版翻译以及答案 Document serial number【KK89K-LLS98YT-SS8CB-SSUT-SST108】

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

英文翻译材料

债权人（商业银行）视角的企业经营业绩评价体系设计框架 ———基于工业工程理论 严化川 (东南大学,江苏南京210000，中信银行南京分行，江苏南京210000) 摘要：每个企业都是一个复杂的、有生命力和连续变化的“社会—技术”系统。系统本身与周围环境有着物质和能量的交换。在公司进行财务活动的过程当中，最为典型的“物质和能量”交换便是现金的交换。现金的流动带动了公司相关的供应链和价值链的正常运转。公司的筹资、投资和股利分配三大理财活动构成企业现金交换的完整过程。作为企业融资的主要提供者的商业银行，面对为数众多的数额巨大的资金需求者，深刻感到单纯以企业个体信誉或对企业状况的主观判断和经验估测作为贷款的依据，必然身陷泥潭，血本无归。因此债权人（商业银行）必须对企业经营业绩进行自主的评价。本文基于工业工程理论，对债权人（商业银行）视角的企业经营业绩评价体系设计框架进行浅析，以期基于此框架所设计的企业经营业绩评价体系能够帮助债权人实现维护自身利益的目标。 关键词： 中图分类号：F832 文献标识码：A 文章编号：1008-4428（2009）08-71-03 企业业绩的测试、评价与改进，是组织系统管理的重要组成部分。作为企业融资的主要提供者的商业银行，面对为数众多的数额巨大的资金需求者，深刻感到单纯以企业个体信誉或对企业状况的主观判断和经验估测作为贷款的依据，必然身陷泥潭，血本无归。因此债权人（商业银行）必须对企业经营业绩进行自主的评价，并且作为企业业绩的评价主体，必须基于自己的视角构建企业经营业绩评价体系，以满足自身对企业经营业绩评价的需求。 基于债权人视角的企业经营业绩评价体系的框架结构应当由评价理念、评价程序、评价方法和评价指标共同构成，它是商业银行以防范信用风险和操作风险为目标的内控制度的重要环节。 一、确立正确的评价理念 管理首先是一种理念，管理的实践是一项系统工程，管理是在一定的理念指导下为了实现现实目标的系统工程。 评价理念是指导企业经营业绩评价的基本原则，是整个评价体系运行的前提。根据工业工程的基本原理，我们应当确立系统变异的观点，从全局\ 整体系统思考的观点，以及价值定向的观点。 （一）系统或过程/流程变异的观点 分析和掌握系统或过程/流程变异的观点是工业工程建立有效的测量系统的重要出发点。 设计企业经营业绩评价体系，需要考虑组织背景对企业经营业绩评价的影响。这里所说的组织背景是指企业的生产经营活动所面临的外部环境和内部环境，包括外部环境、技术、组织战略、组织结构、规模、文化等变量。 工业工程理论提出：企业是一个复杂的，有生命，连续变化，“今天和昨天不一样”的大系统，具有时变的动态特征。近些年来，经济全球化使企业变得更加复杂化和动态化，企业面对市场变化、竞争规则、经济、市场和资源条件都同已有的经验极不同，企业面临着日益增大的商务风险，并且这种风险还处在不断变化当中。 因而在设计企业业绩评价体系时，我们必须按照工业工程所指出的那样，利用数据统计方法和量化分析掌握系统或过程/流程的变异，了解变异的本质，并对之实施管理控制。鉴于了解工作性能/业绩方面统计思考起着更加关键的作用，我们应当按照以下要点进行统计思考： 1、所有的工作都是相互关联的过程或流程的一部分。 2、变化（变异或变差）总是存在于每个过程/流程中。 3、85%以上的问题是过程流程变化造成的。 4、过程决策必须建立在合适的过程数据基础上。 （二）从全局/整体进行系统思考的观点

材料科学与工程专业英语 短句词汇翻译 前10课

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 coefficient 1.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 nanotub 1、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。Metallic materials have large numbers of nonlocalized electrons，many properties of metals are directly attributable to these electrons. 2、许多聚合物材料是有机化合物，并具有大的分子结构。Many of polymers are organic compounds,and they have very large molecular structures. 3、半导体材料的典型特征介于导体材料（如金属、金属合金）与绝缘体（陶瓷材料和聚合体材料）之间。Semiconductors have electrical properties that are intermediate between the electrical conductors ( viz. metals and metal alloys ) and insulators ( viz. ceramics and polymers ). 4、生物材料不能产生毒性，并且不许与人体组织互相兼容。Biomaterials must not produce toxic substances and must be compatible with body tissues. Unit3： 微观结构microstructure 宏观结构macrostructure 化学反应chemical reaction 原子量atomic 电荷平衡balanced electrical charge 带正电子的原子核positively charge nucleu 1、从我们呼吸的空气到各种各样性质迥异的金属，成千上完中物质均是由100多种院子组成的。These same 100 atoms form thousands of different substances ranging from the air we breathe to the metal used to support tall buildings.

材料科学基础专有名词英文翻译

Fundamentals of Materials Science 材料科学基础名词与术语 第一章绪论 metal: 金属 ceramic: 陶瓷polymer: 聚合物Composites: 复合材料Semiconductors: 半导体Biomaterials: 生物材料 Processing: 加工过程 Structure: 组织结构 Properties: 性质 Performance: 使用性能 Mechanical properties: 力学性能 Electrical properties: 电性能 Thermal behavior: 热性能 Magnetic properties: 磁性能 Optical properties: 光性能 Deteriorative characteristics: 老 化特性 第二章原子结构与原子键 Atomic mass unit (amu): 原子质量单位 Atomic number: 原子数 Atomic weight: 原子量 Bohr atomic model: 波尔原子模型Bonding energy: 键能 Coulombic force: 库仑力 Covalent bond: 共价键 Dipole (electric): 偶极子electronic configuration: 电子构型electron state: 电位 Electronegative: 负电的 Electropositive: 正电的 Ground state: 基态 Hydrogen bond: 氢键 Ionic bond: 离子键 Isotope: 同位素 Metallic bond: 金属键 Mole: 摩尔 Molecule: 分子 Pauli exclusion principle: 泡利不相 容原理 Periodic table: 元素周期表 Polar molecule: 极性分子 Primary bonding: 强键 Quantum mechanics: 量子力学 Quantum number: 量子数 Secondary bonding: 弱键 valence electron: 价电子 van der waals bond: 范德华键 Wave-mechanical model: 波粒二象 性模型 第三章金属与陶瓷的结构 Allotropy: 同素异形现象 Amorphous: 无定形 Anion: 阴离子 Anisotropy: 各向异性 atomic packing factor(APF): 原子堆积因数body-centered cubic (BCC): 体心立方结构Bragg’s law: 布拉格定律 Cation: 阳离子 coordination number: 配位数 crystal structure: 晶体结构 crystal system: 晶系 crystalline: 晶体的 diffraction: 衍射 face-centered cubic (FCC): 面心立方结构第五章晶体缺陷 Alloy: 合金 A metallic substance that is composed of two or more elements. 由两种及以上元素组成的金属材料。 Weight percent (wt%)：质量百分数 Concentration specification on the basis of weight (or mass) of a particular element relative to the total alloy weight (or mass). Stoichiometry: 正常价化合物 For ionic compounds, the state of having exactly the ratio of cations to anions speci-fied by the chemical formula. 在离子化合物中，正、负离子的比例严格遵守化学公式定义的化合价关系。 Imperfection: 缺陷，不完整性 A deviation from perfection; normally applied to crystalline materials wherein there is a deviation from atomic/molecular order and/or continuity. 对完美性的偏离，在材料科学领域中通常指晶体材料中原子/分子在排列顺序/连续性上的偏离。 Point defect: 点缺陷 A crystalline defect associated with one or, at most, several atomic sites. 一种仅波及一个或数个原子的晶体缺陷。 Vacancy: 空位 A normally occupied lattice site from which an atom or ion is missing. 一个缺失原子或离子的晶格节点位置。 Vacancy diffusion: 空位扩散

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

英语三级翻译大全

1.首先，我们要让他相信这是可能的。 First , we should convince him that it is possible. 2.坏天气仍可能再持续好几天. It remains possible that the bad weather will last for several more days. 3.如果出了问题，谁来负责。 If problems arise , who can be responsible for it . 4.我试图向他解释，但他却生气地转过脸去。 I tried to explain , but he turned away from me in anger. 5.人们通常将阳光视为生命的必要条件之一。 People often view sunshine as one of the necessary conditions for life . 6.我昨天不该喝那么多啤酒的。 I shouldn’t have drunk so much beer yesterday. 7.你本不必过来那么早。会议9点菜开始。 You needn’t have been here so early. The meeting begins at 9 o’clock. 8.过去一遇到问题，她就去找她姐姐帮忙。 She would turn to her sister for help whenever there was a problem. 9.地面时湿的。刚才一定是下过雨了。 The ground is wet .It must have just rained. 10.难道她不该涨工资吗？ Shouldn’t she have a pay-raise? 11.他开会迟到了，大家的目光都集中到他的身上。 He was late for the meeting and all people were focused their eyes on him. 12.他妈妈周末不让他出房门，因为他没做完作业。 His mother confined him to the room for the weekend because he didn’t finish his homework. 13.医生建议我们不要让皮肤过多地暴露在阳光下。 The doctor advice us not to expose our skin to the sunshine too much.

翻译材料

Chapter 3 of S. T. Coleridge’s Biographia Literaria To anonymous 匿名的critics in reviews综述，评论, magazines, and news-journals 新闻杂志 of various name and rank, and to satirists 讽刺作家with or without a name in verse诗 or prose散文, or in verse-text aided by prose-comment, I do seriously believe and profess声称，表明, that I owe full two-thirds of whatever reputation and publicity I happen to碰巧 possess. For when the name of an individual has occurred so frequently, in so many works, for so great a length of time, the readers of these works—(which with a shelf or two of beauties, elegant Extracts and Anas, form nine-tenths of the reading of the reading Public [14])—cannot but be familiar with the name, without distinctly remembering whether it was introduced for eulogy颂词 or for censure责备. And this becomes the more likely, if (as I believe) the habit of perusing periodical works may be properly added to Averroes' catalogue of Anti-Mnemonics记忆术, or weakeners 削弱器 of the memory [15]. But where this has not been the case, yet the reader will be apt to倾向于 suspect that there must be something more than usually strong and extensive in a reputation, that could either require or stand so merciless and long-continued a cannonading炮轰. Without any feeling of anger therefore—(for which indeed, on my own account, I have no pretext)—I may yet be allowed to express some degree of surprise, that, after having run the critical gauntlet严酷考验，夹叉射击 for a certain class of faults which I had, nothing having come before the judgment-seat in the interim在其间, I should, year after year, quarter after quarter, month after month—(not to mention sundry petty periodicals of still quicker revolution, "or weekly or diurnal")—have been, for at least seventeen years consecutively, dragged forth拖出来 by them into the foremost ranks of the proscribed被禁的, and forced to abide the brunt冲击，主要冲力 of abuse, for faults directly opposite, and which I certainly had not. How shall I explain this? Whatever may have been the case with others, I certainly cannot attribute this persecution迫害，烦扰 to personal dislike, or to envy, or to feelings of vindictive怀恨的，有报复心的 animosity憎恶，仇恨. Not to the former, for with the exception of a very few who are my intimate friends, and were so before they were known as authors, I have had little other acquaintance with literary characters, than what may be implied in an accidental introduction, or casual meeting in a mixed company. And as far as words and looks can be trusted, I must