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1、Unit OneUnit One Mold Materials and Heat Treatment1 Engineering Materials 2 Kinds of Steel 3 Polymers4 Mold Materials5 Heat Treatment of Metals Passage One Engineering MaterialsUnit One Mold Materials and Heat TreatmentMaterials may be grouped in several ways. Scientists often classify materials by
2、their state: Solid， liquid， or gas. They also separate them into organic（once living） and inorganic（never living） materials. For industrial purposes ， materials are divided into engineering materials or nonengineering materials. Engineering materials are those used in manufacture and become parts of
3、 products. Nonengineering materials are the chemicals， fuels， lubricants， and other materials used in the manufacturing process which do not become part of the product. Engineering materials may be classified into four groups: Metals， ceramics， polymers， and composite materials. 11. Metals Unit One
4、Mold Materials and Heat TreatmentMetals and alloys，which include steel， aluminum， mag- nesium， zinc， cast iron， titanium， copper， nickel， and many others， have the general characteristics of good electrical and thermal conductivity， relatively high strength ， high stiffness， ductility or formability
5、， and shock resistance . They are particularly useful for structural or load -bearing applications. Although pure metals are occasionally used， combinations of metals called alloys are normally designed to provide improvement in a particular desirable property or permit better combinations of proper
6、ties. 2. Ceramics Unit One Mold Materials and Heat TreatmentCeramics， such as brick， glass， tableware， insulators， and abrasives， have poor electrical and thermal conductivity . Although ceramics may have good strength and hardness， their ductility， formability， and shock resistance are poor. Conseq
7、uently ， ceramics are less often used for structural or load -bearing applications than metals. However， many ceramics have excellent resistance to high temperatures and certain corrosive media and have a number of unusual and desirable optical， electrical， and thermal properties. 3. Polymers Unit O
8、ne Mold Materials and Heat TreatmentPolymers include rubber， plastics， and many types of adhesives . They are produced by creating large molecular structures from organic molecules， obtained from petroleum or agricultural products， in a process known as polymerization. Polymers have poor electrical
9、and thermal conductivity， low strengths， and are not suitable for use at high temperatures. Some polymers have excellent ductility， formability， and shock resistance while others have the opposite properties. Polymers are lightweight and frequently have excellent resistance to corrosion. 4. Composit
10、e materials Unit One Mold Materials and Heat TreatmentComposite materials are formed from two or more mate- rials， whose properties cannot be obtained by any single ma- terial. Concrete， plywood， and fiberglass are typical， al - though crude， examples of composite materials. With com- posite materia
11、ls we can produce lightweight， strong， duc- tile， high heat -resistant materials that are otherwise unob- tainable， or produce hard yet shock -resistant cutting tools that would otherwise shatter . Unit One Mold Materials and Heat Treatment Consequently， ceramics are less often used for structural o
12、r load - bearing applications than metals. 因此，与金属相比，陶瓷很少用于结 构件或承载件。less . than = not so . as比少 , be used for .是“用于 ”的意思。例如:A hammer is used for driving in nails. They are produced by creating large molecular structures from organic molecules， obtained from petroleum or agricultural products， in a pr
13、ocess known as polymerization. 它们是由来自石油或农产品的有机分 子形成的巨大分子结构所产生的，这个过程称为聚合。 “obtained from petroleum or agricultural products”是简化句，等于which are obtained from .，修饰前面的“molecules”。 Composite materials are formed from two or more materials， whose properties cannot be obtained by any single material. 复合材料由两种
14、或 两种以上的材料组成，其性能绝非构成其中的任何一种单一材料所能拥 有。be formed from .由组成 “producing properties that cannot be obtained by any single material”的主语是复合材料。 Notes:New Words and Expressions: Unit One Mold Materials and Heat Treatmentlubricant lu brik nt n.润滑剂 ceramicssi r miks n.陶瓷，陶瓷制品 polymer p lim n.聚合物 composite k mp
15、zit adj.合成的，复合的; n.混合物 zinczi k锌 cast iron铸铁 titaniumt i teinj m n.钛 nickel nik（）l n.镍 stiffness stifnis n.硬度，刚度 ductilityd k tiliti n.韧性，可延展性 formabilityf m biliti n.可成型性 shock resistance抗冲击性 load -bearing承载 tableware teib（）lw n.餐具 Unit One Mold Materials and Heat Treatmentabrasive breisiv n.研磨剂，磨料（具）; adj.研磨的 thermal conductivity导热性 adhesive d hi siv n.黏结剂，黏胶剂 molecularm u lekjul adj.分子的 molecule m likju l n.分子 polymerization p lim rai zei n n.聚合 corrosionk r u n n.腐蚀 plywood plaiwud n.夹板 fibreglass faib l s n.玻璃纤维 crudekru d a
