2022年材料科学与工程专业学习英语.docx
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1、精选学习资料 - - - - - - - - - 材料科学与工程专业英语Unit1 Materials Science and Metallurgical Engineering Materials are properly more deep-seated in our culture than most of us realize. Trans -portation, housing, clothing, communication, recreation and food production-virtually every segment of our everyday lives i
2、s influenced to one degree or another by materials. Historically, the development and advancement of societies have been intimately tied to the members abilities to produce and manipulate materials to fill their needs. In fact, early civilizations have been designated by the level of their materials
3、 development i.e.Stone Age, Bronze Age. The earliest humans has access to only a very limited number of materials, those that occur naturally stone, wood, clay, skins, and so on. With time they discovered techniques for producing materials that had properties superior to those of the natural ones: t
4、hese new materials included pottery and various metals. Furthermore, it was discovered that the properties of a material could be altered by heat treatments and by the addition of other substances. At this point, materials utilization was totally a selection process, that is, deciding from a given,
5、rather limited set of materials the one that was best suited for an application by virtue of its characteristic. It was not until relatively recent times that scientists came to understand the relationships between the structural elements of materials and their properties. This knowledge, acquired i
6、n the past 60 years or so, has empowered them to fashion, to a large degree, the characteristics of materials. Thus, tens of thousands of different materials have evolved with rather specialized characteristics that meet the needs of our modern and complex society. The development of many technologi
7、es that make our existence so comfortable has been intimately associated with the accessibility of suitable materials. Advancement in the under-standing of a material type is often the forerunner to the stepwise progression of a technology. For example, automobiles would not have been possible witho
8、ut the availability of inexpensive steel of some other comparable substitutes. In our contemporary era, sophisticated electronic devices rely on components that are made from what are called semiconducting materials. Materials Science Engineering Materials science is an interdisciplinary study that
9、combines chemistry, physics, metallurgy, engineering and very recently life sciences. One aspect of materials science involves studying and designing materials to make them useful and reliable in the service of humankind. It strives for basic understanding of how structures and processes on the atom
10、ic scale result in the properties and functions familiar at the engineering level. Materials scientists are interested in physical and chemical phenomena acting across large magnitudes of space and time scales. In this regard it differs from physics of chemistry where the emphasis is more on explain
11、ing the properties of pure substances. In materials science there is also an emphasis on developing and using knowledge to understand how the properties of materials can be controllably designed by varying the compositions, structures, and the way in which the bulk and surfaces phase materials are p
12、rocessed. In contrast, materials engineering is, on the basis of those structure properties correlations, designing or engineering the structure of a material to produce a predetermined set of properties. In other words, materials engineering mainly deals with the use of materials in design and how
13、materials are manufactured. 名师归纳总结 - - - - - - -第 1 页,共 38 页精选学习资料 - - - - - - - - - Structure is a nebulous term that deserves some explanation. In brief, the structure of a material usually relates to the arrangement of its internal components. Subatomic structure involves electrons within the ind
14、ividual atoms and interactions with their nuclei. On an atomic level, structure encompasses the organization of atoms or molecules relative to one another. The next large structural realm, which contains large groups of atoms that are normally agglomerated together, is termed microscopic meaning tha
15、t which is subject to direct observation using some type of microscope. Finally, structural elements that may be viewed with the naked eye are termed macroscopic. The notion of property deserves elaboration. While in service use, all materials are exposed to external stimuli that evoke some type of
16、response. For example, a specimen subject to forces will experience deformation; or a polished metal surface will reflect light. Property is a material trait in terms of the kind and magnitude of response to a specific imposed stimulus. Generally, definitions of properties are made independent of ma
17、terial shape and size. Virtually all important properties of solid materials may be grouped into six different categories; mechanical, electrical, thermal, magnetic, optical, and deteriorative. For each there is s characteristic type of stimulus capable of provoking different responses. Mechanical p
18、roperties relate deformation to an applied load or force: examples include elastic modulus and strength. For electrical properties, such as electrical conductivity and dielectric constant, the stimulus is an electric filed. The thermal behavior of solids can be represented in terms of heat capacity
19、and thermal conductivity. Magnetic properties demonstrate the response of a material to the application of a magnetic field. For optical properties, the stimulus is electromagnetic or light radiation: index of refraction and reflectivity are representative optical properties. Finally, deteriorative
20、characteristics indicate the chemical reactivity of materials. In addition to structure and properties, two other important components are involved in the science and engineering of materials, namely processing and performance. With regard to the relationships of these four components, the structure
21、 of a material will depend on how it is processed. Furthermore, a materials performance will be a function of its properties. Thus, the interrelationship between processing, structure, properties, and performance is linear as follows: ProcessingStructurePropertiesPerformance Why Study Materials Scie
22、nce and Engineering. Why do we study materials. Many an applied scientists or engineers, whether mechanical, civil, chemical, or electrical, will be exposed to a design problem involving materials at one time or another. Examples might include a transmission gear, the superstructure for a building,
23、an oil refinery component, or an integrated circuit chip. Of course, materials scientists and engineers are specialists who are totally involved in the investigation and design of materials. Many times, a materials problem is to select the right material from many thousands available ones. There are
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