国产精品尤物福利片在线观看_少妇免费毛片久久久久久久久_久久久久成人精品免费播放动漫_日韩av综合在线观看

歡迎來到010在線作文網!

材料專業英語課件: Classification of Material

教案 時間:2021-08-31 手機版

  Basic Classifications and Engineering Materials

  Solid materials have been conveniently grouped into three basic classifications: metals,ceramics and polymers.This scheme is based primarily on chemical makeup and atomic structure, and most materials fall into one distinct grouping or another, although there are some intermediates. In addition,there are three other groups of important engineering materials—composites, semiconductor, and biomaterials. Composites consist of combinations of two or more different materials, whereas semiconductors are utilized because of their unusual electrical characteristics;biomaterials are implanted into the human body.A brief explanation of the material types and representative characteristics is offered next.

  Metals: Metallic materials are normally combinations of metallic elements. They have large numbers of nonlocalized electrons;that is,these electrons are not bound to particular atoms. Many properties of metals are directly attributable to these electrons. Metals are extremely good conductors of electricity and heat,and are not transparent to visible light:a polished metal surface has a lustrous appearance. Furthermore, metals are quite strong,yet deformable, which accounts for their extensive use in structural applications.

  Ceramics: Ceramics are compounds between metallic and nonmetallic elements: they are most frequently oxides, nitrides,and carbides.The wide

  range of materials that falls within this classification includes ceramics that are composed of clay minerals, cement, and glass. These materials are typically insulative to the passage of electricity and heat, and are more resistant to high temperatures and harsh environments than metals and polymers.With regard to mechanical behavior,ceramics are hard but very brittle.

  Polymers:Polymers include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon,hydrogen, and other nonmetallic elements; furthermore,they have very large molecular structures.These materials typically have low densities and may be extremely flexible.

  Composites: A number of composite materials have been engineered that consist of more than one material type.Fiberglass is a familiar example,in which glass fibers are embedded within a polymeric material. A composite is designed to display a combination of the best characteristics of each of the component materials. Fiberglass acquires strength from the glass and flexibility from the polymer. Many of the recent material developments have involved composite materials.

  Semiconductors: Semiconductors have electrical properties that are intermediate between the electrical conductors and insulators. Furthermore,the electrical characteristics of these materials are extremely sensitive to the presence of minute concentrations of impurity atoms,which concentrations may be controlled over very small spatial regions.The semiconductors have made

  possible the advent of integrated circuitry that has totally revolutionized the electronics and computer industries over the past two decades.

  Biomaterials: Biomaterials are employed in components implanted into the human body for replacement of diseased or damaged body parts.These materials must not produce toxic substances and must be compatible with body tissue(i.e.must not cause adverse biological reactions).All of the above materials--metals,ceramics,polymers,composites and semiconductors--may be used as biomaterials.For example,some of the biomaterials such as CF/C(carbon fibers/carbon)and CF/PS (polysulfone) are utilized in artificial hip replacements.

  Advanced Materials

  Materials that are utilized in high-technology (or high-tech) applications are sometimes termed advanced materials.By high technology we mean a device or product that operates or functions using relatively intricate and sophisticated principles;examples include electronic equipment(VCRs,CD players,etc.),computers,fiberoptic systems,spacecraft,aircraft,and military rocketry.These advanced materials are typically either traditional materials whose properties have been enhanced or newly developed,high—performance materials.Furthermore,they may be of all material types(e.g.metals,ceramics,polymers),and are normally relatively expensive.

  Modern Materials Needs

  In spite of the tremendous progress that has been made in the discipline of materials science and engineering within the past few years,there still remain technological challenges,including the development of even more sophisticated and specialized materials,as well as consideration of the environmental impact of materials production.Some comment is appropriate relative to these issues so as to round out this perspective.

  Nuclear energy holds some promise,but the solutions to the many problems that remain will necessarily involve materials from fuels to containment structures and facilities for the disposal of radioactive waste.

  Significant quantities of energy are involved in transportation.Reducing the weight of transportation vehicles(automobiles,aircraft,trains,etc.),as well as increasing engine operating temperatures,will enhance fuel efficiency.New high strength,low—density structural materials remain to be developed,as well as materials that have higher—temperature capabilities,for use in engine components.

  Furthermore,there is a recognized need to find new,economical sources of energy,and to use the present resources more efficiently.Materials will undoubtedly play a significant role in these developments.For example,the direct conversion of solar energy into electrical energy uses silicon materials.To ensure a viable technology,materials that are highly efficient in this conversion process yet less costly must be developed.

  Additionally,environmental quality depends on our ability to control air and water pollution.Pollution control techniques employ various materials. In addition, materials Processing and refinement methods need to be improved so that they produce less environmental degradation,that is,less pollution and less despoilage of the landscape from mining of raw materials. Also, in some materials manufacturing processes,toxic substances are Produced,and the ecological impact of their disposal must be considered.

  Many materials that we use are derived from resources that are noenewable,that is not capable of being regenerated.These include polymers, for which the prime raw material is oil, and some metals.These noenewable resources are gradually becoming depleted, which necessitates: (1)the discovery of additional reserves, (2)the development of new materials having comparable properties with less adverse environmental impact, and/or (3) increased recycling efforts and the development of new recycling technologies· As a consequence of economi

  cs of not only production but also environmental impact and ecological factors,it is becoming increasingly important to consider the“cradle—to—grave’’life cycle of materials relative to the overall manufacturing process.

  (Selected from Materials Science and Engineering:An Introduction,by William D Callister,2002)

【材料專業英語課件: Classification of Materials】相關文章:

1.金屬材料課件

2.金屬材料說課課件

3.建筑材料說課課件

4.材料力學授課課件

5.語文寫作材料的合理構建課件

6.材料力學彎曲課件

7.美術素描課件材料

8.太陽和月亮課件材料


本文來源http://www.nvnqwx.com/jiaoan/2434478.htm
以上內容來自互聯網,請自行判斷內容的正確性。若本站收錄的信息無意侵犯了貴司版權,請給我們來信(zaixianzuowenhezi@gmail.com),我們會及時處理和回復,謝謝.
国产精品尤物福利片在线观看_少妇免费毛片久久久久久久久_久久久久成人精品免费播放动漫_日韩av综合在线观看
欧美二区在线视频| 久久久av电影| 91精品国产高清久久久久久久久 | 久久久国产精品x99av| 一区二区三区四区久久| 日韩精品一区二区三区不卡| 91久久嫩草影院一区二区| 国产成人无码av在线播放dvd | av动漫免费看| 国产精品久久一区| 日韩欧美一区二区三区四区| 91精品久久久久久| 九色精品美女在线| 欧美亚洲黄色片| 久久亚洲一区二区| 在线免费一区| 国产九区一区在线| 国产精品福利在线观看| 欧美在线www| 久久久噜噜噜www成人网| 亚洲高清在线观看一区| av日韩一区二区三区| 国产精品视频中文字幕91| 动漫3d精品一区二区三区| 91精品国产亚洲| 亚洲自拍av在线| 91免费欧美精品| 日韩av综合在线观看| 国产日韩中文字幕| 精品国产免费人成电影在线观...| 欧美一级日本a级v片| 国产a视频免费观看| 视频一区二区三| 久久99欧美| 日韩久久久久久久| 久久99久久久久久| 欧美在线视频一二三| 国产极品粉嫩福利姬萌白酱| 日本一区网站| 久久久久久av无码免费网站下载 | 精品国产一区二区三区免费| 欧美婷婷久久| 久久精品日韩| 人人妻人人澡人人爽欧美一区 | 国产精品日韩欧美综合| 人人妻人人做人人爽| 久久久99免费视频| 精品免费一区二区三区蜜桃| 久久综合九色九九| 国产免费毛卡片| 亚洲国产精品久久久久婷婷老年| 91精品国产一区| 日韩免费毛片视频| 国产精品精品视频一区二区三区| 精品婷婷色一区二区三区蜜桃| 欧美日韩第一页| 97免费视频在线| 日本一区二区高清视频| 97精品伊人久久久大香线蕉| 亚洲bt天天射| 日韩亚洲综合在线| 国产日韩精品在线| 亚洲一卡二卡区| 日韩一区二区在线视频| 精品欧美一区二区在线观看视频| 麻豆精品传媒视频| 亚洲v日韩v综合v精品v| 久久久久久久久一区| 国产精品一区在线免费观看| 亚洲欧洲精品在线| 久久资源av| 黄色免费高清视频| 一区二区视频在线免费| 97久久伊人激情网| 欧洲成人一区二区| 在线观看欧美亚洲| 久久久久久久久久国产精品| 欧美日韩亚洲一区二区三区四区| 宅男av一区二区三区| 久久精品日产第一区二区三区| 国产综合免费视频| 午夜精品久久久久久久久久久久久| 精品国产欧美一区二区三区成人| 精品一区二区三区日本| 午夜精品美女自拍福到在线| 久久精品亚洲一区| 91免费人成网站在线观看18| 精品视频在线观看| 亚洲激情一区二区| 伦理中文字幕亚洲| 久久婷婷人人澡人人喊人人爽| 欧美精品一区二区性色a+v| 亚洲色精品三区二区一区| 久久久黄色av| 国产suv精品一区二区三区88区| 国产亚洲一区二区三区在线播放| 日本久久久久久| 宅男在线精品国产免费观看| 国产成人精品一区二区三区| 国产成人亚洲综合| 国产免费一区| 激情五月五月婷婷| 日本高清不卡在线| www.日韩av.com| 国产欧美日韩中文字幕| 青青草国产免费| 亚洲国产婷婷香蕉久久久久久99| y97精品国产97久久久久久| 国产精品999视频| 国产免费视频传媒| 色乱码一区二区三在线看| 精品国产乱码久久久久久88av| 色老头一区二区三区| 国产裸体舞一区二区三区| 亚洲精品免费av| 欧美精品一区二区三区国产精品| 久久久久久久久久亚洲| 国产精品av在线播放| 毛片一区二区三区四区| 日本不卡视频在线播放| 亚洲欧美日韩另类精品一区二区三区 | 国产成人无码av在线播放dvd | 91精品久久久久久久久| 国产免费一区视频观看免费 | 狠狠精品干练久久久无码中文字幕| 国产成人avxxxxx在线看| 高清在线观看免费| 国产日本欧美一区二区三区在线| 欧日韩不卡在线视频| 日韩av一区二区三区在线观看| 欧美激情综合色综合啪啪五月| 国产精品青青草| 久久久久网址| 久久国产欧美精品| 国产日产欧美a一级在线| 国产中文日韩欧美| 黄色动漫网站入口| 欧美亚洲色图视频| 秋霞无码一区二区| 亚洲a在线观看| 亚洲精品国产suv一区88| 欧美成人精品一区二区三区| 国产精品视频永久免费播放| 国产成人精品在线视频| 久久精品91久久久久久再现| 久久久在线观看| 91久久精品www人人做人人爽| 国产免费一区二区视频| 91免费视频国产| 久久久久久高清| 久久久久久久久网| 精品久久国产精品| 久久亚洲国产成人精品无码区 | 国产伦精品一区二区三区免| 国产午夜大地久久| 国产美女91呻吟求| 亚洲自拍欧美另类| 亚洲成人午夜在线| 欧美一区二区三区在线播放| 日日摸日日碰夜夜爽无码| 日本一区二区三区免费观看| 日本a视频在线观看| 欧洲成人免费视频| 欧美精品卡一卡二| 国产精品一区二区三区免费| 91国产一区在线| 91超碰中文字幕久久精品| 久久香蕉综合色| 久久久国产精品亚洲一区| 久久久999国产精品| 国产精品日韩在线观看| 精品国产aⅴ麻豆| 亚洲精品免费av| 欧美专区福利在线| 国产日韩欧美夫妻视频在线观看| 91九色丨porny丨国产jk| 久久av综合网| 日韩中文字幕在线播放| 久久香蕉国产线看观看网| 亚洲一区二区久久久久久| 日韩免费av片在线观看| 日韩精品视频久久| 99久久无色码| 精品国产一区二区三区久久狼5月 精品国产一区二区三区久久久狼 精品国产一区二区三区久久久 | 国产欧美日韩在线播放| 91av在线网站| 国产精品视频精品| 欧美激情精品在线| 日本免费高清一区二区| 黄色免费视频大全| 国产男女免费视频| 久久国产乱子伦免费精品| 国产精品乱子乱xxxx| 精品久久久久av| 欧美一区二区激情| 国产在线一区二区三区播放| 成人国产在线看| 久久九九热免费视频| 精品丰满人妻无套内射| 日本一区二区三区在线播放|