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عـــــذاري 08-19-2013 11:20 PM

التصنيفات العامة للمواد
 
[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]

What are materials, exactly

That's a big question - because materials are the basic substances that make up, well, you name it! Materials can be natural - like wood, or human-made - like plastic. There are now about 300,000 different known materials (if you named one every second, it would take you more than three whole days and nights just to get through the list!). And as materials scientists create and combine materials in new ways, the number's almost infinite.

Most materials fit into a few big, general categories:


Metals

[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]
Whole periods of human civilization - such as the Bronze and Iron ages - are named for metals. These were the first materials to be "engineered," that is, people changed them to fit what they needed to do, rather than just letting their natural properties determine what they could be used for. These days, materials scientists are using metals in ways no one could have pictured even a few years ago - for example, shaping copper into tiny wires a thousand times skinnier than a strand of your hair!


Ceramics

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Think about a china teapot - that's one type of ceramic. But ceramics can also be used to create bone and tooth replacements, super-strong cutting tools, or to conduct electricity. With the addition of oxygen or nitrogen, metals become ceramics, too.


Semiconductors

[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]
One of these materials - silicon - is making it possible for you to read these words right now! That's because silicon is the essential material in an electronic computer chip. "Semiconductor" means a material can conduct electricity with a bit of help in the form of added "impurities." Your CD, DVD player, and telephone - all depend on semiconductors.


Polymers
[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]


Polymers are just very big molecules made of smaller molecules linked together into long, repeating chains. You may not know it, but you're in touch with polymers every day more than any other kind of material. Rubber bands are made of polymers, so are paints and every kind of plastic. And by the way, most of the food you eat is made of natural polymers!

Others are little tougher to define...


Composites
[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]


Composites are combinations of materials, which can be as simple as concrete reinforced with steel bars or as leading edge as an ultralight, carbon-fiber bicycle. The places where different materials meet - the "interfaces" - often produce new properties that are radically different, and better, than those in any single material.


Biomaterials
[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]
Every part of your body is a material! Bone, muscles, fingernails, hair, and skin are all examples of different types of materials found in your body with remarkable properties that help you survive - from keeping you upright, and protecting you from heat or cold, to cutting and grinding your food. Some scientists try to mimic nature's designs to create materials for other uses, such as using the foam structure of bone as an inspiration for designing materials that are lightweight and strong.

And some are just plain weird...


Exotic and Strange Materials

[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]
Materials scientists are discovering and creating entirely new types of materials - such as buckyballs and nanotubes, which are very tiny spheres or cylinders made of carbon atoms. Then there are aerogels, which are extremely lightweight porous materials made almost entirely of air! Nanotechnology is taking materials science into a new dimension, as scientists create new materials atom-by-atom and molecule-by-molecule - leading to properties and performance never before imagined.

[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]


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sama 08-21-2013 08:28 PM

Thank you a lot for this beneficial essay which is about kinds of materials
God bless you

عـــــذاري 08-22-2013 12:41 AM

أشكرك على تواجدك الرائع بارك الله فيك


الساعة الآن 06:49 PM.

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