Aluminum:
Aluminum is very abundant in the earth is never found free, nor can it, by present methods be obtained commercially from clay in which it exist in such great quantities. There is but not commercial ore called bauxite (hydrate aluminum oxide) generally belived to consist of mixture of monohydrate Al2O3.H2O and try hydrate Al2O3.3H2O, the chief impurities are oxide, silica, clay.
Manufacture: bauxite is first purified and then dissolved in fused cryolite (double fluoride of aluminum and sodium). The aluminum is separated from this solution by electrolysis at about 910 oC.
Physical and Mechanical properties:
1. Pure aluminum has silvery color and luster while the commercial grades show a characteristics lush ting.
2. The high purity has much greater resistance to corrosion than the ordinary steel.
3. It ductile and meal able.
4. Its specific gravity is 2.7.
5. Melting point =658oC ,boiling point=2057oC.
6. its good conductor to heat and electricity.
7. it forms useful alloy with iron, copper ,zinc.
8. Its unaffected by ordinary atmospheric influences but is corroded in sea water. Its soluble in alkyl and hydrochloric acid. When there is excess in silicon present in
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
|