منتدى طلبة هندسة المنيا
بسم الله الرحمن الرحيم
عزيزى الطالب عزيزتى الطالبة يرجى التكرم بتسجيل الدخول اذا كنت عضو معنا
او التسجيل ان لم تكن عضو وترغب فى الانضمام الى اسرة المنتدى
سنتشرف بتسجيلك
شكرا
ادارة المنتدى

منتدى طلبة هندسة المنيا


 
الرئيسيةمجلة جديدةاليوميةمكتبة الصورس .و .جبحـثالأعضاءالمجموعاتالتسجيلدخول

شاطر | 
 

 alluminuim alloys

استعرض الموضوع السابق استعرض الموضوع التالي اذهب الى الأسفل 
كاتب الموضوعرسالة
ahmed mawad

avatar

الجنس : ذكر
عدد المساهمات : 931
العمر : 28
نقاط : 2482
السٌّمعَة : 29
تاريخ التسجيل : 06/10/2009
الموقع : فى المنيا بدرس
تاريخ الميلاد : 31/07/1989

مُساهمةموضوع: alluminuim alloys   الأربعاء فبراير 24, 2010 9:00 am

Properties
Aluminum is a soft, lightweight metal normally with a dull gray
appearance caused by a thin layer of oxidation that forms quickly when
the metal is exposed to air. Aluminum oxide has a higher melting point than pure aluminum.
Aluminum is nontoxic (as the metal), nonmagnetic, and nonsparking. It
has a tensile strength of about 49 megapascals (MPa) in a pure state and
400 MPa as an alloy. Aluminum is about one-third as dense as steel or copper; it is malleable, ductile, and easily machined and
cast. It has excellent corrosion resistance and
durability because of the protective oxide layer.
Aluminum is one of
the few metals which retains full silvery reflectance, even in finely
powdered form, which makes it a very important component of silver
paints.
Aluminum's crystal structure is an FCC structure, hence the high
ductility of the pure metal.
Aluminum mirror finish has the highest
reflectance of any metal in the 200–400 nm (UV) and the 3000–10000 nm
(far IR) regions, while in the 400–700 nm visible range it is slightly
outdone by silver and in the 700–3000 (near
IR) by silver, gold, and copper. It is the second-most
malleable metal (after gold) and the sixth-most ductile. Aluminum is a good thermal and electrical conductor. Aluminium is
capable of being a superconductor, with a
superconducting critical temperature of 1.2 Kelvin.
Applications
General
use


A piece of aluminum metal about 15 centimeters long,
with a U.S. cent included for scale.
Whether
measured in terms of quantity or value, the global use of aluminum
exceeds that of any other metal except iron, and it is important in
virtually all segments of the world economy.

Relatively pure aluminum is
encountered only when corrosion resistance and/or workability is more
important than strength or hardness. Pure aluminum serves as an -1-
excellent reflector (approximately 99%) of visible light and a good reflector
(approximately 95%) of infrared. A thin layer of aluminum
can be deposited onto a flat surface by chemical vapor deposition or
chemical means to form optical coatings and mirrors. These coatings form an
even thinner layer of protective aluminum oxide that does not
deteriorate, as silver coatings do. Nearly all
modern mirrors are made using a thin
coating of aluminum on the back surface of a sheet of float glass. Telescope mirrors are also made
with aluminum, but are front coated to avoid internal reflections,
refraction, and transparency losses. These first surface mirrors are
more susceptible to damage than household back-surface mirrors.



Pure
aluminum has a low tensile strength, but when
combined with thermo-mechanical processing, aluminum alloys display a marked
improvement in mechanical properties, especially when tempered. Aluminum alloys form
vital components of aircraft and rockets as a result of their high
strength-to-weight ratio. Aluminum readily forms alloys with many
elements such as copper, zinc, magnesium, manganese and silicon (e.g., duralumin). Today, almost all bulk
metal materials that are referred to loosely as "aluminum," are
actually alloys. For example, the common aluminum foils are alloys of 92%
to 99% aluminum.
Some of the many uses for aluminum metal are in:
·
Transportation (automobiles, aircraft, trucks, railroad cars, marine vessels, bicycles etc.)
· Packaging (cans, foil, etc.)
· Water treatment
· Treatment
against fish parasites such as Gyrodactylus salaris.
·
Construction (windows, doors, siding, building wire, etc.)
·
Cooking utensils
· Electricaltransmission lines
· MKM steel and Alnico magnets
· Super purity
aluminum (SPA, 99.980% to 99.999% Al), used in electronics and CDs.
· Heat sinks for electronic
appliances such as transistors and CPUs.
· Powdered aluminum is
used in paint, and in pyrotechnics such as solid rocket fuels and thermite.
· In the blades of propswords and knives used in stage combat.
Aluminum
Compounds
· Aluminium fluorosilicate (Al2(SiF6)3) is used in the
production of synthetic gemstones, glass and ceramics.
· Aluminium ammonium sulfate
(Al(NH4)(SO4)2) is used: as a mordant, in water purification and
sewage treatment, in paper production, as a food additive, and in leather tanning.


الرجوع الى أعلى الصفحة اذهب الى الأسفل
معاينة صفحة البيانات الشخصي للعضو http://miniaeng.yoo7.com
 
alluminuim alloys
استعرض الموضوع السابق استعرض الموضوع التالي الرجوع الى أعلى الصفحة 
صفحة 1 من اصل 1
 مواضيع مماثلة
-
» مقطع فديو رائع ((1)) عن المواد الذكية

صلاحيات هذا المنتدى:لاتستطيع الرد على المواضيع في هذا المنتدى
منتدى طلبة هندسة المنيا :: ¤©§][§©¤][هندسة الانتاج والتصميم الميكانيكى][¤©§][§© :: اكاديمية هندسة الانتاج والتصميم الميكانيكى-
انتقل الى: