Downloaded 124 times
More Related Content
Aluminium
- 1. S U BM I T T E D B Y : V A R U N G U L I A 1 2 M E U 0 8 9 ALUMINIUM
- 2. INTRODUCTION Aluminium isa chemical element with symbol Al and atomic number 13. Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal in the Earth's crust. It is a soft, nonmagnetic, ductile metal. Insoluble in water and alcohol. High electrical and thermal conductivity.
- 3. CHARACTERISTICS Aluminium isa relatively soft, durable, lightweight. Appearance ranges from silver to dull grey (depends on surface roughness). Yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Melting point: 660 °C Boiling point: 2500 °C Density: 2.70 g/cm³
- 4. CORROSION RESISTANCE Whenthe surface of aluminium metal is exposed to air, a protective oxide coating forms almost instantaneously. If the oxide becomes scratched and aluminium metal exposed, more oxide is formed and the protected layer renewed. This oxide layer is corrosion resistant. This oxide layer is one of the main reasons for aluminium good corrosion properties. The layer is stable in the general pH range 4 – 9.
- 5. STRENGTH Aluminium alloyscommonly have tensile strengths of between 70 and 700 MPa. Aluminium does not become brittle at low temperatures. At high temperatures, aluminium’s strength decreases. The low density of aluminium does not affect its strength.
- 6. CONDUCTIVITY Aluminium isan excellent conductor of heat and electricity. Aluminium conductor weighs approximately half as much as a copper conductor having the same conductivity. Resistivity: 2,82×10−8 Ωm Thermal Conductivity : 202.4 W/mK Commonly used material in power transmission lines.
- 7. REFLECTIVITY Aluminium isa good reflector of both visible light and heat. Aluminium serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) infrared radiation. Aluminium is extremely reflective, when polished and that together with its low weight, makes it an ideal material for reflectors ,for example, light fittings or rescue blankets.
- 8. DUCTILITY & MALLEABILITY High Ductility & Malleability. Large coefficient of linear expansion. Aluminium is the 2nd most malleable and 6th most ductile metal. MACHINING Aluminium is easily worked using most machining methods – milling, drilling, cutting, punching, bending, etc. Furthermore, the energy input during machining is low.
- 9. FORMABILITY With themetal either hot or cold, this property is also exploited in the rolling of strips and foils, as well as in bending and other forming operations. IMPERMEABLE AND ODOURLESS Aluminium foil, even when it is rolled to only 0.007 mm thickness, is still completely impermeable. Non-Toxic Releases no aroma or taste substances which makes it ideal for packaging sensitive products such as food or pharmaceuticals.
- 10. ISOTOPES 22 knownisotopes from 21Al to 42Al. 4 isomers Only 27Al is stable 26Al is a radioactive isotope 27Al has a natural abundance of 99.9+ % Other than 26Al, all radioisotopes have half-lives under 7 minutes Aluminium isotopes have found practical application in dating marine sediments, manganese nodules, glacial ice.
- 11. OCCURRENCE Aluminium ishighly reactive and does not occur in the free state. It is widely distributed and it is third in abundance on earth. Aluminium has three principal ores Gibbsite or Hydrargillite, Al2O3.3H2O, Bauxite, Al2O3.2H2O, Diaspore, Al2O3.H2O, and Cryolite, AlF3.3HF. Aluminium also occurs in the form of its Aluminium Oxide, Al2O3, in the semiprecious stones.
- 12. EXTRACTION In atwo-stage process the metal is extracted from the bauxite ore under pressure and heat using the called Bayer process. The aluminium hydroxide is then heated to produce aluminium oxide (alumina). the second process is the electrolysis of alumina. In this process alumina is dissolved in molten cryolite and split into molten Al and O2 by passing an electric current. From two tons of aluminium oxide thus one ton of primary metal is extracted.
- 13. BAYER’s PROCESS ConvertBauxite to Alumina. Crush and Grind: The ore is then fed into large grinding mills and mixed with a caustic soda solution (sodium hydroxide) at high temperature and pressure. Digesters: The slurry is pumped to a digester where the chemical reaction to dissolve the alumina takes place. Flash Cooling: The slurry is pumped into a series of flash tanks to reduce the pressure and heat.
- 14. Settlers: Settlingis achieved primarily by using gravity, although some chemicals are added to aid the process. Precipitation: The clear sodium aluminate from the settling and filtering operation is pumped into precipitators. Calcination : Calcination is a heating process to remove the chemically combined water from the alumina hydrate.
- 15. Al2O3 +2 NaOH → 2 NaAlO2 + H2O 2 NaAlO2 + CO2 → 2 Al(OH)3 + Na2CO3 + H2O 2 H2O + NaAlO2 → Al(OH)3 + NaOH 2 Al(OH)3 → Al2O3 + 3 H2O
- 16. HALL-HEROULT PROCESS ConvertAlumina to Aluminium. The aluminium oxide is mixed with cryolite (made of sodium fluoride and aluminium fluoride) and then heated to about 980 °C to melt the solids. The molten mixture is then electrolysed with a very large current. Aluminium ions are reduced to form aluminium metal (at the cathode). Oxygen gas is formed at the anode.
- 18. ALUMINIUM ALLOY’s Aluminumalloys can be can be classified as Wrought alloys Cast alloys Each of these alloys can be further classified as Non Heat treatable alloys Heat treatable alloys
- 19. WROUGHT ALLOY Eachalloy is given a four-digit number, where the first digit indicates the major alloying element. There are 7 series of Wrought alloy
- 20. 1000 seriesare pure Al with a min 99% aluminium content by weight and can be work hardened. 2000 series are alloyed with Cu, can be hardened to strengths comparable to steel. 3000 series are alloyed with Manganese. 4000 series are alloyed with silicon. They are also known as silumin. 5000 series are alloyed with Magnesium. 6000 series are alloyed with magnesium and silicon. They are easy to machine, are weldable. 7000 series are alloyed with zinc.
- 21. CAST ALLOYS Castaluminium alloys are cost-effective products. Low melting point Have lower tensile strengths than wrought alloys Most important cast aluminium alloy system is Al–Si There are 9 series of Cast Al Alloys:
- 22.
- 23. USES OF ALUMINIUM TRANSPORT Aluminum alloys are widely used for aeronautical applications because of high strength weight ratio. Aluminium-Scandium alloys are used in Aerospace industries. In automobiles for reducing weight of the vehicle thus reducing fuel consumption. In trucks and buses (sheet and plate for bodies) In Cars(engine blocks, cylinder heads,body panels)
- 24. PACKAGING Aluminium isused in the form of alloy sheet for beverage can bodies and tops. As foil for household and commercial wrap, and in manufactured packaging products such as cartons for fruit juice and packaging for pharmaceuticals. 1000 series alloys as foil for food wrapping.
- 25. In construction,aluminium is used in sheet products for roofing and wall cladding, in extrusions for windows and doors, and in castings for builders' hardware. In the electrical sector, aluminium is used in the form of wire, normally reinforced with steel to form cables. House hold and consumer items such as utensils
- 26. RECYCLING Aluminium istheoretically 100% recyclable without any loss of its natural qualities. Recycling involves melting the scrap, a process that requires only 5% of the energy used to produce aluminium from ore. Recycled aluminium is known as secondary aluminium, but maintains the same physical properties as primary aluminium.
- 27. ALUMINIUM LIFE CYCLE Aluminium is the perfect ‘eco-metal’. Very little Al is lost in the remelting process. Increased recovery, dismantling and sorting of spent products has led to even greater recycling of aluminium.
- 28.
- 29.