I’ve done my presentation on Aluminium and will be talking to you about its properties, where it’s found and its uses and why it’s the best material for these purposes.
Aluminium. Chemical symbol Al. Atomic weight approx 27 Atomic number 13 and electronic configuration 2-8-3.
Appearance- pure aluminium is a shiny silvery white material. Down to the molecular level aluminium has a polycrystalline structure where the metal has cooled from different areas of the material where. Where these areas meet are called the grain boundary. This structure gives aluminium its many properties.
Density – The first thing you notice about aluminium is its relatively lightweight. It has a density of 2,7g/mm3. This is about 1/3 the weight of a piece of steel the same size.
Resists Corrosion – like many other metals aluminium is very reactive in air and thus a fine layer of aluminium oxide is created on the surface. This provides provides a highly effective barrier to the ravages of air, temperature, moisture and chemical attack. 0.000000635cm
Highly reflective – Free electrons in the metal absorb the light energy then immediately re emit it.emits 90* of the light that it absorbs. This would not happen if free electrons wernt present.
Ductile – Aluminium can be bent and shaped extremely easily. This is because of it polycrystalline structure. Along the grain boundaries of the material dislocations in the atoms occur. It is the movement of these dislocations that makes this metal very ductile. This is good for shaping aluminium but very bad for its strength.
Strength – like many other of aluminiums properties it depends on the purity of the material 99.996 per cent pure aluminium has a tensile strength of about 49 megapascals (MPa), Unlike materials such as steel, aluminium gets stronger as temperature drops. rising to 700 MPa following alloying and suitable heat treatment.
Conductance – aluminium is one of the best conductors of electricity. Because it is a metal it ontains almost a soup of free flowing electrons which make it very easy for a current to flow through it. Aluminium itself conducts about 63% of that of copper of the same mass.
Aluminium is also a great conductor of heat conducting about 220 Watts
Aluminium is the most abundant metal in the earths crust. Only the non metal elements oxygen and silicon are more abundant. The largest deposits of aluminium are found in Australia, Guinea and West Indies. Aluminium does not occur in its pure form but as either an aluminium silicate or as bauxite which consists of aluminium oxide and commonly iron oxide also. As seen in the picture the aluminium ore is a redish colour this is caused by the iron ore mix. Bauxite is produced through chemical weathering of rocks in tropical climate.
The method now used for aluminium’s commercial production is the electrolysis. An iron pot, lined with carbon, is charged with cryolite and heated to about 800ï¿½C by the electric current. For the electrolysis, a bundle of carbon rods is used as the anode, while the pot itself forms the cathode. The oxygen liberated combines with the carbon of the anode to form carbon dioxide, while the aluminium falls to the bottom of the vessel. More alumina is added and the process continued, the molten metal being drawn off from time to time.
Aircrafts – Mainly because of its lightweight. This feature is utilized by aircraft and can cut the weight down by up to 5 tonnes. This means planes can fly fast and be more economical. This also applies to all transportation allowing increased loading capacity also. Usually it isn’t actually pure aluminium because of its poor strength but instead alloys of aluminium which can be as strong as 700 Mpa.
Buildings – Aluminium is used in construction mainly because of its corrosion resistance. Its is also a very easy material to shaped and mould making it ideal for the uses in construction
Electrics – Aluminium is a very economical material as an electric conductor and is widely utilized in power transmission cables. Aluminium only has 60% conductivity of copper but weighs a 1/3 as much making it ideal for large power cables.
Heat – aluminium is about 3 times as thermal conductive as steel. This feature is used in cooking utensils, engines, air conditioners and it is also being used in energy saving equipment such as solar cells.
Reflective – Because aluminium is reflective of most electric, heat and light waves it is being more commonly used in the insulation of homes.
Harsh conditions – Unlike steel which gets brittle in cold conditions aluminium get stronger making it the perfect material to use in harsh conditions. Aluminium is now being used on snow-mobiles
Cans – aluminium is a non toxic material, smooth, easily washable and is hygienic because no germs an grow on it. Also because malleability it can be shaped into any shaped or form making it ideal for packaging
Because of aluminiums low melting point approx 600 C it is the ideal material in this age of energy and resource saving to recycle.