Material	Aluminium
	Aluminium is a widely used light weight metal. Raw aluminium is not very strong and it is therefore often alloyed with silicon. Normally about 1% silicon is used, but for casting alloys the silicon content can be up to 12%. Raw aluminium has poor corrosive resistance, but thanks to a protective self generating oxide layer, the material can be used in corrosive environments. The quality of the oxide layer can be controled through an anodizing process, and in this way achieve decorative effects and improve corrosion protection.
Danish Name	Aluminium
Category	Metals, Light metals
Products	Bicycle, aluminium Space frame for car Mast for sailing boat, aluminium Flow, aluminium stacking chair Paper puncher Bicycle trailer
Processes	Metal casting Metal forming Welding Anodizing
Similar materials	Foamed aluminium
References	Metallurgi for ingeniører Maskinståbi
Environmen- tal notes	Aluminium is easily recycled without quality loss. However caution should be payed to alloying elements which can limit recyclability. Due to its low weight, aluminium indirectly causes significant energy savings, e.g. in transport equipment. A rule of thumb is that an aluminium part weights about half of the equivalent steel part. To produce 1 kg of virgin aluminium it takes 170 MJ of energy while recycling aluminium only 'costs' about 10 MJ/kg. Since aluminium typically is a mixture of the two, the energy content is about 100 MJ/kg. The energy content in aluminium is often justified by energy savings in the use phase, particularly for transport equipment like cars, ships and trains.
Additional Info	Chemical symbol Al, atomic number 13, melting point 658 C, density 2.7, recrystalises at 150C.
Photo	Thomas Nissen (Computer graphics)
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