Aluminum density is 2.7 d/cm3 – about one third that of steel density. It is a silvery white metal. Its melting point is 660 oC. Aluminium is up to three times lighter than steel.
ELECTRICAL AND THERMAL CONDUCTIVITY
Aluminum is an excellent conductor of electricity and heat; therefore it is suitable for the production of electrotechnical components and various types of heat exchangers. A dense and solid film of Al2O3 oxide forms on the surface of Aluminum items, protecting the Aluminum against corrosion in the atmosphere, water, concentrated nitrogen and many other acids, and other media. The thermal conductivity of Aluminum at 27oC is 237 W/(m•K). An Aluminum conductor having the same conductivity characteristics as a copper conductor is twice as light. The thermal conductivity of Aluminum at 27 oC is 237 W/(m•K).
RESISTANCE TO CORROSION
Aluminum is resistant to corrosion in concentrated nitrogen and sulphuric acids, in water, watery solutions, humid gases, and when the pH of solutions varies between 4 and 9. Alkaline solutions with a pH > 9 rapidly destroy Aluminum by producing soluble aluminates. Aluminum is also unstable in acids having no oxidising properties.
At low temperatures Aluminum does not become brittle, and its resistance increases. At high temperature, the metal’s resistance decreases. If the temperature continuously exceeds 100º C, the resistance drops significantly, therefore this should be considered in the developmental stage of structures. When Aluminum is exposed to oxygen in the air, a very thin layer of oxide – only several hundredths of micrometer µm – is formed (µm equals one thousandth of a millimetre). This layer is very dense and reliably protects against corrosion. When damaged, the layer restores itself again.
Its resistance to corrosion and conductivity to heat and electricity are well known and proven in practice.
Compared to other metals, Aluminum exhibits a large amount of longitudinal expansion. This must be considered when developing some models.
Aluminum is a non-magnetic, or to be more precise, a paramagnetic metal.
Most often, a welding method is applied for profiles. Furthermore, extensively tested methods of fusion and friction welding, cohesion and fitting are applied.
MACHINE PROCESSING AND MOULDING
Aluminum can be processed by the following technologies:
The methods and modes of processing are selected according to the chemical composition of an Aluminum alloy, its structural condition and the application of billets.
Machine processing requires little amount of energy power. In fact, Aluminum can be processed and used in new items without limitations, and without reducing its quality. Plus, only a small percent of the metal is lost in the re-fusing process.
The advantage of Aluminum processing from an environmental viewpoint is energy savings. Only five per cent of the energy necessary for the production of new (primary) metal is used in the re-fusing process. It can be recycled many times without deterioration in its quality.
Aluminum boxes are efficient in reflecting or screening electromagnetic waves.
Aluminum has an enormous number of highly positive characteristics; therefore Aluminum is the most widely used metal after iron. It is no wonder that some people consider Aluminum to be the metal of the future.