Design Characteristics of Aluminium
Aluminium and its alloys possess many useful architectural properties. We detail below those qualities that are particularly relevant to the building and associated industries.
Aluminium is the most common metallic element and its oxide form, known as bauxite, is the third most abundant substance.
In the presence of moisture direct contact between aluminium and other metals should be avoided otherwise bi-metallic corrosion may occur. Where there is such potential for bi-metallic corrosion then the different metals must be isolated from each other by means of a suitable gasket or by coating or painting the contact area. There is no risk of bi-metallic corrosion in dry conditions.
Aluminium is highly resistant to weathering, even in polluted industrial atmospheres and also resists attack from many acids.
The excellent corrosion resistance of aluminium is due to the permanent presence on the surface of an invisible oxide film, making the material environmentally passive. If the surface is cut or scratched the protective film immediately reforms. Unless some substance or condition destroys this oxide coating, the metal remains resistant to corrosion.
The working qualities of aluminium make for ease of fabrication. Its forming and handling characteristics are among its most important advantages. Favourable comparisons can often be made with less expensive materials as its lower degree of workability results in reduced processing costs.
Aluminium does not burn in the form of sheets, extrusions, castings, foil, etc. Even the thinnest gauge material will not burn or support combustion.
The thermal conductivity of aluminium is around four times that of steel, and its specific heat twice that of steel. Heat is therefore conducted away faster, and a greater heat input necessary to bring aluminium to a given temperature than with steel.
As defined by BS476:Part 4 aluminium alloys are non-combustible and provide Class 1 surface spread of flame to BS476:Part 5.
Due to its natural oxide surface-coating aluminium can safely be used in areas of food preparation and service. Please contact our technical department for information on aluminium’s reaction to specific foodstuffs.
As with all other common metals, aluminium lends itself to the primary joining techniques including bolting, bonding, brazing, screwing, riveting, and welding.
Aluminium is the lightest of all common metals with a specific gravity of 2.7, being approximately one third that of steel.
The excellent strength to weight ratio of aluminium delivers substantial weight saving benefits of up to 50% when compared with equivalent steel assemblies. Significant cost savings are also achieved in terms of transportation (fuel economy) and easier / faster handling and fixing (fewer personnel).
Most alloy grades can be easily and economically machined. Aluminium alloy can be milled, turned, etc. at relatively high speeds resulting in faster production times and lower part prices.
The non-magnetic properties of aluminium make it very suitable for use in computer rooms and similar applications involving electronic equipment. Aluminium is also used for electrostatic screening purposes.
Reflection of radiant energy
Aluminium is an excellent reflector of light and heat. About 75% of light and 90% of heat are reflected, making it widely used for lighting fixtures, decorative trims, and insulating applications.
Aluminium has the advantage of a high scrap value and is therefore economic to recycle into reusable high-grade metal.
Recycling aluminium needs only 5% of the energy required to extract from bauxite ore.
Today the use of reprocessed aluminium accounts for 30% of the production of the primary metal. This process can be continually repeated.
Temperature (effects of)
Temperatures typically encountered within normal living environments do not effect the performance of aluminium or aluminium alloys.
Commercially pure aluminium (99.5%) produced in temper hardened condition has a useful degree of hardness and excellent forming qualities.
Substantial increases in metal strength are obtained by alloying aluminium with small percentages of other metals including copper, manganese, magnesium, silicon and zinc.
Many alloys can also be heat treated to further increase strength.