What are the general properties of aluminum? (page 3-24)
Aluminum is a soft, nonmagnetic, and corrosion-resistant silvery metal. It has a low melting point, high thermal and electrical conductivity, and light weight - which is one-third that of iron, brass, or copper. Aluminum's conductivity is surpassed only by silver and copper. Aluminum has a fairly high coefficient of expansion and oxidizes readily.
Aluminum is a versatile construction material. Its various alloys are strong, corrosion resistant, ductile, heat resistant, or a combination of these characteristics.
The most notable characteristic of aluminum is its corrosion resistance. Aluminum is made corrosion-resistant by the transparent film of aluminum oxide that quickly forms upon exposure. This film causes the aluminum to be fairly impervious to further chemical action. When aluminum comes in direct contact with metals other than zinc, cadmium, magnesium, and nonmagnetic stainless steel, it is subject to various types of galvanic action. Therefore, aluminum should be directly insulated from other metals.
Commercial aluminum is an alloy of pure aluminum with varying but small amounts of iron and silicon that increase its strength and decrease its corrosion resistance. The joining of commercial aluminum is done by welding, brazing, resistance welding methods, inert-gas shielded arc processes, soldering, and adhesive bonding.
Aluminum is not an effective sound absorber and is not generally used in wall, floor, or ceiling applications as a sound reflector. The use of acoustical tiles in combination with aluminum can compensate for aluminum's poor acoustical properties.