Characteristics of Aluminum


Aluminum and its alloys have excellent features including good appearance, light weight, superior physical and chemical properties, as well as they are able to machine and resistant to corrosion, considered as the most economical and practical material in many application fields. The density of aluminum is only 2.7×103 kilograms per cubic meter, about one-third of the density of steel, copper or brass. With light weight, aluminum is commonly used for the manufacture of automobiles, trains, subways, ships, aircrafts, rockets, spacecrafts and other transports in land, sea and air, to reduce dead weight and increase loading capacity. Under most environmental conditions including air, water (or brine), petrochemical and other chemical systems, aluminum shows excellent corrosion resistance.

Aluminum’s surface is highly reflectivity, so it can efficiently reflect back the radiation, visible light, radio waves and radiation heat. And the surface through the anodic oxidation and dark anodized can be reflective or absorptive. The polished aluminum is excellent in reflection within a wide wavelength range, thus with a variety of decorative purposes and reflection functional uses.

Aluminum is non-ferromagnetic. This is an extremely important feature for the electrical and electronic industries. Aluminum has excellent conductivity, about two-thirds of the conductivity of copper. However, aluminum’s density is only one-third of the density of copper, thus aluminum’s conductivity is approximately twice than copper under the condition of equal length and quality. In addition, with cheaper than copper and low cost, aluminum is popular in the electric power industry and electronics industry. Currently, some particular aluminum alloys with high specific resistance have also been successfully developed; these alloys can be used for the high-torque motor. Aluminum has high thermal conductivity, ranking only second to copper, about 50%~60% of copper, while three times larger than that of iron. Although thermal conductivity of copper is the best, work pieces with the same size made by copper are much heavier and more expensive than those made by aluminum. Therefore, aluminum is still the preferred material to make radiators. In terms of the cost performance, aluminum is very favorable for the production of heat exchangers, evaporators, heating appliances, cooking utensils, as well as cylinder heads and radiators of automobiles.

Aluminum cannot ignite spontaneously, which is very important for industries involved in stevedoring or contacting with flammable and combustible materials. Aluminum has little toxicity, often used for the manufacture of food and beverage containers. In recent years, aluminum foils are more and more widely applied to the packaging of cigarettes, medicines and food, and it has become an important material for the packaging industry.

Aluminum’s surface is fine in the natural state, soft and shiny. And for aesthetic reasons, it can be colored or painted with texture pattern. Aluminum powder, with wide applications, great demand and many varieties, is a large class of metallic pigments. In modern life, aluminum has been widely used in the construction industry and general merchandise. In addition, aluminum has superior sound-absorbing property, therefore ceilings of some radio rooms or modern buildings are made by aluminum.

Aluminum has excellent plasticity. Pure aluminum is soft with low strength, good scalability and superior machinability, and it is able to be pulled into fine wires and rolled into foils. So, it is widely used in wire and cable manufacturing, radio industry and packaging industry. Adding a small amount of aluminum in some metals will significantly improve its performance. For example, adding a small amount of magnesium and copper in aluminum can make tough aluminum alloy. Another example is aluminum bronze (aluminum of 4%~15%), which has very high corrosion resistance, with hardness close to low-carbon steel and metallic luster not easy to darken, commonly used for jewelry, construction industry, machine parts and tools manufacture, pickling equipments and other equipments in contact with dilute sulfuric acid, hydrochloric acid and hydrofluoric acid, as well as for the production of brushes and clamp holders of electric welding machines, heavy gears and worm gears, metal forming dies, machine tool slide guides, non-sparking tools, non-magnetic chains, pressure vessels, heat exchangers, compressor blades, ship propellers and anchors, etc. And adding magnesium in aluminum can make magnesium-aluminum alloy which has its hardness larger than pure magnesium and aluminum as well as retains light weight, commonly used for the manufacture of aircraft fuselages, rocket bodies, doors and windows, ships. In addition, adding other metal components in aluminum can make a variety of aluminum alloy, of which, some aluminum alloys are even better than structural steel in intensity. Aluminum is also very easy to connect through a variety of methods, including welding, resistance welding, brazing, soldering, bonding and mechanical methods such as riveting and bolting. Compared with iron, aluminum is not easy to be corroded, which extends its service life. Therefore, aluminum has a high recyclability. And recycled aluminum has almost no difference with primary aluminum, which makes aluminum become the favorite of environmentalists.