Aluminium is an essential part of our daily lives. It is the third most abundant element after oxygen and silicon and the most abundant metal in the crust, constituting more than 8% of the earth’s crust.
As the sustainable material of choice, its applications span from everyday items like fuel-efficient vehicles and cans to cutting edge technologies for Space X and the Falcon 9. Combining strength and versatility, aluminium can be made thin enough to be crushed by human hands. At the same time, it can stand up to the most extreme applications, such as military aviation or space travel.
Aluminium’s intrinsic properties have made it extremely popular for a variety of applications.
Lightweight: Its density is 2.7 g/cm3, or one-third that of steel. In vehicles, aluminium reduces weight and fuel consumption.
Strong: Aluminium’s strength can be adapted to different applications by modifying the composition of its alloys. Certain alloys are as strong as steel.
Corrosion resistant: Aluminium naturally generates a protective oxide coating, making it particularly useful for protection and conservation.
Conductive: Based on weight, aluminium is twice as good a conductor of heat and electricity as copper, and is plays a major role in power transmission lines.
Ductile: Its excellent formability enables manufacturing of deep-drawn and/or complex shapes like cans or car body parts
Reflective: As a reflector of heat and light, aluminium is well-suited for applications such as solar technology and rescue blankets. Properly coated aluminium roofs can reflect up to 95% of the solar energy that strikes them, dramatically improving energy efficiency.
Impermeable and odorless: Releasing no taste or toxins, aluminium is ideal for food and pharmaceutical packaging. Aluminium foil provides a complete barrier to light, oxygen, moisture, and bacteria.
Recyclable: Aluminium is 100% and infinitely recyclable with no deterioration in quality.
Crash energy absorbent: Pound for pound, aluminum absorbs twice the crash energy that steel does in an accident, and can fold like an accordion to direct energy away from a vehicle’s occupants.
Spark resistant: Unlike steel wire, rigid aluminum does not spark and will not rust, making it the safer choice for electrical applications in coal mines, grain elevators, and refineries.
Aesthetical: aluminium can be used for decorative surfaces, with mat, bright and structured variances.
Aluminium can be produced in one of two ways:
- through primary production with ore extraction, refining, and smelting
- through secondary production, since aluminium is 100% and infinitely recyclable
Aluminium production begins with bauxite, a common ore which is refined into aluminium oxide trihydrate (alumina) using a technique known as the Bayer process. It is then reduced via a smelting process into metallic aluminium. Up to four tons of bauxite are needed to produce one ton of aluminium metal.
Once formed, aluminium is alloyed with other materials - usually iron, silicon, zinc, copper, or magnesium - to create metals with different properties. A serial number designates the type of alloy. For example, 1000 series alloys comprise almost pure aluminium, while 7000 series alloys include zinc as the major alloying element.
In its alloy form, aluminium can be processed in a number of ways. Most of the time it is extruded, cast, or rolled.
- Extrusion: A solid aluminium cylinder called a billet (available in a variety of alloys, pretreatments, and dimensions) is heated and squeezed through a die with a shaped opening to create a desired profile. Extrusions are widely used in construction, road, and rail applications.
- Casting: Using either sand casting or die casting techniques, the aluminium alloy is shaped according to a mold.
- Rolling: Aluminium passes through a hot-rolling mill and then a cold-rolling mill, which can progressively reduce the thickness of the metal down to as low as 0.05 mm. Rolled products are categorized as foil (less than 0.2 mm thick), sheet (0.2-6 mm), or plate (thicker than 6 mm).
Secondary Production (Recycling):
Aluminium is fully recyclable with no loss in quality, making it the most cost-effective material to recycle. 75% of the aluminium produced since its discovery is still in use today, and the aluminium industry is constantly refining its recycling processes.
Aluminium Through History
- Ancient peoples used aluminium oxide clays for tanning hides, dyeing fabrics, dressing wounds, and fireproofing.
- Jules Verne described an aluminium space rocket in his 1865 novel From the Earth to the Moon.
- In 1886, a US college student, Charles Hall, and a French engineer, Paul Héroult, separately developed an electrolysis process to extract aluminium from aluminium oxide. • In 1887, Austrian engineer Karl Josef Bayer developed a chemical process to extract alumina from bauxite. Both the Bayer and Hall-Hérout processes are still used today to produce nearly all the world’s aluminium.
- At the turn of the 20th century, industrialists used aluminium for power transmission lines and elevated train electrical wiring.
- In 1903, the Wright brothers built an engine with an aluminium crankcase for the engine of their first powered airplane.
- Aluminium foil entered the market in 1910.
- Alloy development began in 1911, improving physical properties and leading to new industrial fields.
- During the Great Depression in the United States, the Works Progress Administration expanded hydroelectric generation capacity and increased production capacity of primary aluminium.
- During World War II, aluminium was vital for aircraft frames, ship infrastructure, radar chaff, and mess kits. Families were encouraged to save aluminium foil, and “tin foil drives” included free movie tickets in exchange for aluminium foil balls.
- In 1959, Coors Brewing Co. pioneered the aluminium can and offered cash for cans returned to the brewery for recycling.
- In 1969, Apollo 11 astronauts Neil Armstrong and Edwin Aldrin deployed a solar wind experiment on the moon with an aluminium panel which collected atomic particles released into Space by the Sun.
- 1988: The Boeing-747-400, the best-selling model of the Boeing 747 family, is introduced. It contains 147,000 pounds (more than 66,000 kilograms) of aluminium.
- In the 1990s, Apple’s Steve Jobs took advantage of aluminium’s strength, weight, and beauty to create laptops, iPads, and iPhones.
- 2015: Ford released the all-aluminium-body F-150 in 2015, shedding 700 pounds.
- 2015: Constellium’s Airware® technology was aboard Orion’s successful first flight test. NASA’s Orion spacecraft is designed for human exploration of deep space.
Did You Know?
- Aluminium is named after the chemical compound “alum,” derived from the Latin term for “bitter salt.”
- The name “Bauxite” comes from “Baux-de-Provence,” the French village where the mineral was first discovered in 1821.
- It is possible to recycle and resell a discarded aluminium can in just 60 days.
- Aluminium was once considered one of the world’s most precious metals. It is said that Napoleon III, Emperor of France, hosted a banquet where the most honored guests were given aluminium cutlery, while everyone else had gold.
- One billion tonnes of aluminium have been produced since 1886, and 75% is still in use today.
- Aluminium is the popular choice for shark cages because the metal is relatively buoyant, won’t corrode in salt water, and is strong enough to protect divers from attacks.
- The energy required to produce new aluminium has dropped more than 25% since 1995 and the industry’s carbon footprint is down nearly 40%.
- The strongest aluminium alloys, the 7000 series, can reach strengths in excess of 72,000 pounds per square inch. A 1.2-inch aluminum wire made from this alloy could hold up a fully-loaded tractor-trailer.