The Danish physicist Hans Christian Ørsted announced the discovery of aluminum in 1825. This new material became one of the most significant enablers of modern technology, including aircraft, motor vehicles, window frames, and many more.
Aluminum chairs do not generally rust because the aluminum oxide layer which forms on the surface of the metal creates a barrier that protects it from oxidizing any further. Aluminum does. Corrosion can result in an unsightly white layer accompanied by the metal’s pitting.
While aluminum resists rust, it does corrode (not the same thing). It can be prevented from happening, which is discussed in this article.
Aluminum Beach Chairs Do Not Rust, But They Corrode
Aluminum has a reputation for not rusting. However, it does corrode.
While many use these terms as the same, they are not the same and involve different processes.
The difference between the two processes is summarized below.
Rusting | Corrosion |
Corrosion refers to the wearing of a way of metal as a result of a chemical reaction. | It is a Process of deterioration of any material, skin, polymers, ceramics, etc. |
It occurs when the metal is exposed to moist air, and a chemical process involving the formation of rust occurs. | When salt air and saltwater contact aluminum, they cause a chalky, white coating and pitting on the surface. |
Rust is a reddish, orange color, and at the end, it makes the steel start to flake. | Corrosion has different colors like blue, green, etc., depending on the material. |
Why Does Aluminum Corrode?
Aluminum is produced when the mineral bauxite is mined, crushed, processed, and smelted.
The chloride in saltwater is extremely corrosive. When the salty air and saltwater touch aluminum, they can cause both the chalky, white coating of aluminum oxide and unpleasant pitting.
While this is less e=invasive and damaging than rust on steel, it is unsightly.
The easiest way to prevent corrosion of aluminum deck chairs is to purchase chairs that have been powder coated. The protective layer of powder coating will prevent any damage caused by the seawater.
Why Does Aluminum Not Rust
Because metal, in its refined metallic state, metal isn’t its natural state; most metals are chemically unstable.
When exposed to the environment, they naturally begin to oxidize, resulting in revert to the original mineral form.
This chemical reaction is corrosion, and its result varies depending on the metal and the environmental factors acting on it.
When aluminum is exposed to water, it oxidizes and “rusts” very fast.
The oxidizing process happens when the aluminum atoms and oxygen atoms bond together.
It creates a layer that perfectly covers the aluminum and protects it from further rusting, hence the material’s reputation for not rusting.
It was only in 2000 that scientists at Stanford University fully understood why aluminum oxide (the protective layer) does not rust any further.
They found that when the water molecules (such as seawater on an aluminum deckchair) come in contact with the aluminum oxide layer, the aluminum and oxygen atoms on the surface move apart.
They sometimes move 50% further apart than their natural molecular positions.
The result is that when the aluminum oxide’s oxidized layer (the outer layer) is exposed to water or wet, the molecules move apart.
This change in molecular structure (caused by the moving apart of the aluminum and oxygen atoms) changes the material just enough so that it becomes chemically inert and doesn’t react rapidly with water molecules or atmospheric oxygen.
This change in molecular structure is why aluminum oxide metal resists corrosion.
What Is Aluminum?
Aluminum is an interesting material as it is a chemical element that seems to resist corrosion even when exposed to air and water. Some interesting facts about aluminum include the following.
- It is very soft and only has a density that is one-third of steel.
- In its natural state, aluminum does not attract magnets.
- It resembles silver in that it has a similar color and reflects light.
- After the surface has oxidized, unlike steel, it won’t oxidize further (rust).
- It is the twelfth most common element in the Universe and is found in abundance in the solar system.
- The earth is 1.59% aluminum by mass, making it the most abundant metallic element.
- Pure aluminum reacts with water, and according to the laws of chemistry, it should dissolve in the rain.
- Fortunately, this doesn’t happen because of a layer of aluminum oxide that covers the underlying material and acts like a protective, rust-resistant shield.
The Advantages And Disadvantages Of Aluminum Are
The advantages and disadvantages of aluminum are summarized below.
The Advantages Of Aluminum
The advantages of aluminum are.
- Aluminum oxidizes quickly, creating a coat of aluminum oxide over the surface and as a barrier against further corrosion
- The Aluminium oxide is clear, colorless, and non-staining and gives aluminum the reputation of not rusting.
- Aluminum can be painted and can be finished in various ways.
- Aluminum conducts electricity even better than copper.
- Aluminum can be fully recycled without losing any of its inherent characteristics.
- Aluminum weighs less than the equivalent-sized steel sample.
Its density is 2.72 tons per cubic meter compared to7.84 tons per cubic meter for steel.
It means that vehicles made from aluminum weigh less, and therefore more cargo can be carried.
Because of this, several ships now have aluminum superstructures, which have lowered their center of gravity, making them smore stable.
The Disadvantages Of Aluminum
- Aluminum requires special processes to be welded.
- It is abrasive to tooling, or more accurately, the aluminum oxide coating that forms upon it.
- The downside of having a lower ton/cubic meter of density is that it is not as strong as other, more dense metals of the same dimensions.
- It is more expensive than steel.
- In its pure state, aluminum should not be used for applications where magnetism is needed.
- It is not ideally used for food storage because aluminum leeches into the food, changing the taste; however, manufacturers overcome this by lining the inside of the cans with a thin layer of plastic.
- Aluminum is flammable in the right conditions (See HMS Sheffield in the Falklands war)
Conclusion
The fact aluminum forms a layer of aluminum oxide over its whole surface, which in turn is chemically inert, and therefore the material won’t oxidize. The problem is that aluminum will corrode, which, while not as invasive as rust, forms unsightly pitting and whitening of the metal.
Ensuring that any deck chairs you purchase have been powder coated will prevent this from happening.
References
- https://news.stanford.edu/pr/00/aluminum511.html
- https://www.aluminumhandraildirect.com/effects-of-salt-water-on-aluminum/
- https://en.wikipedia.org/wiki/Aluminium