Why Doesn't Aluminium Corrode?

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In summary: The oxide layer on the surface of aluminium is most likely microcrystalline rather than fully crystalline like corundum. This is due to the rapid reaction with oxygen in the air, which results in a thin and protective layer of aluminium oxide forming on the surface.In summary, the reason why aluminium does not corrode is because it reacts immediately with air oxygen to form a very resistant and protective layer of aluminium oxide. This oxide layer also prevents the formation of carbonate when heat is applied to aluminium, as it is stable and inert. The terms corindone and corundum both refer to crystalline forms of aluminium oxide, with the latter being commonly used in industry for its high melting point and hardness. However, the oxide layer on
  • #1
Jadaav
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Hi guys,

I wanted to know why does Aluminium not corrode and why does it not form a carbonate when heat is applied to it?
 
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  • #2


It reacts immediately with air oxygen as soon as it comes in contact wit air, forming a very resistant and protective layer of aluminium oxide (corindone).
 
  • #3


lightarrow said:
It reacts immediately with air oxygen as soon as it comes in contact wit air, forming a very resistant and protective layer of aluminium oxide (corindone).

Thanks:)

That means that the corindone protects the aluminium from corrosion.

And what about its reaction with heat to form carbonate? Does the corindone also protects it from heat or ?
 
  • #4


Jadaav said:
Thanks:)

That means that the corindone protects the aluminium from corrosion.

And what about its reaction with heat to form carbonate? Does the corindone also protects it from heat or ?
What exactly do you mean with "reaction with heat"?
 
  • #5


ah I meant when heat is applied to it
 
  • #6


well, when I searched for corindone It lead me to corundum instead, guess its the same thing ?

'Aluminium oxide is the family of inorganic compounds with the chemical formula Al2O3. It is an amphoteric oxide and is commonly referred to as alumina, corundum as well as many other names, reflecting its widespread occurrence in nature and industry. Its most significant use is in the production of aluminium metal, although it is also used as an abrasive due to its hardness and as a refractory material due to its high melting point.'

This solves my questions about the corrosion and carbonate of Aluminium.

but still has a doubt of corindone and corundum, reply please
 
  • #7


Jadaav said:
ah I meant when heat is applied to it
So you mean:

Al2O3 + 3CO2 -->heat--> Al2(CO3)3 ?

If you mean that reaction it's strange because usually carbonates decomposes, with heat. E.g. :

MgCO3-->heat--> MgO + CO2

Anyway, aluminium oxide doesn't react with CO2 essentially because it's extremely stable (inert) and also because it's not very basic (it's amphoteric).
 
  • #8


lightarrow said:
So you mean:

Al2O3 + 3CO2 -->heat--> Al2(CO3)3 ?

If you mean that reaction it's strange because usually carbonates decomposes, with heat. E.g. :

MgCO3-->heat--> MgO + CO2

Anyway, aluminium oxide doesn't react with CO2 essentially because it's extremely stable (inert) and also because it's not very basic (it's amphoteric).

Why you react Aluminium oxide with Carbon dioxide?
 
  • #9


I have now understood it completely:)

Aluminium oxide is a non-reactive gas and can only react as an acid or base.:)

that's going to help me very much for my exam:D

thanks very much mate;)
 
  • #10


Jadaav said:
well, when I searched for corindone It lead me to corundum instead, guess its the same thing ?
Yes, forgive my mistake, I thought in english was the same as in italian...
 
  • #11


Jadaav said:
I have now understood it completely:)

Aluminium oxide is a non-reactive gas and can only react as an acid or base.

If you are calling aluminum oxide a gas, you have still a lot to understand.

Note that corundum is a name for crystalline aluminum oxide. I doubt oxide layer on the metal surface is crystalline, microcrystalline at best.
 
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  • #12


lightarrow said:
Yes, forgive my mistake, I thought in english was the same as in italian...

Nevermind;),

Didn't expect to have this question in my exam, but glad that I could answer.

I didn't put aluminium oxide in the exam, hope fully.

It was only asked to explain briefly:D
 
  • #13


Borek said:
If you are calling aluminum oxide a gas, you have still a lot to understand.

Note that corundum is a name for crystalline aluminum oxide. I doubt oxide layer on the metal surface is crystalline, microcrystalline at best.

I know, I'm still at a low level though.
 
  • #14


Borek said:
Note that corundum is a name for crystalline aluminum oxide.
Correct.
I doubt oxide layer on the metal surface is crystalline, microcrystalline at best.
Yes, I agree with you.
 

Related to Why Doesn't Aluminium Corrode?

1. Why is Aluminium considered corrosion-resistant?

Aluminium is considered corrosion-resistant because it forms a thin layer of oxide on its surface when exposed to air, which acts as a protective barrier against further corrosion.

2. How does the oxide layer on Aluminium prevent corrosion?

The oxide layer on Aluminium is formed through a process called passivation, where the metal reacts with oxygen in the air to create a protective barrier. This layer prevents oxygen and moisture from reaching the underlying metal, thus preventing corrosion.

3. Is Aluminium completely immune to corrosion?

No, Aluminium is not completely immune to corrosion. While its oxide layer provides excellent protection against most forms of corrosion, it can still corrode under certain conditions, such as in highly acidic or alkaline environments.

4. Can Aluminium corrode in saltwater?

Yes, Aluminium can corrode in saltwater. While its oxide layer does provide some protection, the high concentration of chloride ions in saltwater can penetrate the layer and cause pitting corrosion, leading to structural damage over time.

5. How can Aluminium be further protected from corrosion?

Aluminium can be further protected from corrosion by applying a protective coating, such as paint or anodizing. These coatings provide an additional barrier against moisture and other corrosive elements, prolonging the lifespan of the metal.

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