Question

aluminium protect itself against corrosion discuss why it is necessary to Anodize aluminum to make it corrosion resistant

Answer 1

As we know that Aluminum is a very reactive metal and reacts with oxygen in air to form aluminum oxide, the oxide layer prevents the inner reactive aluminum from further corrosion.

But still this thin layer of aluminum oxide cannot protect the inner reactive aluminum from corrosion when heated or kept in water for a long time.

In the process of anodising in an electrolytic tank a graphite rod is used as cathode and an aluminum article which is to be anodised is placed in anode and an mildly acidic solution or just water is used as an electrolyte, when electricity is passed through the solution the water molecules break up and oxygen gas starts evolving from the anode, the oxygen gas reacts with the aluminum article and forms a very much more thicker layer of Aluminum oxide over the aluminum article. After anodising the layer of aluminum becomes more thicker, less lustrous, less reactive and more Resistance to corrosion.

I hope this will help you.

Answer 2

Answer:

Oxygen, which is liberated at anode, reacts with aluminium and forms a uniform oxide layer of aluminium, which protects the metal from corrosion. This is why anodising of aluminium is essential.