Why exactly does NaOH corrode certain metals in the presence of moisture? (1 Viewer)

[Chrisssss]

I was wondering why exactly sodium hydroxide corrodes certain metals such as galvanised metals, tin, aluminum etc. in the presence of moisture.
Anyone who can help, thanks in advance.

 

[Lucid Scintilla]

Corrosion does not just describe a single chemical degradation or
reaction. It is a whole family of chemical reactions. What metals corrode
and under what conditions depends upon the metal and the environment in
which it is surrounded.

In the case of aluminium the corrosion is a series of reactions with oxygen and water to form a mixture of aluminium oxides.

The problem of metal corrosion when exposed to air concerns to the existence of impurities of the air, like sulphur dioxide, chlorides, etc, and water. Such impurities may deposit over the surface of the metal and cause reaction with oxygen of the air.

In time, the layer that deposits over the metal surface will lead to galvanic cells, which corrode the metal. That is why it is necessary to keep the surface dry,
in order to avoid corrosion.

 

[xiao1985]

Not too sure that answers the question Lucid.

Why NaOH though?
To my knowledge, presence of alkaline environment retards the standard corrosion process (as a result of Le Chatelier's principle).

I can understand the impurities in the air, in particular water, can result in the corrosion of metal. But NaOH?