[WOB] Corrosion/Aluminum

[Knute Ream <knute@xxxxxxxxx>]

<pveltri@domain.elided> wrote:

>    Aluminum CAN corrode, it can also rust.
[...]
>    Aluminum is usually more RESISTANT to corrosion than other metals
>because there are several
>different kinds of protective finishes (anodizing, painting, enamels,
>electroplating, etc.)  that
>can be applied to aluminum.
>
>- -MR. SUPER ANAL
>98 M3 blue/grey

Minor clarification necessary:

Aluminum is considered more resistant to corrosion only because the
oxidizing layer prevents further oxidation.  (That's the "milky" looking
patina that untreated aluminum develops when you let it sit)  This works
just fine unless the aluminum in question is in moving contact with
something that will wipe off that "protective" layer of oxidation (such as
gears, etc.).  Great for brackets and stationary parts, terrible for moving
parts with wear surfaces.  That's one of the prime reasons BMW gets into
the Nikasil / Alusil on the inside of the cylinder bores of their aluminum
blocks...

Regards,

- -Knute

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