Re: Anodized planes ?

Date:         27 Aug 99 03:08:12 
From:         James Matthew Weber <>
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At 10:28 PM 8/16/99 +0000, JF Mezei wrote:
>Bicycles and airplanes use a lot of similar technologies. Both need to
>be strong and light.
>One example is bicycle wheel rims. Most are high tech aluminium (and
>some now carbon-fibre).
>For rims and other parts, anodisation is often used. It not only
>provides a very long lasting and clean finish, but, i am told, also
>strengthens the aluminium. (is that true ?).

Yes, but there is a very important BUT....

Anodization can only be done with essentially Pure aluminum and only after
the part is in it's final configuration, it  probably cannot be done with
aluminium Alloys, which are used in aircraft. The process involves dumping
the finished item in hot, concentrated sulfuric acid as the positive
terminal. The Acid Attacks the exposed aluminum until it is completely
covered in a thick layer of oxide. Unfortunately you can only get away with
that with essentially pure aluminium...

Pure aluminium has poor structural strength, so while anodizing it will
harden it, it would still lack the strength required
to build structural parts..

If you attempt to machine the part after anodization, the oxide layer
cracks because it is hard and brittle, making the anodization process
worthelss. This would make things like bending parts, and riveting them in
place effectively impossible.

James Matthew Weber   (623) 587 7514 .  Fax  (623) 434 7598