Re: anodized aluminum for high vacuum?

Am Sun, 26 Oct 2003 18:41:41 GMT, Repeating Decimal postete:


>Except for thickness, what are the important differences between the surface
>of aluminum oxidized in air with respect to anodized aluminum? 

The porosity, the well defined thickness, the optical quality, the
improved sturdiness and finally the acidity.

>>From what I understand, clean aluminum surfaces in air are immediately oxidized.

Yes. If you have a clean Aluminum surface (i.e. by etching with NaOH),
just dip it into concentrated H3PO4. This forms AlPO4 at the surface.
This passivation looks and is a bit better than an uncontrolled
re-oxidation at the air, but it cannot replace a good anodization.

Kind regards,

Ansgar Kursawe
-- 
The two most common things in universe are hydrogen and bureaucracy.