I think unsealed and sealed means that the little tubes formed in the
anodising process are left open ended or sealed over. For bonding (and etch
priming) it is normal to have unsealed for better mechanical bonding. All
anodising will seal with time as its a natural process. Time being hours or
at the most days.
I think I'm correct here.
I had many parts Sulphuric etched where they were not bonded. Correct I
think this reduces fatigue life but then an anodised part could be a lot
stronger than a coroded part. I think I avoided anodising any parts subject
to high repetetive stressing.
Jerry
lts@avnet.co.uk
http://www.avnet.co.uk/touchdown
----- Original Message -----
From: Paul & Liz Atkinson <paulliz@cix.co.uk>
Subject: Re: Corrosion treatment
> In article <0.59bbd9ec.2560481a@aol.com>, Fillinger@aol.com () wrote:
>
>
> > Note that some builders have commercially anodized the aluminum parts.
> > I can't say how much better this is; they may add to this thread. But
> > aluminum corrosion is an electrolytic process, and can occur buried in
> > resin and thus in the absence of air (but latter also promotes it --
> > e.g., acid or salty atmosphere). A clean, rough surface is probably
> > the most important thing to have.
> >
> > Regards,
> > Fred Fillinger, A063
>
> Fwiw I anodised my bits! It wasn't too painful - or expensive. It is
> important to use the right process though - Chromic not sulphuric. If you
> specify the correct DEFSTAN (which Andy Draper can tell you; I have long
> since forgotten I am afraid) you can be sure the job will be done right.
> Chromic only treats to a depth of about 2 microns whereas sulphuric goes
> much deeper and forms a hard but brittle surface which will reduce the
> fatigue resistance of the part. I was advised to have the parts sealed but
> again I cant remember why, but no doubt the Anodizer could give the
> reason. Whether this is any better than Alodyne I don't know, but I do
> remember that Alodyne didn't cost much less than letting a professional do
> the job for me so I put my faith in anodizing.
>
> Paul Atkinson
>
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