-----Original Message-----
From: Jerry Davis <lts@avnet.co.uk>
Date: Thursday, November 18, 1999 10:54 AM
Subject: Re: Corrosion treatment
>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 agree that you are correct here. Its surface free energy that determines
the quality/strength of the bond. surface free energy is diminished by
hydration and contamination; a plus for Alodine treatment in that it can
avoid both of these.
Mechanical bonding is (outside of the Eastern block who believe differently)
a misnomer; roughening of parts to be bonded does virtually nothing from a
mechanical point of view. What it does do is increase surface area for all
that surface free energy to get working and, if the roughening has been done
recently, increases temporarily that energy.
Duncan McFadyean
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