D_Meredith79 said...Mark _australia said...
Nick
Resins will not laminate to aluminium well. It will stick, but the strength of the bond is much less than say epoxy/carbon laminate cured and then more epoxy/carbon laminated on top of it. I think it is the oxide layer that stuffs it.
Aluminium needs a good sanding followed by treating with an etching solution.
From memory it is sulfuric acid, potassium chromate or dichromate and some other stuff - possibly expensive to go and buy all the stuff you need just to make a little bit.
I have it somewhere in the Ciba-Geigy data sheets I have for Araldite resins but I'd never find it (just moved house) so perhaps Google and / or the Ciba-Geigy & West Systems websites.
maybe that kind of searching may identify an off the shelf etching solution for you?
Would sanding the aluminium with a course grit sanding disc/paper not fix both issues at the some time as it would remove any oxide layer that was present too?
D
Yes and no.
It will remove the old oxide layer but aluminium is highly reactive in air and instantly reoxidises.
It is the thin oxide layer that protects aluminium and makes it non reactive in air.
If you continuously remove that, it reacts exactly as you would expect from its position on the periodic table. i.e. it self destructs in a few minutes.
So the problem is not how to get the oxide layer off the aluminium. It is how do you treat the aluminium oxide to make something stick to it.
I have previously used alodine for this as a base for paint but I don't know if it would work for what you want to do.
It's also poison so if you use it, be careful.
