Anodizing

[RST Engineering]

I've had some good luck anodizing 5052-H32 Aluminum using drano as a
cleaner, battery acid as an electrolyte, and rit as a color dye.

I'd prefer to use muriatic acid (26% HCl) as the electrolyte. Has
anybody tried it or have a reason that it wouldn't work as well?

Thanks,

Jim

[IanM]

<http://www.coleparmer.com/techinfo/chemcomp.asp>
> Chemical Compatability Results
>
>
>
> The Material Selected Aluminum
> Interacting with the Chemical Hydrochloric Acid 20%
> Has a Compatibility Level of D-Severe Effect

<http://scifun.chem.wisc.edu/chemweek/aluminum/aluminum.html>
> The protective oxide coating on aluminum is frequently enhanced by
> the process of anodization. Aluminum metal is made the anode in an
> electrolytic cell, where aluminum metal is oxidized, and its
> protective oxide coating is thickened. The oxide coating on aluminum
> renders it impervious to most acids. However, any chemicals that form
^===============================
> a strong complex with aluminum ions, e.g., OH- and Cl- ions, will
=========================================^ ^==============
> react with the oxide coating. Therefore, aluminum will dissolve in
==================================================================
> hydrochloric acid and sodium hydroxide solutions.
================^

Also even if you manage to anodize, wash and seal it, trace Cl- ions in
the pores of the oxide layer will cause fairly rapid corrosion in
service. Google: aluminum chloride corrosion

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:

[Uwe Hercksen]

RST Engineering schrieb:

Hello,

read this http://electrochem.cwru.edu/encycl/art-a02-anodizing.htm
"The most widely used bath is dilute sulfuric acid, typically about 1
molar or 10 weight percent concentration. Other baths used for
particular applications are made with oxalic acid or phosphoric acid."

Bye

[whit3rd]

On Monday, August 1, 2011 12:55:39 PM UTC-4, RST Engineering wrote:
> I've had some good luck anodizing 5052-H32 Aluminum using drano...

> I'd prefer to use muriatic acid (26% HCl) as the electrolyte. Has
> anybody tried it or have a reason that it wouldn't work as well?

'Drano' is a brand name of drain cleaners, the most common variant
of which is largely NaOH (lye). It is very much incompatible with aluminum.
Muriatic acid is just as bad.

I think sulfuric acid is the usual anodizing medium for aluminum.