----- Original Message ----- 
From: Ken Mc Gowan 
To: [log in to unmask] 
Sent: Friday, April 20, 2001 4:04 PM
Subject: Anodising Al


Hi Liu,

The normal rule for Al is that the purer it is the easier to anodise,also that wrough material tends to be better than cast.

Typical good alloys are:

N5-O H2, H4 Al + 3.5 % Mg

N51-O H2, H4 Al + 2.7% Mg + 0.75% Mn + 0.1% Cr

H9-TB, TF Al + 0.6% Mg + 0.5% Si 

The designations I use are British Standards. BS 1470-75 refers.

If you want to experiment make up some 10% v/v sulphuric acid, let it cool to 20/25 C. Scrub the face to be bonded with scotchbrite or wrt and dry to remove surface soil and oxides.Make up a circuit with a controllable 50V rectified output (A/V). Use a peice of chemical lead as the cathode (negative) and the Al anode (positive) in the vessel containing the electrolyte.

Set the power output on your rectifier to 15 A for every square foot of the panel being anodised (adding together both sides). Let it cook away for 20 to 30 min. Check the temp and current a couple of times during the cycle.

After this time simply take it out and wash it under tap water and dry either in an oven or with an air line. It is then suitable for bonding to FR4 or most other inert surfaces.

I would use a typical anerobic adhesive, presumably like you would use in SMT etc.

If this is not possible try to find a local guy doing anodising or someone who makes window frames etc.Aesf may help you here www.aesf.org

Final idea might be to ask the aluminium supplier does he sell to anybody doing sulphuric anodising?

Slan,

Ken McGowan