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Potentiel electrochimique de l'aluminium revetu d'Alodine 1200

Je cherche à savoir si la valeur du potentiel électrochimique de l'aluminium 6061 (-0.8 V) varie lorsque celui ci est révêtu d'Alodine 1200. Si c'est le cas de combien varie t'il?

Médéric GAUTIER
- Paris, France

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Hi Mederic,

The electrochemical potential of aluminum alloy 6061 coated with any chromate conversion varies as a function of (1) the thickness of the coating, (2)the density of the coating which is a secondary function of time, temperature, pH, concentration and chemical accelerators (potassium_ferrocyanide.html is most popular)) used in the application of the coating, (3) surface rms finish of the aluminum, and (4) the chemical surface preparation of the surface prior to application.

No applicator can hold these parameters constant enough to give a fixed potential for the coated panel.

U S MIL-C-5541 shows two Classes of coatings. Class I is very heavy and almost completely resistive. Class III is low thickness, sometimes even "clear" and is meant for electrical contact. Both Classes are subject of highly controversal definitions of contact pressure and method of measurement.

Your best chance is to require your applicator shop to furnish you with panels of their lowest and their thickest coatings, then you measure the range of potential that you may expect from production work.

Take two aspirin and call me in the morning.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

I am interested by answer to that question (14818).

Quintard
- Niort, France