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Aluminum Anodizing

anodized aluminum product Article Contents: Aluminum Anodizing Practice Aluminum Anodizing Steps Electropolishing Alkaline Solution ...

June 11, 2010

Solution Type for Electropolishing

Electropolishing method can also be used for cleaning metal materials that have been plate by other metal material like corrode that stick on the metal surface or oxide film that create a film layer on the metal base. The metal which will be polished act as Anode, anode on this process is connected to positive pole of DC current source.

The effect of this electropolishing then the metal will change more bright because of the covered layer on the surface like being peels and the rest is new metal surface. A normal metal will convert the metal on the surface become a metal ion and usually will dissolve in the solution. Especially for Aluminum this surface metal are not dilute in the solution but covert into Aluminum oxide which have noble properties and stick in the aluminum surface. Aluminum oxide have characteristic as inhibitor and will burden the current flow from aluminum to the solution. More long the process, more aluminum metal covered by aluminum oxide, and finally the current flow will stop because all the surface have covered by aluminum oxide that can’t conduct the electric current.






The solution type for electropolishing can use chemicals composition are as the list below:

ChemicalsWeight (%) Current Flow (Amp/ft2) Voltage, voltTemperature, oCTime, min
Orthophosphoric Acid
Sulfuric Acid
Chromic Acid
Water
65
15
6
 14
200 - 25012 - 1570 - 802 - 5
Orthophosphoric Acid
Sulfuric Acid
Chromic Acid
Water
43
43
3
11
300-50012 - 1570 - 802 - 5
Orthophosphoric Acid
Sulfuric Acid
Chromic Acid
Water
36
36
4
24
200-40012 - 1570 - 901 - 5
Orthophosphoric Acid
Chromic Acid
Water
82
12
6
209-40012 - 1570 - 801 -3
Trisodium Phosphate
Soda Ash (anhydrous)
5
15
30-6012 - 1580 - 905 - 8
Hydrofluoboric Acid1.2515-3020-303010-20

In addition to the above solutions, solution of perchloric acid and acetic anhydride have also been recommended for polishing of aluminum. The use of this electrolyte, however, involves taking certain precautions, because of the risk of explosion effect.

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