Electropolishing Aluminum
What can you tell me about aluminum electropolishing?
Q. What can you tell me about aluminum electropolishing? –M.N.
A. Electropolishing is typically associated with the finishing of stainless steel, however, aluminum can be electropolished as well. Electropolishing of aluminum is an excellent substitute for bright dipping, which produces chemical byproducts that are toxic. A basic primer on the process is available at pfonline.com/articles/electropolishing-as-a-pretreatment-for-anodizing.
Electropolishing bath chemistry is based on a mixture of acids, but a process using sodium carbonate/trisodium phosphate is also used. A commercial formulation is:
| Component | Concentration |
|---|---|
| Sufuric acid | 70% by volume |
| Phosphoric acid | 15% by volume |
| Nitric acid | 1% by volume |
| Water | 14% by volume |
| Operating conditions | Range |
| Temperature | 165-185°F |
| Time | 2-15 min |
| Voltage | 10 |
| ASF | 30-50 |
More information is available in the ASM Metals Handbook, Volume 5, available from ASM International at asminternational.org. This book is expensive, but an excellent addition to your plating library.
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