Single Crystal Ni electropolishing

I am hoping there is someone that can help me with my Ni EP problem. I am doing some research and being held up by poor Ni surface finishes.
We have tried solutions of phosphoric + sulfuric, sulfuric, hydrochloric, etc. and are having either bubble trails, pitting, or a combination of the two. Are there any solutions that do not evolve bubbles in the polishing regime? So far our most successful bath is sulfuric (10M) with 0.7M NiSO4 running at 6V, CD approx between 1 and 2A /cm^2 with heavy bubbling. I appreciate any help.
Thanks, Adam
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AdamStandley wrote:

Etchant 134 Electrolytic 5-10 volt for 5 -60 s in 70 ml H3PO4 in 30 ml H2O
Check out other etchants in specification ASTM E407
Ed
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AdamStandley wrote:

Glacial acetic containing 8% of 60% perchloric worked for me on medium carbon steel, after I had problems with the other acids you mention. Might be worth a try on Ni, assuming the Ni doesn't catalyse a detonation or anything horrible like that. Voltage needs to be 30-60V, maybe 100 mA / cm^2. Use less perchloric for reduced conductivity.
Joe
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