The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Suggestions for how to electropolish niobium, tantalum, and their alloys

2003

I am interested in learning how to electropolish niobium and tantalum alloys. Our group precleans the material with a warm 9 parts HCl and 1 part hydrogen peroxide solution at 120 degrees Fahrenheit. We have tried Electroglow 300 which contains phosphoric and sulfuric acid plus additional unnamed components, Electroglow 300 plus varying amounts of HCl, nitric acid, and sulfuric acid. These solutions have been also activated with up to 10 percent hydrogen peroxide. In additional we have tried straight laboratory grade sulfuric acid, nitric acid, and sulfuric acid (concentrated and diluted with methanol [affil links] and w/wo 10 percent hydrogen peroxide). None of the solutions appear to be attacking the refractory metal surface.

I have done a literature search and talked to a few vendors. Most solutions contain HF or perchloric acid which we would like to avoid as they are more toxic.

I would appreciate any suggestions.

Sincerely,

James M. Carlson, Ph.D.
- Gilroy, California USA

---

Our method of niobium polishing does not use acids, however we use high voltage.

Anna Berkovich
Russamer Lab

Pittsburgh, Pennsylvania

2003

We electro-polish Niobium cavities with 10 % Hydrofluoric and 90% sulfuric using around 14 to 16 volts dc

Jim Follkie
- Newport News, Virginia, USA
February 9, 2010

---

Please check US Patent Application 20100213078 "Electrolyte composition for electropolishing niobium and tantalum and method for using same".
Sincerely

Ryszard Rokicki
- Macungie, Pennsylvania USA
January 4, 2011