Metal finishing Q&As since 1989

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Surface contaminant and electropolish methods for biomaterials

I tried to get some smooth surface for metallic biomaterials, e.g. 316LSS, Nitinol. I polished these metal by mechanical polishing using 0.05 µm Alumina paste. But these are always some contaminants such as small particles. I ultrasonically cleaned these surface in soap, acetone [on eBay or Amazon] and DI water bath but it seemed not work well. Any suggestions on getting rid of these particles will be welcome. By the way, anyone know how to polishing these biomaterials by electrochemical methods. I saw some suggestions on nitinol using electropolishing but lack of details.

Thanks,

Bill Bai
- Syracuse, New York
2003

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Electropolishing removes embedded contaminants and leaves a microscopically smooth, corrosion resistant surface. However, it requires equipment, chemicals, wastewater treatment, permits, expertise, etc. Go to the www.finishing.com Home page and Search for electropolish. One respondent suggests sending parts to a commercial electropolisher (try Jobshops below) if you manufacture fewer than 10,000 parts per year. Also, a jobshop should be familiar with standards such as ASTM B912-02 Passivation of Stainless Steels Using Electropolishing and perhaps ASTM F86 Surface Preparation and Marking of Metallic Surgical Implants. Not sure what you mean by "metallic biomaterials," but the suitability of the alloy depends upon the application. I do know that Nitinol (N01555) is used for stents. Carpenter Technology www.carpentertechnology.com has a free, useful booklet Biodur® and Other Specialty Alloys for Medical Applications.ì Also, if implants are involved, do a search for surgical implant at www.astm.org.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2003