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On the Mechanism of Niobium Electropolishing

Chandra, Ashwini
http://rave.ohiolink.edu/etdc/view?acc_num=osu1330544777

Abstract Details

2012, Master of Science, Ohio State University, Materials Science and Engineering.
Pure Niobium is the material used to make Superconducting Radio Frequency (SRF) cavities. These cavities need to be free from surface defects like pits, bumps and protrusions to achieve the best performance. Electropolishing is commonly used as a final process to give a good surface finish to the niobium surface. The standard electrolyte used for electropolishing niobium is a 1:9 ratio of HF (48%) and H2SO4 (96%) respectively. The mechanism of electropolishing is not fully understood and also the best electropolishing parameters need to be determined. Acid concentration, stirring, temperature and amount of material removed are the parameters expected to affect the surface finish. Their effect is studied using electrochemical polarization measurement, galvanostatic and potentiostatic techniques. The electro-dissolution occurring needs to be under mass transport control for the phenomenon of electropolishing to occur. This is characterized by the presence of a current density plateau in the niobium polarization curves. However Galvanostatic experimental result analysis points to other interfering transport processes as well. Results based on microscopy, surface profile measurement and current transient measurements for different electrode configurations indicate the presence of natural convection as one of the reason which could be causing deviation from a perfect semi infinite linear diffusion model.
Gerald S. Frankel, ScD (Advisor)
Michael Sumption, PhD (Committee Member)
Rudolph Buchheit, PhD (Committee Member)
131 p.
Materials Science
Electropolishing; niobium; polarization curve; galvanostatic experiments; convection; diffusion

Recommended Citations

Citations

  • Chandra, A. (2012). On the Mechanism of Niobium Electropolishing [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1330544777

    APA Style (7th edition)

  • Chandra, Ashwini. On the Mechanism of Niobium Electropolishing. 2012. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1330544777.

    MLA Style (8th edition)

  • Chandra, Ashwini. "On the Mechanism of Niobium Electropolishing." Master's thesis, Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1330544777

    Chicago Manual of Style (17th edition)

osu1330544777
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© 2012, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.