Chirkov - literature review of Nb electroplating

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Literature Review of Nb Electroplating (Dmytro Chirkov - 20')
Speaker: Dmytro Chirkov - Legnaro National Laboratories of INFN | Duration: 20 min.
Abstract
The main aim of this work is try to understand if expensive techniques of niobium coating could be replaced by cheaper electroplating method.
Nowadays electrochemical surface treatment is one of the most used approaches in industry.
Aqueous solutions has been the most widely used process mainly because of advantages such us low cost, non-flammability, high solubility of electrolytes, high conductivities resulting in low ohmic losses, high solubility of metal salts and high rates of mass transfer. However, despite these advantages there are several limitations in using aqueous solutions such as limited potential windows, gas evolution processes that can result in hydrogen embrittlement, passivation of substrates, electrodes and deposits, and the necessity for hazardous complex agents such as cyanide, causing environmental contamination. These are the reasons why new non-aqueous solutions to electrodeposit niobium have been researched.
One of the main limitations in using aqueous solutions is their narrow electrochemical window. The major reason for carrying out electrodeposition in non-aqueous electrolytes (such as conventional organic solvents, ionic liquids and molten salts) is water and air stability and the wide electrochemical window of these media.
Alternatively, also high temperature molten salts have been used extensively for niobium electrodeposition. They have wide potential windows, high conductivities and high solubility for metal salts. In fact, they have most of the advantages of aqueous solutions and overcome most of the limitations of aqueous solutions, but their one major limitation is the very high temperature (more than 750 °C).
Therefore, the alternative to high temperature molten salts was an ionic substance that melts at a low temperature. Over the last few decades, room temperature ionic liquids have been widely studied in various scientific fields due to their interesting properties, such as negligible vapour pressures, high chemical and thermal stability, acceptable intrinsic ionic conductivity and wide potential window.
Ionic liquids are molten salts with melting points below 100 °C and they consist entirely of cations and anions. The development of ionic liquids, especially air and water stable types, has attracted extensive attention since they have outstanding physical properties.
The aim of this work will be the analysis of available literature data in order to have precise knowledge about niobium behavior in the different electrolytes and to get new information about possible electrolytes based on ionic liquids.

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Chirkov - literature review of Nb electroplating

  1. 1. Literature Review of Nb Electroplating<br />DmytroChirkov<br />LNL-INFN <br />1<br />
  2. 2. Overview<br />Motivation <br />The process of electroplating<br />Electrolytes<br /><ul><li>Aqueous electrolytes
  3. 3. Non-aqueous electrolytes
  4. 4. Electrolytes with organic solvents
  5. 5. High-temperature melts
  6. 6. Ionic liquids</li></ul>Conclusions<br />2<br />
  7. 7. Motivation<br />The main aim of this work is try to understand if expensivetechniques for Nb coating could be replaced by cheaper electroplating method<br />3<br />
  8. 8. The process of electroplating<br />Cathode<br />Mn+ + ne- -> M<br />2H+ + 2e- -> H2<br />Anode<br />M -> Mn+ + ne-<br />2H2O -> O2 + 4H+ + 4e-<br />4<br />
  9. 9. Electrolytes<br />All electrolytes could be divided into two groups<br />Aqueous electrolytes<br />Non-aqueous electrolytes<br /><ul><li>Electrolytes with organic solvents
  10. 10. High-temperature melts
  11. 11. Ionic liquids</li></ul>5<br />
  12. 12. Aqueous electrolytes<br />Diagram E – pH for system Nb –H2O<br />6<br />
  13. 13. Aqueous electrolytes<br />Reactions which can occur on cathode in niobium salts aqueous solutions and their potentials <br />Niobium can’t be isolated by electrolysis of aqueous solutions of its compounds, since the water would be electrolyzed preferentially<br />7<br />
  14. 14. Aqueous electrolytes<br />8<br />Ajogin F.F. Galvanotechnic. Handbook. 1987<br />
  15. 15. Aqueous electrolytes<br />9<br />Kadaner L.I., Fedchenko V.M. <br />About electrodeposition of Ni-Nb and Fe-Nb alloys. 1987<br />Ni-Nb alloy<br />
  16. 16. Aqueous electrolytes<br />10<br />Kadaner L.I., Fedchenko V.M. <br />About electrodeposition of Ni-Nb and Fe-Nb alloys. 1987<br />Fe-Nb alloy<br />
  17. 17. Non-aqueous electrolytes<br /><ul><li>Electrolytes with organic solvents
  18. 18. High-temperature melts
  19. 19. Ionic liquids</li></ul>11<br />
  20. 20. Electrolytes with organic solvents<br />Kuznetsov V. V., Grigoriev V. P., Osipov O. A. <br />Method of electrochemical deposition of niobium. 1973<br />The extreme high vapor pressure, flammability and explosiveness makes these solutions dangerous<br />12<br />
  21. 21. Electrolytes with organic solvents<br />Compact bright Ni-Nb coatings <br />with Nb content ≤1%<br />13<br />Fialkov U. Y., Grishchenko V. F. <br />Electrodeposition of metals from non-aqueous solutions. 1985<br />
  22. 22. High-temperature melts<br />Electrolyzer - hermetically sealed<br />Have been obtained pure Nb with impurities of <br />C - 0,02wt%; O < 0,05wt%; N - 0,02wt%<br />14<br />Yagodin G.A., Technology of rare metals in atomic technique. <br />Moscow, Atomizdat. 1974 <br />
  23. 23. High-temperature melts<br />Outgassing the mixture under vacuum at 400 ⁰C for one week to remove adsorbed moisture.<br />Have been obtained dense coherent deposits of Nb<br />15<br />On the electrodeposition and characterization of niobium from fused fluoride electrolytes G. P. Capsimalis, E. S. Chen.<br /> Journal of Applied ElectrochemistryV17, #2 / March, 1987<br />
  24. 24. Ionic liquids<br />Ionic liquids are molten salts with melting points below 100 °C<br />16<br />
  25. 25. Ionic liquids<br />Niobium Electrodeposition from Low-Valent Niobium Species <br />Graham T. Cheek<br />Niobium contents of 10 - 12 % in the co-deposited niobium-aluminum coatings<br />17<br />
  26. 26. Ionic liquids<br />It was confirmed that aluminium alloys containing Nb could be electrodeposited. However, niobium could not be deposited in the pure form.<br />Niobium content in alloy – from 3 % to 13%<br />18<br />Electrochemical Behaviour of Dissolved Nb,Mo and Ta Species in MoltenChloroaluminates. Geir Martin Haarberg and Gery Stafford<br />
  27. 27. Ionic liquids<br />Layer of niobium deposited on Ni is not very uniform<br />19<br />Electrodeposition of Ta and Nb using ionic liquid. GuiseppinaBarbato. <br />A thesis for the degree of Master of Applied Science<br />
  28. 28. Ionic liquids<br />Electrodeposition of Nb3Sn alloy film from Lewis basic NbCl5-SnCl2-EMIC melt Koura N. Electrochemistry V77, I9, September 2009, P798-800 <br />Have been obtained Nb-Sn alloy <br />with Nb content – 69,1wt% <br />20<br />
  29. 29. Conclusions<br />The electrodeposition of Nb is not possible from aqueous solutions because the electrochemical potential for this metal falls outside the window of stability for water<br />Non-aqueous solutions could be used for Nb electroplating <br />With high-temperature melts could be obtained Nb coatings<br />Ionic liquids are a relatively new class of materials with properties (wide potentional window, inflammability, low vapour pressure) that makes them attractive for electroplating of Nb<br />21<br />
  30. 30. Thanks for your attention!!!!<br />22<br />

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