Literature Review of Nb Electroplating Dmytro Chirkov LNL-INFN 1
Chirkov - literature review of Nb electroplating
Jun 25, 2015
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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.
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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Transcript
1
Literature Review of Nb Electroplating
Dmytro ChirkovLNL-INFN
2
Overview
• Motivation • The process of electroplating• Electrolytes
Aqueous electrolytes Non-aqueous electrolytes
Electrolytes with organic solvents High-temperature melts Ionic liquids
• Conclusions
3
Motivation
The main aim of this work is try to understand if
expensive techniques for Nb coating could be
replaced by cheaper electroplating method
4
The process of electroplating
CathodeMn+ + ne- → M2H+ + 2e- → H2
AnodeM → Mn+ + ne- 2H2O → O2 + 4H+ + 4e-
5
Electrolytes
All electrolytes could be divided into two groups
• Aqueous electrolytes
• Non-aqueous electrolytes Electrolytes with organic solvents High-temperature melts Ionic liquids
6
Aqueous electrolytes
Diagram E – pH for system Nb –H2O
7
Aqueous electrolytes
№ Reaction E0, V
1 2H++2e-H2 0
2 Nb5++5e-Nb -0,96
3 Nb3++3e-Nb -1,1
Reactions which can occur on cathode in niobium salts aqueous solutions and their potentials
Niobium can’t be isolated by electrolysis of aqueous solutions of its compounds, since the water would be electrolyzed preferentially
8
Aqueous electrolytes
Parameters of electrolyze
Current density 10-20 A/dm2
Temperature 40-60 °C
Current efficiency 0,1%
Electrolyte
HNbO3 15-17 g/l
HF 120-140 g/l
NH4F 15-20 g/l
Formaldehyde 7-15 g/l
Ajogin F.F. Galvanotechnic. Handbook. 1987
9
Parameters
Current density, A/dm2 5-20
Temperature , °C 50-70
Nb content, % 6
Electrolyte g/l
Nb 10-20
Ni2CO3 10-20
HBF6 50-150
EDTA 30-40
OK-3 100-150
PV-20 10-30
NH4OH For pH 2,5-3
Aqueous electrolytesKadaner L.I., Fedchenko V.M.
About electrodeposition of Ni-Nb and Fe-Nb alloys. 1987
Ni-Nb alloy
10
Parameters
Current density, A/dm2 5-15
Temperature , °C 15-25
Nb content, % 10
Electrolyte g/l
Nb 10-20
FeCl2 10-20
HBF6 100-200
OK-3 100-150
PV-20 10-30
NH4OH For pH 1,5-2
Aqueous electrolytesKadaner L.I., Fedchenko V.M.
About electrodeposition of Ni-Nb and Fe-Nb alloys. 1987
Fe-Nb alloy
11
Non-aqueous electrolytes
Electrolytes with organic solvents
High-temperature melts
Ionic liquids
12
Electrolytes with organic solvents
Electrolyte
NbCl5 10-15 g/l
Methanol 300-500 ml/l
Propyl acetate 20-30 ml/l
Benzol 500-600 ml/l
Parameters of electrolyze
Current density 0,5-1,5 A/dm2
Temperature 40-50 °C
Time 10 min
Thickness 1 μm
The extreme high vapor pressure, flammability and explosiveness makes these solutions dangerous
Kuznetsov V. V., Grigoriev V. P., Osipov O. A. Method of electrochemical deposition of niobium. 1973
13
Electrolyte
NbCl5 40-100 g/l
NiCl3 0,1 – 0,3 g/l
Ethanol 96-100%
Parameters of electrolyze
Current density 20 A/dm2
Temperature 40-50 °C
Current efficiency 0,5 – 1%
Thickness 1 μm
Compact bright Ni-Nb coatings with Nb content ≤1%
Electrolytes with organic solventsFialkov U. Y., Grishchenko V. F.
Electrodeposition of metals from non-aqueous solutions. 1985
14
Electrolyte
K2NbF7 17,5%
KCl 55%
KF 27,5%
Parameters of electrolyze
Current density CathodicAnodic
60-80 A/dm2
15-23 A/dm2
Temperature 700-800 °C
Electrolyzer - hermetically sealedHave been obtained pure Nb with impurities of
C - 0,02wt%; O < 0,05wt%; N - 0,02wt%
High-temperature meltsYagodin G.A., Technology of rare metals in atomic technique.
Moscow, Atomizdat. 1974
15
Electrolyte
(Li-Na-K)F-eutectic2,5 wt% K2NbF7
Parameters of electrolyze
Current density 0,5-3,5 A/dm2
Temperature 725-800 °C
Outgassing the mixture under vacuum at 400 ⁰C for one week to remove adsorbed moisture.
Have been obtained dense coherent deposits of Nb
High-temperature meltsOn the electrodeposition and characterization of niobium from fused
fluoride electrolytes G. P. Capsimalis, E. S. Chen. Journal of Applied Electrochemistry V17, #2 / March, 1987
16
Ionic liquidsIonic liquids are molten salts with melting points
below 100 °C
17
Ionic liquids
Electrolyte
AlCl3 : EMIC melt(EMIC - 1-ethyl-3-methylimidazolium chloride)
Niobium contents of 10 - 12 % in the co-deposited niobium-aluminum coatings
Niobium Electrodeposition from Low-Valent Niobium Species Graham T. Cheek
18
Electrolyte
AlCl3 52 mol%
NaCl 48 mol%
Parameters of electrolyze
Temperature 190 °C
It was confirmed that aluminium alloys containing Nb could be electrodeposited. However, niobium could
not be deposited in the pure form.Niobium content in alloy – from 3 % to 13%
Ionic liquidsElectrochemical Behaviour of Dissolved Nb, Mo and Ta Species in
Molten Chloroaluminates. Geir Martin Haarberg and Gery Stafford
19
Electrolyte[BMP]-Tf2N : 0,25M NbF5 : 0,25M LiF
(BMP - 1-butyl-1-methyl-pyrrolidinium) (Tf2N - bis(tri-fluoromethylsulfonylimide)
Parameters of electrolyze
Current density 0,5-1 A/dm2
Temperature 100 °C
Layer of niobium deposited on Ni is not very uniform
Ionic liquidsElectrodeposition of Ta and Nb using ionic liquid. Guiseppina Barbato.
A thesis for the degree of Master of Applied Science
20
Parameters of electrolyze
Current density 100 A/dm2
Pulse period 10 ms
Duty ratio 0,2
Temperature 160 °C
Ionic liquids
Electrolyte
NbCl5 19.2 mol%
SnCl2 10 mol%
EMIC 70,8 mol%
Have been obtained Nb-Sn alloy with Nb content – 69,1wt％
Electrodeposition of Nb3Sn alloy film from Lewis basic NbCl5-SnCl2-EMIC melt Koura N. Electrochemistry V77, I9, September 2009, P798-800
21
Conclusions• 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
• Non-aqueous solutions could be used for Nb electroplating
• With high-temperature melts could be obtained Nb coatings
• 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
22
Thanks for your attention!!!!
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