Applications of Green Technology in the
Manufacture of Turbine Blades
Karl S. Ryder
Scionix Laboratory,
Department of Chemistry,
University of Leicester,
Leicester, LE1 7RH,
UK
[email protected]
Contents
•
What is an ionic liquid
•
Eutectic-based ionic liquids and how to make them
•
Applications
 Immersion Ag for PCB's
 Cr plating
 Al Plating
 Battery applications
•
Electro polishing
•
RS Industrial Fellowship scheme
•
Results (RR3010 blades), XPS
•
Closing remarks
Ionic liquids: definition
Ionic material that melts below 100 ºC
•
Unusual solvent properties
•
Very low / negligible vapour pressure - do not evaporate
•
Most liquids thermally stable >200 ºC
•
Immiscible with many organic solvents
•
Some have wide potential windows
•
Large and unsymmetrical ions -> low lattice energy and
hence low melting point
Historical perspective
1914
EtNH3+NO3-
1980’s
Pyridinium eutectic with AlCl3
researched for Al deposition and Al
batteries
1990’s
cations
Prevalence of imidazolium based
2000’s
liquids
Environmentally more benign ionic
Liquid preparation
• Just mix two components (often r.t. solids) to
make liquid!
• Endothermic reaction, entropy driven
10 ILs have been produced in over 200 kg batches
One IL made on the tonne scale (for electropolishing)
Electropolishing
Electrochemical dissolution:
 ChCl / EG liquid
 High current efficiency
 Low toxicity
 No strong acids
 Comparable finish
Electropolishing
Pilot plant
 Functional process line
 Pre treatment
 Process, 50 L IL
 Rinse
Works very well for 300
series stainless steels and
high value performance
alloys, Ni / Co, Ti etc.
Electropolishing
Better surface finish (market)
Non-corrosive (social)
Benign liquid – ChCl/glycol (social)
Improved current efficiency (>80%) (economic)
Less gas evolution (environmental)
Metal recoverable (environmental)
 SS or Ti / IrO2 Cathodes
 Ti Jigs
 Standard pump / tank fittings
 Less gassing
 Better current efficiency
Electropolishing
Royal Society Industry Fellowship (KSR)
Started July 2010:
• Explore electropolishing of superalloys with IL processes
• Study composition of alloy
• Determine etch rate
• Explore removal of scale (effect on surface melting)
• Explore removal of casting shell
Electropolishing
Strategy:
• Polish metal
• Vary conditions
• Characterise surface
• Heat treat
Electropolishing; surface characterisation
Electrolytic polishing in IL removes
virtually all residual shell.
Electropolish
First results suggest alloy
composition is not effected by etch
Surface roughness greatly
reduced
Sample 1 (pale)
Ni(3p)
Electropolishing
Partially immersed , polished blade (RR3010)
20 mins process time.
Electropolishing
Fully immersed , polished blade (RR3010)
60 mins, total process time.
Eapp = 5.8 V
Electropolishing
Fully immersed , polished blade
(RR3010)
60 mins, total process time.
Eapp = 5.8 V
Some trapped shell loosened!
Electropolishing: recycling
Spent polishing liquid from the electropolishing process can be
recycled and reused:
(a) Spent liquid
(b) Equal volume of water added
 Settlement
 Filtration
 Heating (remove water)
(c) Recylced liquid
Conclusions
Electropolishing of superalloy turbine blades in DES type (choline
chloride based) ionic liquids:
•
•
•
•
•
•
Effective in removing Ni-based surface scale
Effective in removing residual shell
Homogeneous dissolution of metal
Isotropic etching (semi-quantitative XPS)
Reducing surface roughness
Softening / loosening trapped shell
Visualising grain structure possible prior to heat treatment possible by
electrolytic etch. This has the potential to save process time and
reduce production costs.
Hard back, 338 pages
ISBN-10: 3-527-31565-9
ISBN-13: 978-3-527-31565-9
Wiley-VCH, Weinheim