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Innovative sol-gel and hybrid coatings

Regional Symposium on Electrochemistry - RS Є -S ЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010. Innovative sol-gel and hybrid coatings. L. Fedrizzi, L. Paussa, F. Andreatta. University of Udine Department of Chemical Science and Technology Udine, Italy.

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Innovative sol-gel and hybrid coatings

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  1. Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6-10, 2010 Innovative sol-gel and hybrid coatings L. Fedrizzi, L. Paussa, F. Andreatta University of Udine Department of Chemical Science and Technology Udine, Italy

  2. Protection system for aluminum alloys • Surface treatment • Top coat Cr(VI) Based coatings: Alternative Conversion Coatings: • Very good effectiveness-to-costs ratio • Self-healing ability • High toxicity • Anodizing Treatment • Silane Based Coatings • Cerium Salt Based Coatings • Sol gel Coatings SUBSTRATE Inorganic and organic systems ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Top-coat + Primer • Chemical Conversion Coating • Corrosion Inhibitors • Organic Coating Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  3. Sol-Gel Technology ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS *Reprinted courtesy of Lawrence Livermore National Laboratory Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  4. Sol-gel System investigated • Substrate • AA2024 • Surface preparation • Alkaline cleaning • Alkaline etch • Acid etch ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • Sol-gel Zirconia Based film • Aqueous solution of inorganic precursor: 0.4M ZrO(NO3)2 • Sol-gel Inorganic-Organic Hybrid film • Inorganic and organic precursors in alcoholic solvent Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  5. Zirconium Oxide Sol-Gels • Starting solution containing metal precursors ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Zr Zr Zr Zr Zr Zr Zr Zr Zr • Sol State Hydrolysis and Condensation Reactions • Gel State Heat treating Zr • Ceramic material Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  6. Zirconia film deposition – S.E.M. observation ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • AA2024 (degreased and pickled) Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  7. Zirconia film deposition – GD-OES analysis ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • ZrO2 deposited on AA2024 (2 dip deposition) wt Al O Zr C Cu Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  8. Zirconia film deposition – T.E.M. observations ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • AA2024 (degreased and pickled) * Picture from The University of Manchester in the framework of MULTIPROTECT European Research Project Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  9. Hybrid coatings & Corrosion Inhibition by Ce species ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Cerium diffusion Cerium diffusion Coating AA2024 Passivation / Inhibition • Cerium Compounds • Low toxicity and cost • Low solubility of oxides and hydroxides Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  10. Hybrid Coatings – Starting precursors O O O O Si O O O O O O O System produced by A. Duran (ICV – Spain) Inorganic Precursor ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Tetraethoxysilane (TEOS) Hybrid Precursor O O Si 3-(methacryloxypropyl)trimethoxysilane (MPS) O O O Organic Precursor Etilenglycol dimethacrylate (EGDMA) Glycidyl methacrylate (GMA) Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  11. Hybrid Coatings – Polymerizationscheme O O O O Si O Si O O O O O O ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS INORGANIC POLYMERIZATION ORGANIC POLYMERIZATION + HYBRID MATERIAL H O H Regional Symposium on Electrochemistry - RSЄ-SЄЄ

  12. Hybrid coating systems developed NON INHIBITED SYSTEM ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS INHIBITED SYSTEM Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  13. Electrochemical tests used ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS ELECTROCHEMICAL METHODS DC METHODS AC METHODS • Open circuit potential • Potentyodinamic Polarization • Electrochemical Impedance Spectroscopy Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  14. Electrochemical cell – Configuration • Electrolytic solution: 0.05M NaCl ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • THREE ELECTRODE SETUP • Pt WIRE COUNTER ELECTRODE • Ag/AgCl REFERENCE ELECTRODE • (3.6 or 14.8) CM2 TEST AREA Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  15. Zirconia film deposition – S.E.M. observation ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • Cracks on coated AA2024 Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  16. Barrier properties – Potentiodynamic Polarization • AA2024 ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Several current spikes detected for the substrate coated with the ZrO2 film without defects; Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  17. Electrochemical systems – OCP AA2024 ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • stable O.C.P. for Al substrare and for the ZrO2 film with large defects; • Unstable O.C.P. for the ZrO2 film without defects ; Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  18. AC method – Electrochemical Impedance Spectroscopy ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • LINEARITY • CAUSALITY • STABILITY E.I.S. P.P.C. E.I.S. fundamental conditions Mathematical methods to validate impedance measurements Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  19. Important aspects – Unstable OCP ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS 19 • impedance measurements of coated metallic substrates with unstable O.C.P. are critical under voltage control; • impedance measurements under voltage control might lead to polarization of the substrate when the O.C.P. is not stable. This causes severe damage of the coating due to the measurement; • impedance data can be acquired for unstable systems under current control. This method enables data acquisition without damage of the metal substrate; • measurements under current control make it possible to follow electrochemical behaviour as a function of immersion time. Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  20. AC method – Electrochemical Impedance Spectroscopy ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Voltage Control (Common approach) Current Control Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  21. Voltage Control– Stable OCP ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Input signal Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  22. Voltage Control– Stable OCP ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS E.I.S. measurement OCPmeasurement Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  23. Current Control – Stable OCP ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Low frequencies Low amplification Middle frequencies Middle amplification High frequencies High amplification (Output signal/noise) Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  24. Current Control – Stable OCP Input signal ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS DI perturbation is a function of Z(jw) Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  25. Current Control – Stable OCP Output signal ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS DI1 DI2 Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  26. Current Control – almost stable OCP • ALTERNATIVE CONVERSION COATINGS • ZIRCONIA SOL-GEL • HYBRID SOL-GEL • CONCLUSIONS CCC 6h DC signal output Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  27. Voltage and Current Control – Stable OCP Bode Module Plot Bode Phase Angle Plot ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS • Impedance data acquired on stable system using voltage control and current control methods are overlapping Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  28. Voltage Control – Unstable OCP Input signal ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  29. Voltage Control – Unstable OCP • O.C.P. measurement for 60 seconds before acquisition of E.I.S. data; • 20mV voltage amplitude; ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Input signal ZrO2 film 1h E.I.S. measurement OCPmeasurement Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  30. Voltage Control – Unstable OCP Bode Module Plot Bode Phase Plot ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS ZrO2 film 1h • E.I.S. data acquisition is not good; • during E.I.S. measurement, the current detected is in the range of 200-300mA; • probable damage of the sample (h); Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  31. Current Control – Unstable OCP Output signal ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  32. Current Control – Unstable OCP ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS ZrO2 film 24h Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  33. Current Control – Unstable OCP • unstable O.C.P.; • perturbation applied under zero current condition; • 20 seconds relaxation time set to enable the recovery of steady-state ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Output signal Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  34. Voltage and Current Control–Unstable OCP Bode Module Plot ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS ZrO2 film 0h voltage control ZrO2 film 0h current control Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  35. Voltage and Current Control–Unstable OCP Nyquist Plot ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS ZrO2 film 0h current control ZrO2 film 0h voltage control ZrO2 film 0h voltage control ZrO2 film 0h current control Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  36. Current Control – Unstable OCP No sample damage; film properties remain good after 336h of immersion ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS ZrO2 film 0h ZrO2 film 24h ZrO2 film 96h ZrO2 film 192h ZrO2 film 336h Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  37. Hybrid coatings & Corrosion Inhibition by Ce species ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Cerium diffusion Cerium diffusion Coating AA2024 Passivation / Inhibition • Cerium Compounds • Low toxicity and cost • Low solubility of oxides and hydroxides Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  38. Progressive degradation • Fast evolution • No recovery of properties Non Inhibited System: EIS in 0.05M NaCl ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  39. Progressive degradation • More protective system • Higher modulus at low frequencies Inhibited System: EIS in 0.05M NaCl ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  40. Comparison Non Inhibited - Inhibited systems ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS 10 mHz NON INHIBITED 0h NON INHIBITED 10h 15 mHz INHIBITED 0h INHIBITED 8h 10 mHz 10 mHz 50 Hz 50 Hz 1 Hz 1 Hz 50 Hz 0h 50 Hz 10h 1 Hz 1 Hz 10 mHz NON INHIBITED 72h 10 mHz NON INHIBITED 194h INHIBITED 196h INHIBITED 70h 50 Hz 15 mHz 10 mHz 50 Hz 50 Hz 50 Hz 72h 196h 1 Hz 1 Hz 1 Hz 1 Hz Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  41. Coating deposited by sol-gel technique • Oxide layer due to passivation of aluminum • AA2024 Equivalent Circuit used to fit E.I.S. data ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS COATING CPEcoat Rcoat Rox CPEox OXIDE LAYER CPEdl Rct SUBSTRATE Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  42. Different starting conditions • Different coating thickness • Similar behaviour for long immersion time • Barrier properties are limited for both systems Coating resistance as a function of time ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS NON INHIBITED INHIBITED Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  43. Different starting conditions due to Ce leaching • Different corrosion rate • Indication of inhibition in the Ce containing system Charge transfer resistance as a function of time ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS NON INHIBITED NO DOPED DOPED INHIBITED Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  44. GD-OES profile vs immersion time in 0.05M NaCl INHIBITED SYSTEM ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Before immersion 56h immersion time Cerium Cerium • Ce amount in the coating changes with immersion time Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  45. Cerium signal in the middle layer • Cerium diffusion to the substrate and in the electrolyte GD-OES profile vs immersion time in 0.05M NaCl INHIBITED SYSTEM ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Cerium Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  46. 3000 hours immersion in 0.05M NaCl • NON INHIBITED SYSTEMS • INHIBITED SYSTEMS Surface morphology of Hybrid systems ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  47. Conclusions • Zirconia Sol-Gel films: Properties • Very thin films and homogeneous deposition • Long term corrosion resistance of ZrO2 sol-gel systems is very good • ZrO2 pre-treatments provide similar barrier properties to Chromatization • Zirconia Sol-Gel films: E.I.S. approach • Measurements performed under voltage control on unstable systems are critical. Methods based on current control should be employed • Inorganic-Organic Hybrid coatings: Properties • Limited barrier properties • Corrosion properties of AA2024 INHIBITED SYSTEM are better than those of NON INHIBITED one • GD-OES measurements show a decrease of available cerium but a fraction moves towards the substrate ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  48. Acknowledgement ALTERNATIVE CONVERSION COATINGS ZIRCONIA SOL-GEL HYBRID SOL-GEL CONCLUSIONS This work was generated in the context of the MULTIPROTECTproject, funded by the European Community as contract N° NMP3-CT-2005-011783 under the 6th Framework Programme for Research and Technological Development. Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  49. Advantages of Sol-gel synthesis INTRODUCTION ZIRCONIA SOL-GEL AA6060 AA2024 HYBRID SOL-GEL ADHESION PROPERTIES (AA6060) CONCLUSIONS • The temperature required are low. • Precursors such as metal alkoxides are frequently volatile. • Organo-metallic precursors involving different metals are frequently miscible. • The chemical conditions are mild. • Highly porous materials and nanocrystalline materials may be prepared in this way. • By appropriate chemical modification of the precursor, control may be achieved over the rates of hydrolysis and condensation, and over colloid particle size and the pore size, porosity and pore wall chemistry of the final material. • Using functionalized precursors, covalent attachment of organic species to porous glass structure is possible. Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

  50. Advantages of Sol-gel synthesis INTRODUCTION ZIRCONIA SOL-GEL AA6060 AA2024 HYBRID SOL-GEL ADHESION PROPERTIES (AA6060) CONCLUSIONS • By using organometallic precursors containing polymerisable organic ligands, materials may be produced which contain both inorganic and organic polymer networks. • Entrapped organic species may be used as templates for creation of pores with controlled size and shape. Subsequent removal of these species (for example by heat treatment) leaves “molecular footprints” with potential as catalytic sites. • Since liquid precursors are used it is possible to cast ceramic materials in a range of complex shapes and to produce thin films or fibers as well as monoliths, without the need for machining or melting. • The optical quality of the materials is often good, leading to applications for optical components. Regional Symposium on Electrochemistry - RSЄ-SЄЄ Sava Center, Belgrade, Serbia, June 6 -10, 2010

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