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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Advances in the development of surfaces functionalities of
titanium
Prof. MariaPia Pedeferri
Department of Chemistry, Materials and Chemical Engineering
“Giulio Natta” - Politecnico di Milano
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation• Allows the thickening of the native oxide TiO2
(few nm thick)• Morphology, structure and thickness depend on
process
parameters: – electrolyte composition– temperature– current
density– cell potential
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation: semicrystalline TiO2 Semicrystalline TiO2
formation
Direct anodising
Anodising + TT
Polymorphs
Anatase band gap 3,2 eV (λ = 384 nm)
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation: semicrystalline TiO2Direct anodising
Electrolyte Current density Final voltage
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Anodic oxidation: semicrystalline TiO2Anodising +TT
Presence of F-
Low final voltage
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Colours on titanium• Reflection and refraction phenomena between
light and the oxide
interfaces (Ti-TiO2 and TiO2-air) generate interference colours
which vary with oxide thickness
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Colours on titanium Interference colours
Reflectance spectrum Constructive interference – 2nd = mλ m = 0,
1, 2, 3...
Destructive interference– 2nd = (m+½λ) m = 0, 1, 2, 3...
Oxide thickness can be calculated Wavelength (nm)
Refl
ecta
nce
(%)
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Colours on titanium Interference colours
Reflectance spectrum
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
From color to… oxidation resistance Potentiodynamic tests
Potential vs current density
Scan rate = 10 mV/min (ASTM G-5)
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
From color to… oxidation resistance Potentiodynamic tests
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Corrosion resistance Different titanium grades (2, 7 and 12)
Anodized grade 2 vs grade 7 and 12
Screening method for the optimization of the
anodisingtreatment
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Corrosion resistance
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Corrosion resistance characterization Potentiodynamic tests
Test method
Solutions: H2O + NaCl
Chlorides 10 – 35 g/L
Temperature 25 - 95°C
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Potentiodynamic tests• Electrochemical characterization
– preliminary results
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Prof. MariaPia Pedeferri, PhDOctober 4-7, 2014 • Rosen Shingle
Creek Golf Resort • Orlando, FL, USA
Thank you for your attention
[email protected]
Advances in the development of surfaces functionalities of
titanium�Anodic oxidationAnodic oxidationAnodic oxidationAnodic
oxidationAnodic oxidationAnodic oxidationAnodic oxidation:
semicrystalline TiO2Anodic oxidation: semicrystalline TiO2Anodic
oxidation: semicrystalline TiO2Colours on titaniumColours on
titaniumColours on titaniumFrom color to… oxidation resistanceFrom
color to… oxidation resistanceCorrosion resistanceCorrosion
resistanceCorrosion resistance characterizationPotentiodynamic
testsSlide Number 20
