fantastic tales of super ceramics professor m. l. mecartney department of chemical engineering and...
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Fantastic Tales of Super CeramicsFantastic Tales of Super Ceramics
Professor M. L. Mecartney
Department of Chemical Engineering and Materials ScienceUniversity of California, Irvine
My Research Group My Research Group Ph.D. StudentsPh.D. Students
Peter DillonPeter Dillon Tiandan ChenTiandan Chen Sungrok Sungrok
BangBang Lynher Lynher
RamirezRamirez
M.S. StudentsM.S. Students Kevin OlsonKevin Olson
Undergraduate Undergraduate StudentsStudents Daniel StricklandDaniel Strickland
(NSF REU)(NSF REU) Joy TrujilloJoy Trujillo (UC (UC
LEADS)LEADS) Jeremy RothJeremy Roth (SURP) (SURP)
External CollaboratorsExternal Collaborators Professor Trudy Professor Trudy
KrivenKriven, University of , University of IllinoisIllinois
Professor Susan Professor Susan Krumdieck, University Krumdieck, University of Canterbury, NZof Canterbury, NZ
How I found ceramic How I found ceramic science, and discovered a science, and discovered a
lifelifeI was once a lowly Classics major, I was once a lowly Classics major,
studying Greek and Latin at Case studying Greek and Latin at Case Western Reserve University….Western Reserve University….
Then I discovered Materials Science and Then I discovered Materials Science and Engineering – Solid State Physics and Engineering – Solid State Physics and Physical Chemistry!!!Physical Chemistry!!!
Undergraduate research on positron Undergraduate research on positron annihilation in alumina (in Physics) and annihilation in alumina (in Physics) and single crystal deformation of ZrOsingle crystal deformation of ZrO22 (in (in MSE)MSE)
Post B.S./B.A. Post B.S./B.A. WanderingsWanderings
Graduate school – M.S. and Ph.D. in Materials Science Graduate school – M.S. and Ph.D. in Materials Science and Engineering at Stanford University (BaTiOand Engineering at Stanford University (BaTiO33 and and SiSi33NN44))
Post-doctoral research – Max-Plank-Institut in Post-doctoral research – Max-Plank-Institut in Stuttgart, Germany (ZrOStuttgart, Germany (ZrO22))
Faculty positions – University of Minnesota, Faculty positions – University of Minnesota, Minneapolis, then University of California, Irvine Minneapolis, then University of California, Irvine (LiNbO(LiNbO33, Pb(Zr,Ti)O, Pb(Zr,Ti)O33, V, V22OO55, , CaO-BCaO-B22OO33-SiO-SiO22, , (Sr,Ba)Nb(Sr,Ba)Nb22OO66, etc.), etc.)
Fantastic CeramicsFantastic Ceramics
Did you know that ceramic conductors Did you know that ceramic conductors are a critical part of fuel cell are a critical part of fuel cell technology?technology?
Did you know that ceramics can be Did you know that ceramics can be stronger than any other material?stronger than any other material?
Did you know that ceramics can be Did you know that ceramics can be deformed just like metals?deformed just like metals?
Did you know that ceramics can conduct Did you know that ceramics can conduct electricity without any resistance?electricity without any resistance?
Super CeramicsSuper Ceramics
Super ionic conductors for fuel cellsSuper ionic conductors for fuel cells Super strong ceramics for cutting Super strong ceramics for cutting
applications applications Super plastic ceramics for net shape Super plastic ceramics for net shape
formingforming NO CERAMIC NO CERAMIC
SUPERCONDUCTORS IN THIS TALK SUPERCONDUCTORS IN THIS TALK
CERAMICSCERAMICS A ceramic is a compound composed A ceramic is a compound composed
of at least one metallic and non-of at least one metallic and non-metallic element metallic element
Ionic/covalent bondingIonic/covalent bonding
Most Ceramics are Most Ceramics are CrystallineCrystalline
ZrO2 NaCl
Typical Grain / Grain Boundary Typical Grain / Grain Boundary StructureStructure
H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics 146, 157 (2000).
Ceramics as Ceramics as Ionic ConductorsIonic Conductors
Loade
Depleted fuel andproduct gases out
Depleted oxidant andproduct gases out
SOFCH2
H2OO O2
PEMFC andPAFC
H2 H2O
O2H+
MCFC
H2
CO2H2O
CO3 CO2
O2
Fuel in Oxidant in
Anode CathodeElectrolyte
(ion conductor)
OVERVIEW OF FUEL CELL TYPES
From Dr. Jack Brouwer NFCRC
Brick Layer ModelBrick Layer Model
Polycrystalline Material Model Equivalent Circuit Model
Modified From S M. Haile, D L West, and J. Campbell, J .Mater. Res. vol 13, pp.1576-1595 (1998).
AFM of YSZ Film on AFM of YSZ Film on Al2O3Al2O3
R.M. Smith, X.D. Zhou, W. Huebner, and H.U. Anderson (2004), "Novel Yttrium-Stabilized Zirconia Polymeric Precursor for the Fabrication of Thin Films," Journal of Materials Research, 19, 2708-2713.
15X Conductivity15X Conductivity IncreaseIncrease in Nano-crystalline Zirconia!in Nano-crystalline Zirconia!
H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics 146, 157 (2000).
Increase in GB Increase in GB ConductivityConductivity
X. Guo and Z.L. Zhang (2003), "Grain Size Dependent Grain Boundary Defect Structure: Case of Doped Zirconia," Acta Materialia, 51, 2539-2547.
Propoxide Sol-Gel TF PreparationPropoxide Sol-Gel TF Preparation
Yttrium Isopropoxide
ScandiumIsopropoxide
Zirconium Propoxide
Hydrolysis:70wt% HNO3, 30 wt% H2O
Spin Coat on Si / Al2O3 Substrate 2000RPM, 45s
Bake à Pyrolize + Crystallize
Solution in Isopropanol à 0.2M Alkoxide Concentration
SEM Characterization:Grain Size + Film Thickness
TEM Characterization:Grain Size + Composition
Glancing Incidence XRD (GID):Grain Size + Crystal Structure
Impedance Spectrometry:Ionic Conductivity à Bulk / Grain / Grain Boundary
Stabilizer Conc (mol%): 4Y / 8Y / 4Sc / 8Sc / 4Y:4Sc
Polymer Precursors
CharacterizationPreparation
DSC / TGA AnalysisàDetermine Tvap - Tpyrolysis – Tcrystallization
Evaporate Alcohol / H2O
Acetate Sol-Gel TF PreparationAcetate Sol-Gel TF Preparation
Yttrium Acetate
ScandiumAcetate
Zirconium Acetate
Hydrolize with Ethylene Glycol
Spin Coat on Si / Al2O3 Substrate 3000RPM, 60s
Evaporate Alcohol à Form Gel
Bake à Pyrolize + Crystallize
Solution in MethanolSEM Characterization:
Grain Size + Film Thickness
TEM Characterization:Grain Size + Composition
Glancing Incidence XRD (GID):Grain Size + Crystal Structure
Impedance Spectrometry:Ionic Conductivity à Bulk / Grain / Grain Boundary
Stabilizer Conc (mol%): 4Y / 8Y / 4Sc / 8Sc / 4Y:4Sc
Polymer Precursors
CharacterizationPreparation
Add GPC to Allow Process to Be Carried Out in Open Air
Adjust Viscosity à Add Methanol to 20 cP
DSC / TGA AnalysisàDetermine Tvap / Tpyrolysis / Tcrystallization
Adapted From: R.M. Smith, X.D. Zhou, W. Huebner, and H.U. Anderson (2004), "Novel Yttrium-Stabilized Zirconia Polymeric Precursor for the Fabrication of Thin Films," Journal of Materials Research, 19, 2708-2713.
Multiple Spin Coated LayersMultiple Spin Coated Layers(Ba-Ti on Si Wafer)(Ba-Ti on Si Wafer)
M.C. Gust, N.D. Evans, L.A. Momoda, and M.L. Mecartney, "In-Situ Transmission Electron Microscopy Crystallization Studies
of Sol-Gel Derived Barium Titanate Thin Films," J. Am. Ceram. Soc. 80 [11] 2828-36 (1997).
Cross Sectional SEM Cross Sectional SEM ZrOZrO22 Thin Film on Si Wafer Thin Film on Si Wafer
Typical Grain Size of Typical Grain Size of ZrOZrO22
Burning QuestionsBurning Questions
Will our nanocrystalline zirconia Will our nanocrystalline zirconia thin films be a super ionic conductor thin films be a super ionic conductor when compared to zirconia with a when compared to zirconia with a larger grain sizes?larger grain sizes?
And why?And why?
Stay tuned for Daniel Strickland’s Stay tuned for Daniel Strickland’s talk at the end of the summer!talk at the end of the summer!
High Strength High Strength CeramicsCeramics
50%Al2O3-25%NiAl2O4-25%ZrO2
Fine Grain Ceramics Are Fine Grain Ceramics Are Strong, But…Strong, But…
At high temperatures, the smaller the At high temperatures, the smaller the grain size, the easier to deform a grain size, the easier to deform a material (creep).material (creep).
These materials were developed to be These materials were developed to be high speed cutting tools, the tips of high speed cutting tools, the tips of which may reach 1500°C.which may reach 1500°C.
Will creep be a problem????Will creep be a problem????
Compression Test Compression Test ResultsResults
0
0. 1
0. 2
0. 3
0. 4
0. 5
0. 6
0. 7
0 5000 10000 15000 20000 25000 30000 35000
Time (s)
Tru
e S
trai
n
50%Al2O3-25%NiAl2O4-25%TZP @ 1425C50%Al2O3-25%NiAl2O4-25%TZP @ 1350C
50% Al2O3-25%NiAl2O4-25%TZP
Undeformed
Average Grain Size (m)
Al2O3: 0.76
NiAl2O4 : 0.49
TZP: 0.42
50% Al2O3-25%NiAl2O4-25%TZP
Deformed at 1425°C
Average Grain Size (m)
Al2O3: 1.39
NiAl2O4 : 0.81
TZP: 0.62
Stress ResponseStress Response
1. E-06
1. E-05
1. E-04
1. E-03
10 100
Stress (MPa)
Str
ain
Rat
e (1
/s)
50%Al2O3-25%NiAl2O4-25%TZP @ 1425C50%Al2O3-25%NiAl2O4-25%TZP @ 1350C
Fine Grain Ceramics May Fine Grain Ceramics May be Super Strong at Room be Super Strong at Room
Temperature…Temperature…
…….but very deformable and .but very deformable and soft at high temperatures.soft at high temperatures.
Superplastic Superplastic CeramicsCeramics
SuperplasticitySuperplasticity The ability of polycrystalline solids to exhibit greater than 100% eloThe ability of polycrystalline solids to exhibit greater than 100% elo
ngation in tension, usually at elevated temperatures about 0.5Tngation in tension, usually at elevated temperatures about 0.5Tm m
Constitutive Law Constitutive Law
Where: έ Strain rate Q Activation energy σ Stress Rg Gas constant n Stress exponent T Temperature (K) d Grain size p Grain size exponent
RT
Q
dA
p
n
expε J.Wakai, J.Wakai, Adv. Ceram. Mater., Adv. Ceram. Mater., 19861986
Applications Applications SPF enables net-shape-forming, fabricate unique complex shaSPF enables net-shape-forming, fabricate unique complex sha
pes from a single piece of materials;pes from a single piece of materials; Eliminates parts and process steps, minimizes manufacturing cEliminates parts and process steps, minimizes manufacturing c
ost.ost. Ceramic knives are made by superplastic forming in Japan.Ceramic knives are made by superplastic forming in Japan.
ExamplesExamples
Y-TZP @1450℃ Kyocera Ceramic Knife
Superplastic DeformationSuperplastic Deformation
Grain boundary slidGrain boundary slidinging
Sudhir, Chokshi, J.Am.Ceram.Soc., 2001
Simulation of Grain Boundary Sliding during deformation
0% SiO2, d=10.2µm 1 wt% SiO2, d=2.8µm 3 wt% SiO2, d=1.7µm
5 wt% SiO2, d= 1.6µm 10 wt% SiO2, d=1.2µm
Grain Size 8Y-CSZ Grain Size 8Y-CSZ Sintered 2 hours at Sintered 2 hours at
16001600ºCºC
A Superplastic CeramicA Superplastic Ceramic8 mol% Y8 mol% Y22OO33 Cubic Stabilized ZrO Cubic Stabilized ZrO2 2 + 5 wt.+ 5 wt.
% SiO% SiO22
Optimal Microstructure Optimal Microstructure for Superplasticityfor Superplasticity
The smaller the grain size, the easier The smaller the grain size, the easier to achieve superplastic deformation.to achieve superplastic deformation.
But during high temperature But during high temperature deformation, grains grow to deformation, grains grow to minimize grain boundary interfacial minimize grain boundary interfacial area.area.
Need to design a material in which Need to design a material in which grain growth is limited.grain growth is limited.
How to Create a Stable Fine Grain How to Create a Stable Fine Grain Structure at High TemperaturesStructure at High Temperatures
Grain growth is rapid in single phase materials, slower in two phase materials (zirconia – silica), but should be very limited in a three-phase microstructure
Two-phase structure Three-phase structure
II. II. Experimental ApproachExperimental Approach
Al2O3
(40nm)ZrO2
(26nm)SiO2 Sol(15nm)
Ball Milling
Dry, Sieve and Press
Sintered at 1450℃Compressive Deformation
XRD, SEM, TEM EDS Analysis
3Al2O3 + 2SiO2 = 3Al2O3•2SiO2
Multiphase ceramic Alumina – Zirconia – Mullite
Nanocrystalline Ceramic with Alumina, Mullite, Zirconia
SEM of AZ30M30
0 20 40 60 80 1001E-5
1E-4
1E-3
AZ30M30 AZ15M15 AZ10M10 AZ30
Tru
e S
tra
in R
ate
(/s
)
True Strain (%)5.0 5.2 5.4 5.6 5.8 6.0 6.2
10-5
10-4
10-3
10-2
10-1
100
101
Calculated strain rate
1 s-1 at 1650
0C
Tru
e S
trai
n ra
te (
s-1)
Inverse Temperature (10000/T)
Deformation Behavior
Steady-state deformation of AZ30M30 High strain rate of AZ30M30
Dislocations generated during deformation
AZ30M30 Deformed Mullite Grain
ConclusionsConclusions
1. Nanocrystalline/fine grain ceramics 1. Nanocrystalline/fine grain ceramics maymay be be supersuperior iior ionic conductors (increased efficiency for fuel cells).onic conductors (increased efficiency for fuel cells).
2. Nanocrystalline/fine grain ceramics have 2. Nanocrystalline/fine grain ceramics have supersuperior streior strength at room temperature.ngth at room temperature.
3. Nanocrystalline/fine grain ceramics behave like metal3. Nanocrystalline/fine grain ceramics behave like metals at high temperatures, but this may be useful for s at high temperatures, but this may be useful for supesuperplasticrplastic forming. forming.
Thanks to the Following Thanks to the Following for Research Supportfor Research Support
NSF Division of Materials Research NSF Division of Materials Research National Fuel Cell Research CenterNational Fuel Cell Research Center NSF REU programNSF REU program UCI SURP programUCI SURP program UC LEADS programUC LEADS program Pacific NanotechnologyPacific Nanotechnology Corona Naval BaseCorona Naval Base