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Fantastic Tales of Super Ceramics. Professor M. L. Mecartney Department of Chemical Engineering and Materials Science University of California, Irvine. Ph.D. Students Peter Dillon Tiandan Chen Sungrok Bang Lynher Ramirez M.S. Students Kevin Olson. Undergraduate Students

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Fantastic tales of super ceramics
Fantastic Tales of Super Ceramics

Professor M. L. Mecartney

Department of Chemical Engineering and Materials Science

University of California, Irvine


My research group

Ph.D. Students

Peter Dillon

Tiandan Chen

Sungrok Bang

Lynher Ramirez

M.S. Students

Kevin Olson

Undergraduate Students

Daniel Strickland (NSF REU)

Joy Trujillo (UC LEADS)

Jeremy Roth (SURP)

External Collaborators

Professor Trudy Kriven, University of Illinois

Professor Susan Krumdieck, University of Canterbury, NZ

My Research Group


How i found ceramic science and discovered a life
How I found ceramic science, and discovered a life

I was once a lowly Classics major, studying Greek and Latin at Case Western Reserve University….

Then I discovered Materials Science and Engineering – Solid State Physics and Physical Chemistry!!!

Undergraduate research on positron annihilation in alumina (in Physics) and single crystal deformation of ZrO2 (in MSE)


Post b s b a wanderings
Post B.S./B.A. Wanderings

Graduate school – M.S. and Ph.D. in Materials Science and Engineering at Stanford University (BaTiO3 and Si3N4)

Post-doctoral research – Max-Plank-Institut in Stuttgart, Germany (ZrO2)

Faculty positions – University of Minnesota, Minneapolis, then University of California, Irvine (LiNbO3, Pb(Zr,Ti)O3, V2O5, CaO-B2O3-SiO2, (Sr,Ba)Nb2O6, etc.)


Fantastic ceramics
Fantastic Ceramics

  • Did you know that ceramic conductors are a critical part of fuel cell technology?

  • Did you know that ceramics can be stronger than any other material?

  • Did you know that ceramics can be deformed just like metals?

  • Did you know that ceramics can conduct electricity without any resistance?


Super ceramics
Super Ceramics

  • Super ionic conductors for fuel cells

  • Super strong ceramics for cutting applications

  • Super plastic ceramics for net shape forming

  • NO CERAMIC SUPERCONDUCTORS IN THIS TALK


Ceramics
CERAMICS

  • A ceramic is a compound composed of at least one metallic and non-metallic element

  • Ionic/covalent bonding



Typical grain grain boundary structure
Typical Grain / Grain Boundary Structure

H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics146, 157 (2000).



Brick layer model
Brick 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 al2o3
AFM of YSZ Film on Al2O3

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 conductivity increase in nano crystalline zirconia
15X ConductivityIncreasein Nano-crystalline Zirconia!

H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics146, 157 (2000).


Increase in gb conductivity
Increase in GB Conductivity

X. Guo and Z.L. Zhang (2003), "Grain Size Dependent Grain Boundary Defect Structure: Case of Doped Zirconia," Acta Materialia, 51, 2539-2547.



Acetate sol gel tf preparation
Acetate Sol-Gel TF Preparation

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 layers ba ti on si wafer
Multiple Spin Coated Layers(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 zro 2 thin film on si wafer
Cross Sectional SEM ZrO2 Thin Film on Si Wafer



Burning questions
Burning Questions

  • Will our nanocrystalline zirconia thin films be a super ionic conductor when compared to zirconia with a larger grain sizes?

  • And why?

  • Stay tuned for Daniel Strickland’s talk at the end of the summer!



50%Al2O3-25%NiAl2O4-25%ZrO2


Fine grain ceramics are strong but
Fine Grain Ceramics Are Strong, But

  • At high temperatures, the smaller the grain size, the easier to deform a material (creep).

  • These materials were developed to be high speed cutting tools, the tips of which may reach 1500°C.

  • Will creep be a problem????



50% Al2O3-25%NiAl2O4-25%TZP

Undeformed

Average Grain Size (mm)

Al2O3: 0.76

NiAl2O4 : 0.49

TZP: 0.42

50% Al2O3-25%NiAl2O4-25%TZP

Deformed at 1425°C

Average Grain Size (mm)

Al2O3: 1.39

NiAl2O4 : 0.81

TZP: 0.62



Fine grain ceramics may be super strong at room temperature
Fine Grain Ceramics May be Super Strong at Room Temperature

….but very deformable and soft at high temperatures.



Superplasticity

The ability of polycrystalline solids to exhibit greater than 100% elongation in tension, usually at elevated temperatures about 0.5Tm

Constitutive Law

J.Wakai, Adv. Ceram. Mater., 1986

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


Applications
Applications

  • SPF enables net-shape-forming, fabricate unique complex shapes from a single piece of materials;

  • Eliminates parts and process steps, minimizes manufacturing cost.

  • Ceramic knives are made by superplastic forming in Japan.

    Examples

Y-TZP @1450℃

Kyocera Ceramic Knife


Superplastic deformation
Superplastic Deformation

Sudhir, Chokshi, J.Am.Ceram.Soc., 2001

Grain boundary sliding



Grain size 8y csz sintered 2 hours at 1600 c
Grain Size 8Y-CSZ Sintered 2 hours at 1600ºC

3 wt% SiO2, d=1.7µm

0% SiO2, d=10.2µm

1 wt% SiO2, d=2.8µm

5 wt% SiO2, d= 1.6µm

10 wt% SiO2, d=1.2µm


A superplastic ceramic 8 mol y 2 o 3 cubic stabilized zro 2 5 wt sio 2
A Superplastic Ceramic8 mol% Y2O3 Cubic Stabilized ZrO2 + 5 wt.% SiO2


Optimal microstructure for superplasticity
Optimal Microstructure for Superplasticity

  • The smaller the grain size, the easier to achieve superplastic deformation.

  • But during high temperature deformation, grains grow to minimize grain boundary interfacial area.

  • Need to design a material in which grain growth is limited.


How to create a stable fine grain structure at high temperatures
How to Create a Stable Fine Grain Structure 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 experimental approach
II. TemperaturesExperimental Approach

3Al2O3 + 2SiO2 = 3Al2O3•2SiO2

Multiphase ceramic

Alumina – Zirconia – Mullite

ZrO2

(26nm)

Al2O3

(40nm)

SiO2 Sol

(15nm)

Ball Milling

Dry, Sieve and Press

Sintered at 1450℃

Compressive

Deformation

XRD, SEM, TEM

EDS Analysis



Deformation Behavior Temperatures

Steady-state deformation of AZ30M30

High strain rate of AZ30M30


Dislocations generated during deformation
Dislocations generated during deformation Temperatures

AZ30M30 Deformed Mullite Grain


Conclusions
Conclusions Temperatures

1. Nanocrystalline/fine grain ceramics may be superior ionic conductors (increased efficiency for fuel cells).

2. Nanocrystalline/fine grain ceramics have superior strength at room temperature.

3. Nanocrystalline/fine grain ceramics behave like metals at high temperatures, but this may be useful for superplastic forming.


Thanks to the following for research support
Thanks to the Following for Research Support Temperatures

  • NSF Division of Materials Research

  • National Fuel Cell Research Center

  • NSF REU program

  • UCI SURP program

  • UC LEADS program

  • Pacific Nanotechnology

  • Corona Naval Base


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