1. Fantastic Tales of Super Ceramics Professor M. L. Mecartney Department of Chemical Engineering and Materials Science University of California, Irvine

2. My Research Group Ph.D. Students Ph.D. Students Peter Dillon Peter Dillon Tiandan Chen Tiandan Chen Sungrok Bang Sungrok Bang Lynher Ramirez Lynher Ramirez M.S. Students M.S. Students Kevin Olson 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

3. 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 ZrO 2 (in MSE)

4. Post B.S./B.A. Wanderings Graduate school – M.S. and Ph.D. in Materials Science and Engineering at Stanford University (BaTiO 3 and Si 3 N 4 ) Post-doctoral research – Max-Plank-Institut in Stuttgart, Germany (ZrO 2 ) Faculty positions – University of Minnesota, Minneapolis, then University of California, Irvine (LiNbO 3, Pb(Zr,Ti)O 3, V 2 O 5, CaO-B 2 O 3 -SiO 2, (Sr,Ba)Nb 2 O 6, etc.)

5. Fantastic Ceramics Did you know that ceramic conductors are a critical part of fuel cell technology? 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 stronger than any other material? Did you know that ceramics can be deformed just like metals? Did you know that ceramics can be deformed just like metals? Did you know that ceramics can conduct electricity without any resistance? Did you know that ceramics can conduct electricity without any resistance?

6. Super Ceramics Super ionic conductors for fuel cells Super ionic conductors for fuel cells Super strong ceramics for cutting applications Super strong ceramics for cutting applications Super plastic ceramics for net shape forming Super plastic ceramics for net shape forming NO CERAMIC SUPERCONDUCTORS IN THIS TALK NO CERAMIC SUPERCONDUCTORS IN THIS TALK

7. CERAMICS A ceramic is a compound composed of at least one metallic and non-metallic element A ceramic is a compound composed of at least one metallic and non-metallic element Ionic/covalent bonding Ionic/covalent bonding

8. Most Ceramics are Crystalline ZrO 2 NaCl

9. Typical Grain / Grain Boundary Structure H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics 146, 157 (2000).

10. Ceramics as Ionic Conductors

12. Brick Layer Model Polycrystalline Material ModelEquivalent Circuit Model Modified From S M. Haile, D L West, and J. Campbell, J.Mater. Res. vol 13, pp.1576-1595 (1998 ).

13. 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.

14. 15X Conductivity Increase in Nano-crystalline Zirconia! H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics 146, 157 (2000).

15. 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.

16. Propoxide Sol-Gel TF Preparation

17. 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.

18. 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).

19. Cross Sectional SEM ZrO 2 Thin Film on Si Wafer

20. Typical Grain Size of ZrO 2

21. Burning Questions Will our nanocrystalline zirconia thin films be a super ionic conductor when compared to zirconia with a larger grain sizes? Will our nanocrystalline zirconia thin films be a super ionic conductor when compared to zirconia with a larger grain sizes? And why? And why? Stay tuned for Daniel Strickland ’ s talk at the end of the summer! Stay tuned for Daniel Strickland ’ s talk at the end of the summer!

22. High Strength Ceramics

25. 50%Al 2 O 3 -25%NiAl 2 O 4 -25%ZrO 2

27. Fine Grain Ceramics Are Strong, But … At high temperatures, the smaller the grain size, the easier to deform a material (creep). 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. These materials were developed to be high speed cutting tools, the tips of which may reach 1500°C. Will creep be a problem???? Will creep be a problem????

28. Compression Test Results

29. 50% Al 2 O 3 -25%NiAl 2 O 4 -25%TZP Undeformed Average Grain Size (  m) Al 2 O 3 : 0.76 NiAl 2 O 4 : 0.49 TZP: 0.42 50% Al 2 O 3 -25%NiAl 2 O 4 -25%TZP Deformed at 1425°C Average Grain Size (  m) Al 2 O 3 : 1.39 NiAl 2 O 4 :0.81 TZP:0.62

30. Stress Response

31. Fine Grain Ceramics May be Super Strong at Room Temperature … ….but very deformable and soft at high temperatures.

32. Superplastic Ceramics

33. Superplasticity The ability of polycrystalline solids to exhibit greater than 100% elongation in tension, usually at elevated temperatures about 0.5T m The ability of polycrystalline solids to exhibit greater than 100% elongation in tension, usually at elevated temperatures about 0.5T m Constitutive Law Where: έ Strain rate Q Activation energy σ Stress R g Gas constant n Stress exponent T Temperature (K) d Grain size p Grain size exponent J.Wakai, Adv. Ceram. Mater., 1986

34. Applications SPF enables net-shape-forming, fabricate unique complex shapes from a single piece of materials; SPF enables net-shape-forming, fabricate unique complex shapes from a single piece of materials; Eliminates parts and process steps, minimizes manufacturing cost. Eliminates parts and process steps, minimizes manufacturing cost. Ceramic knives are made by superplastic forming in Japan. Ceramic knives are made by superplastic forming in Japan.Examples Y-TZP @1450 ℃ Kyocera Ceramic Knife

35. Superplastic Deformation Grain boundary sliding Sudhir, Chokshi, J.Am.Ceram.Soc., 2001

36. Simulation of Grain Boundary Sliding during deformation

37. 0% SiO 2, d=10.2µm 1 wt% SiO 2, d=2.8µm 3 wt% SiO 2, d=1.7µm 5 wt% SiO 2, d= 1.6µm 10 wt% SiO 2, d=1.2µm Grain Size 8Y-CSZ Sintered 2 hours at 1600 º C

38. A Superplastic Ceramic 8 mol% Y 2 O 3 Cubic Stabilized ZrO 2 + 5 wt.% SiO 2

39. Optimal Microstructure for Superplasticity The smaller the grain size, the easier to achieve superplastic deformation. The smaller the grain size, the easier to achieve superplastic deformation. But during high temperature deformation, grains grow to minimize grain boundary interfacial area. But during high temperature deformation, grains grow to minimize grain boundary interfacial area. Need to design a material in which grain growth is limited. Need to design a material in which grain growth is limited.

40. 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

41. II. Experimental Approach Al 2 O 3 (40nm) ZrO 2 (26nm) SiO 2 Sol (15nm) Ball Milling Dry, Sieve and Press Sintered at 1450 ℃ Compressive Deformation XRD, SEM, TEM EDS Analysis 3Al 2 O 3 + 2SiO 2 = 3Al 2 O 3 2SiO 2 Multiphase ceramic Alumina – Zirconia – Mullite

42. Nanocrystalline Ceramic with Alumina, Mullite, Zirconia SEM of AZ30M30

43. Deformation Behavior Steady-state deformation of AZ30M30High strain rate of AZ30M30

44. Dislocations generated during deformation AZ30M30 Deformed Mullite Grain

45. Conclusions 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.

46. Thanks to the Following for Research Support NSF Division of Materials Research NSF Division of Materials Research National Fuel Cell Research Center National Fuel Cell Research Center NSF REU program NSF REU program UCI SURP program UCI SURP program UC LEADS program UC LEADS program Pacific Nanotechnology Pacific Nanotechnology Corona Naval Base Corona Naval Base