Tanner Guerra interned at the University of California, Santa Barbara where he worked with a graduate student and research group studying thermal barrier coatings (TBCs). TBCs are ceramic coatings used to protect hot components of engines and turbines from high temperatures. The group's research focused on characterizing new TBC materials and testing their phase stability, resistance to calcium-magnesium-alumino-silicates, and toughness. As an intern, Tanner helped prepare and analyze samples using X-ray diffraction and Raman spectroscopy to determine the materials' microstructural phases under different heating conditions.

1. Tanner Guerra – DMSE FPOP 2014
UCSB Summer
Internship:
Thermal Barrier Coatings
Tanner Guerra

2. Tanner Guerra – DMSE FPOP 2014
Where I worked
University of California, Santa Barbara

3. Tanner Guerra – DMSE FPOP 2014
Where I worked
• Top 3 Graduate Materials Dept.
• Home
• California
Why?

4. Tanner Guerra – DMSE FPOP 2014
Who I worked with
• Interned for 3rd year grad student Stefan Heinze
• We were under the Levi Group, consisting of a few
post-docs, and around 10 grad students and their
interns
• Group Leader, Carlos Levi, a Professor of
Materials and Mechanical Engineering at UCSB
• Industry Partner

5. Tanner Guerra – DMSE FPOP 2014
What is a Thermal Barrier Coating
(TBC)?
What do you think?
• Metal or Ceramic?
• Applications
• Importance
• Material
Properties

6. Tanner Guerra – DMSE FPOP 2014
TBCs
• Ceramics! …basically
• Applications: Hot portions of Cars and Airplanes,
such as a turbine or engine.
• Importance: Protects elements that you want to
keep cool relative to the environment
• Material Properties…
• Historically 7YSZ

7. Tanner Guerra – DMSE FPOP 2014
What is 7YSZ?
• 7 mol% Yttria Stabilized Zirconia
Yttria = YO1.5 Zirconia = ZrO2
• One of the First TBCs used
• Still used today
• Correct mol % discovered through experiments
empirically

8. Tanner Guerra – DMSE FPOP 2014
TBC Application

9. Tanner Guerra – DMSE FPOP 2014
CERAMIC
BASICALLY…

10. Tanner Guerra – DMSE FPOP 2014

11. Tanner Guerra – DMSE FPOP 2014

12. Tanner Guerra – DMSE FPOP 2014
Layer Function

13. Tanner Guerra – DMSE FPOP 2014
Important Material Properties
• Low Thermal Conductivity
• Strain Tolerance
• Toughness
• Phase Stability
• Compatibility with other layers
• Resistance to calcium–magnesium–alumino-
silicates (CMAS)

14. Tanner Guerra – DMSE FPOP 2014
What the Group Does
• Examine, investigate, and characterize new TBCs
(we didn’t “make” new TBCs)
• Conduct research on CMAS resistance, phase
stability, and toughness
• Confer with industry partner about different
theories and problems

15. Tanner Guerra – DMSE FPOP 2014
What I do
• Concerned with learning and helping understand
the new TBCs.
• Sample Prep, a lot of it
• Use Powder XRD (X-Ray Diffractometer) and
Raman Spectroscopy machines in order to help
determine the microstructural phase of the
material
• Determine how to test for toughness in the
material

16. Tanner Guerra – DMSE FPOP 2014
Phases
• What are the microstructural phases?
- I am concerned with three simple forms.
- Monoclinic, Tetragonal, and Cubic
Monday, August 20, 2007 Can change this on the Master Slide 16

17. Tanner Guerra – DMSE FPOP 2014
Bad vs. Good
• In terms of what we wanted, Tetragonal was
good, cubic was ok, and monoclinic was bad.
• Cubic – (in our case) too brittle, but still very hard
(not nearly perfect)
• Monoclinic – causes deleterious effects because
the material often starts in a different phase. This
is due to a change in volume, causing cracking
and breaking of the material.
Wednesday, August 20, 2014 Yolo 17

18. Tanner Guerra – DMSE FPOP 2014
Phase Stability
Monday, August 20, 2007 Can change this on the Master Slide 18
c: cubic
t: tetragonal
m: monoclinic

19. Tanner Guerra – DMSE FPOP 2014
Ternary Phase Diagram
Wednesday, August 20, 2014 Yolo 19
- Keep in mind this
is at one
temperature.
- Zirconia (Base),
Yttria, Ytterbia,
Tantala

20. Tanner Guerra – DMSE FPOP 2014
Sample Prep (Phase Stability)
• Simple.
• Study powder on XRD and Raman machines
• To test phase stability, put in furnace at different
temperatures for 100 hours or 400 hours and
compare results to the original powder.
Monday, August 20, 2007 Can change this on the Master Slide 20
(XRD) (Raman)

21. Tanner Guerra – DMSE FPOP 2014
Sample Prep. (Toughness [3-point bend])
• Most ceramics start as a powder
• Press powders with high pressure into pill form
• Sinter these pills, like what Jose did.
- put in at and temp ramped to ~1700*C and
then cooled after sitting for a day at temp.
• Slow speed saw into toughness test bars
• Surface Grind sample to get extremely smooth
finish
• Then cut a chevron notch into each bar
Monday, August 20, 2007 Can change this on the Master Slide 21

22. Tanner Guerra – DMSE FPOP 2014
Data
• Well, we are still waiting on results… December?
Monday, August 20, 2007 Can change this on the Master Slide 22

23. Tanner Guerra – DMSE FPOP 2014
Thank you!
• Thanks for listening, hope you
enjoyed learning about my internship
and high-performance ceramic
coatings.
Wednesday, August 20, 2014 Yolo 23