tanner tbc talk
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Tanner Guerra – DMSE FPOP 2014
UCSB Summer Internship:
Thermal Barrier Coatings Tanner Guerra
Tanner Guerra – DMSE FPOP 2014
Where I worked
University of California, Santa Barbara
Tanner Guerra – DMSE FPOP 2014
Where I worked
• Top 3 Graduate Materials Dept. • Home • California
Why?
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
Tanner Guerra – DMSE FPOP 2014
What is a Thermal Barrier Coating (TBC)?
What do you think?
• Metal or Ceramic? • Applications • Importance • Material
Properties
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
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
Tanner Guerra – DMSE FPOP 2014
TBC Application
Tanner Guerra – DMSE FPOP 2014
CERAMIC BASICALLY…
Tanner Guerra – DMSE FPOP 2014
Tanner Guerra – DMSE FPOP 2014
Tanner Guerra – DMSE FPOP 2014
Layer Function
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)
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
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
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
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
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
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
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)
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
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
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
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