1. Flexible Assessment of Thermal Transport Properties of Thermal Barrier Systems Measured by The Hot Disk Method Caroline Goddard 1, Tobias Öhman 2 ; Nicolaie Markocsan 2 ; Mattias Gustavsson 3, Lars Östergren 4 1-University of Manchester; 2-University West; 3-Hot Disk AB; 4-Volvo Aero

2. Project Supported by VINNOVA Participants: Univ. West / Univ. Manchester, Hot Disk AB, VAC

3. Requirements of Thermal Conductivity of TBCs Performance of layers (lab) – LF Lower-cost/flexible testing – HD Quality Control? (on-line) – HD

4. Hot Disk Sensor

5. Laser Flash TechniqueTransient Plane Source (Hot Disk) Most accepted methodNew possibility Non Contact methodContact method Laboratory method onlyPotential to be used directly on components Measures Thermal Diffusivity then calculates Thermal Conductivity Measures Thermal Conductivity directly Higher equipment costLower equipment cost Need to know the thickness, density and specific heat capacity Need to know the thickness of the sample and its dimensions Must be a specific size and shape

6. HD Technique – Apparent (Thin Film) vs. Bulk Properties

7. Apparent Coating Properties - Setup

8. Influence of Surface Roughness

9. Comparisons LF vs. HD The results show that it is possible to obtain comparable results between the Hot Disk method and the Laser Flash method for coatings A and B. Coating C did not show agreement with LF.

10. Comparisons LF vs. HD The surface roughness has a significant effect. It is possible to develop a method for measuring thermal conductivity of TBC by “Thin Films” apparent property approach. Approach does not allow non-destructive testing. Zirconia coatings range from 300µm thick to over 700µm thick and the method cannot reliably measure coatings 550µm or thicker. ( Presently preparing for tests at elevated temperatures. )

11. Other Possibilities – Quality Control? APPARENT properties (less stable) if coating thinner than 0.5 mm BULK properties (stable), only if coating thicker than 0.5 mm Investigating inhomogeneous variations vs. depth from surface, for thicker coatings basis (on-line testing)