1. Baden, 09.03.2006 Acceptable limits of degradation of TBC for high-efficient turbines (HET TBC) Department Materials (ALSTOM) Lab of Crystallography (ETH Zürich) CTI project Nr. 7820.3 EPRP-IW Project startNov. 1. 2005 Project duration24 months

2. Outline 1Evolution of coating microstructure with heat treatment 2Measurements of coating macro-strains 3SEM pictures of Sulzer Metco coatings

3. Evolution of coating microstructure with heat treatment Measurements allow to determine: 1Monoclinic content 2Cell parameters of tetragonal YSZ (and Yttrium content) 3Stresses and grains size Coating D2426 was treated at 1100ºC for various times and then measured by XRD.

4. Evolution of monoclinic content with heat treatment Monoclinic increases after 1h of heat treatment and is stable after 24h of heat treatment

5. Evolution of Yttrium content with heat treatment After 1h of heat treatment the Yttrium content seems to increase. Both cell parameters a and c decreases. After 24h of heat treatment, the Yttrium content decreases, the cell parameter a remains constant and c increases.

6. Evolution of particle size and strains with heat treatment Peak profile is described with a pseudo-Voigt function (mixing of a Gaussian with a Lorentzian function). The Lorentzian part of the peak profile is described by:  s is the micro-strains broadening of the peak profile which is described by a tensors having only 4 non zero components (S 400, S 004, S 220, S 202 )

7. Evolution of particle size and strains with heat treatment The particle size can be obtained from the following expression: Grain size does not change after 24h heat treatment

8. Evolution of particle size and strains with heat treatment Heat treatment time (hours) S 400 S 004 S 220 S 202 00.784730.38320-0.215430.15859 10.694680.36941-0.114500.11464 240.668690.33691-0.112880.10068 Micro-strains decrease with heat treatment time as can be seen from the decrease of all S hkl values

9. Measurements of coating macro-strains Macro-strains are measured from peak shift for different coating orientations (angle  )  S1S1 S2S2 S3S3 Since d 0 is usually difficult to know one can use the d value for  =0 for d 0.

10. Measurements of coating macro-strains - One observes 0.1% strains in the coating from the peak shift measurement - A whole pattern fitting was performed and strains where calculated from cell parameters giving much lower values - This difference can be explained by an shift of the diffraction plane which can lead to error in the peak shift measurement

11. SEM pictures of Sulzer Metco coatings Sample was too big to allow EDX measurements (too small working distance) The polishing was not good enough and we had to polish the sample again The coating looks homogeneous and only one ‘non-molten’ particle was found (in the right side picture) Substrate Coating‘Non-molten’ particle