This title appears in the Scientific Report :
2007
Please use the identifier:
http://dx.doi.org/10.1016/j.surfcoat.2007.07.071 in citations.
Compatibility of Mixed Zone Constituents (YAG, YAP, YCrO3) with a Chromia-Enriched TGO Phase During the Late Stage of TBC Lifetime
Compatibility of Mixed Zone Constituents (YAG, YAP, YCrO3) with a Chromia-Enriched TGO Phase During the Late Stage of TBC Lifetime
The effects of chromia accumulation in the TGO scale of late-stage MCrAlY-based EB-PVD TBC systems are addressed by comparing mixed zone microstructures from isothermal as well as cyclic oxidation tests at 1100 degrees C with phase relationships derived from the 1100 degrees C isothermal section of...
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Personal Name(s): | Braue, W. |
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Mechnich, P. / Fritscher, K. / Niewolak, L. | |
Contributing Institute: |
Werkstoffstruktur und Eigenschaften; IEF-2 |
Published in: | Surface and coatings technology, 202 (2007) S. 670 - 675 |
Imprint: |
Amsterdam [u.a.]
Elsevier Science
2007
|
Physical Description: |
670 - 675 |
DOI: |
10.1016/j.surfcoat.2007.07.071 |
Document Type: |
Journal Article |
Research Program: |
Rationelle Energieumwandlung |
Series Title: |
Surface and Coatings Technology
202 |
Subject (ZB): | |
Publikationsportal JuSER |
The effects of chromia accumulation in the TGO scale of late-stage MCrAlY-based EB-PVD TBC systems are addressed by comparing mixed zone microstructures from isothermal as well as cyclic oxidation tests at 1100 degrees C with phase relationships derived from the 1100 degrees C isothermal section of the ternary system Al2O3-Cr2O3-Y2O3. For this approach the c-ZrO2 phase zirconia coexisting with mixed zone constituents is considered an excess component. Compacted powder pellets were processed via co-decomposition of nitric salt solutions. The reaction products were characterized by X-ray diffraction and Raman spectroscopy.Characteristics of the ternary Al2O3-Cr2O3-Y2O3 relevant for the mixed zone include (i) a continuous solid solution series between the orthorhombic phases YAlO3 (YAP) and YCrO3, (ii) a limited Cr vs. Al substitution (16 mol%) in Cr-YAG Y-3(Al1-xCrx)(5)O-12 and (iii) extended phase fields involving Cr-YAG and sesquioxide phases which represent typical late-stage mixed zones in the excess-zirconia model scenario. The YCrO3 phase was found to be limited to very chromia-rich environments only. A high chromium enrichment of the mixed zone may be established upon extensive cycling through the miscibility gap in the alumina-chromia system. Later in TBC lifetime the thickness of the mixed zone is increasing due to outward growth of the Al2-xCrxO3 phase into the bottom TBC layer which results in a morphological instability of the TGO/ TBC interface. (c) 2007 Elsevier B.V. All rights reserved. |