Thermal barrier coating (TBC)
Thermal barrier coating (TBC) database consists from four separate sets containing thermodynamic parameters for the ZrO2-RE2O3-Y2O3-Al2O3 systems (RE=Gd, Sm, Nd, La). The data can be used to calculate phase relations between top coat and thermally grown oxide (Al2O3) in thermal barrier coating system. Nowadays Y2O3 stabilized ZrO2 (YSZ) in t’ modification is used as top coat. However it is known that co-doping of YSZ by rare earth decreases thermal conductivity and therefore these materials are promising candidates for TBC. Additionally it is found that rare earth zirconates with pyrochlore structure RE2Zr2O7 have substantially lower thermal conductivity than YSZ and therefore they are also suggested as new candidate materials for TBC. The database include thermodynamic descriptions of ZrO2-based solid solutions with fluorite, tetragonal and monoclinic structure, rare earth based solid solutions, aluminate solid solutions (YAG, YAM, YAP, REAP, b-alumina structures), zirconates with pyroclore structures, LaYO3 perovskite and d-Zr3Y4O12 phase. Database can be used to estimate stability of TBC during thermal cycling and stability against partitioning of non-equilibrium t’-phase into equilibrium assemblage tetragonal + fluorite.
The data have been generated based on experimental studies of phase equilibria, calorimetric measurements and vapour pressure data by group in Max-Planck-Institute Stuttgart and further developed in Technical University of Freiberg [1-6].
The database should not be used to calculate equilibria in metallic, metal-oxygen systems and those involving gas phase.
Olga Fabrichnaya, Technical University of Freiberg, Germany
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- Zinkevich M. Thermodynamics of rare earth sesquioxides. Progress in Materials Science, 2007, 52, 597-647.
- Fabrichnaya O., Seifert H.J., Up-date of a thermodynamic database of the ZrO2-Gd2O3-Y2O3-Al2O3 system for TBC applications, J. Phase Equilibria and Diffusion, 2011, 32, 2-16.
- Fabrichnaya O., Savinykh G., Zienert T., Schreiber G., Seifert H.J. Phase relations in the ZrO2-Sm2O3-Y2O3-Al2O3 system: experimental investigation and experimental modelling, Int. J. Mater. Res., 2012, (available on-line)
- Fabrichnaya O., Savinykh G., Schreiber G., Seifert H.J., Phase relations in the ZrO2-Nd2O3-Y2O3-Al2O3 system: experimental study and thermodynamic modelling, J. Eur. Ceram. Soc., 32, 2012, 3171-3185.
- Fabrichnaya O., Savinykh G., Schreiber G., Phase relations in the ZrO2-La2O3-Y2O3-Al2O3 system: experimental study and thermodynamic modelling, J. Eur. Ceram. Soc., 33, 2013, 37-49.