Clarke, David R

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Engineering Conferences International

Engineering Conferences InternationalECI Digital ArchivesThermal Barrier Coatings IV ProceedingsSummer 6-24-2014Zirconia-doped yttrium tantalates as a potentialnext generation thermal barrier coating materialDavid R. ClarkeHarvard University, clarke@seas.harvard.eduFollow this and additional works at: http://dc.engconfintl.org/thermal_barrier_ivPart of the Materials Science and Engineering CommonsThis Conference Proceeding is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion inThermal Barrier Coatings IV by an authorized administrator of ECI Digital Archives. For more information, please contact franco@bepress.com.Recommended CitationDavid R. Clarke, "Zirconia-doped yttrium tantalates as a potential next generation thermal barrier coating material" in "ThermalBarrier Coatings IV", U. Schulz, German Aerospace Center; M. Maloney, Pratt & Whitney; R. Darolia, GE Aviation (retired) Eds, ECISymposium Series, (2015). http://dc.engconfintl.org/thermal_barrier_iv/13Tuesday, June 24, 2014  Session 3 ZIRCONIA-DOPED YTTRIUM TANTALATES AS A POTENTIAL NEXT GENERATION THERMAL BARRIER COATING MATERIAL  David R. Clarke School of Engineering and Applied Sciences Harvard University, Cambridge, MA 02138 clarke@seas.harvard.edu  Yttria-stabilized zirconia (YSZ) has been the coating material of choice for thermal protection in gas turbine engines for at least twenty-five years.  Over that time, gas turbine temperatures have steadily increased and the demands on the coatings have been met largely through a combination of improved processing, enhanced performance bond-coats and modifications of superalloy compositions as well as improved cooling designs.  With further increases in turbine temperature though it is unlikely that YSZ can maintain its pre-eminence and the next generation of thermal barrier coatings will have to be made from another oxide composition.   While the principal requirements of any new coating material must include being stable at higher temperatures and having lower thermal conductivity than YSZ, any new coating material will also have to satisfy several additional, often conflicting requirements.  These include having high fracture toughness at high temperatures.  In this talk, I will describe our studies on compositions in the zirconia-doped yttrium tantalate system since they not only exhibit very low thermal conductivities at all temperatures but also exhibit a high-temperature second-order, displacive phase transition, a prerequisite for toughening at high temperatures. The underlying physical basis for the low thermal conductivity of these compounds and the evidence for a second-order, ferroelastic transformation will be described in detail. Also a comparison with other potential materials will be presented.    

Zirconia-doped yttrium tantalates as a potential next generation thermal barrier coating material

https://dc.engconfintl.org/cgi/viewcontent.cgi?article=1012&amp;context=thermal_barrier_iv

Zirconia-doped yttrium tantalates as a potential next generation thermal barrier coating material

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