Thermal properties and phase analysis of titania doped yttria-zirconia ceramics for use as high temperature thermal barrier coatings (TBCS)

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Proceedings titleProceedings of the ASME Turbo Expo
ConferenceASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, GT2011, 6 June 2011 through 10 June 2011, Vancouver, BC
Pages709717; # of pages: 9
SubjectBulk density; Calorimetric analysis; Cubic phasis; Doped sample; High temperature; Microstructural analysis; Monoclinic phasis; Operating temperature; Phase analysis; Powder blends; Primary objective; Tetragonal phase; Theoretical models; Titania; Titania content; X-ray diffraction techniques; Young's Modulus; YSZ ceramics; Yttria-zirconia ceramics; Blowers; Calorimetry; Ceramic materials; Doping (additives); Exhibitions; Marine applications; Mechanical properties; Plasma spraying; Sintering; Specific heat; Thermal barrier coatings; Titanium dioxide; X ray diffraction; Zirconia; Thermal conductivity
AbstractTitania doped YSZ ceramic samples were subjected to calorimetric, thermal and microstructural analyses to assess the value of titania as a dopant for use as thermal barrier coating in modern gas turbine engines. The primary objective of titania addition was to effectively stabilize the tetragonal phase at operating temperatures while lowering the thermal conductivity. Powder blends with 5, 10, and 15 wt% titania added to standard 7YSZ powder were sintered at 1200°C for 325hrs after plasma spraying. Basic physical properties related to the thermal conductivity of the material such as bulk densities and Young's modulus were determined. Phase analysis of all samples was performed using x-ray diffraction techniques so the percentage of monoclinic, tetragonal, and cubic phases could be determined. For all titania samples, it was shown that the composition was predominantly tetragonal with slightly decreasing amounts of monoclinic phases present with increasing titania content. The results of calorimetric analysis showed a marginal decrease in the specific heat capacities of the sintered titania doped samples. Similarly, thermal diffusivities were lowered by the addition of titania, though only slightly, since it has been previously shown that diffusivity is more strongly linked to sample porosity. Using these results, the experimental thermal conductivities for all titania doped samples were determined and compared to theoretical conductivities based solely on the mechanical properties of the ceramic. The results showed a decrease in thermal conductivity with the addition of titania, though with higher values than that predicted from the theoretical model. Experimental thermal conductivities were also shown to decrease with temperature initially, while increasing slightly at higher temperatures, which is most probably due to the radiation effect. Copyright © 2011 by ASME.
Publication date
AffiliationNational Research Council Canada (NRC-CNRC); Aerospace (AERO-AERO)
Peer reviewedYes
NPARC number21271253
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Record identifierd74127cb-ff5d-4320-b20f-8d58ad9a4118
Record created2014-03-24
Record modified2016-05-09
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