0
Research Papers

Structure and Thermal Conductivity of Nanostructured Hafnia-Based Thermal Barrier Coating Grown on SS-403 OPEN ACCESS

[+] Author and Article Information
M. Noor-A-Alam

e-mail: mnooraalam@miners.utep.edu

A. R. Choudhuri

e-mail: ahsan@utep.edu

C. V. Ramana

e-mail: rvchintalapalle@utep.edu
Department of Mechanical Engineering,
University of Texas at El Paso,
El Paso, TX 79968

1Corresponding author.

Manuscript received April 20, 2012; final manuscript received March 5, 2013; published online June 27, 2013. Assoc. Editor: Debjyoti Banerjee.

J. Nanotechnol. Eng. Med 4(1), 011007 (Jun 27, 2013) (5 pages) Paper No: NANO-12-1069; doi: 10.1115/1.4024046 History: Received April 20, 2012; Revised March 05, 2013

Yttria-stabilized hafnia (YSH) coatings were grown onto stainless steel 403 (SS-403) and Si substrates. The deposition was made at various growth temperatures ranging from room temperature (RT) to 500 °C. The microstructure and thermal properties of the YSH coatings were evaluated employing grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and photoacoustic measurements. GIXRD studies indicate that the coatings crystalize in cubic structure with a (111) texturing. Well-grown triangular dense morphology was evident in SEM data. EDS analysis indicates the composition stability of YSH coatings. The grain size increases with the increasing growth temperature. Thermal conductivity measurements indicate lower thermal conductivity of YSH coatings compared to either pure hafnia or yttria-stabilized zirconia.

FIGURES IN THIS ARTICLE
<>

Increasing the efficiency of the gas turbines for power generation systems is being considered with pronounced attention [1]. In order to increase the efficiency of the gas turbine by means of increasing the operating temperature, the turbine material should be chemically and mechanically stable at higher temperature. Thermal barrier coatings (TBC) are employed to protect the metallic surface from high temperature exposure for a long period of time. The coating is usually made of ceramic material and applied as a thin layer over the metallic surface, which makes insulation between the components and very high temperature environment. In this way, TBCs help the structural material to sustain at ambient temperature for prolonged time, which consequently allows very high operating temperature. At the same time, the thermal conductivity of the coating material has to be low enough to get the sufficient temperature drop between coating and the substrate. This allows the operating temperature to be increased furthermore and reduces the cooling requirement. Extensive efforts have been directed in recent past towards the development of high-quality TBCs for gas turbine systems [1-14]. The mostly used and industrial standard current TBC materials are based on yttria-stabilized zirconia (YSZ). It has been reported that this material is only stable up to 1200 °C, because of its phase transformation after this temperature. Because the phase change associated with the volume change initiates cracks, the ultimate result is the failure of the TBC [15]. Therefore, some of the recent works have been directed towards the development of new or alternate TBC materials with the low thermal conductivity at higher temperature for prolonged time exposure to the hot gas environment [1,15-15]. Hafnia-based materials have demonstrated a great potential to be applied as thermal barrier coating at higher temperature [1]. It has been reported that hafnia can be stabilized in cubic structure by yttria doping, which is stable at higher temperature [18-20]. So, yttria-stabilized hafnia (YSH) shows a great promise as a next generation TBC material for advanced turbine technology. Several works have been directed toward the investigation of thermal conductivity of TBC material using various methods [1,2,5,17]. Very few efforts have focused on the thermal conductivity of YSH. Matsumoto et al. [1] and Rosencwaig and Gersho [21] explored the thermal conductivity and sintering behavior of YSH at higher temperature grown by electron beam physical vapor deposition (EBPVD). In the literature, nanostructured materials showed the lower thermal conductivity compared to the traditional microstructure. This work is focused towards the development of nanostructured yttria-stabilized hafnia using physical vapor deposition (PVD) technique and investigation of their structural and thermal properties.

The RF magnetron sputtering physical vapor deposition (PVD) method was employed to fabricate the coatings. YSH coatings were grown onto two different substrates, namely 403 stainless steel (2.5 cm diameter and 2 mm thickness) and Si (1.2 cm × 1.2 cm × 1 mm). YSH target (5 cm diameter, 0.4 cm thick) purchased from Plasmaterials Inc. was used for sputtering. The composition of yttria in YSH was maintained at 7.5 wt.%, while the hafnia is 92.5% (7.5 YSH). The YSH target with the Cu backing plate was placed on a 2-inch sputter gun, which is vertically placed in the middle of the chamber. All the substrates were thoroughly cleaned and dried with nitrogen before introducing them into the vacuum chamber. The substrates were placed on the disk shape sample holder, having holes to expose the substrates to the plasma. The sample holders are placed at a distance of 8 cm up from the sputter gun. A base pressure of ∼0.21 mPa was initially created using a high-capacity turbo pump. The high vacuum was ensured by measuring the vacuum level using an ion gauge sensor. Initially, the plasma was created using a sputtering power of 30 W applied to the target while introducing high purity argon (Ar) into the chamber. As soon as plasma was ignited, the power was slowly increased to 100 W, keeping the shutter closed above the gun. The Ar flow was controlled by a MKS mass flow meter. Before starting any deposition on the substrates, a presputtering of the YSH target was carried out for 10 min using the full Ar flow. The YSH coating was deposited at various temperatures (T) in the range of RT–500 °C. The deposition duration was maintained to obtain a thickness of ∼1 μm. The substrates were heated by halogen lamps, and the desired temperature was controlled by an Athena X25 controller.

Structural characterization of the grown coatings was made using X-ray diffraction (XRD). The measurements were performed using a Bruker D8 Advance X-ray diffractometer. The ex situ measurements were carried out as a function of the coatings' fabrication conditions. A Hitachi S-4800 scanning electron microscope (SEM) was used to analyze the morphology of the coating. The thickness of the coatings was measured from the cross-sectional images. The nominal composition of the coatings was examined by energy dispersive X-ray spectrometry (EDS). Photoacoustic (PA) method was used to measure thermal conductivity of the coatings. In the PA measurement, a laser beam operating at a wavelength of 0.8 mm was used as the heating source. The laser beam is concentrated using a mirror and directed to the sample mounted at the bottom of the PA cell. The laser beam is periodically irradiated on the sample surface to get the sufficient heating. A 70-nm-thick film of Ni is deposited on the top of the YSH coating by e-beam evaporation in order to absorb the laser beam. A least square fitting is employed to obtain thermal conductivity of the coatings [21-23].

Crystallography.

Figure 1 shows the XRD patterns of YSH coatings on SS-403 as a function of growth temperature. It is evident that the YSH coatings crystallize in cubic structure. No significant effect of growth temperature is evident in the patterns. The patterns indicate that the YSH coating crystallites exhibit (111) texturing. The other orientations are also visible, but the (111) peak intensity is relatively very high. When the XRD patterns are compared, it is evident that the peak becomes sharper and more intense and the full width half maxima (FWHM) of the (111) peak decreases with increasing growth temperature. This observation indicates that the average grain size increases with increasing of growth temperature. The coatings grown at 500 °C exhibit the maximum intensity and the minimum value of FWHM.

The lattice parameter of YSH coatings calculated using XRD patterns is 0.52 nm, which is exactly the same as that of the YSH coating grown on Inconel-738 reported in previous work [23]. This value of lattice parameter shows a good match with that of cubic HfO2 reported in literature [24]. However, since the ionic radii of Y+3 (0.1019 nm) is larger than that of Hf+4 (0.083 nm), the incorporation of Y+3 into the hafnia structure enhances the interatomic distance in close proximity, keeping the face-centered cubic structure stable [25].

Surface Morphology.

The surface morphology of YSH coatings is shown in Fig. 2. It is evident from the SEM images that the growth temperature plays an important role in the growth and distribution characteristics of the grains. Although all the coatings grown at various temperatures are characterized by the long and dense grains, the surface morphology looks a little different with the variation of temperature. At lower temperature (e.g., 200 °C), the grains look elongated and stretched in one direction. All the grains are not equally grown or similarly distributed. Some of them are smaller compared to other big triangular-shaped grains and are not distributed in the same manner. The surface energy might not be enough for the grain growth in the favored orientation. On the other hand, the coatings grown at higher temperatures (300–500 °C) demonstrate more or less similar thin and dense grains distributed in the same directions. This might be because of the fact that the activation energy is sufficient for the uniform growth of the grains at higher temperatures. However, 400 °C seems to be the critical temperature for the perfect crystallization in terms of the shape, size, and distribution of the crystallites. At this temperature, the fully grown grains are uniformly distributed in all directions and form dense porous structure all over the sample. The long and triangular-shaped grains of YSH coatings grown by the sputtering technique show a good agreement with the morphology of YSH coating grown by EB deposition technique [1,26].

The interface morphology of YSH coating is examined using cross-sectional SEM imaging analysis for samples grown on silicon. The cross-sectional SEM image of a representative YSH sample grown at 500 °C on Si is shown in Fig. 3. Such imaging analysis is employed to verify the thickness of the coating and also to look at the interface morphology. It is obvious from Fig. 3 that the YSH coating exhibits columnar structure. Figure 4 shows the effect of growth temperature on the average grain size measured from the SEM images. The average grain size shows an increasing trend with the increase of the growth temperature. At low temperature, the adatoms have to pass a longer time to complete the atomic jump process on the substrate surface, due to the lower energy gain of the adatoms. Because of the insufficient energy, the species in the process of hopping might be trapped in the place of their first landing, resulting in the amorphous phase [27,28-27,28]. As the mobility of the adatoms increases with the increase of temperature, the species can fit in their suitable position and enhance the growth of the grains in large extent. This results in the higher grain size at higher growth temperature [29,30-29,30]. It is evident from Fig. 4 that the grain size versus growth temperature data shows a good fitting with the first order exponential increment.

Composition.

Figure 5 shows EDS spectra YSH coatings (top panel) grown at 500 °C on SS-403 substrates along with that of bare SS-403 substrate (bottom panel) for comparison. It can be seen that the EDS spectrum of the substrate exhibits the constituent elements present while the coating-related elements (Y and Hf) are totally absent. The EDS spectrum of YSH coating indicates the composition of the constituents in the coating. The peaks shown in the EDS spectrum correspond to the elements Hf, Y, and O present in the YSH coating. The spectrum shows the respective energy positions and the specific X-ray lines from these elements. The intensity of the peaks corresponds to the composition of each element, as labeled in Fig. 5. Absence of any extra peak other than the peaks from these three elements indicates that there is no impurity from any foreign elements. It was found from the EDS analysis that the same composition of the target used for the deposition retains in the coating when grown using magnetron sputtering.

Thermal Conductivity.

As was described in the previous work, the thermal diffusivity can be quantified either from amplitude data or from phase data [23]. The thermal conductivity is calculated using the thermal diffusion model (Rosencwaig–Gersho theory) for an optically opaque sample, the detail theory of which was explained in previous works [21,23]. Figure 6 shows the phase shift as a function of the modulation frequency for the YSH coatings grown at Ts = RT–500 °C. The variation of thermal conductivity with respect to the growth temperature of the YSH coatings is shown in Fig. 7.

The thermal conductivity of YSH coatings on SS-403 was found as 1.5 W/m-K, which is lower than that of pure hafnia or bulk YSH. The thermal conductivity of nanocrystalline, monoclinic pure hafnia is 2.57 ± 0.12 W m−1K−1 and that of bulk YSH is ∼2.3 W m−1 K−1 [25,31]. The uncertainty of thermal conductivity is found as ±0.08 W/m.K based on the ±0.2-deg uncertainty of the experiment [21]. The thermal diffusion through the crystalline materials is attributed by three major phenomena: (a) phonon–phonon interactions; (b) imperfections; and (c) grain boundary scattering. The lower thermal conductivity of YSH compared to the pure hafnia is due to the incorporation of yttrium into the hafnia structure. Y+3 introduces oxygen vacancies in the hafnia crystal, which are actually the structural vacancies due to charge compensation of Y+3 ions substituting for Hf+4 ions. This leads to the extra phonon scattering from the vacancies, resulting in decrease in thermal conductivity. It is evident from Fig. 7 that there is no variation of the thermal conductivity with growth temperature (in the range of RT–500 °C) when the coatings are grown on SS-403. This indicates the increase of grain size with growth temperature in this range is not enough to increase the thermal conductivity significantly. It also means no effect of thickness on the thermal conductivity, as the thickness varies slightly with the variation of growth temperature. The change in structure of the coating with the variation of thickness is not enough to affect the thermal conductivity when the coatings are grown on SS-403.

YSH coatings crystallize in cubic structure with dense, porous triangular-shaped grains. Higher temperature favors the crystallization, and the average grain size increases with the increase of the growth temperature. RF magnetron sputtering shows a stoichiometric deposition of the YSH coating on substrates, giving the same composition in the coating as used in the target. YSH exhibits lower thermal conductivity compared to that of the YSZ or pure hafnia.

This material is based upon work supported by the Department of Energy under Award Number DE-FE0000765.

 

 Nomenclature
  • EDS =

    energy dispersive X-ray spectrometry

  • FWHM =

    full width at half maxima

  • GIXRD =

    grazing incidence X-ray diffraction

  • L =

    grain size

  • PA =

    photoacoustic

  • RT =

    room temperature

  • SEM =

    scanning electron microscopy

  • T =

    growth temperature

  • TBC =

    thermal barrier coating

  • YSH =

    yttria-stabilized hafnia

  • YSZ =

    yttria-stabilized zirconia

Matsumoto, K., ItohY., and KamedaT., 2003, “EB-PVD Process and Thermal Properties of Hafnia-Based Thermal Barrier Coating,” Sci. Technol. Adv. Mater., 4, pp. 153–158. [CrossRef]
David, R. C., and Simon, R. P., 2005, “Thermal Barrier Coating Materials,” Mater. Today, 8(6), pp. 22–29. [CrossRef]
Padture, N. P., Gell, M., and Jordan, E. H., 2002, “Thermal Barrier Coatings for Gas–Turbine Engine Applications,” Science, 296, pp. 280–284. [CrossRef] [PubMed]
Lima, R. S., Kucuk, A., and Berndt, C. C., 2001, “Evaluation of Microhardness and Elastic Modulus of Thermally Sprayed Nanostructured Zirconia Coatings,” Surf. Coat. Technol., 135, pp. 166–172. [CrossRef]
Soyez, G., Eastman, J. A., Thomson, L. J., Bai, G. R., Baldo, P. M., McCormick, A. W., DiMelfi, R. J., Elmustafa, A. A., Tambwe, M. F., and Stone, D. S., 2000, “Grain-Size-Dependent Thermal Conductivity of Nanocrystalline Yttria Stabilized Zirconia Films Grown by Metal-Organic Chemical Vapor Deposition,” Appl. Phys. Lett., 77, pp. 1155–1157. [CrossRef]
Wang, N., Zhou, C., Gong, S., and Xu, H., 2007, “Heat Treatment of Nanostructured Thermal Barrier Coating,” Ceram. Int., 33, pp. 1075–1081. [CrossRef]
Girolamo, G. Di., Marra, F., Blasi, C., Serra, E., and Valente, T., 2011, “Microstructure, Mechanical Properties and Thermal Shock Resistance of Plasma Sprayed Nanostructured Zirconia Coatings,” Ceram. Int., 37(7), pp. 2711–2717. [CrossRef]
Gurrappa, I., and Sambasiva, A., 2006, “Thermal Barrier Coatings for Enhanced Efficiency of Gas Turbine Engines,” Surf. Coat. Technol., 201, pp. 3016–3029. [CrossRef]
Zhu, D., and Miller, R. A., 1998, “Sintering and Creep Behavior of Plasma-Sprayed Zirconia- and Hafnia-Based Thermal Barrier Coatings,” Surf. Coat. Technol., 108, pp. 114–120. [CrossRef]
Shaw, L. L., Goerman, D., Ren, R., and Gell, M., 2000, “The Dependency of Microstructure and Properties of Nanostructured Coatings on Plasma Spray Conditions,” Surf. Coat. Technol.130, pp. 1–8. [CrossRef]
Cao, X., Vassen, R., Fischer, W., Tietz, F., Jungen, W., and Stover, D., 2003, “Lanthanum–Cerium Oxide as a Thermal Barrier Coating for High Temperature Applications,” Adv. Mater., 15(17), pp. 1438–1442. [CrossRef]
Evans, A. G., Mumm, D. R., Hutchinson, J. W., Meier, G. H., and Pettit, F. S., 2001, “Mechanisms Controlling the Durability of Thermal Barrier Coatings,” Prog. Mater. Sci., 46, pp. 505–553. [CrossRef]
Zhu, Z., He, L., Chen, X., Zhao, Y., Mu, R., He, S., and Cao, X., 2010, “Thermal Cycling Behavior of La2Zr2O7 Coating With the Addition of Y2O3 by EB-PVD,” J. Alloys Compd., 508, pp. 85–93. [CrossRef]
Liu, Z.-G., Ouyang, J.-H., Wang, B.-H., Jhou, Y., and Li, J., 2008, “Preparation and Thermo-Physical Properties of NdxZr1xO2x/2 (x = 0.1, 0.2, 0.3, 0.4, 0.5) Ceramics,” J. Alloys Compd., 466, pp. 39–44. [CrossRef]
Ma, W., Mack, D., Malzbender, J., Vaben, R., and Stover, D., 2008, “Yb2O3 and Gd2O3 Doped Strontium Zirconate for Thermal Barrier Coatings,” J. Eur. Ceram. Soc., 28, pp. 3071–3081. [CrossRef]
Saruthan, B., Francois, P., Fritcher, K., and Schulz, U., 2004, “EB-PVD Processing of Pyrochlore-Structured La2Zr2O7-Based TBCs,” Surf. Coat. Technol., 182, pp. 175–183. [CrossRef]
Zhang, J., and Desai, V., 2005, “Determining Thermal Conductivity of Plasma Sprayed TBC by Electrochemical Impedance Spectroscopy,” Surf. Coat. Technol., 190(1), pp. 90–97. [CrossRef]
Dubourdieu, C., Rauwel, E., Roussel, H., Ducroquet, F., Holländer, B., Rossell, M., Tendeloo, G. V., Lhostis, S., and Rushworth, S., 2009, “Addition of Yttrium Into HfO2 Films: Microstructure and Electrical Properties,” J. Vac. Sci. Technol. A, 27(3), pp. 503–514. [CrossRef]
Lee, C.-K., Cho, E., Lee, H.-S., Hwang, C. S., and Han, S., 2008, “First-Principles Study on Doping and Phase Stability of HfO2,” Phys. Rev. B, 78, p. 012102. [CrossRef]
Rauwel, E., Dubourdieu, C., Holländer, B., Rochat, N., Ducroquet, F., Rossell, M. D., Tendeloo, G. V., and Pelissier, B., 2006, “Stabilization of the Cubic Phase of HfO2 by Y Addition in Films Grown by Metal Organic Chemical Vapor Deposition,” Appl. Phys. Lett., 89, p. 012902. [CrossRef]
Rosencwaig, A., and Gersho, A., 1976, “Theory of the Photoacoustic Effect With Solids,” J. Appl. Phys., 47(1), pp. 64–69. [CrossRef]
Wang, X., Hu, H., and Xu, X., 2001, “Photo-Acoustic Measurement of Thermal Conductivity of Thin Films and Bulk Materials,” ASME J. Heat Transfer, 123, pp. 138–144. [CrossRef]
Noor-A-Alam, M., and Ramana, C. V., 2012, “Structure and Thermal Conductivity of Yttria-Stabilized Hafnia Ceramic Coatings Grown on Nickel-Based Alloy,” Ceram. Int., 38, pp. 2957–2961. [CrossRef]
Terki, R., Bertrand, G., Aourag, H., and Coddet, C., 2008, “Cubic-to-Tetragonal Phase Transition of HfO2 From Computational Study,” Mater. Lett., 62(10–11), pp. 1484–1486. [CrossRef]
Winter, M. R., and Clarke, D. R., 2006, “Thermal Conductivity of Yttria-Stabilized Zirconia–Hafnia Solid Solutions,” Acta Mater., 54, pp. 5051–5059. [CrossRef]
Matsumoto, K., Itoh, Y., and Ishiwata, Y., 2003, “Thermal Conductivity and Sintering Behavior of Hafnia-Based Thermal Barrier Coating Using EB-PVD,” International Gas Turbine Congress (IGTC) Proceedings, Tokyo, Japan, Nov. 2–7, p. 131.
Kalidindi, N. R., Manciu, F. S., and Ramana, C. V., 2011, “Crystal Structure, Phase, and Electrical Conductivity of Nanocrystalline W0.95Ti0.05O3 Thin Films,” ACS Appl. Mater. Interfaces, 3, pp. 863–868. [CrossRef] [PubMed]
Mudavakkat, V. H., Noor-A-Alam, M., Bharathi, K. K., AlFiafy, S., Dissanayeke, K., Kayani, A., and Ramana, C. V., 2011, “Structure and AC Conductivity of Nanocrystalline Yttrium Oxide Thin Films,” Thin Solid Films, 519, pp. 7947–7950. [CrossRef]
Bharathi, K. K., Vemuri, R. S., Noor-A-Alam, M., and Ramana, C. V., 2012, “Effect of Annealing on the Microstructure of NiFe1.925Dy0.075O4 Thin Films,” Thin Solid Films, 520, pp. 1794–1798. [CrossRef]
Gullapalli, S. K., Vemuri, R. S., Manciu, F. S., Enriquez, J. L., and Ramana, C. V., 2010, “Tungsten Oxide (WO3) Thin Films for Application in Advanced Energy Systems,” J. Vac. Sci. Technol. A, 28(4), pp. 824–828. [CrossRef]
Ramana, C. V., Noor-A-Alam, M., Gengler, J. J., and Jones, J. G., 2012, “Growth, Structure, and Thermal Conductivity of Yttria-Stabilized Hafnia Thin Films,” ACS Appl. Mater. Interfaces, 4, pp. 200–204. [CrossRef] [PubMed]
Copyright © 2013 by ASME
View article in PDF format.

References

Matsumoto, K., ItohY., and KamedaT., 2003, “EB-PVD Process and Thermal Properties of Hafnia-Based Thermal Barrier Coating,” Sci. Technol. Adv. Mater., 4, pp. 153–158. [CrossRef]
David, R. C., and Simon, R. P., 2005, “Thermal Barrier Coating Materials,” Mater. Today, 8(6), pp. 22–29. [CrossRef]
Padture, N. P., Gell, M., and Jordan, E. H., 2002, “Thermal Barrier Coatings for Gas–Turbine Engine Applications,” Science, 296, pp. 280–284. [CrossRef] [PubMed]
Lima, R. S., Kucuk, A., and Berndt, C. C., 2001, “Evaluation of Microhardness and Elastic Modulus of Thermally Sprayed Nanostructured Zirconia Coatings,” Surf. Coat. Technol., 135, pp. 166–172. [CrossRef]
Soyez, G., Eastman, J. A., Thomson, L. J., Bai, G. R., Baldo, P. M., McCormick, A. W., DiMelfi, R. J., Elmustafa, A. A., Tambwe, M. F., and Stone, D. S., 2000, “Grain-Size-Dependent Thermal Conductivity of Nanocrystalline Yttria Stabilized Zirconia Films Grown by Metal-Organic Chemical Vapor Deposition,” Appl. Phys. Lett., 77, pp. 1155–1157. [CrossRef]
Wang, N., Zhou, C., Gong, S., and Xu, H., 2007, “Heat Treatment of Nanostructured Thermal Barrier Coating,” Ceram. Int., 33, pp. 1075–1081. [CrossRef]
Girolamo, G. Di., Marra, F., Blasi, C., Serra, E., and Valente, T., 2011, “Microstructure, Mechanical Properties and Thermal Shock Resistance of Plasma Sprayed Nanostructured Zirconia Coatings,” Ceram. Int., 37(7), pp. 2711–2717. [CrossRef]
Gurrappa, I., and Sambasiva, A., 2006, “Thermal Barrier Coatings for Enhanced Efficiency of Gas Turbine Engines,” Surf. Coat. Technol., 201, pp. 3016–3029. [CrossRef]
Zhu, D., and Miller, R. A., 1998, “Sintering and Creep Behavior of Plasma-Sprayed Zirconia- and Hafnia-Based Thermal Barrier Coatings,” Surf. Coat. Technol., 108, pp. 114–120. [CrossRef]
Shaw, L. L., Goerman, D., Ren, R., and Gell, M., 2000, “The Dependency of Microstructure and Properties of Nanostructured Coatings on Plasma Spray Conditions,” Surf. Coat. Technol.130, pp. 1–8. [CrossRef]
Cao, X., Vassen, R., Fischer, W., Tietz, F., Jungen, W., and Stover, D., 2003, “Lanthanum–Cerium Oxide as a Thermal Barrier Coating for High Temperature Applications,” Adv. Mater., 15(17), pp. 1438–1442. [CrossRef]
Evans, A. G., Mumm, D. R., Hutchinson, J. W., Meier, G. H., and Pettit, F. S., 2001, “Mechanisms Controlling the Durability of Thermal Barrier Coatings,” Prog. Mater. Sci., 46, pp. 505–553. [CrossRef]
Zhu, Z., He, L., Chen, X., Zhao, Y., Mu, R., He, S., and Cao, X., 2010, “Thermal Cycling Behavior of La2Zr2O7 Coating With the Addition of Y2O3 by EB-PVD,” J. Alloys Compd., 508, pp. 85–93. [CrossRef]
Liu, Z.-G., Ouyang, J.-H., Wang, B.-H., Jhou, Y., and Li, J., 2008, “Preparation and Thermo-Physical Properties of NdxZr1xO2x/2 (x = 0.1, 0.2, 0.3, 0.4, 0.5) Ceramics,” J. Alloys Compd., 466, pp. 39–44. [CrossRef]
Ma, W., Mack, D., Malzbender, J., Vaben, R., and Stover, D., 2008, “Yb2O3 and Gd2O3 Doped Strontium Zirconate for Thermal Barrier Coatings,” J. Eur. Ceram. Soc., 28, pp. 3071–3081. [CrossRef]
Saruthan, B., Francois, P., Fritcher, K., and Schulz, U., 2004, “EB-PVD Processing of Pyrochlore-Structured La2Zr2O7-Based TBCs,” Surf. Coat. Technol., 182, pp. 175–183. [CrossRef]
Zhang, J., and Desai, V., 2005, “Determining Thermal Conductivity of Plasma Sprayed TBC by Electrochemical Impedance Spectroscopy,” Surf. Coat. Technol., 190(1), pp. 90–97. [CrossRef]
Dubourdieu, C., Rauwel, E., Roussel, H., Ducroquet, F., Holländer, B., Rossell, M., Tendeloo, G. V., Lhostis, S., and Rushworth, S., 2009, “Addition of Yttrium Into HfO2 Films: Microstructure and Electrical Properties,” J. Vac. Sci. Technol. A, 27(3), pp. 503–514. [CrossRef]
Lee, C.-K., Cho, E., Lee, H.-S., Hwang, C. S., and Han, S., 2008, “First-Principles Study on Doping and Phase Stability of HfO2,” Phys. Rev. B, 78, p. 012102. [CrossRef]
Rauwel, E., Dubourdieu, C., Holländer, B., Rochat, N., Ducroquet, F., Rossell, M. D., Tendeloo, G. V., and Pelissier, B., 2006, “Stabilization of the Cubic Phase of HfO2 by Y Addition in Films Grown by Metal Organic Chemical Vapor Deposition,” Appl. Phys. Lett., 89, p. 012902. [CrossRef]
Rosencwaig, A., and Gersho, A., 1976, “Theory of the Photoacoustic Effect With Solids,” J. Appl. Phys., 47(1), pp. 64–69. [CrossRef]
Wang, X., Hu, H., and Xu, X., 2001, “Photo-Acoustic Measurement of Thermal Conductivity of Thin Films and Bulk Materials,” ASME J. Heat Transfer, 123, pp. 138–144. [CrossRef]
Noor-A-Alam, M., and Ramana, C. V., 2012, “Structure and Thermal Conductivity of Yttria-Stabilized Hafnia Ceramic Coatings Grown on Nickel-Based Alloy,” Ceram. Int., 38, pp. 2957–2961. [CrossRef]
Terki, R., Bertrand, G., Aourag, H., and Coddet, C., 2008, “Cubic-to-Tetragonal Phase Transition of HfO2 From Computational Study,” Mater. Lett., 62(10–11), pp. 1484–1486. [CrossRef]
Winter, M. R., and Clarke, D. R., 2006, “Thermal Conductivity of Yttria-Stabilized Zirconia–Hafnia Solid Solutions,” Acta Mater., 54, pp. 5051–5059. [CrossRef]
Matsumoto, K., Itoh, Y., and Ishiwata, Y., 2003, “Thermal Conductivity and Sintering Behavior of Hafnia-Based Thermal Barrier Coating Using EB-PVD,” International Gas Turbine Congress (IGTC) Proceedings, Tokyo, Japan, Nov. 2–7, p. 131.
Kalidindi, N. R., Manciu, F. S., and Ramana, C. V., 2011, “Crystal Structure, Phase, and Electrical Conductivity of Nanocrystalline W0.95Ti0.05O3 Thin Films,” ACS Appl. Mater. Interfaces, 3, pp. 863–868. [CrossRef] [PubMed]
Mudavakkat, V. H., Noor-A-Alam, M., Bharathi, K. K., AlFiafy, S., Dissanayeke, K., Kayani, A., and Ramana, C. V., 2011, “Structure and AC Conductivity of Nanocrystalline Yttrium Oxide Thin Films,” Thin Solid Films, 519, pp. 7947–7950. [CrossRef]
Bharathi, K. K., Vemuri, R. S., Noor-A-Alam, M., and Ramana, C. V., 2012, “Effect of Annealing on the Microstructure of NiFe1.925Dy0.075O4 Thin Films,” Thin Solid Films, 520, pp. 1794–1798. [CrossRef]
Gullapalli, S. K., Vemuri, R. S., Manciu, F. S., Enriquez, J. L., and Ramana, C. V., 2010, “Tungsten Oxide (WO3) Thin Films for Application in Advanced Energy Systems,” J. Vac. Sci. Technol. A, 28(4), pp. 824–828. [CrossRef]
Ramana, C. V., Noor-A-Alam, M., Gengler, J. J., and Jones, J. G., 2012, “Growth, Structure, and Thermal Conductivity of Yttria-Stabilized Hafnia Thin Films,” ACS Appl. Mater. Interfaces, 4, pp. 200–204. [CrossRef] [PubMed]

Figures

Grahic Jump Location
Fig. 1

XRD patterns of YSH coatings on SS-403 substrates

Grahic Jump Location
Fig. 2

SEM images of YSH coatings grown on SS-403 substrates

Grahic Jump Location
Fig. 3

SEM image of the Si-YSH interface grown at 500 °C

Grahic Jump Location
Fig. 4

Grain size of YSH on SS-403 as a function of growth temperature

Grahic Jump Location
Fig. 5

EDS spectrum of YSH coatings grown at 500 °C showing the composition in the coating (top panel). The EDS spectrum of the bare SS-403 substrate is also shown for comparison (bottom panel).

Grahic Jump Location
Fig. 6

Phase shift with respect to modulation frequency for YSH on SS-403 grown at RT (a), 300 °C (b), and 500 °C (c)

Grahic Jump Location
Fig. 7

Variation of thermal conductivity of YSH on SS-403 with growth temperature

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In