Phase transformations in air plasma-sprayed yttria-stabilized zirconia thermal barrier coatings

Osorio, Julián D.; Lopera-Valle, Adrián; Toro, Alejandro; Hernández-Ortiz, Juan P.
June 2014
Dyna;Jun2014, Vol. 81 Issue 185, p13
Academic Journal
Phase transformations in air plasma sprayed thermal barrier coatings composed of ZrO2 - 8 wt.% Y2O3 (zirconia - 8 wt.% yttria) are studied using X-Ray diffraction and Rietveld refinement measurements. Samples of TBC deposited onto Inconel 625 substrate were fabricated and heat treated at two different conditions: exposition to 1100°C up to 1000 hours and exposition to temperatures between 700°C and 1100°C during 50 hours. According to Rietveld refinement measurements, the content of the cubic phase in the top coat increases with time and temperature; it starts at 7.3 wt.% and reaches 15.7 wt.% after 1000 hours at 1100°C. The presence of a cubic phase in high amounts is undesirable due its lower mechanical properties compared with the tetragonal phase. After 800 hours of exposure to high temperature, the amount of Y2O3 in the tetragonal phase reduces to 6.6 wt.% and a fraction of this phase transforms to a monoclinic structure during cooling. The monoclinic phase reached 18.0 wt.% after 1000 hours. This phase is also undesirable, not only due to its higher thermal conductivity, but also because the tetragonal to monoclinic transformation implies a volume change of circa 5%, which favors crack formation and propagation and compromises the coating integrity.


Related Articles

  • Air Plasma-Sprayed Yttria and Yttria-Stabilized Zirconia Thermal Barrier Coatings Subjected to Calcium-Magnesium-Alumino-Silicate (CMAS). Li, Wenshuai; Zhao, Huayu; Zhong, Xinghua; Wang, Liang; Tao, Shunyan // Journal of Thermal Spray Technology;Aug2014, Vol. 23 Issue 6, p975 

    Yttria (YO) and zirconia (ZrO) stabilized by 8 and 20 wt.%YO thermal barrier coatings (TBCs) subjected to calcium-magnesium-alumino-silicate (CMAS) have been investigated. Free-standing YO, 8 and 20 wt.%YSZ coatings covered with synthetic CMAS slurry were heated at 1300 °C in air for 24 h in...

  • Optimizing Compliance and Thermal Conductivity of Plasma Sprayed Thermal Barrier Coatings via Controlled Powders and Processing Strategies. Tan, Yang; Srinivasan, Vasudevan; Nakamura, Toshio; Sampath, Sanjay; Bertrand, Pierre; Bertrand, Ghislaine // Journal of Thermal Spray Technology;Sep2012, Vol. 21 Issue 5, p950 

    The properties and performance of plasma-sprayed thermal barrier coatings (TBCs) are strongly dependent on the microstructural defects, which are affected by starting powder morphology and processing conditions. Of particular interest is the use of hollow powders which not only allow for...

  • Effect of Deposition Rate on the Stress Evolution of Plasma-Sprayed Yttria-Stabilized Zirconia. Shinoda, Kentaro; Colmenares-Angulo, Jose; Valarezo, Alfredo; Sampath, Sanjay // Journal of Thermal Spray Technology;Dec2012, Vol. 21 Issue 6, p1224 

    The deposition rate plays an important role in determining the thickness, stress state, and physical properties of plasma-sprayed coatings. In this article, the effect of the deposition rate on the stress evolution during the deposition (named evolving stress) of yttria-stabilized zirconia...

  • A Study of Water Crystal Growing Based on Dilution and Succussion Theory of Homeopathy. Hsu, Yi-Chu; Liang, Yong-Shang; Cheng, Po-Yuan // Applied Mechanics & Materials;2014, Issue 607-609, p61 

    By studying the formation of snowflakes, scientists have found that frequency data can be stored in water. Using the homeopathic principles of dilution and succussion, this study explored the relationship between aqueous information transmission and differences in the formation of water...

  • Melting Refining Mechanisms in Supersonic Atmospheric Plasma Spraying. Zhao, Wei; Wu, Jiu; Bai, Yu; Han, Zhi // Plasma Chemistry & Plasma Processing;Dec2012, Vol. 32 Issue 6, p1227 

    In recent years, Yttria-stabilized zirconia based thermal barrier coatings (TBCs) are deposited by newly-developed high-efficiency supersonic atmospheric plasma spraying (SAPS) technology. The final microstructure of the plasma-sprayed coatings is strongly dependent on the size distribution of...

  • Columnar-Structured Mg-Al-Spinel Thermal Barrier Coatings (TBCs) by Suspension Plasma Spraying (SPS). Schlegel, N.; Ebert, S.; Mauer, G.; Vaßen, R. // Journal of Thermal Spray Technology;Jan2015, Vol. 24 Issue 1/2, p144 

    The suspension plasma spraying (SPS) process has been developed to permit the feeding of sub-micrometer-sized powder into the plasma plume. In contrast to electron beam-physical vapor deposition and plasma spray-physical vapor deposition, SPS enables the cost-efficient deposition of...

  • Phosphor-Doped Thermal Barrier Coatings Deposited by Air Plasma Spray for In-Depth Temperature Sensing. Di Peng; Lixia Yang; Tao Cai; Yingzheng Liu; Xiaofeng Zhao; Zhiqi Yao // Sensors (14248220);Oct2016, Vol. 16 Issue 10, p1490 

    Yttria-stabilized zirconia (YSZ)-based thermal barrier coating (TBC) has been integrated with thermographic phosphors through air plasma spray (APS) for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 μm) on the bottom and a regular...

  • Splat interface bonding formation during plasma spraying of LZO coating. Liu, T.; Yang, E.-J.; Yang, G.-J.; Li, C.-X.; Li, C.-J. // Materials Research Innovations;Jul2014 Supplement 4, Vol. 18 Issue S4, p973 

    Plasma sprayed ceramic coatings of low thermal conductivity are becoming important candidates for next generation thermal barrier coatings. The rare earth ceramic materials are regarded as promising materials which can be applied by plasma spraying. However, the lower mechanical strength of...

  • Restriction of Phase Transformation in Carbon Nanotube-Reinforced Yttria-Stabilized Zirconia. Mohapatra, Pratyasha; Rawat, Siddharth; Mahato, Neelima; Balani, Kantesh // Metallurgical & Materials Transactions. Part A;Jul2015, Vol. 46 Issue 7, p2965 

    The present research aims to investigate the effect of multi-walled carbon nanotube (MWNT) reinforcement on the mechanism of transformation toughening in zirconia matrix, and consequently, its fracture toughness. Monoclinic zirconia (un-doped ZrO), partially stabilized zirconia (3 mol pct...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics