Low Thermal Conductivity Yttria-Stabilized Zirconia Thermal Barrier Coatings Using the Solution Precursor Plasma Spray Process

Sm0.4Ce0.6O1.8 specimen with a defective fluorite structure was synthesized and its thermophysical properties were characterized for thermal barrier coatings (TBCs) application. At high temperature, Sm0.4Ce0.6O1.8 exhibited much lower thermal conductivity than 7wt% yttria-stabilized zirconia (7YSZ)-the commonly used composition in current TBCs. Sm0.4Ce0.6O1.8 also possessed large thermal expansion coefficient, which could help reduce the thermal mismatch between the ceramic coating and bond coat.

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Phase stability and thermal conductivity of nanostructured tetragonal yttria–stabilized zirconia thermal barrier coatings deposited by air–plasma spraying

Ceramics International ◽

10.1016/j.ceramint.2017.06.142 ◽

2017 ◽

Vol 43 (15) ◽

pp. 12633-12640 ◽

Cited By ~ 23

Author(s):

Kuo Jiang ◽

Songbai Liu ◽

Xin Wang

Keyword(s):

Thermal Conductivity ◽

Plasma Spraying ◽

Thermal Barrier Coatings ◽

Phase Stability ◽

Yttria Stabilized Zirconia ◽

Thermal Barrier ◽

Air Plasma ◽

Air Plasma Spraying ◽

Stabilized Zirconia ◽

Barrier Coatings

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Low Thermal Conductivity YSZ Thermal Barrier Coatings Made by the Solution Precursor Plasma Spray Process

Volume 6: Ceramics; Controls, Diagnostics and Instrumentation; Education; Manufacturing Materials and Metallurgy ◽

10.1115/gt2014-26244 ◽

2014 ◽

Author(s):

E. H. Jordan ◽

C. Jiang ◽

M. Gell ◽

J. Roth

Keyword(s):

Thermal Conductivity ◽

Thermal Barrier Coatings ◽

Plasma Spray ◽

Thermal Protection ◽

High Fracture Toughness ◽

Thermal Barrier ◽

Solution Precursor Plasma Spray ◽

Barrier Coatings ◽

Low Thermal Conductivity ◽

Solution Precursor

The vast majority of thermal barrier coatings (TBCs) are made using 7 wt% yttria stabilized zirconia (7YSZ) due to its high thermal expansion coefficient, high fracture toughness, relatively low thermal conductivity and modest use of rare earth elements (Y). Lower thermal conductivity in TBCs is highly desirable because it would allow thinner coatings and/or improved thermal protection. By arranging the porosity in layers using the solution precursor plasma spray (SPPS) process it has been demonstrated that a 7YSZ coating with 15–23% porosity can be reproducibly fabricated having a thermal conductivity of about 0.6W/m·K, approximately half of the thermal conductivity of air plasma spray (APS) TBCs. Preliminary tests show that both cyclic furnace durability and erosion resistance are comparable to APS TBCs.

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A Comparative Study on the Synthesis and Properties of Yttria Stabilized Zirconia (YSZ) and Lanthana Doped YSZ Plasma Sprayed Thermal Barrier Coatings

ASME 2013 Gas Turbine India Conference ◽

10.1115/gtindia2013-3563 ◽

2013 ◽

Author(s):

S. T. Aruna ◽

N. Balaji ◽

B. Arul Paligan

Keyword(s):

Thermal Conductivity ◽

Thermal Barrier Coatings ◽

Gas Turbines ◽

Operating Temperature ◽

Yttria Stabilized Zirconia ◽

Thermal Barrier ◽

Spray Parameters ◽

Stabilized Zirconia ◽

Barrier Coatings ◽

Plasma Sprayed

Ceramic thermal barrier coatings (TBCs) have been used for decades to extend the life of combustors and high temperature turbine stationary and rotating components to increase the operating temperature and in turn the performance of gas turbines or diesel engines can be increased. At present, thermal barrier coatings (TBCs) of Y2O3 partially stabilized ZrO2 (YSZ) films are widely used. In recent years ceramic compositions useful in thermal barrier coatings having reduced thermal conductivity are being explored to further increasing the operating temperature of gas turbines and improve the engine efficiency. In the present study, a comparison of the properties of state-of-the art 8wt% yttria stabilized zirconia (YSZ) and lanthana doped YSZ plasma sprayed coatings is presented. Plasma sprayable powders were prepared in the laboratory by a single step precipitation method and characterized. Both the powders had good flowability. These powders were plasma sprayed at identical critical plasma spray parameters. The coatings were characterized for phase, microstructure and thermal conductivity. Both the powders and coatings exhibited tetragonal form of zirconia and no traces of lanthana were observed. Both the coatings exhibited similar porosity levels. Microstructure of the coatings revealed porous coating with good adhesion of the bondcoat with the topcoat. Plasma sprayed 8wt% YSZ and lanthana doped YSZ exhibited thermal conductivity values of 0.88 and 0.67 W m−1 K−1 respectively which is lower than that reported in literature. This study shows that lanthana doping in YSZ helps in lowering the thermal conductivity and hence this coating may be a potential candidate for TBC application.

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