Thermal shock resistance and failure analysis of La2(Zr0.75Ce0.25)2O7-based TBCs produced by atmospheric plasma spraying

Gadolinium zirconate with excellent high-temperature phase stability and sintering resistance has become a very promising candidate material for a new generation of thermal barrier coatings (TBCs). However, the low fracture toughness of gadolinium zirconate greatly limits its application. In this study, gadolinium zirconate (GZ) and two kinds of toughened gadolinium zirconate (GZ/YSZ prepared by mixed powder of Gd2Zr2O7 and YSZ and GSZC prepared by (Gd0.925Sc0.075)2(Zr0.7Ce0.3)2O7 powder) double-layered TBCs were prepared by atmospheric plasma spraying (APS). The fracture toughness of the GZ/YSZ coating and GSZC coating were 9 times and 3.5 times that of GZ coating, respectively. The results of thermal shock test showed that the three TBCs exhibit different failure mechanisms. During the thermal shock test, cracking occurred at the interfaces between the YSZ layer and the BC or GZ/YSZ layer, while GSZC TBC failed due to premature cracking inside the GSZC layer. The particle erosion rate of the GZ, GZ/YSZ, and GZSC coatings were 1.81, 0.48, and 1.01 mg/g, respectively, indicating that the erosion resistance of coatings is related to their fracture toughness. Furthermore, the superior erosion resistance of the GZ/YSZ and GSZC coatings can be attributed to the conversion of crack propagation path during the erosion test.

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Thermal shock behaviors of YSZ thick thermal barrier coatings fabricated by suspension and atmospheric plasma spraying

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2014.03.046 ◽

2014 ◽

Vol 249 ◽

pp. 48-55 ◽

Cited By ~ 36

Author(s):

Yuexing Zhao ◽

Dachuan Li ◽

Xinghua Zhong ◽

Huayu Zhao ◽

Liang Wang ◽

...

Keyword(s):

Thermal Shock ◽

Plasma Spraying ◽

Thermal Barrier Coatings ◽

Atmospheric Plasma Spraying ◽

Atmospheric Plasma ◽

Thermal Barrier ◽

Barrier Coatings

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THERMAL SHOCK BEHAVIOR OF AIR PLASMA SPRAYED CoNiCrAlY/YSZ THERMAL BARRIER COATINGS

Surface Review and Letters ◽

10.1142/s0218625x14500693 ◽

2014 ◽

Vol 21 (05) ◽

pp. 1450069 ◽

Cited By ~ 2

Author(s):

ZI WEI LIU ◽

WEI WU ◽

JIA JIE HUA ◽

CHU CHENG LIN ◽

XUE BIN ZHENG ◽

...

Keyword(s):

Thermal Shock ◽

Thermal Barrier Coatings ◽

Thermal Shock Resistance ◽

Structural Changes ◽

Cold Water ◽

Atmospheric Plasma ◽

Thermal Barrier ◽

Air Plasma ◽

Barrier Coatings ◽

Shock Resistance

The structural changes and failure mechanism of thermal barrier coatings (TBCs) during thermal shock cycling were investigated. TBCs consisting of CoNiCrAlY bond coat and partially yttria-stabilized zirconia (YSZ) top coat were deposited by atmospheric plasma spraying (APS) on a nickel-based alloy substrate and its thermal shock resistance performance was evaluated. TBCs were heated at 1100°C for 15 min followed by cold water quenching to ambient temperature. Microstructural evaluation and elemental analysis of TBCs were performed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The crack features of YSZ coatings in TBCs during thermal shock cycling, including those of horizontal (parallel to the substrate) and vertical cracks (perpendicular to the substrate), were particularly investigated by means of SEM and image analysis. Results show that horizontal and vertical cracks have different influences on the thermal shock resistance of the coatings. Horizontal cracks that occur at the interface of YSZ and thermally growth oxidation (TGO) cause partial or large-area spalling of coatings. When vertical and horizontal cracks encounter, network segments are formed which lead to partial spalling of the coatings.

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