Effects of Phase Contents in Feedstock Powder and Methods of Thermal Shock Test on Lifetime of Thermal Barrier Coatings

2018 ◽  
Author(s):  
Kwangyong Park ◽  
Byungil Yang ◽  
Insoo Kim ◽  
Kyungic Jang ◽  
Sangwon Myoung ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Plasma Spraying ◽  
Monoclinic Phase ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Thermal Shock Test ◽  
Cycle Times ◽  
Shock Testing ◽  
Barrier Coating ◽  
System Use

The thermal durability of thermal barrier coating systems (TBCs) obtained using feedstock powders with different purity and phase content was investigated by thermal shock testing with different cycle times, including the effects on the sintering and phase transformation behaviors. Three kinds of 8 wt.% yttria-stabilized zirconia, namely regular purity (8YSZ), high purity (HP1 and HP2), and no monoclinic phase (NMP), were employed to prepare top coats by atmospheric plasma spraying on a NiCoCrAlY bond coat using a high-velocity oxy-fuel system. Use of 8YSZ, HP1, HP2, and NMP for plasma spraying affected the microstructure and lifetime of the TBC in furnace cyclic testing (FCT) at 1100 °C with 24 hour and 1 hour cycle times. In 24h cycling time, the TBCs deposited using NMP powder showed the highest durability, while that formed from HP showed lifetime performance similar to that obtained with regular purity 8YSZ. The TBC obtained with nMP also exhibited the lowest monoclinic phase transition rate, followed by those obtained using HP and 8YSZ. However, the 1 hour cycle test had the opposite result. Therefore, the coating material should be selected depending on the usage environment.

Structure Evolution of 7YSZ Thermal Barrier Coating During Thermal Shock Testing

2015 ◽  
Vol 30 (12) ◽  
pp. 1261
Author(s):  
ZHANG Xiao-Feng ◽  
ZHOU Ke-Song ◽  
ZHANG Ji-Fu ◽  
ZHANG Yong ◽  
LIU Min ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Structure Evolution ◽  
Thermal Barrier ◽  
Shock Testing ◽  
Barrier Coating

Thermal Shock Testing of Thermal Barrier Coating/Bondcoat Systems

2004 ◽  
Vol 13 (4) ◽  
pp. 389-397 ◽  
Author(s):  
Ann Bolcavage ◽  
Albert Feuerstein ◽  
John Foster ◽  
Peter Moore
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Barrier ◽  
Shock Testing ◽  
Barrier Coating

scholarly journals Thermal Shock Behavior and Particle Erosion Resistance of Toughened GZ Coatings Prepared by Atmospheric Plasma Spraying

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1477
Author(s):  
Zining Yang ◽  
Weize Wang ◽  
Shujuan Deng ◽  
Huanjie Fang ◽  
Ting Yang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Thermal Shock ◽  
Plasma Spraying ◽  
Erosion Resistance ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Thermal Shock Test ◽  
Particle Erosion ◽  
Shock Test ◽  
Gadolinium Zirconate

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.

Durability of Amorphous and Crystalline BMAS Thermal Barrier Coatings Produced by Plasma Spraying

2016 ◽  
Vol 258 ◽  
pp. 383-386 ◽  
Author(s):  
Ladislav Čelko ◽  
David Jech ◽  
Karel Dvořák ◽  
Ivo Šulák ◽  
Lenka Klakurková ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Amorphous Phase ◽  
Bond Coat ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Polycrystalline Nickel ◽  
Cooling Period ◽  
Nickel Based Superalloy ◽  
Barrier Coating ◽  
The Difference

Barium-Magnesium-Aluminium-Silicate (BMAS) powder was produced from a mixture of initial compounds BaO–MgO–Al2O3–SiO2 by means of solid state synthesis at the temperature of 1200 °C for 3 hours in a laboratory furnace. Synthetized powder was crushed into the fraction of 15-45 μm in a planetary ball mill. Thermal barrier coating system consisting of CoNiCrAlY (bond coat) and BMAS (top coat) was sprayed by atmospheric plasma spray technique onto the polycrystalline nickel-based superalloy substrate. During plasma spraying process, the BMAS underwent phase transformation and the amorphous phase within the top coat was produced. Therefore, after the spraying, several samples were crystallized via annealing in a furnace (4 hours at 1200 °C or 24 hours at 1000 °C) or by subjecting them to several passes of plasma jet. Both samples with an amorphous phase and fully-crystallized samples were subjected to the fire in a burner-rig test (propane-oxygen flame, single 3 + 3 minute cycle), where the top coat reached the temperature of 1150 °C. Top coat failure occurred during the cooling period due to the transformation of the amorphous phase into the crystalline one and/or due to the difference in thermal conductivity and expansion between the top coat and the bond coat.

Investigation of Thermal Shock Behavior of Plasma-Sprayed NiCoCrAlY/YSZ Thermal Barrier Coatings

2012 ◽  
Vol 472-475 ◽  
pp. 246-250 ◽  
Author(s):  
Hossein Jamali ◽  
Reza Mozafarinia ◽  
Reza Shoja Razavi ◽  
Raheleh Ahmadi Pidani
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Thermal Shock Test ◽  
Barrier Coatings ◽  
Microstructural Evaluation ◽  
Mismatch Stress ◽  
Thermal Shock Behavior ◽  
Plasma Sprayed

ZrO2-8wt.%Y2O3 (8YSZ) thermal barrier coatings (TBCs) were deposited by atmospheric plasma spraying (APS) on NiCoCrAlY-coated Inconel 738LC substrates. The thermal shock behavior was investigated by quenching the samples in water with temperature of 20-25°C from 950°C. To study of failure mechanism results from thermal cycling, microstructural evaluation using scanning electron microscope (SEM), elemental analysis using energy dispersive spectroscopy (EDS) and phasic analysis using x-ray diffractometry (XRD) were done. The results revealed that failure of the TBC system was due to the spallation of ceramic top coat. Thermal mismatch stress was the major factor of TBC failure in thermal shock test.

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