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.

scholarly journals Effect of Particle In-Flight Behavior on the Microstructure and Fracture Toughness of YSZ TBCs Prepared by Plasma Spraying

Coatings ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 309 ◽  
Author(s):  
Yanqiu Xiao ◽  
Erzhou Ren ◽  
Mingyang Hu ◽  
Kun Liu
Keyword(s):  
Fracture Toughness ◽  
Plasma Spraying ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Flight Behavior ◽  
Structural Defects ◽  
Yttria Partially Stabilized Zirconia ◽  
Higher Temperature ◽  
Plasma Sprayed ◽  
Unmelted Particles

The present study aims to elaborate particle in-flight behavior during plasma spraying and its significance in determining the microstructure and mechanical properties of plasma sprayed yttria partially stabilized zirconia (YSZ) thermal barrier coatings (TBCs). The as-sprayed YSZ coatings were characterized in terms of defects (such as pores, unmelted particles and cracks) and fracture toughness. The results showed that, due to the higher temperature and velocity of in-flight particles in a supersonic atmospheric plasma spraying (SAPS) compared to that of atmospheric plasma spraying (APS), denser coatings were formed leading to a better fracture toughness. The percentage of defects of the microstructure was similar to the temperature and velocity of particles in-flight during plasma spraying. Furthermore, the structural defects had a strong effect on its mechanical behavior. The total defect percentage and fracture toughness in SAPS-TBCs spanned 6.9 ± 0.17%–13.26 ± 0.22% and 2.52 ± 0.06 MPa m1/2–1.78 ± 0.19 MPa m1/2; and 11.11 ± 0.36%–17.15 ± 0.67% and 2.13 ± 0.08 MPa m1/2–1.4 ± 0.12 MPa m1/2 in APS-TBCs.

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.

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