scholarly journals Preparation and Thermal Shock Resistance of Gd2O3 Doped La2Ce2O7 Thermal Barrier Coatings

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1186
Author(s):  
Lihua Gao ◽  
Fang Jia ◽  
Xiaoliang Lu
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Shock Resistance ◽  
Atmospheric Plasma ◽  
Ceramic Layer ◽  
Thermal Barrier ◽  
Spray Parameters ◽  
Layer By Layer ◽  
Barrier Coating ◽  
Shock Resistance

As one of the promising thermal barrier coating (TBC) candidates, stoichiometric (La0.8Gd0.2)2Ce2O7 (LGC) coatings were prepared by atmospheric plasma spraying (APS), using (La0.8Gd0.2)2Ce2.5O8 as a spray powder and optimized spray parameters. It was found that spray distance and spray power both play an important role in the phase composition and microstructure of the coating. The LGC coating exhibited lower thermal conductivities than that of La2Ce2O7 (LC) coating, which is ~0.67 W/m·K at 1200 °C. Double-ceramic-layer (DCL) optimum (La0.8Gd0.2)2Ce2O7/YSZ (LGC/YSZ) thermal barrier coating was prepared and its thermal shock behavior was investigated. The LGC/YSZ DCL TBCs had better thermal shock resistance ability than that of LC/YSZ TBCs, which was around 109 cycles at 1100 °C. However, the failure mode was similar to that of LC/YSZ DCL TBCs, which was still layer-by-layer spallation in the top ceramic layer due to the sintering of the ceramic coating.

Study on Thermal Shock Resistance of Nano-CeO2–Y2O3 Co-Stabilized ZrO2 (CYSZ) Ceramic Powders Thermal Barrier Coating of Aircraft Engine

2019 ◽  
Vol 14 (11) ◽  
pp. 1597-1605
Author(s):  
Yang Lyu ◽  
Xuan Shao ◽  
Wen-Xue Wang ◽  
Hui Tang
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Shock Resistance ◽  
Ceramic Coatings ◽  
Precipitation Method ◽  
Thermal Barrier ◽  
Ceramic Powders ◽  
Alloy Matrix ◽  
Barrier Coating ◽  
Shock Resistance

In this paper, nano-CeO2–Y2O3 co-stabilized ZrO2 ceramic powders (CYSZ) were firstly prepared by co-precipitation method, and CYSZ powder was spray-granulated, followed by thermal plasma spraying of nano-CYSZ thermal barrier coating on 35Cr2Ni4 MoA alloy matrix. After XRD and SEM analysis, the five CYSZ ceramic coatings (CeO2 content 0, 1, 5, 10, 15 mol%) prepared were tetragonal phase structures before and after the thermal shock experiment, and the thickness of CYSZ ceramic coating was about 200 μm. Adding appropriate amount of nano CeO2 promoted the formation of micro-cracks in the coating, released the coating stress, slowed down the thermal shock damage process, and prevented the transformation from t-ZrO2 to m-ZrO2. The AFM morphology showed that the coating surface grains grow vertically after thermal shock cycle, which indicated that the entry of Ce4+ into ZrO2 lattice resulted in lattice distortion and made the grains more stable. When the content of CeO2 is 1 mol%, the thermal shock resistance excellent is 84 times. Therefore, the addition of CeO2 can effectively improve the thermal shock resistance performance of CYSZ thermal barrier coating, meeting the requirements of high temperature working conditions of aeroengine and hot-end components.

scholarly journals Thermal Shock Resistance and Thermal Insulation Capability of Laser-Glazed Functionally Graded Lanthanum Magnesium Hexaluminate/Yttria-Stabilised Zirconia Thermal Barrier Coating

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3865
Author(s):  
Muhammed Anaz Khan ◽  
Annakodi Vivek Anand ◽  
Muthukannan Duraiselvam ◽  
Koppula Srinivas Rao ◽  
Ramachandra Arvind Singh ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Insulation ◽  
Thermal Shock Resistance ◽  
Functionally Graded ◽  
Thermal Barrier ◽  
Laser Glazing ◽  
Heat Management ◽  
Barrier Coating ◽  
Shock Resistance

In this work, functionally graded lanthanum magnesium hexaluminate (LaMgAl11O19)/yttria-stabilised zirconia (YSZ) thermal barrier coating (FG-TBC), in as-sprayed and laser-glazed conditions, were investigated for their thermal shock resistance and thermal insulation properties. Results were compared with those of a dual-layered coating of LaMgAl11O19 and YSZ (DC-TBC). Thermal shock tests at 1100 °C revealed that the as-sprayed FG-TBC had improved thermal stability, i.e., higher cycle lifetime than the as-sprayed DC-TBC due to its gradient architecture, which minimised stress concentration across its thickness. In contrast, DC-TBC spalled at the interface due to the difference in the coefficient of thermal expansion between the LaMgAl11O19 and YSZ layers. Laser glazing improved cycle lifetimes of both the types of coatings. Microstructural changes, mainly the formation of segmentation cracks in the laser-glazed surfaces, provided strain tolerance during thermal cycles. Infrared rapid heating of the coatings up to 1000 °C showed that the laser-glazed FG-TBC had better thermal insulation capability, as interlamellar pores entrapped gas and constrained heat transfer across its thickness. From the investigation, it is inferred that (i) FG-TBC has better thermal shock resistance and thermal insulation capability than DC-TBC and (ii) laser glazing can significantly enhance the overall thermal performance of the coatings. Laser-glazed FG-TBC provides the best heat management, and has good potential for applications that require effective heat management, such as in gas turbines.

Fabrication and Characterization of Ceramic/Metal Gradient Thermal Barrier Coating

2007 ◽  
Vol 336-338 ◽  
pp. 2643-2646
Author(s):  
Jin Sheng Xiao ◽  
Chun Zhi Hu ◽  
Wen Hua Zhao ◽  
Wei Biao Fu
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Shock Resistance ◽  
Hole Drilling ◽  
Thermal Barrier ◽  
Hole Drilling Method ◽  
Thermal Residual Stresses ◽  
Gradient Coating ◽  
Barrier Coating ◽  
Shock Resistance

Four Coating schemes and two substrate materials are designed to evaluate the characteristics of the ceramic/metal gradient thermal barrier coating. The gradient coating is successfully prepared by plasma spray with single torch and single feeder. The coating performance is evaluated by observing microstructure, measuring thermal shock resistance and thermal residual stress. The coating microstructure is observed by scanning electron microscope (SEM). Diffractive peaks for the gradient coating are got at different zone by X-ray spectroscopy (XRS). The thermal shock experiment shows that the thermal shock resistance property of the gradient coating is better than that of the non-gradient coating. The measurements of thermal residual stresses in different coating schemes are carried out by hole-drilling method, the results show that compressional stress presents on 1Cr18Ni9Ti substrate and tensile stress presents on 2Cr13 substrate.

scholarly journals Thermal Shock Resistance of Bilayered YSZ Thermal Barrier Coating

2018 ◽  
Vol 55 (5) ◽  
pp. 452-460 ◽  
Author(s):  
Dong Heon Lee ◽  
Tae Woo Kim ◽  
Kee Sung Lee ◽  
Chul Kim
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Shock Resistance ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Shock Resistance

Study on Performance of 8YSZ Thick Gradient TBC

2014 ◽  
Vol 607 ◽  
pp. 43-46 ◽  
Author(s):  
Jin Qin ◽  
Gang Chen ◽  
Zhi Ming Du ◽  
Yu Hui Jin
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Double Layer ◽  
Bonding Strength ◽  
Thermal Shock Resistance ◽  
Layer Structure ◽  
Thermal Barrier ◽  
Double Layer Structure ◽  
Barrier Coating ◽  
Shock Resistance

Plasma spray zirconia gradient thermal barrier coating (TBC) and the traditional double-layer structure thermal barrier coating were both studied in this paper. NiCoCrAlY alloy powder was used as bottom bonding materials, 8YSZ (8mol% yttrium stabilized zirconia) was used as top layer materials and the different proportions mixed powder of 8YSZ and NiCoCrAlY was used as gradient layers materials. Bonding strength of thickness gradient coating was measured by tensile experiment. Thermal cycle experiment was carried on to test the thermal shock resistance of TBC. The microstructure after thermal shock experiment was observed to analyze the failure mechanism of TBC. The research result shows that the bonding strength and thermal shock resistance of gradient TBC are much better than the traditional double-layer structure TBC. With the increasing of top layer thickness, thermal shock life of TBC substantially reduces. With the decreasing of ZrO2 composition proportion in gradient layer, thermal shock life of TBC significantly rises. This result has important significance for the future study of thick TBC.

Effects of Powder Morphology, Microstructure, and Residual Stresses on Thermal Barrier Coating Thermal Shock Performance

1996 ◽  
Author(s):  
J. Wigren ◽  
J.-F. de Vries ◽  
D. Greving
Keyword(s):  
Residual Stresses ◽  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Spray Parameters ◽  
Powder Morphology ◽  
Barrier Coatings ◽  
Barrier Coating

Abstract Thermal barrier coatings are used in the aerospace industry for thermal insulation in hot sections of gas turbines. Improved coating reliability is a common goal among jet engine designers. In-service failures, such as coating cracking and spallation, result in decreased engine performance and costly maintenance time. A research program was conducted to evaluate residual stresses, microstructure, and thermal shock life of thermal barrier coatings produced from different powder types and spray parameters. Sixteen coatings were ranked according to their performance relative to the other coatings in each evaluation category. Comparisons of residual stresses, powder morphology, and microstructure to thermal shock life indicate a strong correlation to thermal barrier coating performance. Results from these evaluations will aid in the selection of an optimum thermal barrier coating system for turbine engine applications.

scholarly journals Thermal shock resistance of yttrium aluminium oxide Y3Al5O12 thermal barrier coating for titanium alloy

2020 ◽  
Vol 14 (1) ◽  
pp. 6514-6525 ◽  
Author(s):  
Mohammed A. Almomani ◽  
Mohamad I. Al-Widyan ◽  
Sulaiman M. Mohaidat
Keyword(s):  
Titanium Alloy ◽  
Titanium Alloys ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Operating Temperature ◽  
Thermal Barrier ◽  
X Ray Diffraction ◽  
X Ray ◽  
Barrier Coating ◽  
Shock Resistance

The high strength-to- weight ratio of titanium alloys allows their use in jet engines. However, their use is restricted by susceptibility to oxidation at high temperatures. In this study, the possibility of increasing the operating temperature of titanium alloys through using Yttrium Aluminum Oxide (YAG) as a thermal barrier coating material for Ti-6Al-4V substrate is studied. The study concludes that YAG can be utilized to increase the operating temperature of Ti-6Al-4V titanium alloy from around 350 °C to 800 °C due to its low thermal conductivity and phase stability up to its melting point. In addition, its lower oxygen diffusivity in comparison with the standard YSZ material will provide a better protection of the titanium substrate from oxidation. In this work, coating was created using atmospheric plasma spray. X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) were used to examine coatings' composition and structure. The coating was characterized by thermal shock test, Vickers hardness test and adhesion strength test. X-ray diffraction indicated that the coating was of a partially crystalline Y3Al5O12 composition. The coating was porous with excellent thermal shock resistance at 800 oC, with a Vickers micro-hardness of 331.35 HV and adhesion strength of 17.6 MPa.

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