scholarly journals Influence of isothermal oxidation on microstructure of YSZ and Mullite-YSZ thermal barrier coatings

2019 ◽  
Vol 23 ◽  
pp. 378-383
Author(s):  
David Jech ◽  
Ladislav Čelko ◽  
Michaela Remešová ◽  
Karel Slámečka ◽  
Pavel Ctibor
Keyword(s):  
Thermal Barrier Coatings ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
Barrier Coatings

NONDESTRUCTIVE IMPEDANCE SPECTROSCOPY EVALUATION OF THE BOND COAT OXIDATION IN THERMAL BARRIER COATINGS

2007 ◽  
Vol 14 (05) ◽  
pp. 935-943 ◽  
Author(s):  
L. YANG ◽  
Y. C. ZHOU ◽  
W. G. MAO ◽  
Q. X. LIU
Keyword(s):  
Impedance Spectroscopy ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Equivalent Circuit Model ◽  
Isothermal Oxidation ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Plasma Sprayed

In this paper, the impedance spectroscopy technique was employed to examine nondestructively the isothermal oxidation of air plasma sprayed (APS) thermal barrier coatings (TBCs) in air at 800°C. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were also used to characterize the microstructure evolution of TBCs. After oxidation, the thermally grown oxide (TGO), which was mainly composed of alumina as confirmed by EDX, formed at the upper ceramic coat/bond coat interface, the lower bond coat/substrate interface, and the bond coat. Impedance diagrams obtained from impedance measurements at room temperature were analyzed according to the equivalent circuit model proposed for the TBCs. Various observed electrical responses relating to the growth of oxides and the sintering of YSZ were explained by simulating the impedance spectra of the TBCs.

Performance of single YSZ, Gd2Zr2O7 and double-layered YSZ/Gd2Zr2O7 thermal barrier coatings in isothermal oxidation test conditions

Vacuum ◽  
2020 ◽  
Vol 177 ◽  
pp. 109401
Author(s):  
Kadir Mert Doleker ◽  
Abdullah Cahit Karaoglanli ◽  
Yasin Ozgurluk ◽  
Akira Kobayashi
Keyword(s):  
Thermal Barrier Coatings ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Oxidation Test ◽  
Test Conditions

Interfacial Kinetics of High Temperature Oxidation in YSZ Thermal Barrier Coatings With Bond Coatings of NiCoCrAlY With 0.25% Hf

2009 ◽  
Author(s):  
Winston Soboyejo ◽  
Patrick Mensah ◽  
Ravinder Diwan
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
High Temperature Oxidation ◽  
Structural Evolution ◽  
Isothermal Oxidation ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Temperature Oxidation ◽  
Barrier Coatings ◽  
Thermally Grown

This paper presents the results of an experimental study of the high-temperature isothermal oxidation behavior and micro-structural evolution in plasma sprayed thermal barrier coatings (TBCs) at temperatures between 900 and 1200 °C. Two types of specimens were produced for testing. These include a standard and vertically cracked (VC) APS. High temperature oxidation has been carried out at 900, 1000, 1100 and 1200 °C. The experiments have been performed in air under isothermal conditions. At each temperature, the specimens are exposed for 25, 50, 75 and 100 hours. The corresponding microstructures and microchemistries of the TBC layers are then examined using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy EDS. Changes in the dimensions of the thermally grown oxide (TGO) layer are determined as functions of time and temperature. The evolution of bond coat microstructures/interdiffusion zones and thermally grown oxide (TGO) layers are compared in TBCs with standard (STD) and vertically cracked (VC) microstructures.

High-Temperature Performance of Self-Healing SiC-YSZ Thermal Barrier Coatings Deposited by Using Various Plasma Spray Concepts

2021 ◽  
Author(s):  
Mohammad Hassanzadeh ◽  
Paweł Sokołowski ◽  
Radek Musalek ◽  
Jan Medricky ◽  
Stefan Csaki
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Plasma Spray ◽  
Gas Turbines ◽  
Isothermal Oxidation ◽  
Atmospheric Plasma ◽  
Flash Method ◽  
Thermal Barrier ◽  
Self Healing ◽  
Barrier Coatings

Abstract In this study; a novel self-healing concept is considered in order to increase the lifetime of thermal barrier coatings (TBCs) in modern gas turbines. For that purpose; SiC healing particles were introduced to conventional 8YSZ topcoats by using various plasma spray concepts; i.e.; composite or multilayered coatings. All topcoats were sprayed by SG-100 plasma torch on previously deposited NiCrAlY bondcoats produced by conventional atmospheric plasma spraying. Coatings were subjected to thermal conductivity measurements by laser flash method up to 1000°C; isothermal oxidation testing up to 200h at 1100°C and finally thermal cyclic fatigue (TCF) lifetime testing at 1100°C. Microstructural coating evaluation was performed by scanning electronic microscope (SEM); in the as-produced and post high-temperature tested states. This was done to analyze the self-healing phenomena and its influence on the hightemperature performance of the newly developed TBCs.

Structure and Performance of YSZ Thermal Barrier Coatings Irradiated by High Intensity Pulsed Ion Beam

2012 ◽  
Vol 538-541 ◽  
pp. 2377-2381 ◽  
Author(s):  
Xian Xiu Mei ◽  
Yue Liu ◽  
Xue Ma ◽  
You Nian Wang
Keyword(s):  
Thermal Barrier Coatings ◽  
High Intensity ◽  
Ion Beam ◽  
Xrd Analysis ◽  
Isothermal Oxidation ◽  
Atmospheric Plasma ◽  
Cubic Phase ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Micro Cracks

The thermal barrier coatings (TBC) of the yttria-stabilized zirconia (YSZ) has been deposited by the atmospheric plasma spraying (APS),followed by the irradiation of high intensity pulsed ion beam (HIPIB) with the voltage of 250 KV and the ion current density of 300 A/cm2 and pulsed times of 2, 5, 10 and 20, respectively. The X-ray diffraction (XRD) analysis reveals that the coating is characterized by the tetragonal ZrO2 phase instead of the cubic phase and the original monoclinic phase after the irradiation. The scanning electron micros cope analysis demonstrates that the HIPIB treatment leads to a smooth TBC surface, but produces micro-cracks and round grain at the surface. This implies that the plasma erupts during the ion beam interaction with the coatings with poor thermal conductivity, and the micro-cracks were produced in the cooling process. The isothermal oxidation experiment performed at 1050°C in air and suggests that the oxidation resistance of the coating can be largely enhanced after HIPIB treatment.

The Influence of Overaluminizing on TGO Formation on Thermal Barrier Coatings Deposited by Low Pressure Plasma Spraying and Chemical Vapour Deposition Methods on Rene 80 Nickel Superalloy

2015 ◽  
Vol 227 ◽  
pp. 321-324 ◽  
Author(s):  
Marek Góral ◽  
Maciej Pytel ◽  
Wojciech Cmela ◽  
Marcin Drajewicz
Keyword(s):  
Thermal Barrier Coatings ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Isothermal Oxidation ◽  
Nickel Superalloy ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Oxidation Test ◽  
High Oxidation Resistance ◽  
Low Pressure Plasma Spraying

The paper presents results of research into isothermal oxidation test of thermal barrier coatings characterized by high oxidation resistance and hot corrosion. Bondcoats were deposited by overaluminizing of MeCrAlY–type coating deposited by LPPS method. The outer ceramic layer of yttrium oxide stabilized zirconia oxide (Metco 6700) was deposited by plasma spray physical vapour deposition (PS-PVD). For comparison purposes additionally LPPS-sprayed were MeCrAlY bondcoats, which were not subsequently aluminized.. The isothermal oxidation test at 1100oC for 1000h shown that thickness of the TGO layer in overaluminized bondcoat was significantly thicker in comparison with conventional LPPS-sprayed MeCrAlY bondcoats.

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