Laser Thermal Gradient Testing and Fracture Mechanics Study of a Thermal Barrier Coating

2019 ◽  
Vol 28 (6) ◽  
pp. 1239-1251 ◽  
Author(s):  
Yingsang Wu ◽  
Pei-feng Hsu ◽  
Yao Wang ◽  
Mary Helen McCay ◽  
D. Edward Croy ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Thermal Barrier Coating ◽  
Thermal Gradient ◽  
Thermal Barrier ◽  
Barrier Coating

Investigations on oxidation, hot corrosion and thermal gradient performance of low k-La2Mo2O9 thermal barrier coating

2021 ◽  
Vol 44 (1) ◽  
Author(s):  
N Dharuman ◽  
M Arulmozhi ◽  
Mukiri Soban Babu ◽  
L John Berchmans ◽  
Gosipathala Sreedhar
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Thermal Gradient ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Low K

Burner Rig Testing of Thermal Barrier Coatings for Lifetime Prediction

2014 ◽  
Author(s):  
Grégoire Witz ◽  
Klaus F. Staerk ◽  
Carlo M. Maggi ◽  
Ulrich Krasselt ◽  
Hans-Peter Bossmann
Keyword(s):  
Failure Mechanism ◽  
Thermal Barrier Coating ◽  
Thermal Gradient ◽  
Field Experience ◽  
Lifetime Prediction ◽  
Cyclic Test ◽  
Thermal Barrier ◽  
Test Results ◽  
Barrier Coating ◽  
Coating Failure

Thermal barrier coating lifetime prediction has been commonly performed using furnace cyclic test results. This testing method causes coating failures driven by the bondcoat oxidation. This allows definition of lifetime prediction models representative of the field experience for thin thermal barrier coating systems where the difference between the bondcoat temperature and the coating surface are limited to 100–200 °C. Thick thermal barrier coating systems can experience coating surface temperatures 500 °C higher than the bondcoat temperature. In such cases sintering and phase transformations in the ceramic layers can also affect the coating lifetime. For this reason cyclic test methods like thermal gradient burner rig and laser heat-flux tests have been developed. They allow to test a coating system with surface temperatures >1400 °C while keeping bondcoat temperature <900 °C. The main issue of such tests is the often limited samples statistic, the reproducibility of the test conditions, and the coating failure mode that is not representative of the field experience. In Alstom, a burner rig test has been developed to solve these issues. It allows to test in parallel 10 samples, with a closed loop control system allowing live adjustment of the heat and cooling air input to keep an individually controlled constant thermal gradient with a homogeneous temperature distribution on the sample surface. Modeling of the test has been performed to understand the coating failure mechanism and to adapt the testing conditions such to get a failure mechanism closer to the relevant degradation mechanisms experienced in the field. Testing of coatings coming from the same production batch in various test campaign shows a low scatter in test results confirming that the burner rig test design allowed solving the test reproducibility and samples statistics issues. Examples will be shown how this burner rig test can be used for the development of lifetime prediction rules for thermal barrier coating systems.

Development of thermal gradient prediction method for thermal barrier coating

2014 ◽  
Vol 15 (6) ◽  
pp. 1029-1033 ◽  
Author(s):  
Yongseok Kim ◽  
Chang-Sung Seok ◽  
Si-Young Lee ◽  
Jae-Mean Koo ◽  
Sang-Hoon Kim ◽  
...  
Keyword(s):  
Thermal Barrier Coating ◽  
Thermal Gradient ◽  
Prediction Method ◽  
Thermal Barrier ◽  
Barrier Coating

Thermomechanical and Thermal Gradient Mechanical Fatigue Lifetime of Thermal Barrier Coating Systems

2017 ◽  
Vol 898 ◽  
pp. 1524-1531
Author(s):  
Zhong Jiao Zhou ◽  
Chang Peng Li ◽  
Guo Feng Chen ◽  
Xu Hua ◽  
Yong Li
Keyword(s):  
Prediction Model ◽  
Thermal Barrier Coating ◽  
Bond Coat ◽  
Thermal Gradient ◽  
Thermal Barrier ◽  
Fatigue Lifetime ◽  
Mechanical Fatigue ◽  
Barrier Coating ◽  
Segmentation Cracks ◽  
Delamination Cracks

Detailed damage analyses of an Y2O3 stabilized ZrO2 top coat (TC)–MCrAlY bond coat (BC)–superalloy thermal barrier coating (TBC) system during thermomechanical fatigue (TMF) and thermal gradient mechanical fatigue (TGMF) tests had been performed in present work. During tests, the lifetime of TBCs was strongly dependent on the strain ranges, pre-oxidation time and the thermal gradient in TBCs. Cracks were initiated in the TGO layer, propagated along the TC/TGO or TGO/BC interface, forming the delamination cracks. When the delamination cracks connected with the segmentation cracks which were initiated and propagated in TC, the TBCs spalled. The failure mechanism and stress were analyzed, which were significantly helpful to establish the TMF/TGMF lifetime prediction model for the TBCs.

HOT CORROSION OF CERIA-YTTRIA STABILIZED ZIRCONIA PLASMA SPRAYED THERMAL BARRIER COATING BY EUTECTIC VANDIUM PENTAOXIDE-SODIUM SULFATE

2018 ◽  
Vol 18 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Mohammed J Kadhim ◽  
Mohammed H Hafiz ◽  
Maryam A Ali Bash
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Monoclinic Phase ◽  
Volume Fraction ◽  
High Volume ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Plan View ◽  
Barrier Coating ◽  
Plasma Sprayed

The high temperature corrosion behavior of thermal barrier coating (TBC) systemconsisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coatwere characterized. The upper surfaces of CYSZ covered with 30 mg/cm2 , mixed 45 wt%Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC andinteraction times from 1 up to 8 h. The upper surface plan view of the coatings wereidentified for topography, roughness, chemical composition, phases and reaction productsusing scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-raydiffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed thephase transformation of nontransformable tetragonal (t') into monoclinic phase, presence ofYVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed theformation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.The formation of these compounds were combined with formation of monoclinic phase (m)from transformation of nontransformable tetragonal phase (t').

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