scholarly journals A prominent driving force for the spallation of thermal barrier coatings: Chemistry dependent phase transformation of the bond coat

2017 ◽  
Vol 137 ◽  
pp. 22-35 ◽  
Author(s):  
L.T. Wu ◽  
R.T. Wu ◽  
P. Xiao ◽  
T. Osada ◽  
K.I. Lee ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Driving Force ◽  
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.

scholarly journals Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

Metals ◽  
2014 ◽  
Vol 4 (4) ◽  
pp. 503-518 ◽  
Author(s):  
Torben Fiedler ◽  
Tatiana Fedorova ◽  
Joachim Rösler ◽  
Martin Bäker
Keyword(s):  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Bond Coat Alloy

Improvement of EB-PVD thermal barrier coatings by treatments of a vacuum plasma-sprayed bond coat

2008 ◽  
Vol 203 (1-2) ◽  
pp. 160-170 ◽  
Author(s):  
U. Schulz ◽  
O. Bernardi ◽  
A. Ebach-Stahl ◽  
R. Vassen ◽  
D. Sebold
Keyword(s):  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Vacuum Plasma ◽  
Plasma Sprayed

Microstructure and Oxidation Resistance of Thermal Barrier Coatings with Different Ceramic Layer

2021 ◽  
Vol 320 ◽  
pp. 31-36
Author(s):  
Marek Góral ◽  
Tadeusz Kubaszek ◽  
Barbara Kościelniak ◽  
Marcin Drajewicz ◽  
Mateusz Gajewski
Keyword(s):  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Ceramic Layer ◽  
Thermal Barrier ◽  
Elemental Mapping ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Bond Coats ◽  
All Ceramic ◽  
Zirconia Oxide

Thermal barrier coatings are widely used for protection of gas turbine parts against high temperature oxidation and hot corrosion. In present work the microstructural assessment of TBCs produced by atmospheric plasma spray (APS) method was conducted. Three types of ceramic powders were used: magnesia- stabilized zirconia oxide (Metco 210), yttria stabilized zirconia oxide (YSZ -Metco 204) and fine-grained YSZ – Metco 6700. As a base material the Inconel 713 was used as well and CoNiCrAlY was plasma sprayed (APS) as a bond coat. The thickness of all ceramic layers was in range 80 – 110 μm. The elemental mapping of cross-section of magnesia-stabilized zirconia showed the presence of Mg, Zr and O in outer layer. In the YSZ ceramic layer the Y, Zr and O were observed during elemental mapping. The isothermal oxidation test was conducted at 1100 °C for 500 h in static laboratory air. On all samples the delamination and spallation of ceramic layers was observed. Chemical composition analysis of coatings showed the presence of two areas: the first one contained elements from bond coats: Ni, Cr, Al, Co and second area contained O, Cr Co and O that suggest the scale formation. The obtained results showed the total degradation of all ceramic layers as a result of internal stresses in bond-coat. Microscopic analysis showed the areas with complete degradation of bond coats and formation of thick oxides layer.

Thermal Cycling Behavior of Lanthanum-Cerium Oxide Thermal Barrier Coatings Prepared by Air Plasma Spraying

2007 ◽  
Vol 336-338 ◽  
pp. 1759-1761 ◽  
Author(s):  
Wen Ma ◽  
Yue Ma ◽  
Sheng Kai Gong ◽  
Hui Bin Xu ◽  
Xue Qiang Cao
Keyword(s):  
Cerium Oxide ◽  
Plasma Spraying ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Room Temperature ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Air Plasma Spraying ◽  
Cyclic Testing ◽  
Barrier Coatings

Lanthanum-cerium oxide (La2Ce2O7, LC) is considered as a new candidate material for thermal barrier coatings (TBCs) because of its low thermal conductivity and high phase stability between room temperature and 1673K. The LC coatings with different La2O3 contents were prepared by air plasma spraying (APS) and their lifetime was evaluated by thermal cyclic testing from room temperature to 1373 K. The structures of the coatings were characterized by XRD and SEM and the deviation of the composition from the powder was determined by EDS analysis. Long time annealing for the freestanding coating at 1673K reveals that the near stoichiometric LC coating is stable up to 240h, and the stability decreases with increasing the deviation from stoichiometric LC composition. During thermal cyclic testing, spallation was observed within the top coat near the bond coat. It is considered that the effect of intrinsic stress caused by the coefficient of thermal expansion (CTE) mismatch between top coat and bond coat is larger than that of thermally grown oxide (TGO) and the bond adherence of top coat with TGO.

scholarly journals The Numerical Modeling of Thermal Stress Distribution in Thermal Barrier Coatings

2017 ◽  
Vol 62 (3) ◽  
pp. 1433-1437
Author(s):  
A. Jasik
Keyword(s):  
Thermal Stress ◽  
Stress Distribution ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Thermal Spraying ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Insulation Layer ◽  
Barrier Coatings ◽  
Thermal Stress Distribution

Abstract The paper presents the results of numerical calculations of temperature and thermal stress distribution in thermal barrier coatings deposited by thermal spraying process on the nickel based superalloy. An assumption was made to apply conventional zirconium oxide modified with yttrium oxide (8YSZ) and apply pyrochlore type material with formula La2Zr2O7. The bond coat was made of NiCoCrAlY. Analysis of the distribution of temperature and stresses in ceramic coatings of different thicknesses was performed in the function of bond-coat thickness and the type of ceramic insulation layer. It was revealed that the thickness of NiCrAlY bond-coat has not significant influence on the stress distribution, but there is relatively strong effect on temperature level. The most important factor influenced on stress distribution in TBC system is related with type and properties of ceramic insulation layer.

Sign in / Sign up

Export Citation Format

Share Document