Finite element thermal stress solutions for thermal barrier coatings

Thermal Barrier Coatings have been widely used in modern turbine engines to protect the nickel based metal substrate from the high temperature service conditions, 1600–1800 K. In this study, some of the failure mechanisms of typical Air Plasma Sprayed Thermal Barrier Coatings (TBC) used in after-burner structures composed of three major layers: Inconel 718 substrate, NiCrAlY based metallic bond coat (BC) and Yttria Stabilized Zirconia (YSZ) based ceramic top coat (TC) are investigated. Investigation of the cracking mechanism of TBC in terms of design and performance is very important because the behavior of TBCs on ductile metallic substrates is brittle. To this end, four-point bending experiments conducted in Kütükoğlu (2015) is analyzed by using the Extended Finite Element Method (XFEM). All the analyses are conducted with the commercial finite element software ABAQUS. Three different models with varying TC and BC thicknesses are studied under four-point bending. It is observed that multiple vertical cracks are initiated in the TC. Cracks initiate at the top of YSZ and propagate through the whole TC. It is observed that the average crack spacing increases with the increasing thickness of the TC. Numerical results are found to be consistent with the experimental results. In other words, the average crack spacing for three different models are similar with the experimental results.

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The Numerical Modeling of Thermal Stress Distribution in Thermal Barrier Coatings

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0221 ◽

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.

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Finite element simulation of surface micro-indentation behavior of yttria stabilized zirconia thermal barrier coatings with microstructural characteristic of columnar grains and sub-grains based on a nonlinear contact model

Computational Materials Science ◽

10.1016/j.commatsci.2013.09.034 ◽

2014 ◽

Vol 82 ◽

pp. 244-256 ◽

Cited By ~ 14

Author(s):

L. Wang ◽

X.H. Zhong ◽

J.S. Yang ◽

S.Y. Tao ◽

W. Zhang ◽

...

Keyword(s):

Finite Element ◽

Thermal Barrier Coatings ◽

Yttria Stabilized Zirconia ◽

Thermal Barrier ◽

Stabilized Zirconia ◽

Barrier Coatings ◽

Element Simulation ◽

Nonlinear Contact ◽

Columnar Grains ◽

Micro Indentation

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Investigation about Thermal Shock Property of Plasma-Spraying Sm2Zr2O7 Thermal Barrier Coatings with Different Substrate Condictions

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.354-355.145 ◽

2011 ◽

Vol 354-355 ◽

pp. 145-148

Author(s):

Hong Song Zhang ◽

Hong Chan Sun

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Thermal Expansion ◽

Residual Stresses ◽

Plasma Spraying ◽

Thermal Barrier Coatings ◽

Thermal Barrier ◽

Shear Stresses ◽

Substrate Thickness ◽

Barrier Coatings

Effect of substrate conditions, including material type, thickness and radius of substrate, on thermal-shocking stresses of plasma spraying Sm2Zr2O7/ NiCrCoAlY TBCs was analyzed through finite element method. Results show that radial stresses decrease with time increasing, and they decrease with the increasing of distance from center to edge along radius. However, axial residual stresses increse abruptly at the edge of specimen. All residual stresses increse with incresing of thermal expansion coefficient of substrate. Radial stresses increase with substrate thickness increasing, however, they are not effectd by substrate thickness if it is great than 20mm.and axial residual stresses and shear stresses are not effected by the substrate thickness. The maximum values of axial stresses and shear stresses were not effected by sustrate radius. and values of radial stresses remian invariable when substrate radius is over 18mm.

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