Modelling the influence of reactive elements on the work of adhesion between a thermally grown oxide and a bond coat alloy

2006 ◽  
Vol 57 (3) ◽  
pp. 223-229 ◽  
Author(s):  
I. J. Bennett ◽  
W. G. Sloof
Keyword(s):  
Bond Coat ◽  
Thermally Grown Oxide ◽  
Work Of Adhesion ◽  
Reactive Elements ◽  
Bond Coat Alloy ◽  
Thermally Grown

Failure of a Thermal Barrier System Due to a Cyclic Displacement Instability in the Thermally grown Oxide

2000 ◽  
Vol 645 ◽  
Author(s):  
Daniel R. Mumm ◽  
Anthony G. Evans
Keyword(s):  
Bond Coat ◽  
Large Scale ◽  
Thermal Exposure ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Oxide Interface ◽  
Barrier Coating ◽  
Out Of Plane ◽  
Plane Displacement ◽  
Thermally Grown

ABSTRACTThe mechanism controlling the cyclic failure of a commercial thermal barrier system has been investigated. The system comprises an electron-beam physical vapor deposited (EB-PVD) yttria-stabilized zirconia thermal barrier coating (TBC), deposited on a (Ni Pt) Al bond coating. The thermally grown oxide (TGO) layer that forms between the TBC and bond coat at high temperature is unstable with respect to out of plane displacement, provided initial perturbations are present. With cyclic thermal exposure, the TGO displaces into the bond coat at periodic interfacial sites. The out-of-plane displacements induce strains above the TGO, normal to the interface, that cause cracking. The cracks nucleate either within the TBC layer or at the TBC/TGO interface, and extend laterally until they coalesce with cracks from other sites and coating failure occurs by large scale buckling. The TGO displacements are accommodated by visco-plastic deformation of the underlying bond coat, and are driven by a lateral component of the growth strain in the TGO. The susceptibility of the TGO to out-of-plane displacement depends critically upon the initial morphology of the metal/oxide interface. The observed material responses are compared with predictions of a ‘ratcheting’ model.

The role of formation of continues thermally grown oxide layer on the nanostructured NiCrAlY bond coat during thermal exposure in air

2012 ◽  
Vol 261 ◽  
pp. 287-297 ◽  
Author(s):  
Mohammadreza Daroonparvar ◽  
Mohammad Sakhawat Hussain ◽  
Muhammad Azizi Mat Yajid
Keyword(s):  
Oxide Layer ◽  
Bond Coat ◽  
Thermal Exposure ◽  
Thermally Grown Oxide ◽  
Thermally Grown

scholarly journals Growth Behavior of Thermally Grown Oxide Layer with Bond Coat Species in Thermal Barrier Coatings

2018 ◽  
Vol 55 (4) ◽  
pp. 344-351
Author(s):  
Sung Hoon Jung ◽  
Soo Hyeok Jeon ◽  
Hyeon-Myeong Park ◽  
Yeon Gil Jung ◽  
Sang Won Myoung ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Thermally Grown Oxide ◽  
Growth Behavior ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Thermally Grown

Characterization of Thermally Grown Oxide on Cold Sprayed CoNiCrAlY Bond Coat in Thermal Barrier Coating

2011 ◽  
Vol 696 ◽  
pp. 324-329 ◽  
Author(s):  
Abreeza Manap ◽  
Dowon Seo ◽  
Kazuhiro Ogawa
Keyword(s):  
Electron Microscopy ◽  
Thermal Barrier Coating ◽  
Bond Coat ◽  
Oxidation Behavior ◽  
Mixed Oxides ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Bond Coats ◽  
Barrier Coating ◽  
Thermally Grown

This paper presents the results of a study of the microstructure and oxidation behavior of thermal barrier coating (TBC) with air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) top coat and CoNiCrAlY bond coat deposited using two different spraying techniques, low pressure plasma spray (LPPS) and cold spray (CS). The objective is to investigate the thermally grown oxide (TGO) thickness and oxide scale composition of TBC subjected to isothermal oxidation and creep tests at 900 °C by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrometry (EDX) analyses in order to evaluate the reliability of the CS technique. It was found that the TGO thicknesses for TBC with CS bond coats were smaller and the TGO was composed of mainly alumina with little or no mixed oxides. TGO growth rate was also affected by the applied stress. Smaller TGO thicknesses were observed for the non-creep TBC for both CS and LPPS bond coats. Overall findings indicate that the oxidation behavior of the TBC with CS bond coat is superior compared to that of the TBC with LPPS bond coat.

Finite Element Analysis of the Effects of Thermally Grown Oxide Thickness and Interface Asperity on the Cracking Behavior Between the Thermally Grown Oxide and the Bond Coat

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Jishen Jiang ◽  
Bingqian Xu ◽  
Weizhe Wang ◽  
Richard Amankwa Adjei ◽  
Xiaofeng Zhao ◽  
...  
Keyword(s):  
Finite Element ◽  
Bond Coat ◽  
Cohesive Zone Model ◽  
Interfacial Crack ◽  
Maximum Tensile Stress ◽  
Thermally Grown Oxide ◽  
Zone Model ◽  
Element Analysis ◽  
Cracking Behavior ◽  
Thermally Grown

Finite element simulations based on an interface cohesive zone model (CZM) have been developed to mimic the interfacial cracking behavior between the α−Al2O3 thermally grown oxide (TGO) and the aluminum-rich Pt–Al metallic bond coat (BC) during cooling from high temperature to ambient temperature. A two-dimensional half-periodic sinusoidal geometry corresponding to interface undulation is modeled. The effects of TGO thickness and interface asperity on the stress distribution and the cracking behavior are examined by parametric studies. The simulation results show that cracking behavior due to residual stress and interface asperity during cooling process leads to stress redistribution around the rough interface. The TGO thickness has strong influence on the maximum tensile stress of TGO and the interfacial crack development. For the sinusoidal asperities, there exists a critical amplitude above which the interfacial cracking is energetically favored. For any specific TGO thickness, crack initiation is dominated by the amplitude while crack propagation is restricted to the combine actions of the wavelength and the amplitude of the sinusoidal asperity.

scholarly journals Degradation of the Mechanical Properties of Aluminide Coatings as a Result of Thermal Cycling

2000 ◽  
Author(s):  
Mark Walter ◽  
Hyungjun Kim
Keyword(s):  
Bond Coat ◽  
State Of The Art ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Bond Coats ◽  
Aluminide Coatings ◽  
Platinum Aluminide ◽  
Pack Cementation Process ◽  
Super Alloy ◽  
Thermally Grown

Abstract Thermal barrier coatings (TBCs) are typically composed of a ceramic top coat, a thermally grown oxide, and an aluminide bond coat. These three layers each have specific roles in protecting super alloy substrates. State-of-the-art TBCs use Zirconia for the ceramic top coat and develop Alumina thermally grown oxide. Although the bond coats almost universally contain aluminides, their composition and processing vary greatly. In this work, a platinum aluminide bond coat system which was processed using an unactivated pack cementation process is studied. This bond coat system was formed on 1 inch diameter CMSX-4 super alloy disks.

scholarly journals Thermal Cycling Induced Bond-Coat Rumpling as a Precursor to TBC Failure

2000 ◽  
Author(s):  
D. R. Clarke ◽  
V. K. Tolpygo
Keyword(s):  
Phase Transformation ◽  
Thermal Cycling ◽  
Bond Coat ◽  
Microstructural Characterization ◽  
Thermally Grown Oxide ◽  
New Model ◽  
Gamma Prime ◽  
Ni3al Phase ◽  
Thermally Grown

Abstract Microstructural observations of TBCs failed under thermal cycling conditions reveal that failure is associated with extensive local separations between either the thermally grown oxide and the TBC or within the TBC itself close to the thermally grown oxide. Based on extensive microstructural characterization and measurements of concentration profiles within the bond-coat, we present a new model for the cause of these separations based on local increases in the density of the bond coat associated with the beta-NiAl to gamma-prime Ni3Al phase transformation. The phase transformation, driven by aluminum depletion required to form the protective alumina thermally grown oxide, is constrained by the overlying TBC thereby generating tensile stresses across the TBC/TGO interface and its vicinity. The observations and evidence for the new model will be described together with the role of thermal cycling.

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