scholarly journals Role of mechanical loads in inducing in-cycle tensile stress in thermally grown oxide

2012 ◽  
Vol 100 (11) ◽  
pp. 111906 ◽  
Author(s):  
Rene Diaz ◽  
Melan Jansz ◽  
Mitra Mossaddad ◽  
Seetha Raghavan ◽  
John Okasinski ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Thermally Grown Oxide ◽  
Mechanical Loads ◽  
Thermally Grown

Tensile stress and creep in thermally grown oxide

2006 ◽  
Vol 5 (5) ◽  
pp. 349-351 ◽  
Author(s):  
Boyd W. Veal ◽  
Arvydas P. Paulikas ◽  
Peggy Y. Hou
Keyword(s):  
Tensile Stress ◽  
Thermally Grown Oxide ◽  
Thermally Grown

The Role of Oxidation-Induced Cavities on the Failure of the Thermally Grown Oxide on Binary β-NiAl Alloys

2003 ◽  
Vol 94 (3) ◽  
pp. 157-162 ◽  
Author(s):  
D. Zimmermann ◽  
V. K. Tolpygo ◽  
M. Rühle ◽  
D. R. Clarke
Keyword(s):  
Thermally Grown Oxide ◽  
Thermally Grown

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 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.

scholarly journals The combined effects of material creep and mechanical loads on the extension of thermally grown oxide instability

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401775122
Author(s):  
Shifeng Wen ◽  
Sibo Zhou
Keyword(s):  
Bond Coat ◽  
Normal Growth ◽  
Thermally Grown Oxide ◽  
Extension Rate ◽  
Oxide Interface ◽  
Mechanical Loads ◽  
Downward Displacement ◽  
Material Creep ◽  
Upward Displacement ◽  
Thermally Grown

The instability of the thermally grown oxide is the fundamental source leading to failure relevant to spallation and delamination of top coat. A finite element model is developed to understand failure mechanism of thermal barrier coating systems. Lateral and normal growth strains are stimulated by ABAQUS field variable expansion. Our results show that the valley region of top coat/thermally grown oxide interface and the peak region of thermally grown oxide/bond coat interface are the initiation locations of cracks. The creep can suppress downward displacement at the valley and promote the upward displacement at the periphery. Large material creep induced by further enhanced residual stress can restrain the increasing trend of the tensile stress within top coat and contribute to changes of thermally grown oxide morphology. Conversely, the applied load can promote the downward displacement at the valley and suppress the upward displacement at the periphery. The larger mechanical loads enhance the displacement rate toward bond coat layer, implying that the larger extension rate of thermally grown oxide instability accelerates the coating failure.

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