On the delamination of thermal barrier coatings in a thermal gradient
نویسنده
چکیده
Thermal barrier coating (TBC) systems are susceptible to delamination failures in the presence of a large thermal gradient. These failures, which occur within the TBC layer, are very different in character from those associated with the thermally grown oxide. Three possible causes of internal delamination are analyzed. In all cases, the thermomechanical properties of the TBC are allowed to vary because of sintering. (a) One mechanism relates to exfoliation of an internal separation in the TBC due to a through thickness heat flux. (b) Another is concerned with edge-related delamination within a thermal gradient. (c) The third is a consequence of sintering-induced stresses. The results of these analyses, when used in combination with available properties for the TBC, strongly suggest that the second mechanism (b) predominates in all reasonable scenarios. Consequences for the avoidance of this failure mode are discussed. 2002 Elsevier Science B.V. All rights reserved.
منابع مشابه
Simulation of the effect of sub- micron interface roughness on the stress distribution in functionally graded thermal barrier coatings (FG- TBC)
In this research, a numerical modeling was utilized to calculate the stresses caused during thermal cycling in a functionally graded thermal barrier coating (FG - TBC). The temperature – dependent material response of this protective material was taken into account and the effects of thermal cycle and interface morphology of the ceramic / metallic layer in functionally graded coating system wa...
متن کاملMonitoring Delamination of Thermal Barrier Coatings during Interruped High-heat-flux Laser Testing Using Upconversion Luminescence Imaging
Upconversion luminescence imaging of thermal barrier coatings (TBCs) has been shown to successfully monitor TBC delamination progression during interrupted furnace cycling. However, furnace cycling does not adequately model engine conditions where TBC-coated components are subjected to significant heat fluxes that produce through-thickness temperature gradients that may alter both the rate and ...
متن کاملDelamination Susceptibility of Coatings Under High Thermal Flux
Delamination of coatings initiated by small cracks paralleling the free surface is investigated under conditions of high thermal flux associated with a through-thickness temperature gradient. A crack disrupts the heat flow thereby inducing crack tip stress intensities that can become critical. A complete parametric dependence of the energy release rate and mode mix is presented in terms of the ...
متن کاملThe Influence of Transient Thermal Gradients and Substrate Constraint on Delamination of Thermal Barrier Coatings
A systematic study of factors affecting the delamination energy release rate and mode mix of a thermal barrier coating attached to a substrate is presented accounting for the influence of thermal gradients combined with rapid hot surface cooling. Transient thermal gradients induce stress gradients through the coating and substrate, which produce overall bending if the substrate is not very thic...
متن کاملAN INVESTIGATION ON EFFECT OF BOND COAT REPLACEMENT ON HOT CORROSION PROPERTIES OF THERMAL BARRIER COATINGS
In the present study NiCrAlY bond coating layer was produced by electroplating against common atmospheric plasma spraying (APS). Both types of the bond coats were applied on IN738LC base metal then, the YSZ (ZrO2-8% Y2O3) thermal barrier top layer was coated by atmospheric plasma spray technique. Hot corrosion is one of the main destructive factors in thermal barrier coatings (TBCs) which come ...
متن کامل