Papers by Keyword: Thermal Barrier Ceramic Coatings

Abstract: This paper analyses the degradation of a ceramic top coating 70%ZrO2 – 30%CaO deposited onto a stainless steel AISI 304 by thermal spray, using Ni-6%Al-5%Mo as overlay coating. These thermal barrier coatings were heat treated for 48, 120 and 288 h at 800 °C to evaluate the degradation of these materials by isothermal oxidation. The microstructure evolution during oxidation was analysed by environmental scanning electron microscopy, transmission electron microscopy and X ray microanalysis. A thermally grown oxide layer was observed between the overlay coating and the ceramic top coating after oxidation. This layer was formed by a mixed Al, Ni and Mo oxides.

Abstract: The intent of this article was to study the failure mechanism of thermal barrier coatings (TBCs) induced by buckling. The main content included the following two parts. The first part investigated the thermal residual stresses fields in TBCs with thermal cycles, which induced by the non-linear coupled effect of temperature gradient, thermal fatigue and creep strain of TBCs. One found that the residual stresses in ceramic coating were compressive and accumulated with thermal cycles, which may be high enough to induce the buckling failure of ceramic coating. The second part studied the critical buckling failure loading of the ceramic coating in TBCs under the condition of the compressive loading by use a theoretical model. Finally, a buckling plane, i.e. s T n − plane, was obtained by combined the above sections and applied to predict the buckling failure of the TBCs system. In this plane, it was divided into the two parts, i.e., non-buckling region and buckling region.