Showing papers by "Anette M. Karlsson published in 2004"
TL;DR: In this article, a numerical procedure for simulating the distortions exhibited by a thermally grown oxide (TGO) upon temperature cycling has been adapted to incorporate the microstructure of the bond coat.
Abstract: A numerical procedure for simulating the distortions exhibited by a thermally grown oxide (TGO) upon temperature cycling has been adapted to incorporate the microstructure of the bond coat. The focus is on the dual phase β/γ′ microstructure that develops upon oxidation of a system with a Pt-aluminide bond coat. The results reveal that the presence of the γ′-phase next to the TGO reduces its distortion locally, because of the superior high-temperature strength of γ′, relative to β. Conversely, in regions where the β-phase exists adjacent to the TGO, it distorts and the TGO propagates downward, while simultaneously lengthening. These results from the simulations are in direct correspondence with experimental observations.
27 citations
TL;DR: In this paper, the authors discuss recent achievements in understanding the residual stress, phase constituents, and electrochemical resistance (or capacitance) of thermal barrier coatings with an emphasis on the thermally grown oxide.
Abstract: The durability of thermal barrier coatings (TBCs) plays an important role in the service reliability and maintainability of hot-section components in advanced turbine engines for aerospace and utility applications. Photostimulated luminescence spectroscopy (PSLS) and electrochemical impedance spectroscopy (EIS) are being concurrently developed as complimentary nondestructive evaluation (NDE) techniques for quality control and liferemain assessment of TBCs. This paper discusses recent achievements in understanding the residual stress, phase constituents, and electrochemical resistance (or capacitance) of TBC constituents—with an emphasis on the thermally grown oxide. Results from NDE by PSLS and EIS are correlated to the nano- and microstructural development of TBCs.
11 citations
01 Jan 2004
TL;DR: In this paper, the authors show that the development of the instabilities can be greatly enhanced due to the thermal mismatch between the substrate and the bond coat, and that this mismatch can be increased by cyclic loading.
Abstract: Platinum modified aluminide bond coat used for oxidation protection in thermal barrier coatings are prone to develop morphological instabilities in the interface to the ceramic top coat. Previous work has shown that thereare a range of factors influencing this development, where key factors are the lateral growth strain in the thermally grown oxide, the relatively low yield strength of the Pt-modified bond coat at high temperature, and cyclic loading. In this study we show that the development of the instabilities can be greatly enhanced due to the thermal mismatch between the substrate and the bond coat.