Abstract
Thermal barrier coating failures almost always occur by spallation due to interlayer stresses. During service, a thermally grown oxide forms between the bond coat and insulating ceramic. This oxide has a significant impact on the life of the coating. In this work, a number of innovative methods are used to study TBC bond coats, topcoats, and interface oxide layers. CoNiCrAlY bond coats produced by APS, VPS, and HVOF spraying are analyzed by X-ray photoelectron spectroscopy (XPS) and compared based on the presence of oxides. Zirconia powders and topcoat layers are examined by X-ray diffraction and Raman scattering in order to study the crystal structure and spatial distribution of different phases. The authors also use Raman microscopy to map the surface of the topcoat layer and XPS to determine the elemental composition. This provides useful data because surface and interface roughness affect the spallation resistance of the oxide layer and thus the expected life of the TBC. Paper includes a German-language abstract.
