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.

Thermal barrier coatings typically consist of a ceramic topcoat and a metallic bond coat that promotes adhesion and protects the substrate from corrosion. This study evaluates surface preparation processes used prior to the application of the bond coat layer. In the experiments, NiCrAlY bond coats are plasma sprayed onto Inconel substrates prepared by various methods, including dry and wet blasting and solid CO 2 cryogenic cleaning. At different points in the process, samples are extracted and characterized based on surface roughness, subsurface hardness, morphology, adhesion, interface contamination, and coating thickness and structure. Paper includes a German-language abstract.

This paper evaluates the effect of bond coat oxidation on the coating life of graded, duplex, and triplex TBC systems deposited on Inconel 617 and 738 substrates by vacuum plasma spraying. In oxidation experiments, the triplex system had the lowest number of cycles to failure. The graded system was found to be superior to the duplex system in terms of oxidation resistance, but inferior in terms of hot corrosion resistance. It was also found that the various TBC systems are more durable on Inconel 738 than on Inconel 617, particularly the graded systems. Paper includes a German-language abstract.

This paper investigates the influence of plasma variations on the microstructure and application rate of aluminum coatings and compares layers obtained using parameters that result in the same particle properties but different changes in stress. Layers produced in the less stable plasma state were found to be more porous and contained a significantly higher number of unfused particles than those produced under relatively stable conditions. These differences are due to the physical properties of the particle beam as revealed by laser illumination. Paper includes a German-language abstract.