Abstract The operating temperature of the combustion chamber of heavy-duty gas turbines has been continually increased in order to improve engine power and efficiency. Part of this improvement is due to the use of ceramic thermal barrier coatings (TBCs), which reduce thermal flow from the combustion gas to the metallic structural part of the components. The most traditional deposition technique for bond coats on combustion chamber components is Air Plasma Spray; whereas this technology is the optimum one for ceramic coatings, due to air entrapment in the plasma jet significant oxidation of Al is produced during bond coats deposition. The thermal design of a thick porous TBC able to reduce the heat flow to the minimum allowable by the materials temperature limits is performed. Paper includes a German-language abstract.

Abstract The HVOF spraying process is used to produce NiCoCrAlYRe layers, which serve as adhesive layers for plasma-sprayed thermal insulation layers. This paper investigates the influence of the HVOF spray parameters on the structure and properties of the layers. The parameters are optimized to produce high layer densities with low degrees of oxidation and the same surface roughness for subsequent TBC coatings. High-temperature oxidation of HVOF-sprayed NiCoCrAlY Re layers by means of TBC layers is investigated at temperatures of 950 and 1000 deg C in time cycles of up to 3000 hours. A vacuum-sprayed layer with the same composition is examined as a reference. Oxidized layers are characterized, and peculiarities such as oxide layer thickness, proportion of the NiAl phase, and imperfections at the boundary layer are measured. It turned out that the less expensive HVOF layer offers the same protective properties as a VPS layer. Paper includes a German-language abstract.