Abstract

With a view to the development of thermal barrier coatings on turbine blades, such coatings were developed on the basis of Y2O3-stabilized ZrO2 and optimized with respect to their reproducibility. Particular attention was given to the spray efficiency and, in particular, the coating porosity. The porosity was measured by Hg porosimetry, which proved to be a reliable method of characterization. The plasma gas flows play an important role for a high reproducibility of the coating properties. High reproducibility of the porosity and spray efficiency was achieved for low argon flows, for which the influences of all the other parameters, such as electric arc current, meandering and sample cooling during plasma spraying or the cathode operating time of the burner, were of minor relevance for the coating properties. The spray efficiency is clearly influenced by the given powder rate and the carrier gas flow for the type of burner used. The change of the grain fraction in the plasma jet was examined for two different powders. Finally, thermal cycling tests were carried out and evaluated for pre-optimized thermal barrier coating samples.

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