Generally, the TBC applied in gas turbines is made up of two components: a bond coat created by the vacuum or low pressure plasma-sprayed MCrAlY (M = Ni, Co) and a top coat of yttria and partially stabilized zirconia produced by the atmospheric plasma spraying (APS) or electron beam-physical vapour deposition (EB-PVD). Zirconium oxide, modified with yttrium oxide (YSZ) is a main material of a ceramic layer. Although, the TBC barrier layers, which are based on ceramics type YSZ, have been used for 30 years, their life is a basic problem, because it limits wider application of them. The basic problem depends on production of a ceramic material, provided for an outer layer of thermal barriers (provided to be used in high temperature creep resisting alloys on a base of nickel and niobium as well), and this material is characterized by reduced thermal conduction, comparing to the YSZ, especially in high temperature. The microstructural characteristics of TBC layers on the basis of a new type of Gd₂Zr₂O₇ compound was presented in this article. The powder of Co-32Ni-21Cr-8Al-0.5Y type sprayed with the VPS method was used as the base layer. The ceramic layer was sprayed with the APS method. The study scope included standard characteristics of the base and ceramic layer microstructure according to criteria assessment used heretofore for standard TBC layers on the YSZ basis. The study performed showed that the layer of a new type is 250mm thick and uniform in this respect on the whole length (2cm) analysed. No vertical or horizontal cracks were found. No delamination effects of individual layers were either noticed. The porosity observed was at the level of approx. 2.5%, but no massive porosity was found.

This work was supported by the Polish Ministry of Education and Science under the research project No PBZ-MNiSW-01/I/2007

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