The thermal barrier coatings (TBC) enable to lower temperature (at approx. 170°C) of operating elements in a hot section of gas turbine to a range, which enables to operate for a long time in conditions of high temperature influence and prolongs operation of them even three or four times. Usually, the TBC coverings are constructed of four layers:

• superalloys on a base of nickel;
• outer ceramic zone, from which low thermal conduction is required;
• bond coat of a type Ni(Co)CrAlY or diffusion layer of a type (Ni,Pt)Al;
• layer of barrier oxides, accrueting as a result of temperature growth TGO (thermally grown oxide).

In this article detailed microstructural characterisation of three types of MCrAlY powders and VPS sprayed coatings such as Ni-23Co-17Cr-12.5Al-0.45Y, Co-32Ni-21Cr-8Al-0.5Y and Ni-22Cr-10Al-Y will be presented. The study scope included chemical and phase composition analysis of powders and layers after spraying process. It was stated that e.g. in a case of powder, comprising 23% Co, the dominating phases are as following: NiAl phase with added cobalt in a form of (Ni,Co)Al and a phase on nickel matrix type Ni(Cr,Y). Shape and surface morphology of the tested powders were also characterized. The microstructural assessment of the layers obtained by spraying the analysed powders was performed in the second part of the article. Phase composition, roughness and morphology of top layer of coatings were assessed.   Criteria assessment of the obtained layers was performed for their application as the base layer in TBCs.

Financial support of Structural Funds in the Operational Programme - Innovative Economy (IE OP) financed from the European Reginal Development Fund - Project No POIG.0101.02-00-015/08 is gratefully acknowledged.

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