|
2784 |
|
Characterization of microstructure and thermal properties of Gd2Zr2O7 and gradient Gd2Zr2O7/YSZ bi-layer type of the TBC coatings |
|
Grzegorz Moskal / Silesian University of Technology, Poland |
|
In this paper, evaluation of a microstructure of the TBC thermal barrier coating was carried out, and these barriers were obtained as a result of spraying by the APS method on: "powder on a base of the Gd2Zr2O7 gadolinium zirconate mono-layer coatings; "mixture of the Gd2Zr2O7:8YSZ powders in proportions 25/75, 50/50 and 75/25 gradient coatings; "standard powder type 8YSZ and powder on a base of the Gd2Zr2O7 gadolinium zirconate coatings type bi-layer. A scope of researches comprised evaluation of an outer sprayed ceramic layer in order to define its phase composition, assessment of tensions and characterization of surface topography and determination of geometrical parameters, which quantitavely describe the surface. In this case, the following methods were applied: the XRD method, sin2(ksi) method and laser microscopy. An analysis of an inner structure of all layers was performed as well, what enabled to define quantitavely architecture of cracks and pores, depending on a type of a layer. By use of the LFA427 appliance, produced by the Netzsch Company, thermal diffusivity of a ceramic layer was characterized as well, determining it on a base of a model for bi-layer systems. A measurement range was from 25°C to 1100°C with added 10 hours of annealing in this temperature. Basing on results of measurements of specific heat and coefficient of linear expansion in a function of temperature, while these results were obtained for pure powders, calculations of a value of a thermal conductivity coefficient for all types of layers, were carried out as well. Financial support of Structural Funds in the Operational Programme - Innovative Economy (IE OP) financed from the European Regional Development Fund - Project No POIG.0101.02-00-015/09 is gratefully acknowledged. |