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Microstructure, mechanical and thermal properties of YSZ thermal barrier coatings deposited by axial suspension plasma spraying

Poliarus Olena, Morgiel Jerzy, Żórawski Wojciech, Góral Anna, Pomorska Małgorzata, Wojciechowski Krzysztof T., Cherniushok Oleksandr

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 2

art. no., e89, 2023

Yttrium-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are indispensable elements of present-day turbine propulsion systems. The ones deposited with atmospheric plasma spraying (APS) are characterized by required low thermal conductivity, but they are unable to survive frequent thermomechanical loading and therefore their application is limited to parts remaining stationary. Expanding capability of TBCs is sought in various areas, but the one realized through modification of most proliferated apparatus used for plasma spraying (PS) (from radial to axial injection) and substituting micrometric powders with the nano-structured suspension needs least changes in the industry established procedures and offers the highest property improvement. The present experiment covered the deposition of ZrO2-8Y2O3 YSZ TBC using both atmospheric and suspension PS processes. They were performed with commercial micrometric and nano-structured YSZ (8% Y2O3) powders. The coatings morphology and microstructure were characterized with 3D profilometry, scanning and transmission electron microscopy (SEM/TEM) methods. Finally, the coating’s hardness and heat conductivity were measured. This complex approach allowed to state that PS of micrometric t’-ZrO2 powder having an admixture of m-ZrO2 phase is capable of only partial improvement in its homogenization. However, the suspension PS process of nano-structured powder eliminated any traces of the monoclinic phase from the coating. The TEM microstructure observations indicated that the suspension PS coating is built by in-flight solidified droplets as well as by the melted ones flattened on arrival. A surface layer of liquefied material on solid droplets increases their adhesion to surface asperities promoting pseudo-columnar growth of the coating. The preservation of monotonic slow increase of thermal conductivity during heating of the suspension PS coating means, that its pseudo-columnar microstructure is better suited to withstand high strains during such treatment.

Oxide layers fabricated by spray pyrolysis on metallic surfaces

Kobierowska K., Karpińska M., Molin S., Jasiński P.

Elektronika : konstrukcje, technologie, zastosowania

2012

Vol. 53, nr 1

74-76

In this paper the possibilities of using spray pyrolysis method to produce yttrium stabilized zircoma layers have been examined. A stainless steel, type 316L, was used as a substrate. It was important to determine the optimal conditions of the films preparation. The basic parameter in the pyrolysis technology process is a surface temperature, which was systematically examined. The layer was intended to be used as protective film for metallic implants. In order to determine the corrosion resistance and protective properties of produced layers, potentiodynamic measurements in mimicking tissue environment solution were carried out. It provided information about the corrosive effects, which occur on the steel surface and on the protective layer. The experimental results showed that improvement of corrosion resistance properties was obtained by spraying the precursor at 390°C.

W niniejszym artykule przebadane zostały możliwości zastosowania meetody pirolizy aerozolowej do wytwarzania warstw z tlenku cyrkonu stabilizowanego itrem na podłożu ze stali nierdzewnej 316L. W pierwszej kolejności bardzo ważne było określenie optymalnych warunków przygotowania warstw. Podstawowym parametrem w procesie napylania warstw metodą pirolizy aerozolowej jest temperatura powierzchni, której wpływ systematycznie przebadano. Przeprowadzone badania wykazały przydatność warstw z zastosowaniem tlenku cyrkonu stabilizowanego itrem wytworzonych metodą pirolizy aerozolowej. W celu określenia odporności na korozję oraz właściwości ochronnych zostały przeprowadzone pomiary potencjodynamiczne w roztworze imitującym środowisko tkankowe. Wyniki uzyskane z pomiarów laboratoryjnych dostarczyły informacji na temat zjawisk korozyjnych zachodzących na powierzchni stali oraz warstw ochronnych. Badania pokazały, że warstwą wykazującą poprawę właściwości antykorozyjnych jest ta, która powstała poprzez napylenie prekursora polimerowego w temperaturze 390°C.