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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

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2023

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Vol. 23, no. 2

art. no., e89, 2023

EN

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.

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Właściwości mechaniczne powłok Cr₃C₂-25(Ni20Cr) natryskiwanych zimnym gazem

Soboń Dominika, Żórawski Wojciech, Makrenek Medard

Mechanik

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2019

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R. 92, nr 2

128--130

PL

Proces natryskiwania zimnym gazem to najnowocześniejsza metoda natryskiwania cieplnego. W artykule przedstawiono wyniki badań powłoki wytworzonej w tym procesie z proszku Cr3C2-25(Ni20Cr) na podłożu ze stopu Al 7075. Ponadto pokazano wyniki własnych badań mikrostruktury i analizy właściwości mechanicznych uzyskanej powłoki. Zastosowane parametry natryskiwania pozwoliły na wytworzenie powłoki charakteryzującej się spójną mikrostrukturą i znikomą porowatością.

EN

The cold gas spraying process is the most modern method of thermal spraying. The article presents the coating produced in this process from Cr3C2-25(Ni20Cr) powder on the Al 7075 alloy substrate. The properties of microstructure and mechanical properties of the deposited coating are also shown. The process parameters of the applied powder allowed to obtain coatings characterized by a consistent microstructure and negligible porosity.

3

Scuffing resistance of plasma-sprayed ceramic coatings.

Żórawski Wojciech

Advances in Manufacturing Science and Technology

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2001

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Vol. 25, nr 3

137-146

EN

Plasma-sprayed coatings are widely used in various branches of industry, yet the process of their wear has not been investigated thoroughly. That knowledge would be particularly useful in the case of coatings sprayed on high-load machine parts, where the fundamental problem is durability and resistance to scuffing. The investigations discussed in this paper focus on the influence of the microstructure of plasma-sprayed coatings on scuffing resistance. The tests involved spaying alumina and chromia powders with three different ranges of grain sizes and evaluating their scuffing resistance under the friction conditions by means of a block-on-roll type tester. It was found that coatings formed by spraying chromia powder with the finest granulation interacting with carbon-graphite demonstrated the highest resistance to scuffing.

PL

Powłoki natryskiwane plazmowo są często stosowane w różnych gałęziach przemysłu, jednak proces ich zużywania nie jest dostatecznie poznany. Dotyczy to zwłaszcza powłok pracujących na wysokoobciążonych częściach maszyn, gdzie podstawowym zagadnieniem jest trwałość i odporność na zatarcie. W pracy przedstawiono wyniki badań wpływu mikrostruktury powłok natryskiwanych plazmowo na odporność na zatarcie. Powłoki z tlenku glinu i tlenku chromu zostały nałożone z proszków o trzech różnych granulacjach. Ocena odporności na zatarcie została przeprowadzona na testerze typu rolka-klocek w warunkach tarcia suchego. Największą odporność na zatarcie wykazała powłoka z tlenku chromu, nałożona z proszku o najmniejszej granulacji, współpracująca z węglografitem.