University of Oulu

Kiilakoski, J., Puranen, J., Heinonen, E. et al. J Therm Spray Tech (2019) 28: 98.

Characterization of powder-precursor HVOF-sprayed Al₂O₃-YSZ/ZrO₂ coatings

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Author: Kiilakoski, Jarkko1; Puranen, Jouni1,2; Heinonen, Esa3;
Organizations: 1Laboratory of Materials Science, Tampere University of Technology, Tampere, Finland
2Elcogen Oy, Vantaa, Finland
3Center of Microscopy and Nanotechnology, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.4 MB)
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Language: English
Published: Springer Nature, 2019
Publish Date: 2019-07-10


Thermal spraying using liquid feedstock can produce coatings with very fine microstructures either by utilizing submicron particles in the form of a suspension or through in situ synthesis leading, for example, to improved tribological properties. The focus of this work was to obtain a bimodal microstructure by using simultaneous hybrid powder-precursor HVOF spraying, where nanoscale features from liquid feedstock could be combined with the robustness and efficiency of spraying with powder feedstock. The nanostructure was achieved from YSZ and ZrO₂ solution-precursors, and a conventional Al₂O₃ spray powder was responsible for the structural features in the micron scale. The microstructures of the coatings revealed some clusters of unmelted nanosized YSZ/ZrO₂ embedded in a lamellar matrix of Al₂O₃. The phase compositions consisted of γ- and α-Al₂O₃ and cubic, tetragonal and monoclinic ZrO₂. Additionally, some alloying of the constituents was found. The mechanical strength of the coatings was not optimal due to the excessive amount of the nanostructured YSZ/ZrO₂ addition. An amount of 10 vol.% or 7 wt.% 8YSZ was estimated to result in a more desired mixing of constituents that would lead to an optimized coating architecture.

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Series: Journal of thermal spray technology
ISSN: 1059-9630
ISSN-E: 1544-1016
ISSN-L: 1059-9630
Volume: 28
Issue: 1-2
Pages: 98 - 107
DOI: 10.1007/s11666-018-0816-x
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: The authors gratefully acknowledge the financial support from the graduate school of the President of Tampere University of Technology and Business Finland (Finnish innovation funding, trade, investment and travel promotion organization), its “Ductile and Damage Tolerant Ceramic Coatings” project and the participating companies.
Copyright information: © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.