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The role of microstructure on wettability of plasma sprayed yttria stabilized zirconia coatings
Komarov, P. ; Čelko, L. ; Remešová, M. ; Skorokhod, K. ; Jech, D. ; Klakurková, L. ; Slámečka, K. ; Mušálek, Radek
Atmospheric plasma spraying utilizing initial powder materials in micrometric size has been successfully used for various applications in different fields of the industry over the past several decades. Nowadays, the new trend in plasma spraying is to use sub-micron or nano-sized powder feedstocks in the form of colloidal suspension. This relatively new technology enables to obtain specific types of dense vertically cracked, fully dense or columnar microstructure. The aim of this work is to investigate the influence of coatings microstructure and topography on its water wetting properties. Two different microstructures, i.e. lamellar and columnar, were sprayed from chemically the same yttria-stabillized zirconia (YSZ) ceramics powders by the means of conventional atmospheric plasma spray and suspension hybrid water stabilized plasma spray techniques, respectively. Microstructural and phase composition of the initial powders and as-sprayed coatings were investigated using optical microscopy, scanning electron microscopy and X-ray diffraction techniques. Topography of coatings surface was measured by means of non-contact optical profilometry. The YSZ coatings wettability was evaluated based on water droplet contact angle using Sessile droplet method. The coatings microstructure reveals the important role in the change of droplet contact angle, where lamellar microstructure was found close to hydrophilic-hydrophobic transition and columnar microstructure was found superhydrophobic
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