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Article

Improvement of Mechanical Properties of Plasma Sprayed Al2O3–ZrO2–SiO2 Amorphous Coatings by Surface Crystallization

1
Institute of Plasma Physics, The Czech Academy of Sciences, Za Slovankou 1782/3, Prague 182 00, The Czech Republic
2
Department of Materials, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague 115 19, The Czech Republic
3
Research and Testing Institute Pilzen, Pilsen 301 00, The Czech Republic
4
Fraunhofer IWS, 01277 Dresden, Germany
*
Author to whom correspondence should be addressed.
Materials 2019, 12(19), 3232; https://doi.org/10.3390/ma12193232
Received: 14 August 2019 / Revised: 20 September 2019 / Accepted: 26 September 2019 / Published: 2 October 2019
(This article belongs to the Special Issue Advances in Thermal Spray Technology)
Ceramic Al2O3−ZrO2−SiO2 coatings with near eutectic composition were plasma sprayed using hybrid water stabilized plasma torch (WSP-H). The as-sprayed coatings possessed fully amorphous microstructure which can be transformed to nanocrystalline by further heat treatment. The amorphous/crystalline content ratio and the crystallite sizes can be controlled by a specific choice of heat treatment conditions, subsequently leading to significant changes in the microstructure and mechanical properties of the coatings, such as hardness or wear resistance. In this study, two advanced methods of surface heat treatment were realized by plasma jet or by high energy laser heating. As opposed to the traditional furnace treatments, inducing homogeneous changes throughout the material, both approaches lead to a formation of gradient microstructure within the coatings; from dominantly amorphous at the substrate–coating interface vicinity to fully nanocrystalline near its surface. The processes can also be applied for large-scale applications and do not induce detrimental changes to the underlying substrate materials. The respective mechanical response was evaluated by measuring coating hardness profile and wear resistance. For some of the heat treatment conditions, an increase in the coating microhardness by factor up to 1.8 was observed, as well as improvement of wear resistance behaviour up to 6.5 times. The phase composition changes were analysed by X-ray diffraction and the microstructure was investigated by scanning electron microscopy. View Full-Text
Keywords: amorphous; nanocrystalline; wear resistant; Vickers microhardness; plasma spraying amorphous; nanocrystalline; wear resistant; Vickers microhardness; plasma spraying
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MDPI and ACS Style

Medricky, J.; Lukac, F.; Csaki, S.; Houdkova, S.; Barbosa, M.; Tesar, T.; Cizek, J.; Musalek, R.; Kovarik, O.; Chraska, T. Improvement of Mechanical Properties of Plasma Sprayed Al2O3–ZrO2–SiO2 Amorphous Coatings by Surface Crystallization. Materials 2019, 12, 3232. https://doi.org/10.3390/ma12193232

AMA Style

Medricky J, Lukac F, Csaki S, Houdkova S, Barbosa M, Tesar T, Cizek J, Musalek R, Kovarik O, Chraska T. Improvement of Mechanical Properties of Plasma Sprayed Al2O3–ZrO2–SiO2 Amorphous Coatings by Surface Crystallization. Materials. 2019; 12(19):3232. https://doi.org/10.3390/ma12193232

Chicago/Turabian Style

Medricky, Jan, Frantisek Lukac, Stefan Csaki, Sarka Houdkova, Maria Barbosa, Tomas Tesar, Jan Cizek, Radek Musalek, Ondrej Kovarik, and Tomas Chraska. 2019. "Improvement of Mechanical Properties of Plasma Sprayed Al2O3–ZrO2–SiO2 Amorphous Coatings by Surface Crystallization" Materials 12, no. 19: 3232. https://doi.org/10.3390/ma12193232

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