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Preparation and Characterization of Advanced Thermally-sprayed Coatings on Magnesium Alloys
Buchtík, Martin ; Hadzima, Branislav (referee) ; Fintová, Stanislava (referee) ; Ptáček, Petr (advisor)
The proposed dissertation thesis deals with the characterization of HVOF and APS-thermally sprayed coatings prepared on the AZ31 and AZ91 magnesium substrates. The theoretical part of the thesis describes in-detail Mg substrates used in the experimental part of the thesis. There are also characterized materials and coatings based on NiCrAlY and FeCrNiMoSiC metals, WC-CoCr cermets, and YSZ ceramic materials. At the end of the theoretical part, the literary research summarizing the characterization and analysis performed on thermally sprayed coatings on Mg alloys. Based on the theoretical knowledge, the characterization of Mg substrates and deposited coatings was performed in terms of the surface morphology, microstructure, and the chemical composition using the light microscopy (LM) and scanning electron microscopy with energy-dispersive spectroscopy (SEM+EDS). The phase composition of the coatings was analyzed using the X-ray diffraction (XRD). The diffractions corresponding to the sprayed coatings were compared with the feedstock powders, i.e. materials used for the spraying of the coatings. The characterization of the prepared coatings in terms of the mechanical and tribological properties was performed. The hardness and microhardness of the coatings as well as the coefficient of friction, and the wear rate were measured. The last chapter of the experimental part deals with the evaluation of the electrochemical corrosion properties by the potentiodynamic measurements in a 3.5% NaCl solution. In the case of exposed samples, the evaluation of the surface and coating/substrate interface was performed using LM and SEM with EDS. The mechanism of the corrosion attack and degradation was determined from the acquired knowledge and base on the results of the short-term measurements. Based on the measured results, it can be stated that the deposited coatings were successfully applied on the surface of both Mg alloys. All the coatings increase the surface hardness of the Mg alloys and significantly improve their tribological properties. However, except for FeCrNiMoSiC coatings, the corrosion properties of Mg alloys deteriorate due to the fact that the corrosion environment can pass through the coating to the less noble Mg substrate and the corrosion microcells are created.
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Structural analysis of Fe48Cr28Ni16Mo4,5Si1,5C1,75 thermally-sprayed coatings on AZ91 magnesium alloy
Kobzinková, Eliška ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The bachelor thesis deals with the analysis of thermally sprayed Fe48Cr28Ni16Mo4,5Si1,5C1,75 coatings on AZ91 magnesium alloy and evaluation of their structural and mechanical properties. The theoretical part deals with magnesium alloys, focusing on AZ91 alloy, thermal spray methods, specifically the High Velocity Oxygen Fuel method of depositing (HVOF), and Fe and Fe-Cr-Ni based materials. The theoretical part concludes with a review of current research in the field of Fe-based coatings deposited by the HVOF method. The experimental part is devoted to the structural analysis of AZ91 magnesium alloy and the Fe-based thermally sprayed coating deposited on this alloy. The microstructure was analyzed by light microscopy (LM) and scanning electron microscopy (SEM). Elemental and phase analysis was performed using energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The hardness of the coating and alloy was measured by the Vickers method. The application of thermally sprayed coating increased the surface hardness from 87 ± 10 HV0.3 (AZ91) to 536 ± 94 HV0.3.
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Structural analysis of Fe48Cr28Ni16Mo4,5Si1,5C1,75 thermally-sprayed coatings on AZ91 magnesium alloy
Kobzinková, Eliška ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The bachelor thesis deals with the analysis of thermally sprayed Fe48Cr28Ni16Mo4,5Si1,5C1,75 coatings on AZ91 magnesium alloy and evaluation of their structural and mechanical properties. The theoretical part deals with magnesium alloys, focusing on AZ91 alloy, thermal spray methods, specifically the High Velocity Oxygen Fuel method of depositing (HVOF), and Fe and Fe-Cr-Ni based materials. The theoretical part concludes with a review of current research in the field of Fe-based coatings deposited by the HVOF method. The experimental part is devoted to the structural analysis of AZ91 magnesium alloy and the Fe-based thermally sprayed coating deposited on this alloy. The microstructure was analyzed by light microscopy (LM) and scanning electron microscopy (SEM). Elemental and phase analysis was performed using energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The hardness of the coating and alloy was measured by the Vickers method. The application of thermally sprayed coating increased the surface hardness from 87 ± 10 HV0.3 (AZ91) to 536 ± 94 HV0.3.
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Preparation and Characterization of Advanced Thermally-sprayed Coatings on Magnesium Alloys
Buchtík, Martin ; Hadzima, Branislav (referee) ; Fintová, Stanislava (referee) ; Ptáček, Petr (advisor)
The proposed dissertation thesis deals with the characterization of HVOF and APS-thermally sprayed coatings prepared on the AZ31 and AZ91 magnesium substrates. The theoretical part of the thesis describes in-detail Mg substrates used in the experimental part of the thesis. There are also characterized materials and coatings based on NiCrAlY and FeCrNiMoSiC metals, WC-CoCr cermets, and YSZ ceramic materials. At the end of the theoretical part, the literary research summarizing the characterization and analysis performed on thermally sprayed coatings on Mg alloys. Based on the theoretical knowledge, the characterization of Mg substrates and deposited coatings was performed in terms of the surface morphology, microstructure, and the chemical composition using the light microscopy (LM) and scanning electron microscopy with energy-dispersive spectroscopy (SEM+EDS). The phase composition of the coatings was analyzed using the X-ray diffraction (XRD). The diffractions corresponding to the sprayed coatings were compared with the feedstock powders, i.e. materials used for the spraying of the coatings. The characterization of the prepared coatings in terms of the mechanical and tribological properties was performed. The hardness and microhardness of the coatings as well as the coefficient of friction, and the wear rate were measured. The last chapter of the experimental part deals with the evaluation of the electrochemical corrosion properties by the potentiodynamic measurements in a 3.5% NaCl solution. In the case of exposed samples, the evaluation of the surface and coating/substrate interface was performed using LM and SEM with EDS. The mechanism of the corrosion attack and degradation was determined from the acquired knowledge and base on the results of the short-term measurements. Based on the measured results, it can be stated that the deposited coatings were successfully applied on the surface of both Mg alloys. All the coatings increase the surface hardness of the Mg alloys and significantly improve their tribological properties. However, except for FeCrNiMoSiC coatings, the corrosion properties of Mg alloys deteriorate due to the fact that the corrosion environment can pass through the coating to the less noble Mg substrate and the corrosion microcells are created.
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