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Fabrication and characterization of solution precursor hydroxyapatite coatings deposited via hybrid water-stabilized plasma gun
Antoš, Zdeněk ; Tkachenko, Serhii (referee) ; Čížek, Jan (advisor)
Hydroxyapatite coatings have been used as a barrier between a metal core of replacement and living tissue for long time in medicine. Plasma spray is a typical technology for preparation these coatings. This thesis concerns a new plasma spray technology with hybrid system of arc stabilization (WSP-H). Simultaneously it uses an innovative method of feeding the initial material in a form of water suspension (SPPS). The aim of this thesis was to produce water solutions of hydroxyapatite and make coatings with WSP-H. These coatings were characterized in terms of their morfology, chemical and phase composition. Their biocompatibility was tested by a cultivation and an analysis of RAW 264.7 and MG-63 cells. The coatings made by SPPS have a very rough surface which is suitable for biological application. The biocompatibility testing discovered that the coatings will by tolerated in a human body very well. This method of production of hydroxyapatite coatings could be a good replacement of older methods after a better optimalisation of the processing parameters and after reaching purity of coating.
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Microstructure and properties of YSZ thermal barier coatings deposited onto CoNiCrAlY bond coats remelted by electron beam
Slavíková, Barbora ; Jan, Vít (referee) ; Dlouhý, Ivo (advisor)
The master thesis is dealing with characterization of the structure and properties of the YSZ thermal barrier coating deposited by water hybrid plasma spray technology on the CoNiCrAlY bond coats modified by using electron beam and vacuum annealing. Deposition of the bond coats was performed via high velocity oxy-fuel technology and cold spray. In case of experimental evaluation, the microstructure and chemical composition of the ceramic top coat deposited with powder and suspension feedstock was analyzed. The same analysis procedure was used also for bond coats after electron beam remelting by using two sets of parameters. Furthermore, the changes in microstructure and chemical composition of the remelted and annealed bond coats was evaluated. Eventually, the micromechanical properties of the top coats and the bond coats were measured. The ceramic top coats deposited with powder feedstock exhibited the structure composed by splats, while the top coats deposited in form of suspension showed fine structure with columnar grains. The dendritic structure was observed on remelted bond coats. The annealing process had an influence on the structure in form of coarsened phases and the chemical composition was changed due to diffusion of the elements.
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Microstructure and properties of YSZ thermal barier coatings deposited onto CoNiCrAlY bond coats remelted by electron beam
Slavíková, Barbora ; Jan, Vít (referee) ; Dlouhý, Ivo (advisor)
The master thesis is dealing with characterization of the structure and properties of the YSZ thermal barrier coating deposited by water hybrid plasma spray technology on the CoNiCrAlY bond coats modified by using electron beam and vacuum annealing. Deposition of the bond coats was performed via high velocity oxy-fuel technology and cold spray. In case of experimental evaluation, the microstructure and chemical composition of the ceramic top coat deposited with powder and suspension feedstock was analyzed. The same analysis procedure was used also for bond coats after electron beam remelting by using two sets of parameters. Furthermore, the changes in microstructure and chemical composition of the remelted and annealed bond coats was evaluated. Eventually, the micromechanical properties of the top coats and the bond coats were measured. The ceramic top coats deposited with powder feedstock exhibited the structure composed by splats, while the top coats deposited in form of suspension showed fine structure with columnar grains. The dendritic structure was observed on remelted bond coats. The annealing process had an influence on the structure in form of coarsened phases and the chemical composition was changed due to diffusion of the elements.
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Fabrication and characterization of solution precursor hydroxyapatite coatings deposited via hybrid water-stabilized plasma gun
Antoš, Zdeněk ; Tkachenko, Serhii (referee) ; Čížek, Jan (advisor)
Hydroxyapatite coatings have been used as a barrier between a metal core of replacement and living tissue for long time in medicine. Plasma spray is a typical technology for preparation these coatings. This thesis concerns a new plasma spray technology with hybrid system of arc stabilization (WSP-H). Simultaneously it uses an innovative method of feeding the initial material in a form of water suspension (SPPS). The aim of this thesis was to produce water solutions of hydroxyapatite and make coatings with WSP-H. These coatings were characterized in terms of their morfology, chemical and phase composition. Their biocompatibility was tested by a cultivation and an analysis of RAW 264.7 and MG-63 cells. The coatings made by SPPS have a very rough surface which is suitable for biological application. The biocompatibility testing discovered that the coatings will by tolerated in a human body very well. This method of production of hydroxyapatite coatings could be a good replacement of older methods after a better optimalisation of the processing parameters and after reaching purity of coating.
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Suspension plasma spraying of sub-stoichiometric titania by hybrid water/argon stabilized plasma torch
Mušálek, Radek ; Ctibor, Pavel ; Medřický, Jan ; Tesař, Tomáš ; Kotlan, Jiří ; Lukáč, František
In this study, suspension plasma spraying of sub-stoichiometric titania was attempted using hybrid water/argon stabilized plasma torch (WSP-H). Porous coatings with fine cauliflower-like columnar microstructure were successfully deposited in two separate experiments with different power levels of the plasma torch. In both cases, high solid-load content (40 wt. %) of the water-based suspension resulted in considerable coating thickness increase per deposition cycle. Coating annealing and partial remelting of the surface asperities were also achieved by additional pass of plasma torch in front of the coating surface. According to X-ray diffraction, all coatings consisted dominantly of rutile phase. Detailed microscopic observation of the as-sprayed and annealed deposits showed that the local coloration of the coating (ranging from dark blue to beige) was driven by the local overheating of the rough coating surface which could also promote the oxygen intake. Moreover, sample annealing was also observed to increase the sample reflectivity as observed by UV-VIS-NIR scanning spectrophotometry
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