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Evaluation of bearing steel´s microstructural parameters with regards to their mechanical properties and lifetime
Hroš, Michal ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The aim of this bachelor thesis is evaluating the impact of microstructural parameters of bearing materials with an emphasis on evaluation carbidic phase with using protocol SEP 1520. Literary section analyzes the specific groups of materials for the manufacture of rolling bearings, specifically focusing on steel, where is discussed their performance, production, heat treatment, micropurity, microstructure and macroscopic requirements. Work on structure of bearing steel as well as the experimental part of the thesis is focused on a more detailed description carbidic phase materials and the systematic evaluation with regards to type of initial a semifinished product for the manufacture of bearings, the heat treatment, the resulting mechanical properties and especially durability.
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Optimizing the conditions of double electron beam remelting in the process of preparing TBC
Hroš, Michal ; Moravčík, Igor (referee) ; Krajňáková, Petra (advisor)
Thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application and typically consisting of ceramic top coat and CoNiCrAlY bond coat (BC), both thermally sprayed. Nanostructured CoNiCrAlY bond coatings were deposited onto Ni-based alloy (Inconel 718) by both HVOF and CGDS spraying techniques. Subsequently the deposits were remelted by electron beam up to depth of about 100 m which resulted in removal of defects on the substrate to the bond coat interface. The primary objective of this thesis was to investigation of the influence of parameters used for EB remelting, including multiple remelting on the microstructural changes, phase modification and final state of the coatings. The amount of porosity in the coatings and surface roughness has been evaluated. Scanning electron microscopy and X-Ray diffraction were performed in order to characterize the phase modification before and after the applied treatment. The results indicated that multiple remelting process improved the coating properties in terms of porosity, smooth surface, strength and chemical homogeneity and at last but not least this study demonstrate that low-temperature processing of CoNiCrAlY bond coat represents an interesting and promising alternative for their manufacturing.
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Optimizing the conditions of double electron beam remelting in the process of preparing TBC
Hroš, Michal ; Moravčík, Igor (referee) ; Krajňáková, Petra (advisor)
Thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application and typically consisting of ceramic top coat and CoNiCrAlY bond coat (BC), both thermally sprayed. Nanostructured CoNiCrAlY bond coatings were deposited onto Ni-based alloy (Inconel 718) by both HVOF and CGDS spraying techniques. Subsequently the deposits were remelted by electron beam up to depth of about 100 m which resulted in removal of defects on the substrate to the bond coat interface. The primary objective of this thesis was to investigation of the influence of parameters used for EB remelting, including multiple remelting on the microstructural changes, phase modification and final state of the coatings. The amount of porosity in the coatings and surface roughness has been evaluated. Scanning electron microscopy and X-Ray diffraction were performed in order to characterize the phase modification before and after the applied treatment. The results indicated that multiple remelting process improved the coating properties in terms of porosity, smooth surface, strength and chemical homogeneity and at last but not least this study demonstrate that low-temperature processing of CoNiCrAlY bond coat represents an interesting and promising alternative for their manufacturing.
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Evaluation of bearing steel´s microstructural parameters with regards to their mechanical properties and lifetime
Hroš, Michal ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The aim of this bachelor thesis is evaluating the impact of microstructural parameters of bearing materials with an emphasis on evaluation carbidic phase with using protocol SEP 1520. Literary section analyzes the specific groups of materials for the manufacture of rolling bearings, specifically focusing on steel, where is discussed their performance, production, heat treatment, micropurity, microstructure and macroscopic requirements. Work on structure of bearing steel as well as the experimental part of the thesis is focused on a more detailed description carbidic phase materials and the systematic evaluation with regards to type of initial a semifinished product for the manufacture of bearings, the heat treatment, the resulting mechanical properties and especially durability.
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