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Modification of HVOF and cold spray deposited coatings via electron beam technology
Vacek, Petr ; Šiška, Filip (referee) ; Čížek, Jan (advisor)
The aim of this thesis was to modify microstructure and coating-substrate interface of CoNiCrAlY coatings deposited by HVOF and cold spray on Inconel 718 substrates. Electron beam remelting and annealing in a protective atmosphere were used to modify the coatings. Microstructure, chemical and phase composition were analyzed. The effect of beam current, transversal velocity and beam defocus on remelted depth was evaluated. As-sprayed microstructure and chemical composition of coatings were analyzed and compared with remelted samples. The effect of annealing of the as-sprayed and remelted samples was evaluated. Remelted layers exhibited dendritic structure. Chemical composition changed only after remelting of interface and part of a substrate. When only the coating was remelted, chemical composition remained the same. Phases coarsened after the annealing. Chemical composition changed after annealing due to the diffusion.
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Optimization of Machining Parameters Abradable Sprayed used in the Aerospace Industry
Krajkovič, Pavel ; Osička, Karel (referee) ; Kalivoda, Milan (advisor)
This thesis is focused on machining of thermal spray coatings. Particularly on testing of machining parameters and their influence on different types of abradable coatings used in the aerospace industry. The aim of research work is to test the parameters, measure cutting forces by using a dynamometer and their impact on the quality of the machined surface. Determination of the optimal machining parameters for different types of coatings based on results of measurements and the evaluation of surface quality. There are also presented techniques of thermal spray application and methods of coating evaluation. Further it describes a method of measuring cutting forces by using the dynamometer and methods of surface quality evaluation.
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Modification of coating-substrate interface character of thermally sprayed coatings using electron beam technology
Mareš, Jiří ; Moravčík, Igor (referee) ; Čížek, Jan (advisor)
Tato práce je zaměřena na modifikaci charakteru rozhraní substrát-nástřik NiCrAlY povlaků nanesených pomocí technologie vodou stabilizované plazmy na substráty z oceli S235JRC+C. Přetavení žárové vrstvy elektronovým paprskem bylo zvoleno jako technologie pro modifikaci a dvě různé modifikace byly zkoumány. V práci byl proveden pokus o stanovení vlivu modifikací na adhezní vlastnosti nástřiku. Dále jsou v práci prezentovány analýzy mikrostruktury, fázového a chemického složení a mikrotvrdosti ve stavu před a po modifikaci. Během studie bylo zjištěno, že dochází ke změnám fázového složení jak během depozice, tak během modifikace elektronovým paprskem. Modifikace elektronovým paprskem způsobila roztavení oxidů původní mikrostruktury nástřiku, které následně rekrystalizovaly na povrchu modifikované vrstvy. Dalším získaným poznatkem bylo, že dochází ke snížení mikrotvrdosti po modifikaci, což bylo způsobeno odstraněním oxidů z mikrostruktury a promícháním materiálu substrátu a původního nástřiku. Adheze nástřiků v as sprayed stavu byla kvantifikována. V případě nástřiků modifikovaných elektronovým paprskem přesná kvantifikace nebyla možná, z důvodu předčasného porušení na rozhraní nástřik-adhezivní pojivo během adhezních testů.
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Formation of Hypereutectic Aluminium Alloys Using Sacrificial Coatings
Gregor, Martin ; Jech, David (referee) ; Čelko, Ladislav (advisor)
Master‘s thesis deals with the forming of hypereutectic aluminium alloys using sacrificial coatings. Literature research is focused on analysing the characteristics of aluminium and its alloys. Attention is also focused to the heat treatment of aluminium alloys and the influence of alloying elements on these alloys. Analysis of characteristics and increase the useful properties of Al - Ni alloys is another object of literary research. Attention is also focused to the analysis of thermal spraying methods by focusing on the principle of individual methods and the characteristics of the coatings made by these methods. The object of experimental part is to prepare the hypereutectic aluminium alloys using sacrificial nickel based coatings. This is an unconventional manufacturing process comprising coating the surface of the aluminium substrate with using HVOF technology and subsequent thermal exposure. Furthermore, the work deals with the metallographic evaluation of prepared samples with a particular focus on the influence of temperature and time of heat treatment on the final structure of the experimental samples.
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Použití metody konečných prvků pro předpověď mechanických vlastností žárově nanášených vrstev
Mušálek, R. ; Kovářík, O. ; Matějíček, Jiří
Feasibility of finite elemenent method (FEM) for prediction of mechanical properties of thermally sprayed coatings was studied. First, finite element models of microstructures with idealized pores were designed. The influence of pores presence on mechanical response of the structure was evaluated. Secondly, mathematical model based on real tungsten coating microstructure was created using OOF2 software and submitted for further FEM analysis using ABAQUS CAE. Values of Young’s moduli in in-plane and out-of plane directions were estimated. The predictions are compared to the experimental data.
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