National Repository of Grey Literature 145 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Oxidation behavior adjustment for TiAl intermetallics by controled atmosphere surface remelting
Prehradná, Jana ; Čížek, Jan (referee) ; Jan, Vít (advisor)
Rešerše se zabývá teorií technologického způsobu zpracování materiálů, tzv. povrchového tavení. V první části rešerše je popsána samotná technologie a základní parametry ovlivňující proces tavení. Ve druhé části je uvedeno srování dvou základních typů laserů, a to Nd:YAG a CO2 laser. CO2 laser byl použit v případě našeho experimentu. Třetí část se zabývá vlastnostmi TiAl intermetalických slitin, především jejich fázemi -TiAl a -Ti3Al. Na závěr teoretické části je zmíněna oxidace TiAl intermetalických slitin. Experimentální část je věnována přetavování povrchu slitiny Ti-46Al-0,7Cr-0,1Si-7Nb-0,2Ni, a to v ochranné atmosféře dusíku. Tato část obsahuje výsledky několika experimentů, na jejichž základě bylo nutné stanovit potřebné parametry pro požadovaný proces tavení. Posledním krokem experimentu byla snaha o zvýšení hmotnosti vzorků v důsledku následné oxidace.
The analysis of Cu-Sn-Sb ternary alloy
Kučera, Jan ; Doubrava, Marek (referee) ; Jan, Vít (advisor)
This bacholor thesis deals with substituting silver-based material, currently used for experimental semi-liquid extrusion. The proposed material is from the Cu-Sb-Sn system. The theoretical part of the work deals with soldering and phase diagrams. The experimental part is devoted to the analysis of three proposed alloys from the Cu-Sb-Sn system, their structural and mechanical properties. Thermal analyzes of the alloys were performed using differential scanning calorimetry (DSC), the microstructure using a light microscope and a scanning electron microscope, and a hardness tester was also used to determine the hardness. The results are summarized in the discussion.
Reaction synthesis of bulk intermetallic materials from cold spray deposits from binary powders containing iron
Dyčková, Lucie ; Krajňáková, Petra (referee) ; Jan, Vít (advisor)
This thesis deals with reaction synthesis of materials Fe–Al, Fe–Cu and Fe–Ni from cold spray. In literature analysis are introduced these systems and for each system there is brief description of binary equilibrium diagram. Furthermore here are some short explanations of diffusion, Kirkendall effect and other possible processing technologies of intermetallic materials. In experimental part, samples of sprayed materials were annealed and then microstructural changes were investigated. This thesis contains photographs of microstructure, results from scanning electron microscopy, X-ray, and measurements of microhardness.
Preparation of Ni-Si mixed layers and study of undergoing reactions during heat treatement
Petr, Jiří ; Pantělejev, Libor (referee) ; Jan, Vít (advisor)
This bachelor's thesis observes the creation and describes the nickel-silicon phases. The theoretical part is devoted to the description of silicides, difusion mechanisms and the basic principle of electroplating. The experimental part describes the creation of Ni-Si layer by using nickel electroplating, heat treatment and observing changes in microstructure based on annealing temperature.
Heat treatement of tool steels
Kubín, Matěj ; Moravčík, Igor (referee) ; Jan, Vít (advisor)
This thesis deals with heat treatment of tool steels. The work is divided into two parts. The theoretical part includes marking, properties and theoretical processing of tool steels. It also contains the technique which is used for sample preparation. In the experimental part there is an examination of the two common sold drills. Samples were made from the drill, on which metallographic analysis and heat treatment was performed.
Biodegradable plastics
Schifferová, Zuzana ; Jan, Vít (referee) ; Molliková, Eva (advisor)
The aim of this bachelor theses is to discuss the process of biodegradation occurring with biodegradable polymers including factors affecting this process. The theses also introduces some types of biodegradable plastics including their properties. At last it discusses waste management of these plastics and their ecological impact.
Influencing the surface roughness of materials created by the SLM technique and the influence of roughness on macroscopic properties
Rotter, Marek ; Havlík, Petr (referee) ; Jan, Vít (advisor)
Theses resumes the principle of SLM method and submits the most used materials for this technology and its properties. The main issue is influencing the surface roughness of these materials, when the electro-chemical polishing in the concentrated sulfuric acid was used with five difference options. It was observed, that the roughness is caused by two factors, fused nonmelted grains of metal powder and layered structure. Polishing at 8 V, 0,5 A and after 40 min was the best results, when the smooth wave surface was achieved. The Ra parameter descended from initial 5,0 m to 3,9 m after this polishing. One of the factors, which causes the high roughness, was eliminated.
Immiscible alloy based on Fe-Cu system
Semerák, Petr ; Havlík, Petr (referee) ; Jan, Vít (advisor)
The aim of this work is the preparation of FeCuMn alloy in equimolar composition by melting and the analysis of the resulting microstructure. The theoretical part of the work deals with miscibility and the use of immiscible systems in practical applications. Furthermore, the influence of cooling rate and the effect of the ratio of the components of the immiscible Fe-Cu system on the resulting microstructure are described. The practical part of the work presents the microstructure of FeCuMn alloy, which was prepared by melting in an induction furnace under a protective atmosphere of argon. Furthermore, the practical part deals with the chemical composition of the individual phases and the shape of the resulting phases. For the FeCuMn alloy, the melting temperature of the phases is analysed, the material is also deformed, and the hardness of the deformed and undeformed material is evaluated. In the subsequent discussion, the results from the experimental part are related to published experimental results by other authors.
Reconstruction of mechanical testing samples from small volumes of materials using electron beam welding
Roubalová, Jana ; Pantělejev, Libor (referee) ; Jan, Vít (advisor)
This thesis is focused on application samples with the inner insert used for Charpy impact test. This insert is welded to additional material by electron beam with pre-selected welded parameters. These parameters were chosen from data of performed experiments on homogenous welds. Resulting heterogenous weld was performed of evaluation of the microstructure, chemical composition and microhardness. Experimental materials were used austenitic steel 17 240 and ferritic steel 17 153 used on high-temperature applications.
Experimental and computational methods for determination of local values of Young´s modulus in polycrystalline materials
Svoboda, Ondřej ; Zelený, Martin (referee) ; Jan, Vít (advisor)
The bachelor thesis combines computational and experimental methods for determination of local Young's modulus of polycrystalline materials. Quantum-mechanical calculations are used for theoretical determination of anisotropic elastic properties and the results are compared with those from nanoindetation measurements. The aim of the bachelor thesis is to apply these two methods to elemental iron as a pre-step for future research of binary Fe-Al alloys.

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