National Repository of Grey Literature 124 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Waste as source of raw material and energy
Krtička, Josef ; Němec, Karel (referee) ; Molliková, Eva (advisor)
Wastes. inceneration plant, dump, recycling, energy, secondary materials, resources, biomass, raw materials resources, energy sources.
Cu-Fe-based immiscible alloys prepared by powder metallurgy route
Lacová, Anna ; Němec, Karel (referee) ; Adam, Ondřej (advisor)
The immiscible Cu-Fe system is often used as a base for advanced heterogeneous alloys. With a suitable selection of alloying elements, it is possible to alloy individual phases and therefore tailor microstructure and final properties of a material as needed. To prepare the mentioned multicomponent alloys, it is necessary to understand the effect of individual alloying elements on the microstructure and properties of the Cu-Fe system. Although mostly used method in production of such materials is casting, mechanical alloying appears to be a suitable alternative, enabling a very fine microstructure to be created. The following bachelor´s thesis is focused on the characterization of Cu50Fe25Cr25 and Cu50Fe25Ni25 alloys and the effect of the alloying elements on their microstructure. Cr and Ni were selected as a BCC and FCC phase enhancing elements, respectively. The alloys were prepared by mechanical alloying using high-energy ball mill, with subsequent densification using spark plasma sintering. The microstructure of milled powders, as well as bulk samples, was examined, and the evolution of the microstructure during sintering evaluated with respect to the alloying elements. In addition, the hardness of bulk samples was measured. During the mechanical alloying a complete mixing was not achieved, as the milled powders were not single phase. However, a metastable FCC supersaturated solid solution was formed at least partially in both alloys, further decomposing into a multiphase microstructure after sintering.
Nickel alloys in aerospace
Šprincl, Jan ; Nopová, Klára (referee) ; Němec, Karel (advisor)
The aerospace industry is one of the fastest growing industries today. Increasing demands on the efficiency and fuel consumption of jet engines can be met, among other things, by using higher quality materials, which clearly include nickel-based superalloys, which can meet these demands. This work provides an overview of these materials: both the building block of the whole structure - nickel, superalloys in general, and especially those nickel-based. It deals with the composition of the microstructure formed by the austenitic matrix ( phases) most often cured by carbide or substitution precipitates, unique mechanical properties, but also the influence of high temperatures and creep on the degradation of these properties. The work also includes a comparison of selected superalloys from different perspectives, especially according to the type of particles that cure the matrix or the effect of loading on the superalloy in the presence of thermal oxidation environment. Depending on the area of application, these materials are predestined for further future development and improvement, because their unique properties in areas with extreme conditions are irreplaceable for the time being.
Titanium and its alloys in aviation
Černota, Jan ; Adam, Ondřej (referee) ; Němec, Karel (advisor)
This bachelor thesis deals with the issue of the use of titanium and its alloys in aviation. First, it deals with titanium as a light metal, its history, occurrence, use, manufacture, and properties. Then about its alloys, their division, and the characteristics of individual alloys, considering their utility for aerospace applications. The main part deals with the use of titanium and its alloys in the aerospace industry, where the performance requirements of materials used in aviation are summarised, how titanium meets these properties and for which components titanium is most often used. The thesis also predicts the development of the use of these materials in the aerospace industry.
Kinetics of fatigue crack propagation in steels P91 and P92
Kander, Jan ; Němec, Karel (referee) ; Věchet, Stanislav (advisor)
The main subject of this master’s thesis was to evalute inluence of loading cycle asymmetry and long-term thermal exposure on fatigue crack growth rate in martensitic P91 and P92 steels. Experiments were carried out in Material and metallurgical research Ostrava Ltd. and their main aim was to study the influences of different loading cycle asymmetries (R = 0,1 and R = 0,6) as well as 5000 hours/600 °C (P91) respectively 5000 hours/650 °C (P92) of thermal exposure on fatigue crack growth rate.
Pyrolytic graphite
Chýlková, Adéla ; Adam, Ondřej (referee) ; Němec, Karel (advisor)
The purpose of this bachelor thesis was to write a literature search summarizing knowledge about carbon-based materials and experimental determination of thermal expansion and thermal balance of samples of various types of graphite and evaluation of measured data. The research part of the work describes most of the currently known types of carbonaceous materials, with a more thorough study of pyrolytic graphite. The whole next chapter was devoted to a more thorough study of pyrolytic graphite. The second part of the thesis is focused on the experimental determination of thermal expansion and thermal balance on selected graphite samples (natural, expanded, pressed expanded and pyrolytic graphite). We used dilatometric analysis and thermogravimetry to solve this task. Finally, the measurement data were processed into graphs and relevant tables and conclusions were deduced.
Casting defect analysis in steel ingot
Krupica, Roman ; Němec, Karel (referee) ; Jan, Vít (advisor)
This thesis deals with the problematics of ingot casting, factors affecting the quality of ingots and defects occurring in them. The first part defines steel casting, defects of steel, their classifications and causes. The other part of the thesis focuses on the laboratory analysis of ingot samples and metallographic characterization of defects.
Cold weapons
Střechovský, Jan ; Němec, Karel (referee) ; Molliková, Eva (advisor)
The aim of this bachelor thesis is a summary of relevant information concerning cold arms. Concerning the amount of content of this topic, this thesis is focused on general knowledge regarding the types, usage and development of cold arms, with mentioning some interesting and less known facts. It also contains deeper analysis of some chosen cold arms or key parts in their manufacture process.
Damascus Steel
Czudek, Szymon ; Němec, Karel (referee) ; Molliková, Eva (advisor)
This bachelor thesis briefly deals with the characterization of iron-based material and describes the process of steel production and raw material used in this process. In the next part, this thesis is about the history of damascus steel, the processes and methods of producing this type of steel and the properties it recieve through these processes. The next chapter discuss specific usage of this material nowadays and in the end it is about other materials that are often erroneously considered for a kind of damascene steel.
The materials for firearms barells
Mrózek, Jan ; Molliková, Eva (referee) ; Němec, Karel (advisor)
The aim of this Bachelor thesis is to summarise information about development and basic description of individual parts of barrel firearms and appropriate use of materials for their production. The content of this thesis are also methods of surface treatment of the barrel rifling. In conclusion, the thesis describes weapon life and deterioration of barrel firearms.

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3 NĚMEC, Karel
2 Němec, Kamil
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