National Repository of Grey Literature 195 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Elastic characteristics of coatings
Olivo, Tomas ; Řehořek, Lukáš (referee) ; Válka, Libor (advisor)
The thesis focuses on the determination of Young's modulus of elasticity in tension of coatings with the inclusion of the effect of porosity using the impulse excitation method (IEM). In the theoretical part, the basics of the impulse excitation method and nanoindentation are discussed. Subsequently, the types of composite materials are presented, followed by a description of the Cold Spray technology used to produce the coatings presented in this work. In the next section, the composite models used to evaluate the measured data are defined. The experimental part is devoted to the description of the preparation of the test specimens, i.e., the substrate-coating system, together with the nanoindentation and pulsed excitation test procedure. Based on these tests, the tensile elastic moduli of the deposited coatings were evaluated using four composite models and compared with the results from the nanoindentation test. The most appropriate of these models was found to be the one based on the rule of mixtures with the inclusion of the nonlinear effect of porosity.
Paint shop Process Improvement through Predictive Simulation
Machačová, Simona ; Hromková, Ivana (referee) ; Videcká, Zdeňka (advisor)
This thesis focuses on the use of simulation to optimise processes in a paint shop. The aim of the thesis is to analyse the existing production processes and suggest improvements using simulation. In the analytical part of the thesis, the processes in the paint shop are described in detail and Petri nets are used to describe the logic of the processes in the paint shop. In the design part of the thesis, the problem and objectives are formulated, and the design of the simulation model is presented. The design describes the elements and methods used in the Plant Simulation software in which the model is created. Furthermore, different scenarios are simulated to optimize the painting process and the deposition areas. The simulation results are compared with the actual state of the paint shop. Finally, the results are discussed and recommendations are proposed to optimize the paint shop processes using simulation. This work presents new approaches to process optimization in industrial manufacturing.
An investigation of friction and lubrication of coated hip joint replacement
Balcárek, Ondřej ; Horák, Zdeněk (referee) ; Nečas, David (advisor)
The thesis focused on studying the effects of a new hydrogel coating and material combinations on the coefficient of friction and formation of lubricating film in the conformal contact of hip joint replacement. Experiments were conducted using a ball-on-cup configuration with a hip pendulum simulator. The formation of the lubricating film was observed using fluorescence microscopy. The results showed that the application of the coating did not have a clear impact on the coefficient of friction. However, for pairs with a coated cup, there was a reduction in CoF by approximately 20%. Generally, lower friction was observed when using a ceramic joint head. Surprisingly, even more interesting results were obtained in the lubrication analysis, where the use of metal heads led to a reduction in the thickness of the lubricating layer. Ceramic pairs exhibited very stable behavior. In addition to friction and lubrication, the topography of the implants was further evaluated, and their wettability was analysed. Although the polymer coating was expected to be highly hydrophilic, the surface properties were only slightly influenced, which partly explains why there was no significant improvement in the tribological behavior of the replacement. As the coating applied is already patented and its effectiveness in reducing wear has been clearly demonstrated, it is appropriate to investigate this issue further, with more attention being paid to long-term experiments. Based on the obtained data, it appears that the short-term benefits of the coating are practically negligible. However, it is important to highlight that, except for minor exceptions, the application of the coating did not lead to a deterioration of properties, which is a significant outcome of this work.
SMV-2023-42: Materials for thermal management
Králík, Tomáš
This contract research dealt with so-called solar white coatings with a very different ability to absorb visible radiation and emit thermal radiation. We have studied special coatings designed for the space environment with high emissivity in the field of thermal radiation and at the same time low absorption of radiation originating from the sun or reflected from cosmic bodies. This type of coating is intended for passive thermoregulation of parts of apparatus moving in the space environment. The aim was to determine the so-called total hemispheric emissivity of each of the samples at the required temperatures. For these coatings, the client's goal was also to evaluate the effect of the morphology of the sample on the resulting emission of thermal radiation. Namely, we tested the flat and pyramidal structured surface of the base material. This unique research required a special modification of the supplied samples, modification of the dedicated method for measuring emissivity and absorptivity at cryogenic temperatures, as well as a new procedure for calibration and evaluation of the received data. We used a previously developed shielding ring around the perimeter of the samples to cover the perimeter of the structured samples, which prevented part of the measured thermal radiation from escaping. The results of this research will be used in the design of the CO2M space mission for monitoring CO2 emissions.
SMV-2023-41: Absorptive coatings for quantum computers
Králík, Tomáš
This contract research focused on the thermal analysis of absorptive layers created by anodic oxidation on aluminium alloy, which are optimized for use at extremely low temperatures. These specific layers were designed for the low-temperature parts of quantum computers, where they play a key role in eliminating the reflection of thermal radiation from the hotter areas of the computer cryostat to the ultra-low temperature areas. Other key requirements for these absorptive layers are high thermal conductivity, necessary for efficient heat transfer within a quantum computer, good mechanical stability and extremely low outgassing to ensure long-term functional behaviour of the layers in challenging low-temperature conditions. The goal of this research was not only to verify the total hemispheric emissivity of three specific types of coatings in the temperature range from 10 K to 300 K. In this case, emissivity is a suitable indicator of the thermal absorptive behaviour of the layer. A study of the emissivity of these layers in the entire spectrum of temperature conditions relevant for quantum computers was carried out. This extensive analysis was intended to provide an insight into the suitability of these absorptive layers for applications in the field of low-temperature technologies, with an emphasis on the requirements of quantum computers.
Adhesion of bituminous binders to aggregate
Vlk, Petr ; Hýzl, Petr (referee) ; Varaus, Michal (advisor)
In 2005 the revised European standard 12697-11:2005 [1] was introduced offering a choice of three different methods. The static method described in part B has some similarities with the replaced Swiss standard for the determination of the affinity between bitumen and aggregates [2] and Czech standard for adhesions of asfalt binder to aggregates ČSN 73 6161 [3]. The result of this study is to compare the static method described in the [3] and a draft changes by Swiss research project [4] with the current revision of the European Standard 12697-11: 2005.
Machinable bioceramic foams prepared by gelcasting method
Šťastný, Přemysl ; Částková, Klára (referee) ; Trunec, Martin (advisor)
Diploma thesis is focused on development of method for preparation individualized bioscaffolds prepared by milling of HA foam prepared by gel casting method and consolidated via epoxy curing reaction. Diploma thesis continues in bachelor thesis Modern processing methods of porous bioceramics. Literature search is filled in the newest knowledge from the field of bioactivity enhancement of scaffolds. Experimental part of diploma thesis described development of system for individualized scaffold manufacturing from HA suspension preparation, preparation of ceramic blocks used as material for machining to final blocks machining. Pressure strength of foam were evaluated, too. Chosen samples were coated with calcium polyphosphate coating for biological response enhancement. Coated samples were given for in-vivo test to partner university in Beijing under the terms of project FP7-NMP-2013-EU-China: "Bioscaffolds"
New generations of PVD coatings
Kantar, Filip ; Kolář, Ladislav (referee) ; Jaroš, Aleš (advisor)
Bachelor thesis deals with methods of coating, cutting tools and a new generation of coatings. In the first part are listed and described basic coating methods. The next part is aimed on coating of PVD methods. In the third part are listed basic tool materials and their characteristics. The last part is focused on new generation of coatings, their application, properties and structures.
Tools for threading and their use
Veselý, Václav ; Polzer, Aleš (referee) ; Sliwková, Petra (advisor)
The bachelor’s thesis Tools for threading and their use deals with issues connected to tools, the materials used and their usage in the field of mechanical engineering. Individual parts of the thesis cover types of tools for threading, methods of threading and materials suitable for tap making. Further, the range of monolithic milling taps in the producers’ supply is also analysed.
Untersuchung von Strukturen und Beschichtungen für tribologisch optimierte Umformwerkzeugoberflächen für die Aluminiumfeinblechbearbeitung
Kořenek, Jakub ; Hänel, Thomas (referee) ; Blecha, Petr (advisor)
V rámci bakalářské práce je provedena rešerše ke stavu techniky z pohledu tribologie, tváření hliníku, povlakování, strukturování a v závěru rozdělení tribologických zkoušek a metod jejich hodnocení. V praktické části jsou vyhodnoceny už dříve provedené pokusy na oscilačním tribometru. Následně byly provedeny pokusy tažení pásu s ohybem a bez ohybu s různými parametry pro jednotlivé zkoušky. Testovány byly různé laserové struktury (křížové, liniové, bodové) s variací jejich hloubky a pokrytí vzorků. V závěru práce jsou výsledky pokusů zhodnoceny z pohledu opotřebení, koeficientu tření a stability tribologického systému v průběhu pokusu. Z výsledků vychází doporučení pro následující pokusy a možné oblasti aplikace jednotlivých struktur.

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