Les aciers inoxydables à haute teneur en molybdène présentent une excellente résistance à la corrosion et ont été récemment utilisés dans des applications marines. L'acier inoxydable de type 254 SMO contient du molybdène (6% Mo) et des quantités plus élevées en éléments d'alliages que les aciers inoxydables plus classiques tels que 304, 316 et 316L. Alors que Anees Uddin Malik et al. montrent que l’acier 254 SMO est moins sensible à la corrosion par piqûre en eau de mer du golfe persique, Abdulsalam et al. démontrent que bien que cet acier présente une bonne résistance à la corrosion, il reste encore sensible à une corrosion caverneuse (surtout en milieu à 16% en masse d’ion chlorure ou à plus de 30°C).La première partie de ce travail traite du comportement électrochimique de l’acier inoxydable 254 SMO immergé dans l’eau de mer naturelle en laboratoire. Ainsi deux sites de la Guyane ont été choisis pour effectuer des prélèvements d’eau. Des analyses physicochimiques de ces eaux sont réalisées et montrent que l’eau du site du Port Larivot contient une quantité en ions chlorures plus importante que celle de l’eau du site du Mahury. Une colonisation par des bactéries et crustacés (balanes) a été mise en évidence, à l’aide du microscope électronique à balayage environnemental. Les mesures électrochimiques, notamment la voltammétrie cyclique a montré l’existence d’une zone de passivation et l’augmentation du courant de passivation par un facteur de 10 en présence d’un biofilm pour l’acier inoxydable immergé en eau du Mahury durant 22 jours. La deuxième partie propose une étude approfondie du comportement de l’interface complexe métal/couche passive/biofilm. Trois différents coupons d’aciers inoxydables (brut, poli et grenaillé) ont été déposés sur site (in-situ) dans un premier temps. Dans une seconde étape, nous avons réalisé des expérimentations mixtes (incubation in-situ et croissance en laboratoire). L’évolution du potentiel d’abandon de ces aciers est très proche pour l’acier brut et l’acier poli. En revanche, celui de l’acier grenaillé, de par la présence des grains d’alumine à sa surface, affiche un comportement différent. Une étude comparative des deux expérimentations montre des différences concernant les paramètres électriques de l’interface complexe métal/couche passive/biofilm. / Stainless steels with high content in molybdenum present an excellent corrosion resistance and were recently used in marine applications. The stainless steel 254 SMO contains molybdenum (6 %) and higher amounts of alloying elements than conventional stainless steels such as 304, 316 and 316L. While Anees Uddin Malik et al. show that 254 SMO steel is less likely to be susceptible to pitting corrosion in Arabian Gulf sea water, Abdulsalam et al. demonstrate that although this steel has good resistance to corrosion, it remains still susceptible to crevice corrosion (especially in environment with 16 chloride percent weight or more than 30 ° C).The first part of this work deals with the electrochemical behaviour of stainless steel 254 SMO immersed in natural seawater at laboratory. Two sites in French Guyane were chosen to take samples of seawater. Physicochemical analyses of these waters are made and show than the in Port Larivot site seawater contains a higher quantity of chloride ion than to Mahury seawater. Colonization by bacteria and crustaceans (barnacles) was highlighted, using the environmental scanning electron microscope. The electrochemical measurements, including cyclic voltammetry showed the existence of a passivation region and increasing the passivation current by a factor of 10 in the presence of biofilm on stainless steel immersed in Mahury seawater during 22 days.The second part offers a detailed study of the behaviour of the interface metal/passive film/biofilm. Three different coupons of stainless steel (crude, polished and blasted) were deposited on the site (in-situ) in the first time. In a second step, we performed experiments mixed (in-situ incubation and growth in the laboratory). The evolution of the free potential of these steels is very close for crude steel and polished steel. Conversely, the blasted steel, by the presence of alumina grains on its surface, shows a different behaviour. A comparative study of those two experiments shows differences in the electrical parameters of the interface metal/passive film/biofilm.

This thesis work has been conducted in the Handheld Laboratory at Husqvarna AB with the purpose of finding the parameters responsible for the performance of the catalytic converters used in the test rig. The catalytic converters are used in the test rig during the long term testing of the chain saws to reduce the hydrocarbon content from the exhaust before it enters into the environment.   To perform this research two approaches were carried out. One with Design of Experiment (DOE) and another using Scanning Electron Microscope (SEM) analysis. In Design of Experiments parameters that are suspected to be influencing the performance of the catalytic converter were refined. Using these parameters a test plan is made with the help of statistical analysis application Minitab and the tests were carried out in the test rig. Using SEM the effects of aging and its effect on microstructure and chemical composition on the catalyst surface was analyzed. The results from the DoE shows that the exhaust flow, collector diameter and distance to the muffler are responsible for the collection of exhaust. Distance to the muffler and collector length are the factors affecting the conversion of the exhaust. In addition to that exhaust flow is also responsible for the duration of heating coil running time.        The results from the SEM analysis shows that the operating temperature is high due to which there is thermal degradation of catalyst and there is also deactivation due to fouling. Another finding is that the flow on to the catalyst is not uniformly distributed

Content: A comprehensive analysis of the molecular and structural components of deer skin and cow hide was undertaken. These skins known to be strong, however they derive their strength from different combinations of molecular and structural properties. Firstly, the physical properties of deer skin and cow hide including the tensile strength, tear strength and denaturation temperature were measured. Secondly, the structure of the collagen fibrils and glycosaminoglycans was investigated using transmission electron microscopy (TEM), and small angle X-ray scattering (SAXS). Finally, the chemical composition of deer skin and cow hide such as amino acids, crosslinks and glycosaminoglycans were analysed. Our results showed that physical properties of deer skin and cow hide are derived from different combinations of several chemical components resulting in different architecture. It was found that the large and “wavy” collagen fibres in deer skin made up of collagen fibrils with small diameters. Additionally, deer skin fibrils appeared to be linked by regular arrays of filaments of large glycosaminoglycans that are distributed uniformly. Deer skin contained higher proportion of trivalent collagen crosslinks. In contrast, the collagen fibrils in cow hide were large, contained a diverse glycosaminoglycan distribution and a higher proportion of tetravalent collagen crosslinks, resulting in straight collagen fibres. This study suggests that although deer skin and cow hide are both strong, they have different structural and molecular features. Take-Away: Deer skin and cow hide have different structural and molecular make up which are reflected in their physical properties particularly strength. Glycosaminoglycans are important for the organisation of collagen fibrils in deer skin and cow hide. Deer skin and cow hide contain different ratios of collagen natural crosslinks which are essential collagen stability.

The theme of this diploma thesis is the design of a scanning electron microscope with a focused ion beam. Specifically, the thesis is focused on the design of the microscope covers and the adjacent workplace of the operator for Tescan Orsay Holding a.s.. Design is solved as the first proposal aimed at future innovation of the design of the entire product line.

The thesis is focused on the medium dynamics simulation in the environmental scanning electron microscope. Specifically, it researches (examines) the conical aperture location effect in the differential pumped chamber and the width of the pumping channel in this chamber. The theoretical part deals with the environmental scanning microscope generally and other tools used in this thesis, e.g. ANSYS Fluen software, fluid turbulence, medium free path of molecules and electrons scattering. In the practical part, the work is focused on data processing from the ANSYS Fluent program and on their evaluation.

This diploma thesis deals with the problems of analysis and the subsequent design of a precision manipulator used as a microscope table. The first part od the final thesis deals with the problems associated with the movement of the test sample within the electron microscope. Subsequently, possiblle design variants were proposed, further developing the next steps fot the correctness and functionality of manipulator. The individual force loads of the components were calculated. The result of the work was constructed as a CAD model with subsequent transfer to the assembly drawing.

First part of this thesis is a theoretical essay which deals with the basics of scanning electron microscopy, with structure and function of a scanning electron microscope, its’ special case of an various pressure scanning electron microscope, electron interaction with surrounding environment and with a scintillation detector. The applied part of the thesis is focused on evaluation of material contrast on Cu-W specimen. Material contrast is evaluated for different pressures of water vapors in the microscope specimen chamber and for different detection conditions.

The aim of my Master's thesis is the design of a scanning electron microscope. The designed concept presents an innovative approach to the problems and respects all technical, ergonomic and aesthetical demands made on it. The main creative part of design process starting from the concept development and ending up with the final solution is preceded by a background research study including a historical, technical and design analysis of the electron microscope. The conclusion of my Master's thesis analyses the final design, its character and its contribution in broader context.

Práce se zabývá návrhem a implementací testovacího zařízení pro manipulačnínmechanismus vzorku v elektronovém mikroskopu. Testovací zařízení a jeho software zajištuje meření několika parametrů mechanismu, jejich statistické vyhodnocení a porovnání se specifikací. Cílem je vytvořit komplexní testovací zařízení s jednoduchým uživatelským rozhraním, s požadavkem náhrady stávajícího nemodulárního a nestabilního řešení a jeho rozšíření o testování dalších parametrů.

Cílem této diplomové práce je zlepšit chování nanomanipulátoru, používaného v elektronovém mikroskopu, při vykonávaní nejmenších kroků pohybu. První částí je analýza mechanismu za účelem nalezení možných řešení problému. Dále se práce zabývá testováním řešení jako je optimalizace tuhosti předepínacích pružin mechanismu anebo změna mazání šnekového převodu mechanismu. Výsledkem práce je výběr nejvhodnějšího řešení problému na základě výsledků testů a následná modifikace nanomanipulátoru.