This thesis is focused on corrosion protection of magnesium alloys AZ 91. Very important is material corrosion in some environments and last but not least surface treatment as grinding, polishing and etching. Theoretical part of this thesis is about magnesium and magnesium alloy. It focuses on properties, in order to determine the best procedure for corrosion protection. It characterize material corrosion- for example corrosion in special environment (atmosphere, water, etc.) or elektrolyte corrosion. Big part of theoretical part is focused on electrochemistry, in particular kinetic aspects (Tafel diagrams, corrosion current, etc.) and potentiostatic testing, where are observed properties of material in relation to potential: corrosion potential Ecorr, brakedown potential Ebd and repassivation potential Erp. This work present preparing, utilization and positive or negative aspects of corrosion protection. Metallography is important too since metallographical preparation is crucial for the research on the material. Described metallography procedures are mounting, grinding, polishing, etching and interpretation. Experimental part of this thesis is in particular about corrosion properties of magnesium alloy AZ 91. It focuses on calculation of corrosion rate in defferent environments. Principle is mass defekt of the alloy. The environments are: destilled water, hot service water and 3% NaCl solution (like sea water). Last but not least are important. procedure manipulation with materials. Very important are choice and composition of solutions, etching time, choice of polishing cloth, lubricant solution and good pressure. Beacuse of this aspects can be show corrosion action of environments on magnesium alloy AZ 91 by photographies.

The project elaborated in frame of Master's studies branch 2303T002 presents a study of welded joints for hot-dip galvanizing. On the basis of literature study it is assumed that zinc influences the properties of welded joints. Samples were made of high strength steels DOMEX and wear-resistant steels HARDOX which were welded using MAG. Subsequently, half of the samples treated with zinc. The evaluation is used tear test and test Vickers hardness. Finally, the project is the comparison of the measured values of galvanized steel and steel without zinc.

This master’s thesis deals with the properties of highstrength steels, mainly with their resistance to corrosion. It describes discusses different types of corrosion and the possibility of protecting materials against corrosion. The thesis also evaluates compares the cost of corrosion protection by using coating and hot dip galvanizing. It describes describes the principles of degreasing and pickling, which is used as an adjustment before hot dip galvanizing. It evaluates there are many procedures for hot dip galvanizing, such as wet, dry or spin method, which is used for small parts. This thesis also evaluates the change of mechanical properties of steels: Hardox 500, Weldox 700 and 500 Weldox after hot dip galvanizing.

The main focus of the thesis is the proposal for the construction of welding jig for the extension of the bus. Welding of individual parts of the assembly is on manual workplace. All parts are made of fabricated structural steel ČSN 41 1373 with galvannealed coating. As an appropriate technology for welding of extension with the optimal parameters method MAG was chosen.

This master´s thesis deals with hot dip galvanizing of steel constructions and their protection from corrosion. This work describes the origin of corrosion of steel and its corrosion in different areas and presents degreasing and pickling before hot dip galvanization. It describes possibilities of making zinc layer by the wet and draw method of hot dip galvanization. Furthermore, it puts forward reactions between zinc and iron, possible defects of the zinc layer and influence of the hot dip galvanizing on the steel constructions. The experimental part examines the influence of the hydrogen charging on the material and the time of the flux operation on the quality of layer. The work further analyses the changing of mechanical properties of steels Hardox 500 and Weldox 700 as a result of the hydrogen embrittlement during pickling by the hydrochloric acid.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20061号 / 工博第4249号 / 新制||工||1658(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 三ｹ田 均, 教授 小池 克明, 教授 木村 亮 高梨 将 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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There is a need to discover advanced materials to address the pressing challenges facing humanity, however there are far too many combinations of material composition and processing conditions to explore using conventional experimentation. One powerful approach for accelerating the rate at which materials are explored is by miniaturizing the scale at which experiments take place. Reducing the size of samples has been tremendously productive in biomedicine and drug discovery through standardized formats such as microwell plates, and while these formats may not be the most appropriate for studying polymeric materials, they do highlight the advantages of studying materials in ultra-miniaturized volumes. However, precise and controlled methods for handling diverse samples at the sub-femtoliter-scale have not been demonstrated. In this thesis, we establish that scanning probes can be used as a technique for realizing and interrogating sub-femtoliter scale polymer samples. To do this, we develop and apply methods for patterning materials with control over their size and composition and then use these methods to study material systems of interest. First, we develop a closed-loop method for patterning liquid samples using scanning probes by utilizing tipless cantilevers capable of holding a discrete liquid drop together with an inertial mass sensing scheme to measure the amount of liquid loaded on the probe. Using these innovations, we perform patterning with better than 1% mass accuracy on the pL-scale. While dispensing fluid with tipless cantilevers is successful for patterning pL-scale features and can be considered a candidate for robust nanoscale manipulation of liquids for high-throughput sample preparation, the minimum amount of liquid that can be transferred using this method is limited by number of factors. Thus, in the second section of this thesis, we explore ultrafast cantilevers that feature spherical tips and find them capable of patterning aL-scale features with in situ feedback. The development of methods of interrogating polymers at the pL-scale led us to explore how the mechanical properties of photocurable polymers depend on processing conditions. Specifically, we investigate the degree to which oxygen inhibits photocrosslinking during vat polymerization and how this effect influences the mechanical properties of the final material. We explore this through a series of macroscopic compression studies and AFM-based indentation studies of the cured polymers. Ultimately, the mechanical properties of these systems are compared to pL-scale features patterned using scanning probe lithography and we find that not only does oxygen prevent full crosslinking when it is present during the post-print curing, but the presence of oxygen during printing itself irreversibly softens the material. In addition to developing new methods for realizing ultra-miniaturized samples for study, the novel scanning probe methods in this work have led to new paradigms for rapidly evaluating complex interactions between material systems. In particular, we present a novel method to quantitatively investigate the interaction between the metal-organic frameworks (MOFs) and polymers by attaching a single MOF particle to a cantilever and studying the interaction force between this MOF and model polymer surfaces. Using this approach, we find direct evidence supporting the intercalation of polymer chains into the pores of MOFs. This work lays the foundation for directly characterizing the facet-specific interactions between MOFs and polymers in a high-throughput manner sufficient to fuel a data-driven accelerated material discovery pipeline. Collectively, the focus of this thesis is the development and utilization of novel scanning probe methods to collect data on extremely small systems and advance our understanding of important classes of materials. We expect this thesis to provide the foundation needed to transform scanning probe systems into instruments for performing reliable nanochemistry by combining controlled and quantitative sample preparation at the nanoscale and high-throughput characterization of materials. To conclude, we present an outlook about the necessary technological advancements and promising directions for materials innovations that stem from this work.

In last decade, there is a large increase in installed capacity of wind power. Asmore wind power is integrated into utility networks, related technologychallenges draw much attention. The doubly fed induction generator (DFIG) isthe mainstream choice for wind turbine generator (WTG) in current market andthe object of this thesis. It is very sensitive to voltage dips. The enhancement oflow voltage ride through (LVRT) is one of the most important issues for DFIG,and many works have already been done to provide solutions.In current works, the voltage dip waveforms that are applied in LVRTrelated works are largely different from waveforms in reality, because they failto consider the the effect of realistic wind farm configurations on waveforms ofvoltage dips and significant influences of additional characteristics of voltagedips. The true impact of the voltage dip needs to be assessed in performanceevaluation and development of LVRT methods. To support the development ofpractical LVRT capacity enhancement solutions, the application of voltage dipknowledge is definitely demanded.In this thesis, the characteristics of realistic waveform voltage dips in windfarm are analyized based on voltage dip knowldege from power quality field,measured voltage dip from industry and realistic wind farm configurations.Classical analysis theory is applied to explain the principles of the impact ofvoltage dip characteristics on dynamic behavior of DFIG. The impacts of manywidely neglected characteristics such as phase angle jump (PAJ), point on wave(POW) of initiation and recovery, voltage recovery process, transformerconfigurations, load effect are revealed and verified by simulations. The impactof many voltage dip characteristics on DFIG are studied for the first time. / De senaste tio åren har sett en stor ökning av installerad effekt av vindkraft.Mer vindkraft i elnäten har lett till större uppmärksamhet om dess tekniskautmaningar. Den dubbelmatad asynkrongenerator (DFIG) är idag denvanligaste förekommande typen i vindkraftverk. Den är mycket känslig förspänningssänkningar. Förbättring av tålighet för spänningssänkningar (LVRT)är en av de viktigaste frågorna för DFIG, och många studier har redan söktlösningar.I befintliga studier om LVRT har spänningssänkningarna skiljt sig väsentligtfrån verkliga vågformer, då de inte har tagit hänsyn till realistiskavindparkkonfigurationer och betydande påverkan av ytterligare egenskaper hosspänningssänkningar. För att stödja utvecklingen av praktiska LVRT lösningarbehövs mer kunskap om spänningssänkningar för att bedöma dess verkligainverkan.Detta examensarbete förbättrar LVRT analysen av DFIG genom att tillämpakunskap om spänningssänkningar från elkvalitetsområdet, tillsammans medrealistiska vindparkskonfigurationer. Inflytandet av ändringar i fasvinkel(PAJ), fasvinkeln vid sänkning och återhämtning (POW), spänningsåterhämtning, transformatorkonfigurationer, last och många andra egenskaperav spänningssänkningar ingår också. Inflytandet av många egenskaper avspänningssänkningar studeras här akademiskt för första gången. Denkaraktäristik av realistiska spänningssänkningar som inträffar vid generatornspoler, och de effekter dessa har, studeras och förklaras genom teoretisk analysoch intensiva simuleringar.