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Preparation and characterization of translucent glass ceramicsKakavandy, Shahow January 2021 (has links)
The purpose of this thesis is to prepare and characterize translucent glass ceramics. The procedure was as follows, first a general background of the field is presented where the problems with current dental glass ceramics are presented, together with their history. The need for a stronger material is then clarified with the addition of new metals. Then the material is created and synthesized using the Sol-Gel process, and a thorough description of the process is presented along with the material used. During this process Manganese, Aluminum, and Magnesium is added to the glass ceramics, and their powder is later pressed using different methods, cold isostatic pressing (CIP) and hot isostatic pressing (HIP). The material is then sintered at different temperatures and a series of testing is then done to the doped glass ceramics. Mechanical testing, Nanoidentation, X-ray powder diffraction and density measurement show that the strongest material is the 0.5mol Manganese doped glass ceramic. The Manganese doped samples are only strong to a certain level of doping, if doped too much become weak. The Magnesium doped samples are also more porous than the other samples.
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Influence of Magnesium in theFormation of Phosphate Spheres : A simple method for the fabrication of sphericalparticles of calcium and magnesium phosphateBerg, Camilla January 2017 (has links)
Calcium phosphates and recently also magnesium phosphates, are used for medical applications, due to their biocompatibility and bioactivity. These properites makes spherical particles of calcium and magnesium phosphate suitable for carrier materials for drug delivery applications. By creating porous and/or hollow particles itis possible to load the particles with a drug and control therelease of the active substance. In this work, an ion-induced method for the synthesis of spherical calcium and magnesium phosphates was developed. A simple precipitation reaction was used, where substituting magnesium ions could replace the function of templates, such as surfactants or micelles, to induce the formation of spheres of a certain size and morphology. Experimental results showed that magnesium had an inhibitory effect on the nucleation and crystal growth of calcium phosphates. By using substituting ions as a structural regulator, it was possible to alter the size, morphology and phase composition of the spheres. At low magnesium concentrations, the spheres had a smooth surface andwere between 200 nanometer to 1 micrometer in diameter and composed of hydroxyapatite and/or magnesium-substituted beta-TCP. At higher magnesium concentrations, the spheres were about 10-50 micrometer with a rough, flaky surface. Results also proved that calcium ionshave the same effect on the crystallisation and self-assembly of magnesium phosphates. Apart from the magnesium concentration, reaction temperature proved to have a high influence on the sphereformation, whereas Ca/P ratio and reaction times above three hours did not affect the sphere formation to the same extent.
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Metallic residues after hydriding of zirconiumAndersson, Patrik, Arvhult, Carl-Magnus January 2012 (has links)
As a part of the production of nitride nuclear fuel for use in fast nuclear reactors, zirconium is hydrided followed by nitriding and mixing with uranium nitride. This work concludes a study of unwanted metallic particles present in a powder that is supposed to be a zirconium hydride. Sponge zirconium was hydrided at different temperatures and different time intervals, and the resulting hydride was milled into a powder. The powders were analyzed using SEM and XRD after which the powders were pressed into pellets for light optical microscopic study. The primary goals were determination of the structure of the particles and thereafter elimination of them. It was seen that hydriding at 500 C results in less metal particles but more experiments need to be conducted to confirm this.
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Solar-driven Hydrogen Production by the use of MIEC Membranes : A Techno-Economic AssessmentNilsson, Mattias January 2012 (has links)
This thesis comprises an assessment of a novel concept to produce high purity hydrogen using mixed oxide ion/electronic conductor (MIEC) membranes and energy provided by solar concentrators (i.e. parabolic troughs or parabolic dishes). The vision of this concept is that it will be used to produce tons of high purity hydrogen for fuel cells, which is a scarce commodity with an increasing demand from residential and transportation power generation applications. The MIEC membrane activates a steam reforming reaction between water and methane to produce hydrogen of high purity on the water side and syngas on the fuel side. Expectations are that this concept has cost advantages over other thermo-chemical water-dissociation methods, using a lower temperature and no electricity for the reaction process. The thesis’ focus is on techno-economic aspects of the concept, as part of an application process for project financing by the European Commission of Research and Innovation. The assessment in the thesis shows that the overall efficiency of the concept is expected to be very low. It also identifies the difficulties of providing stable working conditions for the concept. Suggestions to improve the concept are proposed to address the most urgent problems of the concept. These suggestions illuminate the opportunities that actually do exist to combine MIEC membranes, solar energy and thermo-chemical water splitting into a working concept. These improvements include using parabolic dishes instead of parabolic troughs, using furnaces with control systems and using a viable flow rate. The production capacity of high purity hydrogen is expected to be approximately 89 mg per minute in a membrane bundle (i.e. 150 thin membrane fibers with an oxygen permeation flux of 1 ml cm-2 min-1) if these improvements were implemented. This would imply that the studied concept needs further development to produce high purity hydrogen in quantities that could meet the shortage on the commercial fuel cell markets.
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The thermal insulating effects of Quartzene® on painting systemsZendehrokh, Arwin, Mariscal, Luis, Hunhammar, Martin, Yussuf Hassan, Ismail, Pettersson, Albert January 2020 (has links)
The European Green Deal 2020 goals for reducing emissions are enforcing rules on the energy performance of buildings. Therefore thermally insulating materials used as coatings are researched to reduce the energy emissions of buildings. An essential field of interest are nanomaterials. Traditional aerogel is a nanomaterial used for insulating applications due to its high porosity and large surface area, resulting in a longer path for heat to travel. However the cost and manufacturing process are highly energy demanding. Svenska Aerogel AB produces Quartzene® (Qz), a silica-based nanomaterial with similar properties as traditional aerogel. Qz can be incorporated into different paint systems to improve their thermal insulating properties. The aim of this project was to investigate the thermal insulating effects of Qz on three different painting systems (A, B, and C). Samples were moulded and their thermal properties were measured with TPS (Transient Plane Source). The thermal conductivity decreased as the wt% of Qz increased, up until around 10 wt% for system C. It became apparent that at higher wt%, it became harder to properly mix the samples into a good dispersion. The thermal conductivity started to increase above 10 wt%. Experiments showed that bigger particles were easier to mix into the paint than smaller.
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Nitridation of Lithium Silicate Phosphate Glasses for Application as Solid Electrolyte : A Material Properties StudyTönnesen, Freddy January 2023 (has links)
The pursuit of sustainable and high-performance materials is of utmost significance in driving the progress of battery technologies. Solid-state technology represents a promising avenue for the development of batteries with improved sustainability and performance. In this context, the present study delves into the examination of composition and the substitution of oxygen with nitrogen within the 50Li2O-xSiO2-(50-x)P2O5 glass system, specifically as applied to Solid-State electrolytes. The objective is to evaluate the influence of these factors on the electrical properties of the glass and their potential implications for Solid-State battery technology. The glass matrix was obtained through the melt-quenching technique, followed by comprehensive characterization using electrochemical impedance spectroscopy. The influence of varying silica content on the conductivity of the glass was investigated. This led to the selection of the glass system with the highest conductivity for further experiments involving nitridation. Subsequent experiments on nitridation aimed to explore the impact of nitrogen incorporation on the conductivity of the glass. By systematically varying the nitrogen content at different temperatures, the study sought to elucidate the relationship between nitrogen content and the resulting increase in glass conductivity. The study reveals a noteworthy finding regarding the impact of nitrogen content on the conductivity of the glass. Specifically, when the nitrogen content was increased, the conductivity increased. In the case of a similar glass composition in pellet form, the conductivity at room temperature increased from Log σ = -8,009 (for glass without nitrogen) to Log σ = -6,951 (for nitrided glass). Additionally, the introduction of nitrogen into the glass resulted in a decrease in activation energy, being reduced from 0,66 eV (for oxide glass) to 0,60 eV (for oxynitride glass). These results indicate a clear correlation between increased nitrogen content and enhanced electrical properties of the investigated glasses; although obtaining a homogeneous bulk glass after nitridation was not feasible. Therefore, the nitrided samples were pelletized and sintered under different thermal conditions to obtain characterizable samples. The findings suggest that nitrogen substitution could be a promising approach for enhancing the electrical properties of the glasses of the title system of composition. Further investigation is required to optimize the process and achieve homogeneous bulk oxynitride glass.
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A Wave Home : Exploring furniture for the moonMiller, André January 2023 (has links)
In this thesis, I have explored the possibilities of what furniture can look like on a moon base. How they will be made and what resources to use. What will the living conditions be like and why producing on a faraway place is important for future interstellar missions. By combining art and design, I will present a realistic concept that fits the need of the astronauts stationed on the moon and know what one might need when on a moon station.
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PCL-Calcium Phosphate 3D Printed Scaffolds For Bone Tissue RegenerationGarcia Perez Delabat, Javier January 2020 (has links)
The design and selection of a biomaterial will depend on its specific application and the required properties for that application, both mechanical physicochemical properties. Biomaterials can be extremely helpful in order to treat and help the human body to heal and repair faster any kind of fracture produced in bones. Calcium phosphate scaffolds produced by sol-gel procedures have been used for this purpose with a great success regarding mechanical properties and biocompatibility. This is the reason why new techniques needs to be developed to be able to produce scaffolds in a faster way and to reach a personalized treatment to each patient. By using 3D printing techniques, a new and promising scope is open for bone tissue engineering due to the possibility of printing scaffolds with any shape and complexity through CAD design and modelling. In this project 3D printed scaffolds with a matrix combination of polymers and calcium phosphate will be produced and studied for bone tissue regeneration. Self-setting alpha tricalcium phosphate (α-TCP) based cement inks combined with polycaprolactone (PCL) were optimized, and 3D printed structure scaffolds were successfully generated by direct ink writing. Afterwards, the scaffolds were subjected to different hardening processes in order to obtain different hydroxyapatite microstructure morphologies and were characterised by different methodologies. It was demonstrated the important effect of obtaining a complete transformation from the α-TCP into hydroxyapatite in the mechanical properties. An improvement in the mechanical properties at compression was achieved with the addition of PCL within the scaffold ́s structure and a different fracture mode of the scaffolds was observed.
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Separate Calcination in Cement Clinker Production : A laboratory scale study on how an electrified separate calcination step affects the phase composition of cement clinkerVikström, Amanda January 2021 (has links)
Cement production is responsible for around 7% of the global anthropogenic carbon dioxide emissions. More than half of these emissions are due to the unavoidable release of carbon dioxide upon thermal decomposition of the main raw material limestone. Many different options for carbon capture are currently being investigated to lower emissions, and one potential route to facilitate carbon capture could be the implementation of an electrified separate calcination step. However, potential effects on the phase composition of cement clinker need to be investigated, which is the aim of the present study. Phases of special interest are alite, belite, aluminate, ferrite, calcite, and lime. The phase composition during clinker formation was examined through HT-XRD lab-scale experiments, allowing the phase transformations to be observed in situ. Two different methods of separate calcination were investigated, one method in which the raw meal was calcined separately, and one method where the limestone was calcined separately. The former yielded an alite amount similar to that of the reference experiments, whereas the latter method yielded a lower amount. It could, unfortunately, not be excluded that the difference was due to poor experimental conditions, and additional experiments are needed to investigate the matter further. The study does, however, indicate that a calcined raw meal might be used to produce a clinker of similar phase composition concerning major phases belite, aluminate, ferrite, alite, and free lime. A raw meal containing calcined limestone might, however, need longer residence time at clinkering temperature too obtain similar phase composition. In addition, a raw meal containing calcined limestone was observed to be carbonated to a greater extent upon reheating than a calcined raw meal. Further experiments are needed to fully understand the effects on clinker composition of an electrified separate calcination step, and several improvements to the experimental method are given in the study.
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Can Bone Void Fillers Carry Load? : Behaviour of Calcium Phosphate Cements Under Different Loading ScenariosAjaxon, Ingrid January 2017 (has links)
Calcium phosphate cements (CPCs) are used as bone void fillers and as complements to hardware in fracture fixation. The aim of this thesis was to investigate the possibilities and limitations of the CPCs’ mechanical properties, and find out if these ceramic bone cements can carry application-specific loads, alone or as part of a construct. Recently developed experimental brushite and apatite cements were found to have a significantly higher strength in compression, tension and flexion compared to the commercially available CPCs chronOS™ Inject and Norian® SRS®. By using a high-resolution measurement technique the elastic moduli of the CPCs were determined and found to be at least twice as high compared to earlier measurements, and closer to cortical bone than trabecular bone. Using the same method, Poisson's ratio for pure CPCs was determined for the first time. A non-destructive porosity measurement method for wet brushite cements was developed, and subsequently used to study the porosity increase during in vitro degradation. The compressive strength of the experimental brushite cement was still higher than that of trabecular bone after 25 weeks of degradation, showing that the cement can carry high loads over a time span sufficiently long for a fracture to heal. This thesis also presents the first ever fatigue results for acidic CPCs, and confirms the importance of testing the materials under cyclic loading as the cements may fail at stress levels much lower than the material’s quasi-static compressive strength. A decrease in fatigue life was found for brushite cements containing higher amounts of monetite. Increasing porosity and testing in a physiological buffer solution (PBS), rather than air, also decreased the fatigue life. However, the experimental brushite cement had a high probability of surviving loads found in the spine when tested in PBS, which has previously never been accomplished for acidic CPCs. In conclusion, available brushite cements may be able to carry the load alone in scenarios where the cortical shell is intact, the loading is mainly compressive, and the expected maximum stress is below 10 MPa. Under such circumstances this CPC may be the preferred choice over less biocompatible and non-degradable materials.
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