Anledningen till att skriva om cellulosalack är att från år till år det finns allt fler möbler med sådan ytbehandlingsom hamnar på konserverings- och restaureringsverkstäder. Dessa möbler kommer framför allt från1950- och 1960-talet (när det var en av dem vanligaste typerna av ytbehandling) men även från 1920- och1930-talet. Idag har möblerna från 1900-talet blivit antikviteter och eftersökta på marknaden. Därför är demvärdefullast med sin ursprungliga ytbehandling som behöver skyddas och bevaras.Den här typen av transparent ytbehandling orsakar många problem för en konservator men jag harkoncentrerat mig på hur man partiellt kan bättra lakuner, som man kan tolka här som tomrum, brist, bortfallav transparent ytbehandling (ordet kommer från latin – lacuna, lacunae).Tidigare har den vanligaste metoden för att restaurera en möbel med förstörd cellulosaytbehandlingvarit att rensa bort den gamla och lägga på helt ny. I moderna tider är det uppenbart att det är inte särskiltmiljövänlig och hälsosamt att rensa bort och lägga på nytt cellulosalack samt med bevaringsattityd är det bättreatt reparera den gamla ytbehandlingen som är originell och autentisk. Som möbelkonservator borde manlära sig att hantera sådan ytbehandlingsproblematik.Därför finns det behov att hitta metoder och material som hjälper att fylla lakuner på ett effektivt sätt.Där har jag också värderat dem utifrån konserverings- och restaureringsgrundregler. Baserade på skriftligakällor samt på min och min handledarens erfarenhet i detta område, har jag i mitt examensarbete genompraktiska experiment presenterat och utvärderat några metoder att fylla lakuner. / The reason to write about cellulose lacquer is that from year to year there are more and more furniture withsuch transparent coatings that come to the conservation and restoration workshops. The furniture comesmainly from the 1950´s and 1960´s (when it was one of the most common type of transparent finishes) butalso from the 1920´s and 1930´s. Today the furniture from the 20th century has become antiques and soughtafter on the market. Therefore, they are still valuable with their original coatings that would need to be protectedand preserved.This type of transparent finishes causes many problems for the conservator, but I have concentratedon how to partially improve the lacunae that you can interpret here as a break in continuity, gaps in transparentcoatings (the word comes from Latin – lacuna, lacunae).Earlier, the most common method of restoring a furniture with damaged transparent coatings was toremove the old and add a whole new one. In modern times, it is obvious that it is not very environmentallyfriendly and healthy to clean up and add new nitrate cellulose laquer, with conservation attitude is better torepair old finishes that are original. One should learn how to handle such transparent coatings problems.Therefore, there is a need to find methods and materials that help fill gaps effectively. I have also evaluatedthem based on preserving and restoration ground rules.Through practical experiments, based on written sources as well as on my and my supervisors experiencein this area, I have presented and evaluated some methods of filling lacunae in my bachelor thesis.

At the Division of Electricity at Uppsala university a project isconducted to develop a smaller wind turbine for conditions in theAntarctica. This is a part of a larger, international researchproject in the field of particle physics known as the Ariannaexperiment. The project consists of developing and installing avertical axle wind turbine of screwed Savonius type. A prototypeof this has been manufactured and installed 2016 in Antarctica forinitial testing and measurement.Wind turbines are subjected to complex and varied loads from windand rotation which gives rise to cyclical strain. The rotor bladesare particularly vulnerable, which imposes high material andconstruction requirements to avoid fatigue and failure, whichoften is caused by vibrations and oscillations. Vibrations can becharacterized in terms of the natural frequencies witch in shortmeans that the system, at specific frequencies, tend to oscillatewith increasing amplitude and at worst, resonate if these areexcited. How a complex design will behave by external periodicinterference is complicated to calculate analytically. Naturalfrequencies are therefore most often calculated using FEM-methodsand computer simulations.The aim of this thesis is to study how oscillating forces interactwith the natural frequencies and rotational loads for a specificSavonius wind turbine. How these are influenced by engineering,design and material selection. The goal is to draw conclusionsabout design and possible materials selection to avoid unnecessaryvibrations. Without this analysis, there is a risk of increasedwear and damage to the structure.The project includes such analysis of two different sizes of theSavonius turbine. A small 200x400 mm and a larger 1000x2000 mm.To understand the problem, a preliminary study of basic harmonicoscillation, strength of materials and of the existing prototypewas made. Following a requirement specification, somedelimitations were made so that the simulations would not be tooextensive. Subsequently, a minor design work was done to obtain 13different configurations of the turbine for simulation using FEM-methods.The result showed that none of the turbines rotational frequenciesis close to the turbine’s natural frequencies. However, accountmust be taken of cogging frequencies in the generator. These arewithin the range of the design's natural frequencies.All simulations of centrifugal force found that there isrelatively little tension at the selected maximum speed of 660 and132 revolutions per minute. However, as the results showed thatthe plates which are mounted between the rotor blades to providestability, creates greater stresses in the structure than thosewithout. Two proposals for the configuration of turbines have beenpresented in the report.

This thesis aims at increased knowledge in two fields of tribological research; both related to making currently used combustion engines greener. The first field regards the possibilities of using a boric acid fuel additive to increase fuel efficiency. The second field is about the severe wear phenomenon scuffing, which can become problematic when cargo ships are operated on low-sulphur fuel to reduce sulphuric emissions. Tribological tests were developed and performed to simulate the applications. Advanced surface analysis was performed to understand changes occurring on the outermost surface of sliding components, which affect friction and wear. Samples from engines were studied to verify the relation between the lab tests and the applications. In the case of boric acid, the coefficient of friction was below 0.02 for large parts of the tests, but varied with test parameters. The corresponding reduction in friction was up to 78% compared with tests without the additive. As an attempt to assess if the substantial fuel savings found in field tests with passenger cars (6%) can be explained by friction reduction in boundary and mixed lubricated parts of the piston assembly, assumptions were presented that would lead to fuel savings close to these 6%. Boric acid was detected on surfaces after the tests, and the tribofilm appearance depended on test parameters. The tribofilms were shown to be affected by storage time and test temperature; a finding that is vital for future studies. In the case of scuffing, mechanisms were studied and accumulation of wear debris had a significant role on scuffing initiation in the lab scale scuffing tests. Regarding the possibility to test materials scuffing resistance, there was a large scatter in the results, and thereby difficult to draw conclusions. Two new piston ring materials were identified to perform somewhat better than the currently used. In conclusion, findings that could facilitate immediate improvement of fuel efficiency of today’s combustion engine vehicles as well as findings that strengthen available hypotheses on scuffing mechanisms are presented. The latter offers improved understanding of scuffing and thereby give possibilities to counteract the higher risk associated with operation on cleaner fuel.

The optical response of several magnetic nanoparticle dispersions is studied by angle resolved transmittance at wavelength of 600 nm in zero-field and under an applied magnetic field of 0.1 T, with the purpose of exploring to what extent this could be used as a method of monitoring the colloidal dispersions. In an external magnetic field, magnetic particles will start to order into needle-like structures aligned with the field, which was observed by microscopy. This will change the light scattering caused by the particles. Results showed a clear effect from applying the magnetic field by a dip in the transmitted intensity at angles around 3-5 degrees. The scattering is compared to that of a homogeneous infinite cylinder and theoretical explanations to the effect are discussed. Spectrophotometry at wavelengths between 300-1100 nm is performed and compared with calculations from Kubelka-Munk approximation to give a first characterization of the particle dispersions. Particles used in this project are magnetite, Fe3O4, and maghemite, gamma-Fe2O3, nanoparticles with sizes ranging from 5-250 nm.

EU Sustainable Development Strategy planned to achieve improvement of life-quality by promoting sustainable production and consumption of raw materials. On November 2018, EU Commission presented a long-term strategy, aiming among others a climate-neutral economy by 2050. Cement production is contributing to 6-10% of the anthropogenic CO2 emissions. Thus, several strategies for total or partial replacement of Portland cement in concrete production have been developed. The use of supplementary cementitious materials (SCM) and alkali-activated materials (AAM) is considered the most efficient countermeasure to diminish CO2 emissions. The broadening of knowledge with particular attention to the sustainable goals is the primary requirement to be fulfilled when novel materials are investigated. This study aims to develop a novel clay-based binder that can be used as a sustainable alternative to produce SCM as well as AAM. Clay is a commonly occurring material, with large deposits worldwide. However, natural clay has a low reactivity and various compositions, depending, e.g. on the weathering conditions. The present research aims exactly at enhancing the reactivity of natural clays occurring in Sweden subjecting them to mechanical activation in a planetary ball mill. Ball milling (BM) is considered a clean technology able to enhance the reactivity of crystalline materials without resorting to high processing temperatures or additional chemicals. BM was able to induce amorphization in clay minerals and to transform the layered platy morphology to spherical shape particles. The efficiency of the process was strictly related to the used process parameters. Higher ball to processed powder (B/P) ratio, longer time of grinding and higher grinding speeds increased the degree of the obtained amorphization. However, an undesired extensive caking and agglomeration occurred in certain setups. The potential of activated clay as a SCM was investigated in specific case studies. The measured compressive strength results showed a direct correlation between the enhanced amorphization degree of the mechanically activated clay and the increased strength values. The pozzolanic activity was induced and enhanced after the mechanical activation of the clay. The reactivity was assessed by the strength activity index (SAI). Furthermore, preliminary tests have shown that the alkali activation of the processed clays produced solidified matrixes with considerable strength.

The erosion or dissolution of stainless steel grade 304 as base metal by molten brazing fillermetal was investigated using one nickel and two iron based filler metals. The difference betweentwo iron filler metal is 5 % Manganese content in one of the filler metal. The Wettability of fillermetal is effected by oxidation of base or filler metal for which high vacuum or non reacting gasis used as a furnace atmosphere to reduce the partial pressure of oxygen. The furnace parameterseffecting erosion of base metal was observed e.g. peak temperature and brazing time. The effectof filler mass was also observed. The erosion depth was measured by light optical microscope.All the three filler metal shows different erosion behavior in nitrogen atmosphere compare tohigh vacuum. In high vacuum some of the elements evaporates at brazing temperature whichchanges the properties of filler metal. This change of composition in filler metal was observed byEDX analysis. SEM analysis was used to identify different element rich phases.

Lightweight design in rail vehicles has been important for quite some time. Structures have been optimised to fulfill their purpose and cut unnecessary weight to reach allowable axle loads. Classically this is done by using steel, thin-walled structures, throughout the car body, or, alternatively, power-pressed aluminum profiles. The use of composites and sandwich structures has, however, been somewhat limited in the railway industry, especially when considering High-Speed trains. The anticipated weight savings, and reduced complexity of this type of structure are believed to have great potential in the future. This thesis covers the development of methods for structural stiffness design of lightweight, load carrying, sandwich panels for high-speed rail vehicles. Focusis on reducing the weight of the vehicles while simplifying the construction to reduce manufacturing costs and assembly times. Significant work is put into understanding the dynamic influence this type of structure has on the car body. / QC 20110516 / Multifunctional body panels

Zr-based materials have found their main application in the nuclear field having high corrosion resistance and low neutron absorption cross-section. The oxide layer that is formed on the surface of these alloys is meant to be the barrier between the metal and the corrosive environment. The deterioration of this protective layer limits the lifetime of these alloys. A better understanding of the transport phenomena, which take place in the oxide layer during oxidation, could be beneficial for the development of more resistant alloys. In the present study, oxygen and hydrogen transport through the zirconia layer during oxidation of Zr-based materials at temperatures around 400C have been investigated using the isotope-monitoring techniques Gas Phase Analysis and Secondary Ion Mass Spectrometry. The processes, which take place at oxide/gas and oxide/metal interface, in the bulk oxide and metal, have to be considered in the investigation of the mechanism of hydration and oxidation. Inward transport of oxygen and hydrogen species can be influenced by modification of the surface properties. We found that CO molecules adsorbed on Zr surface can block the surface reaction centers for H2 dissociation, and as a result, hydrogen uptake in Zr is reduced. On the other hand, coating the Zr surface with Pt, resulted in increased oxygen dissociation rate at the oxide/gas interface. This generated enhanced oxygen transport towards the oxide/metal interface and formation of thicker oxides. Our results show that at temperatures relevant for the nuclear industry, oxygen dissociation efficiency decreases in the order: Pt > Zr2Fe > Zr2Ni > ZrCr2 ≥ Zircaloy-2. Porosity development in the oxide scales generates easy diffusion pathways for molecules across the oxide layer during oxidation. A novel method for evaluation of the gas diffusion, gas concentration and effective pore size of oxide scales is presented in this study. Effective pore sizes in the nanometer range were found for pretransition oxides on Zircaloy-2. A mechanism for densification of oxide scales by obtaining a better balance between inward oxygen and outward metal transport is suggested. Outward Zr transport can be influenced by the presence of hydrogen in the oxide/metal substrate. Inward oxygen transport can be promoted by oxygen dissociating elements such as Fe-containing second phase particles. The results suggest furthermore that a proper choice of the second-phase particle composition and size distribution can lead to the formation of dense oxides, which are characterized by low oxygen and hydrogen uptake rates during oxidation.

The main focus in the present work concerns calculations on steel/slag equilibria. Thermodynamic software and databases are now powerful and accurate enough to give reliable results when applied to complex metallurgical processes. One example is the decarburization process of high alloyed steels. It is shown that using advanced thermodynamic models, without a complicated kinetic description of the system, reasonable agreement with experimental data is obtained. The calculations are performed using the Thermo-Calc software. Within this work a Java interface for Thermo-Calc has been implemented. Java gives graphical possibilities and a graphical interface has been created that facilitates calculations that involve both metallic phases as well as oxides and make them feasible also for an industrial user. / QC 20101118

This study examines whether woven metal mesh is an appropriate option for usage in beds and what material the mesh should consist of to best be suited for the purpose. The woven steel mesh’s construction was based on a reference model that consists of cross-linked rods and wires. Since the aim of the project was to reach a conclusion of the mesh’s usability in beds, different parameters were examined and taken into consideration. These parameters were the durability of the mesh when carrying human weight, acoustic properties to minimize chatter when lying on the mesh and rolling properties. The durability was examined using COMSOL multiphysics. Acoustics were studied through a literature review and rolling properties were calculated using measurements on the reference model. A material investigation was done in the database software CES EduPack. It was found that steel, stainless steel and aluminum fulfilled the requirements set on durability. Stainless steel was considered too expensive and steel too heavy. Using aluminum halves the weight of the mesh in comparison to steel but doubles the price, in this case however the weight was considered to be a parameter of greater importance overriding price.