Rapporten beskriver ett designprojekt, som är en del av examensarbetet på 15p, Vad händer när mode påverkar möbeldesign? En kollektion strandmöbler och badkläder, utfört av Veronica Lindahl, avgångsstudent på utbildningsprogrammet möbeldesign på Carl Malmsten, Centrum för Träteknik & Design vid Linköpings universitet. Syftet med denna rapport är att beskriva processen av detta examensarbete. Valet av produkter tog avstamp från min bakgrund i Halmstad. En möbel för stranden och något att ha på sig. Att koppla samman mode och möbeldesign tilltalar mig. Målet var att produkterna skulle komplettera och inspirera varandra. Att tänka på hur produkterna skulle presenteras var också en del i arbetet. Upplägget i denna rapport är enligt ordningen i min designprocess. Det börjar med en insamlingsetapp. Efter detta följer en lång skissetapp, därefter material, tillverkning och slutligen en resultatanalys med tankar och reflektioner över vad jag kommit fram till. Arbetet startade med samtal med handledaren Daniel Östman, där vi diskuterade val av examensarbete samt vad jag ville få ut av arbetet. Jag valde att göra ett projekt med mig som uppdragsgivare, eftersom det är så jag vill arbeta i framtiden. Ledorden i mitt arbete har varit modedesigns påverkan på möbeldesign, en möbel för stranden och något att ha på sig, trä och tyg, material som klarar utomhusklimatet. Resultatet är en funktionell, bärbar strandstol med två lägen som är lätt, går att fälla ihop och kan bäras på ryggen. Detta är en produkt som jag skulle vilja se på stranden. Detsamma gäller badplaggen, de väcker nyfikenhet och är ett mer påklätt badmode. Vid presentationen av produkterna använde jag mig av en stiliserad strand som gav en känsla av hur produkterna skulle användas i den miljö de var avsedda för. I framtiden vill jag arbeta med att kombinera modeskapande och möbeldesign. Jag har upptäckt många intressanta möjligheter och uppslag i vad som händer när mode påverkar möbeldesign.

The objective of this work was to use LEFM in order to assess the detrimental influence of surrounding chloride-containing environments for stainless steels, hardened steel as well as for a cast aluminium alloy. An additional aim was also to use LEFM to assess the influence of porosity on the fatigue properties for different commercial cast aluminium alloys and manufacturing methods. The environmental influence on fatigue performance was mainly evaluated from fatigue crack growth measurements using compact tension (CT) specimens. In addition, fatigue performance in the high cycle regime was studied using spot welded specimens and smooth specimens. Corrosion fatigue tests for stainless steels were performed in different chloride-containing aqueous solutions and compared to the behaviour in air. Variables, which have been investigated, included temperature, redox potential and fatigue test frequency. The environmental influence on fatigue performance has also been compared to localised corrosion properties. Fatigue crack propagation rates were found to be higher in 3% NaCl than in air for all stainless steels investigated. The highest alloyed austenitic steel, 654SMO, showed the least influence of the environment. For duplex stainless steels the environment enhanced fatigue crack propagation rate to a higher degree than for austenitic stainless steels. This is explained by a material-dependent corrosion fatigue mechanism. In the high cycle regime, fatigue properties for spot welded stainless steels specimens were found to be decreased between 30%-40% due to the presence of 3% NaCl. For the hardened steel 100CrMnMo8 a fracture mechanics approach was employed for prediction of corrosion fatigue properties. In this model corrosion pit growth rate and the threshold stress intensity factor for fatigue crack propagation are needed as input parameters. For the high pressure die cast aluminium alloy the environmental influence of fatigue initiation through pre-exposure of smooth specimens was studied. Depending on environment used for pre-exposure, fatigue strength was found to be reduced by up to 50 % compared to the fatigue strength in air. Fatigue strength reduction was clearly associated to corrosion pits in the aluminium material. A fracture mechanics model was further successfully used to predict the environmental influence. The influence of porosity on the fatigue strength for the cast aluminium alloys tested has been described by a Kitagawa diagram. In design, the Kitagawa diagram can be used to predict the largest allowable pore size if the load situation in the component is known. The size of the porosity could either be evaluated directly from x-ray images or from metallographic prepared cross-sections using a method of extreme value analysis / QC 20100907

This thesis concerns computer simulation of diffusional processes in alloys. The main focus is on the development of simulation techniques for diffusion in single-phase domains, but also diffusion controlled phase-transformations and interfacial processes are discussed. Different one-dimensional simulation techniques for studying the Kirkendall effect are developed and analyzed. Comparisons with experimentally observed marker migration show good agreement for small shifts and comparisons with observed Kirkendall porosity show reasonable agreement under the assumption that a certain supersaturation is needed before the vacancies coalesce into pores. A convenient approach in simulations of kinetics is to use thermodynamic software, e.g. Thermo-Calc, to calculate thermodynamic quantities, e.g. chemical potentials, required in the simulation. The main drawback with such an approach is that it will generate a large amount of additional computational work. To overcome this problem a method that decreases the amount of computational work has been developed. The new method is based on artificial neural networks (ANN). By training the ANN to estimate thermodynamic quantities a significant increase in computational speed was obtained. By calculating the dissipation of available driving force due to diffusion inside migrating interfaces an approach for including the effect of solute drag in computer simulations of grain growth and phase transformations has been developed. The new method is based on an effective interfacial mobility and simulations of grain growth have been performed in binary and ternary systems using experimentally assessed model parameters. / QC 20100930

<p>The major part of the present work, deals with the reduction kinetics of Cu₂O powder and a Cu₂O-WO₃ powder mixture by hydrogen gas, studied by ThermoGravimetric Analysis (TGA). The reduction experiments were carried out both isothermally and non-isothermally on thin powder beds over different temperature intervals. During the experiments, the reductant gas flow rate was kept just above the starvation rate for the reaction to ensure that chemical reaction was the rate-controlling step. The activation energy for the reactions was evaluated from isothermal as well as non-isothermal reduction experiments.</p><p>In the case of the reduction of Cu₂O, the impact of the stability of the copper oxide on the activation energy for hydrogen reduction under identical experimental conditions is discussed. A closer investigation of additions of Ni or NiO to Cu₂O did not have a perceptible effect on the kinetics of reduction.</p><p>In the case of the reduction of the Cu₂O-WO₃mixture, the reaction mechanism was found to be affected in the temperature range 923-973 K, which is attributed to the reaction/transformation in the starting oxide mixture. At lower temperatures, Cu₂O was found to be preferentially reduced in the early stages, followed by the reduction of the tungsten oxide. At higher temperatures, the reduction kinetics was strongly affected by the formation of a complex oxide from the starting materials. It was found that the Cu₂O-WO₃mixture underwent a reaction/transformation which could explain the observed kinetic behavior.</p><p>The composition and microstructures of both the starting material and the reaction products were analyzed by X-ray diffraction (XRD) as well as by microprobe analysis. vi Kinetic studies of reduction indicated that, the mechanism changes significantly at 923 K and the product formed had unusual properties. The structural studies performed by XRD indicated that, at 923 K, Cu dissolved in W forming a metastable solid solution, in amorphous/nanocrystalline state. The samples produced at higher as well as lower temperatures, on the other hand, showed the presence two phases, pure W and pure Cu. The SEM results were in conformity with the XRD analysis and confirmed the formation of W/Cu alloy. TEM analysis results confirmed the above observations and showed that the particle sizes was about 20 nm.</p><p>The structure of the W/Cu alloy produced in the present work was compared with those for pure copper produced from Cu2O produced by hydrogen reduction under similar conditions. It indicated that the presence of W hinders the coalescence of Cu particles and the alloy retains its nano-grain structure. The present results open up an interesting process route towards the production of intermetallic phases and composite materials under optimized conditions.</p>

<p>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.</p><p>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.</p><p>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.</p><p>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.</p>

<p>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.</p><p>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.</p>

<p>Humans are exposed to metals and metal-containing materials daily, either conscious, e.g. using metal tools or objects, or unconscious, e.g. during exposure to airborne metal-, and metal-containing particles. The diffuse dispersion of metals from different sources in the society, and the concern related to its potential risk for adverse effects on humans have gained an increased public and governmental attention both on a national and international level. In this context, the knowledge on metal release from metallic objects or metal-containing particles is essential for health risk assessment.</p><p>This thesis focuses on the study of metal release from powder particles of stainless steel and Cu-based materials exposed to synthetic body fluids mainly for simulating lung-like environments. The study comprises: i) development of a suitable experimental method for metal release studies of micron sized particles, ii) metal release data of individual alloy constituents from stainless steel powder particles of different particle sizes, and iii) Cu release from different Cu-based powder particles. In addition, the influence of chemical and physical properties of metallic particles and the test media are investigated. Selected results from Ni powder particles exposed to artificial sweat are presented for comparison. The outcome of this research is summarized through ten questions that are formulated to improve the general understanding of corrosion-induced metal release from metallic particles from a health risk perspective.</p><p>A robust, reproducible, fairly simple, and straightforward experimental procedure was elaborated for metal release studies on particles of micron or submicron size. Results in terms of metal release rates show, for stainless steel powder particles, generally very low metal release rates due to a protective surface oxide film, and Fe preferentially released compared to Cr and Ni. Metal release rates are time-dependent for both stainless steel powder particles and the different Cu-containing powders investigated. The release of Cu from the Cu-containing particles depends on the chemical and compositional properties of the Cu-based material, being either corrosion-induced or chemically dissolved. Moreover, the test medium also influences the metal release process. The metal release rate increases generally with decreasing pH of the test media. However, even at a comparable pH, the release rate may be different due to differences in the interaction between the particle surface and specific media.</p><p>The nature of particles is essentially different compared to massive sheet in terms of physical shape, surface composition and morphology. The surface area, and even the surface composition of metallic particles, depend on the particle size. The specific surface area of particles, area per mass, is intimately related to the particle size and has a large effect on the metal release process. Release rates increase with decreasing particle size due to a larger active surface area that takes part in the corrosion/dissolution process. The surface area that actually is active in the corrosion and metal release process (the effective area) governs the metal release process for both particles and massive sheet of metals or alloys. For particles, the effective surface area depends also on agglomeration conditions of particles during exposure.</p>

<p>Recrystallization kinetics, during and after hot deformation, has been investigated for decades. From these investigations several equations have been derived for describing it. The equations are often empirical or semi-empirical, i.e. they are derived for certain steel grades and are consequently only applicable to steel grades similar to these. To be able to describe the recrystallization kinetics for a variety of steel grades, more physically based models are necessary.</p><p>During rolling in hot strip mills, recrystallization enables the material to be deformed more easily and knowledge of the recrystallization kinetics is important in order to predict the required roll forces. SSAB Tunnplåt in Borlänge is a producer of low-carbon steel strips. In SSAB’s hot strip mill, rolling is conducted in a reversing roughing mill followed by a continuous finishing mill. In the reversing roughing mill the temperature is high and the inter-pass times are long. This allows for full recrystallization to occur during the inter-pass times. Due to the high temperature, the rather low strain rates and the large strains there is also a possibility for dynamic recrystallization to occur during deformation, which in turn leads to metadynamic recrystallization after deformation. In the finishing mill the temperature is lower and the inter-pass times are shorter. The lower temperature means slower recrystallization kinetics and the shorter inter-pass times could mean that there is not enough time for full recrystallization to occur. Hence, partial or no recrystallization occurs in the finishing mill, but the accumulated strain from pass to pass could lead to dynamic recrystallization and subsequently to metadynamic recrystallization.</p><p>In this work a newly developed physically based model has been used to describe the microstructural evolution of austenite. The model is based on dislocation theory where the generated dislocations during deformation provide the driving force for recrystallization. The model is built up by several submodels where the recrystallization model is one of them. The recrystallization model is based on the unified theory of continuous and discontinuous recovery, recrystallization and grain growth by Humphreys.</p><p>To verify and validate the model, rolling in the hot strip mill was modeled using process data from SSAB’s hot strip mill. In addition axisymmetric compression tests combined with relaxation was modeled using experimental results from tests conducted on a Gleeble 1500 thermomechanical simulator at Oulu University, Finland. The results show good agreement with measured data.</p>

<p>The role of intrinsic hydrodynamic instability of the premixed flame (known as Landau-Darrieus instability) in various flame phenomena is studied by means of direct numerical simulations of the complete system of hydrodynamic equations. Rigorous study of flame dynamics and effect of Landau-Darrieus instability is essential for all premixed combustion problems where multidimensional effects cannot be disregarded.</p><p>The present thesis consists of three parts. The first part deals with the fundamental problem of curved stationary flames propagation in tubes of different widths. It is shown that only simple "single-hump" slanted stationary flames are possible in wide tubes, and "multi-hump" flames in a laminar flow are possible in wide tubes only as a non-stationary mode of flame propagation. The stability limits of curved stationary flames in wider tubes are obtained, together with the dependence of the velocity of the stationary flame on the tube width. The flame dynamics in wider tubes is shown to be governed by a large-scale stability mechanism resulting in a highly slanted flame front.</p><p>The second part of the thesis is dedicated to studies of acceleration and fractal structure of outward freely propagating flames. It is shown that in direct numerical simulation the development of Landau-Darrieus instability results in the formation of fractal-like flame front structure. The fractal excess for radially expanding flames in cylindrical geometry is evaluated. Two-dimensional simulation of radially expanding flames in cylindrical geometry displays a radial growth with 1.25 power law temporal behavior after some transient time. It is shown that the fractal excess for 2D geometry obtained in the numerical simulation is in good agreement with theoretical predictions. The difference in fractal dimension between 2D cylidrical and three-dimensional spherical radially expanding flames is outlined. Extrapolation of the obtained results for the case of spherical expanding flames gives a radial growth power law that is consistent with temporal behavior obtained in the survey of experimental data.</p><p>The last part of the thesis concerns the role of Landau-Darrieus instability in the transition from deflagration to detonation. It is found that in sufficiently wide channels Landau-Darrieus instability may invoke nucleation of hot spots within the folds of the developing wrinkled flame, triggering an abrupt transition from deflagrative to detonative combustion. It is found that the mechanism of the transition is the temperature increase due to the influx of heat from the folded reaction zone, followed by autoignition. The transition occurs when the pressure elevation at the accelerating reaction front becomes high enough to produce a shock capable of supporting detonation.</p>

<p>A paper that shows motion when being exposed to heat has in this study been called a paper muscle. A paper muscle can be used for many different applications, e.g. smart advertisement or indicators in printed paper products. The muscles created in the present work were prepared by gluing or printing a polymer layer onto paper. The polymer layers consisted of MELINEX, MYLAR or toner, which are known to expand when exposed to heat. Furthermore, all three material systems showed bending when exposed to heat.</p><p>A mechanical bilayer model was implemented and used to quantitatively study the parameters that influence the bending of the muscles. The model indicated that the dimensional changes of the polymer layers relative to that of the copy paper was found to be approximately 0,1-0,5 % within the temperature range 23-60 °C. The experiments showed that the combined dimensional changes within the polymer and paper layers were not linear with respect to temperature, and that there was a significant difference in bending for muscles cut in the MD and in the CD. Also, when assuming that the polymer is the active component, the observed coefficient of thermal expansion was a factor ~10 greater compared to published literature data. These findings led to the conclusion that it was indeed the dimensional changes within the paper that were the dominant cause of the bending. This was confirmed by a muscle, comprising a bilayer of paper cut in the MD and the CD, which bended when exposed to heat. The results also indicate that a large part of the bending could be attributed to the hygrocontraction of paper.</p>