The Argon Oxygen Decarburization (AOD) process is one of the major stainless steel refining routes. Several parameters come into play deciding the outcome of the process. The task focuses on studying an optimized processing in an AOD converter using the UHT’s Converter Automation System (UTCAS)-process control program. The process parameters that mostly influence the process are studied and their effect on the process are analyzed. The 304, 409, 316, 430, 201, 2205 stainless steel grades are chosen for this study. The input temperature, input element content (carbon, chromium, nickel, silica, molybdenum and manganese), input steel mass are varied individually keeping all the other parameters constant and their effect on the process is analyzed. The parameters like process time, amount of gases (O2, N2 and Ar) consumed, amount of reducing agent (FeSi) and amount of alloy addition are taken into consideration to decide the optimal outcome of the process. The number of gas blowing steps is also varied to study its influence on the AOD process. This is done at different process initial input to also study the effect varying parameters on the stainless steel process. After analyzing the effect of all the parameters suggestible range of values for the parameters are proposed for on optimal blowing in an AOD converter.

Den största energiförlusten i ett rörsystem har vid flertal tillfällen bevisats vara friktionsförluster. Studien ämnar därför besvara om den typ av förluster kan minskas med hjälp av invändig behandling med superhydrofobisk coating.   Studien använder två småskaliga testanläggningar. Ett cirkulationssystem och en förenklad anläggning för friflödestest. På båda anläggningarna görs en fast installation av mätutrustning i direkt anslutning till ett 1,5m långt teströr, för att kalkylerad och uppmätt data inte skall påverkas av kringsystemen. Mätutrustning används för att kontrollera volymflöde, hastighet, temperatur och tryckfall. Insamlad data används sedan för att jämföra friktionsförluster före och efter invändig applicering av en superhydrofobisk coating.   Resultatet av studiens tester visar att den superhydrofobiska coating som använts, till skillnad från förväntat resultat, har en negativ effekt på flödet vid prövade applikationer och förlusterna ökade efter ytbehandling. / The greatest loss of energy in a pipe system has many times been proven to be frictional loss. This study with that in mind, will try to answer if this type of loss can be prevented using a superhydrophobic coating on the inside of a pipe.   This study uses two small-scale systems, one circulation system and one simplified system for freeflow testing. On both systems, measuring equipment is fixated close to the 1,5m test-pipe. Therefore, calculated and measured data is not distorted by the surrounding components. Measuring equipment is used to check volumetric flow, velocity, temperatures and differential-pressure. This data is later used to compare the frictional losses before and after applying the superhydrophobic coating.   The results, after completed tests are the opposite of the expected results. The coating that has been used for this study causes a negative effect and, in turn results in a substantial increase of frictional loss.

Manganese-Aluminium is an alloy with attractive ferromagnetic propertieswhenL10-structured ( -phase). If sucient permanent magnetic propertiescan be achieved at a low cost, it has potential to be a new permanentmagnet material on the market. In this thesis, drop synthesized ingots ofMn55Al45C2 were crushed and examined as solid pieces and as powders.The goal was to better understand how the material behaves magneticallyafter synthesis in relation to its chemical composition and cooling rate. Representativecross-sections of solid ingot pieces were created by mounting thepieces in polyfast followed by polishing. The surfaces were studied withScanning Electron Microscopy and Energy-dispersive X-ray spectroscopy tomap the chemical composition and then by Magnetic Force Microscopy andMagneto-optic Kerr eect to see how the chemical composition inuencesthe magnetic properties. It was found that areas richer in aluminium (Al),compared with the rest of the surface, behaved non-magnetically. The resultsfrom X-ray diraction on the powders suggests that the Al-rich areasconsists of the non-magnetic- and 2-phases.The powder that was extracted from the top of one of the drop synthesizedingots was nearly pure -phase but did not have an impressive magnetization.A complementary magnetic measurement was done on a solid piece from thetop part. This piece was found to reach a higher magnetization at a lowereld. The result indicates that crushing the material, even just by hand witha mortar and pestle, greatly reduces the magnetization.

Photochromism has been investigated extensively during recent years. The large interest for information storage in memory applications is associated with the bi-stable character of the photochromism phenomena. In molecular photochromics, two isomers with different absorption spectrum can be obtained according to the specific wavelength of the light exposure. This reversible transformation process can be considered as optical writing/erasing step of a memory. Here we first report the absorption spectra of solid-state films based on the blends consisting of PC molecules, the spirooxazine 1,3-dihydro-1,3,3-trimethylspiro[2H-indole-2,3’-[3H]phenanthr[9,10-b](1,4)oxazine] (PIII, Sigma-Aldrich, 32,256-3) and a polymer matrix host, poly(2-methoxy-5(2’-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV). The bi-stability in conjugated polymer matrix is studied by following the time evolution of the optical properties of the blends. Thereafter, the electrical performance of PC-polymer diodes is characterized and reported. While the PIII molecules in the blend bulks are switched to their low energy gap state, forming external energy levels above the valence band of MEH-PPV, the injected charges (hole-dominated) will be trapped by the low energy gap isomer of PIII and that leads to current modulation. PIII molecules can be switched between two energy gap states upon the photo-stimulation, and the I-V characteristics of the device can also be controlled reversibly via the photoisomerization. The retention time of the diode’s electrical switching fits quite well with the absorption characteristics of the blend films; this correspondence builds a good link between the film property and the device behavior. Furthermore, we observed a two-trap system in the blend diodes from the I-V curves, and a model is proposed which can explain the schematic concept of the trap-limited current modulation. To combine the knowledge and information from the investigations above, we tested a novel device design based on a bi-layer of the PC and polymer materials, and the promising result for future work is presented in the end.

This thesis discusses a model for simulation of the Powder Bed Fusion (PBF) process of metallic powder with the capability to become amorphous. The temperature field in the PBF process is predicted by a three-dimensional thermal finite element model in three dimensions using a layer-by-layer approach, meaning that the scanning strategy of the moving laser spot is consolidated into a single heat source acting on the entire layer momentarily. This temporal reduction enables simulations of large domains and many layers while it becomes less computational demanding compared to a detailed transient model that incorporates a scanning sequence. Predictions of the amorphous and crys- talline phase fractions are performed with a phase model coupled to the temperature field simulation. The phase model is based on differential scanning calorimetry measure- ments and optimized to fit continuous heating transformation into a crystalline state of an amorphous sample. The simulations are performed on the commercial available glass forming alloy AMZ4. Bulk Metallic Glass (BMG) have an amorphous structure and possesses desirable me- chanical, magnetic and corrosion properties such as high yield stress, low magnetic losses and high corrosion resistance. Glass forming alloy has the potential to become amorphous provided that the solidification rate is rapid enough to avoid crystallization. However, traditional manufacturing techniques, such as casting, limits the cooling rates and size of components due to limited heat conduction in the bulk. With Additive Manufacturing (AM) on the other hand, it is possible to produce BMG’s as the melt pool is very small and solidification can be achieved very rapid to bypass crystallization. Yet, crystals may form by devitrification (crystal formation upon heating of the amorphous phase) because of thermal cycling in previous layers. Simulation of the process will aid the understanding of glass formation during AM and the development of process parameters to control the level of devitrification.

No description available.

The concrete technology has during the last century changed dramatically where the concept of high strength concrete has gone from 30MPa to well over 100MPa. UHPC has many areas of application and is used more and more frequently in all manner of structures. It is also a suitable concrete in areas and environments that are demanding and harsh for the concrete due to its overall excellent durability properties which suggest lifespans of reinforced structure elements that far exceeds what is economically available to design for today with a low cost of maintenance. The aim of this research was to produce Ultra High-Performance Concrete using mostly locally available materials. Tests were made on the binary materials where the particle packing was optimized through the Punkte method. A series of smaller mortar mixes was made where the effect of different proportions of i.e. silica fume, flyash, superplasticizer had on the concrete mix. The fresh and hardened properties of the mix as mini cone flow, slump flow, density, compressive strength and flexural strength was evaluated to obtain a mix which exhibited the properties sought for, high strength and good workability. The results showed that it is difficult to find an optimum mixture since the design of a recipe always has compromises and rarely all criteria’s can be met fully. The concrete produced had a W to C ratio between 0,21, 20wt% of silica fume, 4,5wt% of superplasticizer and max filler size of 1mm. Some mixes of the concrete were also produced with flyash replacement and with steel fibers. This resulted in concretes exhibiting compressive strength over 140MPa, flexural strength of 18MPa without fiber reinforcement and with self-consolidating properties. The replacement of cement with 30wt% of flyash resulted in better workability and long term(1year) compressive strength almost equaled the concrete without flyash replacement.

The main goal for this project was to design, manufacture and evaluate a thermoelectric cooler, TEC, prototype. One of the biggest challenges with TECs is that they need to be very reliable and have a long lifetime. The two biggest contributing factors to degradation and breakdown stem from thermal expansion mismatch, resulting in cracks, and from material diffusion between the thermoelectric material and connecting materials. The thermoelectric material in this case is Bismuth telluride, Bi2Te3, obtained from two suppliers. The thermoelectric cooler prototype was successfully manufactured. The prototype, which consisted of 38 thermoelectric elements, showed a maximum temperature difference of 65.1 degrees Celsius. A commercial TEC of the same size had a maximum temperature difference of 68 degrees Celsius. The figure of merit and grain size of p- and n-doped Bismuth Telluride from two different suppliers have been measured as means of testing the thermoelectric material prior to manufacturing, and to compare the suppliers. In this report, the figure of merit is a measure of how well a material converts electrical current to a heat gradient. The figure of merit for bismuth telluride, Bi2Te3, from both suppliers was found to be between 0.4 and 0.8 through the Harman method. Since studies show that smaller grains for Bi2Te3 result in a more durable material, the morphology was investigated. However, no grains could be observed with light optical microscopy with an applied etchant, or scanning electron microscopy. A cohesion tape test showed that Bismuth telluride from one of the suppliers is more fragile than the other.

Cubic carbides (titanium, tantalum, niobium, and zirconium carbides) can constitute a significant proportion of so-called cubic and cermet grades, where it is added to substitute a portion of tungsten carbide. It is thus critical to understand and be able to thermodynamically model the cubic carbide systems. In order to do this, the thermodynamic descriptions of lower order systems, such as the Ti-Cr-C system, need to be well studied. To approach this goal, an extensive literature survey of thermodynamic data and phase diagram information on the Ti-Cr-C system, the Ta-Cr-C system, the Nb-Cr-C system and the Zr-Cr-C is presented in this work. Experiments are performed in the Ti-Cr-C system using powder metallurgy and heat treatments. The solubility of Cr in FCC_TiC phase was experimentally measured at 1773K and compared with previous studies showing that the solubility reported earlier is too large. Thereafter, a re-optimization of FCC_TiC and liquid interaction parameters of the Ti-Cr-C system was performed taking into account the experimental data obtained both from previous studies and this work. The Gibbs energy descriptions of the Cr-carbide end members were compared between the one from the in-house database [SandvikTDB] and from other studies. With the new description, the solubility of Cr in FCC_TiC is better described.

The report discusses the destruction of toxic and non-toxic solids, liquids and gases through lasers. In order to completely understand the project first chapters describes the basics about laser and plasma separately, from definition to types, components and categories. Differences between laser and microwave system are covered in this chapter as well. Besides lasers there are different technologies that are currently being used to destroy toxic and non-toxic materials. These technologies were studied and comparison tables are made in order to discern between different destruction technologies. For the destruction of toxic and non-toxic materials through lasers two mathematical models have been developed, molecular dissociation model and plasma exploitation model, and later the experimental work was carried out on one of the toxic material. Mathematical modeling and experimental work is in accordance with each other as discussed in results and discussion. Mathematical model shows that all the materials discussed in the report can be destroyed by lasers but in order to carry further experiments on all other toxic and non-toxic materials, a proposal is made for the laser reactor using CAD model (Solid Edge) and drawing software (AutoCAD). Tables and mathematical calculations have been placed in appendix at the end of the report.