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  • 251.
    Bigdeli, Sedigheh
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Developing the third generation of Calphad databases: what can ab-initio contribute?2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Developing the third generation of Calphad databases with more physical basis valid within a wider temperature range is the aim of the present work. Atomistic scale (ab-initio) methods, particularly techniques based on DFT theory, are used for modelling dierent phenomena, so as to gauge the capacity for use in Calphad modelling. Several systems are investigated in this work for studying dierent phenomena, such as magnetism and vibration of atoms. In the case of pure elements (unaries), thermodynamic properties of Mn, Al and C are optimized in the whole temperature range by the help of new models. In addition, DFT results and specic characteristics of these elements are also used to develop models for describing magnetic properties and atomic vibrations. With regards to coupling between DFT and Calphad, the EMTO technique is used for determining the magnetic ground state of the metastable hcp phase in Fe and Mn, and the TU-TILD technique is used for modelling solid phases above the melting point. TU-TILD is also used for calculating thermodynamic properties of bcc Mn at nite temperatures. The same phenomena are investigated in higher-order systems, i.e. the binaries Fe-Mn and Mn-C. Thermodynamic properties and phase diagrams of these systems are assessed against experimental data. Moreover, the revised magnetic model is used for modelling magnetic properties in these systems.

    It is shown through this investigation that although the DFT methods are powerful tools for model development and for resolving discrepancies between dierent experimental datasets, they should not be overly-trusted. Caution must be taken when using DFT results, since the approximations and assumptions for computational implementations may cause some errors in the results. Moreover, implementing them into Calphad software as a connected methodology is not currently accessible due to the computational limitations.

    It is concluded that coupling between the DFT and Calphad approaches can currently be achieved by using DFT results as an input in Calphad modelling. This will help to improve them until they can be integrated into the Calphad approach by the progress of computational possibilities.

    One of the advantages of developing the third generation Calphad databases is the possibility of using the 0 K DFT results in Calphad modelling, since the new databases are valid down to 0 K. This has not been possible in the past, and such potential opens a new door to bring more physics into the Calphad approach.

  • 252.
    Bigdeli, Sedigheh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Korbmacher, Dominique
    Grabowski, Blazej
    Körmann, Fritz
    Duff, Andrew Ian
    Blomqvist, Andreas
    Neugebauer, Jörg
    DFT based calculations of thermodynamic properties for paramagnetic bcc-Mn at high temperaturesManuscript (preprint) (Other academic)
    Abstract [en]

    In developing the third generation of Calphad databases, density-functional-theory methods are particularly important for validating physical models and for providing input data where experiment is unavailable. Since Cal-phad modelling needs data at finite temperatures additional sampling tech-niques are required, and the recently developed TU-TILD method is one such technique that allows for an efficient and accurate calculation of free energies. It is used in the present work for the complicated paramagnetic bcc phase of Mn. Our results show a good agreement with experimental data, validating that this method is well suited for calculating thermody-namic properties of magnetically complex and dynamically unstable phases as needed for Calphad modelling. It is also shown that a transition from bcc to the ω phase occurs below 1200 K.

  • 253.
    Bigdeli, Sedigheh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Qing, Chen
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    A new description for pure C; in developing the third generation of Calphad databases.In: Journal of Phase Equilibria and DiffusionArticle in journal (Other academic)
    Abstract [en]

    In connection to developing the third generation of Calphad databases a new thermodynamic description is presented for unary carbon. Models used in this work have more physical basis and are valid down to 0 K. The anisotropy in graphite, caused by weak Van der Waals inter-plane forces makes it difficult to fit the heat capacity data by a single Einstein tempera-ture for modelling the harmonic vibration of the atoms. By using multiple Einstein temperatures this problem is solved and a good agreement with the experimental data at low temperatures is achieved. Diamond is mod-eled using new models too, and the two-state model is used for modelling the liquid phase.

  • 254.
    Bigdeli, Sedigheh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    A thermodynamic assessment of the binary Fe-Mn system for the third generation of Calphad databases2017Manuscript (preprint) (Other academic)
    Abstract [en]

    In developing the third generation of Calphad databases, after having proper models for the unaries, the next step is to assess higher-order systems, i.e. binaries, ternaries etc. A new description for the Fe-Mn system is presented in this work, based on the Calphad approach. New models with a stronger physical basis are used to model Gibbs energy of the phases. For this purpose, the revised magnetic model is used to fit the magnetic properties versus the most recent experimental and DFT data. An acceptable magnetic phase diagram is reproduced, which results in a more reasonable fit for the phase diagram and will prevent possible artefacts in higher-order systems. The descriptions are valid down to 0 K, which make them very useful as an input for modelling phase transformations occurring at low temperatures.  

  • 255.
    Bigdeli, Sedigheh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Zhu, Li-Fang
    Glensk, Albert
    Grabowski, Blazej
    Lindahl, Bonnie
    Hickel, Tilmann
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    An insight into using DFT data for Calphad modelling of solid phases in the third generation of Calphad databases, case study for Al2017Manuscript (preprint) (Other academic)
    Abstract [en]

     In developing the next generation of Calphad databases, new models are used in which each term contributing to the Gibbs energy has a physical meaning. Harmonic vibrations of atoms are modelled using the Einstein temperature; anharmonic vibrations, electronic and magnetic contributions to the solid phases are represented by specific terms. The two-state model is used for the liquid phase. To continue the development, a new description for unary aluminum is presented in this work. In particular, finite temperature density-functional-theory (DFT) results are used to discuss and suggest the most applicable and physically based model for Calphad assessments of solid phases above the melting point. 

  • 256.
    Bilen, Idil
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Direct Reduced Iron Production from EAF Slags in Fixed Bed Furnace2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electric arc furnace (EAF) slags are basic characteristic slags that include approximately 40 % iron oxide compounds. Iron oxide can be recycled and re-used in the process to decrease amount of waste product besides reducing loss of raw materials. According to result of survey performed by The European Association Representing Metallurgical Slag Producers and Processors (EUROSLAG) in 2010, 8.5 million tons of EAF slag is produced in Europe. High percentage of EAF slag is re-used in road construction as aggregate. However it can be re-cycled in the internal use for metallurgical processes as well. In order to re-use EAF slag in the process as a raw material, direct reduction is a new approach. Direct reduction is reduction of iron containing raw materials with gas or solid reductants without melting of charge. In this study, reduction conditions of 39 % Fe2O3 containing EAF slag in tube furnace was examined. As the reducing agent, metallurgical coke was used. EAF slag was milled and pelletized in raw material preparation step. Pellets were charged to fixed bed type tube furnace in a graphite boat at 1050, 1100 and 1150°C respectively with 150 and 200% of stoichiometrically required amount of metallurgical coke. 5, 10, 15, 30, 60, 90 and 120 minutes process durations were performed. Direct reduced pellets were milled to be characterized by using X-Ray Diffraction (XRD) and chemical analysis methods. Results indicate that increased temperature, process duration and stoichiometry have a positive impact on direct reduction of EAF slag in terms of iron metallization. 90 % metallization degree has been achieved as the result of the study with the process conditions of 200 % stoichiometry and 90 minutes process duration at 1150 °C.

  • 257.
    Birgmark, Anja
    Karlstad University, Faculty of Technology and Science.
    Wear of Coater Blades2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 258.
    Bjurenstedt, Anton
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Imperfections in Recycled Aluminium-Silicon Cast Alloys2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In striving to produce high quality cast components from recycled aluminium alloys,imperfections have to be considered, because recycled aluminium usually containsmore of it. However, there are great energy savings to be made by using recycledaluminium; as little as 5% of the energy needed for primary aluminium productionmay be required. High quality castings are dependent on, besides alloy chemistry, bothmelt quality and the casting process; the focus of this work is related to the meltquality.This thesis aims to increase knowledge about imperfections, foremost about Fe-richparticles, oxides/bifilms, and porosity. Experiments were performed at industrialfoundry facilities and in a laboratory environment. Melt quality was evaluated byproducing samples with the reduced pressure test (RPT), from which both densityindex (DI) and bifilm index (BI) could be measured, results that were related to tensiletest properties. Data from tensile test samples were analysed, and fracture surfacesand cross sections were studied in both light microscope and in scanning electronmicroscope (SEM). For the purpose of investigating nucleation of primary Fe-richparticles (sludge) differential scanning calorimetry (DSC) was used.In the analysis of results, a correlation between the morphology of particles and tensileproperties were found. And elongated Fe-rich β-particles were seen to fracturethrough cleavage towards the centre. However, DI and BI have not been possible torelate to tensile properties.The nucleation temperature of primary Fe-rich particles were found to increase withincreased Fe, Mn, and Cr contents, i.e. the sludge factor (SF), regardless of cooling rate.For a set SF, an increase of cooling rate will decrease the nucleation temperature.

  • 259.
    Bjurenstedt, Anton
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    On the influence of imperfections on microstructure and properties of recycled Al-Si casting alloys2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are great energy savings to be made by recycling aluminium; as little as 5% of the energy needed for primary aluminium production may be required. Striving to produce high quality aluminium castings requires knowledge of microstructural imperfections, which is extra important when casting recycled aluminium that generally contains higher levels of imperfections compared to primary aluminium. Imperfections include amongst others Si, Fe, and Mn as well as oxides. Si is needed for castability, but it may also initiate fracture. There are different types of Fe-rich intermetallics influencing properties of castings, generally in a negative direction. Oxides constitute cracks and they are elusive because they are difficult to quantify.

    This thesis aims to increase knowledge about imperfections in recycled aluminium castings originating from alloying elements and the melt. Experiments were performed in advanced laboratory equipment, including X-radiographic imaging during solidification and in-situ tensile testing in a scanning electron microscope. Experiments were also performed at industrial foundry facilities.

    The experiments showed that the nucleation temperature of primary α-Fe intermetallics increased with higher Fe, Mn, and Cr contents. Primary α-Fe are strongly suggested to nucleate on oxides and to grow in four basic morphologies. Lower nucleation frequency of α-Fe promoted faster growth and hopper crystals while higher nucleation frequency promoted slower growth rates and massive crystals. Results also showed that a decrease in the size of the eutectic Si and plate-like β-Fe intermetallics improved tensile properties, foremost the elongation to fracture. In β-Fe containing alloys the transversely oriented intermetallics initiated macrocracks that are potential fracture initiation sites. In alloys with primary α-Fe foremost clusters of intermetallics promoted macrocracks. In fatigue testing, a transition from β-Fe to α-Fe shifted the initiation sites from oxides and pores to the α-Fe, resulting in a decrease of fatigue strength. Oxides in Al-Si alloys continue to be elusive; no correlations between efforts to quantify the oxides and tensile properties could be observed.

  • 260.
    Bjurenstedt, Anton
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Casari, Daniele
    Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Mathiesen, Ragnvald H.
    Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
    Dahle, Arne K.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    In-situ study of morphology and growth of primary α-Al(FeMnCr)Si intermetallics in an Al-Si alloy2017In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 130, 1-9 p.Article in journal (Refereed)
    Abstract [en]

    Morphology and growth of primary α-Al(FeMnCr)Si intermetallics have been studied in-situ during solidification of a commercial secondary aluminum alloy employing X-radiographic imaging combined with deep-etching. The α-Al(FeMnCr)Si intermetallics were found to nucleate primarily on surface oxides, and the continued growth yielded both rhombic dodecahedrons and elongated rod-like morphologies. Both morphologies were observed as hopper and massive types, where the hopper intermetallics had the higher growth rates. The growth rate, which determines the type, appears to be linked to nucleation frequency; higher nucleation frequency promoted massive types and lower nucleation frequency promoted hopper intermetallics. 

  • 261.
    Bjurenstedt, Anton
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Dahle, Arne
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    The effect of Fe-rich intermetallics on crack initiation in cast aluminium: an in-situ tensile studyManuscript (preprint) (Other academic)
  • 262.
    Bjurenstedt, Anton
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Jarfors, Anders
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    On the complexity of the relationship between microstructure and tensile properties in cast aluminum2015In: International Journal of Modern Physics B, ISSN 0217-9792, Vol. 29, no 10-11, 1540011Article in journal (Refereed)
    Abstract [en]

    The relationship between microstructure and mechanical properties in cast aluminium alloys is very complex. This relationship is also strongly affected by the casting process and melt handling. In the current study the mechanical properties were investigated and correlated with microstructural features such as porosity, Fe-rich particles, SDAS, Si-length. Process quality measures such as bifilm index, density index, and sludge factor were also investigated. The aim of the work was to understand the critical interactions between material microstructure and process quality in the development of high performance materials.

  • 263.
    Bjurenstedt, Anton
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Jarfors, Anders
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    The effects of Fe-particles on the tensile properties of Al-Si-Cu alloys2016In: Metals, ISSN 2075-4701, Vol. 6, no 12, 314Article in journal (Refereed)
    Abstract [en]

    The effect of Fe-rich particles has been a topic for discussion in the aluminum casting industry because of the negative impact they exert on the mechanical properties. However, there are still contradictions on the effects of various morphologies of Fe-particles. In this study, microstructural characterization of tensile tested samples has been performed to reveal how unmodified and modified Fe-rich particles impact on the tensile behavior. Analysis of additions of Fe modifiers such as Mn and Cr, showed higher amounts of primary Fe-rich particles (sludge) with increased porosity and, as result, degraded tensile properties. From the fracture analysis of tensile tested HIPed samples it could be concluded that the mechanical properties were mainly governed by the Fe-rich particles, which were fracturing through cleavage, not by the porosity.

  • 264.
    Bjurenstedt, Anton
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Liljenfors, Tomas
    Assessment of Quality when Delivering Molten Aluminium Alloys Instead of Ingots2013In: Light Metals Technology 2013 / [ed] Ian Stone, Brian McKay and Zhongyun Fan, 2013, Vol. 765, 266-270 p.Conference paper (Refereed)
  • 265.
    Bjurman, Martin
    et al.
    Studsvik Nuclear, Sweden.
    Forssgren, Björn
    Ringhals AB, Sweden.
    Efsing, Pål
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Fracture mechanical testing of in service thermally aged cast stainless steel2016In: Fatigue and Fracture Test Planning, Test Data Acquisitions and Analysis, ASTM International, 2016, Vol. 1598, 58-80 p.Conference paper (Refereed)
    Abstract [en]

    Embrittlement of Duplex Stainless Steels by thermal aging shortens the service life of structural components in Light Water Reactors (LWRs). This is an important issue when life extension programs are aiming at 60-80 years in service, as ductile failure is a design prerequisite. Cast and welded austenitic stainless steels, which contain some ferrite, are known to be affected by thermal aging. Historically, many LWR components of complex geometry have been cast in the Mo-containing quality CF8M. Aging is mainly attributed to two types of phase transformations occurring within the minor ferritic phase; Demixing of the ferrite by spinodal decomposition into Cr-rich a´ and Fe-rich a regions; and precipitation of G-phase, carbides and other secondary phases.

    The present program of two in-service aged pipe bend castings from the Pressurized Water Reactor (PWR) Ringhals 2 Steam Generator. These components are large castings of stainless steel quality CF8M. The manufacturing process produces a non-uniform microstructure with coarse ferrite and a high degree of directionality affecting properties as well as the methodology for testing.

    The materials were exposed to primary circuit PWR water for 72 kh at 291ºC and 325ºC, respectively, followed by 22 kh at a reduced service temperature.

    Fracture mechanical evaluation using the J-R technique at RT and 300ºC as well as instrumented Charpy-tests ranging from -196ºC to +400ºC are conducted. Effects of large microstructural heterogeneity and anisotropy from the casting and heat treating processes are tested and evaluated. The change of these parameters effect on aging embrittlement and fracture mechanisms within each phase as well as phase interaction are also studied.

  • 266.
    Björkblad, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    On the prediction of crack propagation in cast steel specimens2005In: Competent Design by Castings: Improvements in a Nordic Project / [ed] Samuelsson, J; Marquis, G; Solin, J, ESPOO: TECHNICAL RESEARCH CENTRE FINLAND , 2005, Vol. 237, 251-272 p.Conference paper (Refereed)
    Abstract [en]

    This investigation deals with the fatigue behaviour of cast steel with respect to defects, crack initiation, crack growth and material parameters. It constitutes the initial part of a larger work in cast materials. The main objectives have been to validate calculations made by FEM and Paris law with data from fatigue tests and to confirm material parameters for Pan's law. Furthermore, the results where put against calculations obtained from the fracture mechanic software AF-GROW. During the accomplishment some difficulties was experienced concerning the initiation of the crack, with result that there where just a few specimens suitable for evaluation by LEFM. However, some conclusions concerning the crack growth behaviour could yet be done. The results in general showed good correspondence, the results from AF-GROW included. Most divergences could be explained by residual stresses and, to some extent, the initiation problems.

  • 267.
    Björklund, Johan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    A study of slag-steel-inclusion interaction during Ladle treatment2006Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The thesis is based on two supplements with two major objectives. In the first supplement equilibrium top slag-steel bulk and inclusions-steel bulk were investigated by comparison between calculated and measured oxygen activity values. This was done by applying different oxide activity models for slags combined with thermodynamic calculations. In the second supplement the inclusion composition is studied during the ladle refining process. The inclusion composition is related to top slag composition and other parameters during ladle

    treatment.

    The work was carried out by collecting data during well controlled sampling procedures at two different steel plants. Extensive inclusion analyses in Scanning Electron Microscope, SEM, were done. The data was used together with thermodynamics for a description of the interaction between slag-steel-inclusion interaction during ladle treatment.

    Evaluation of inclusion composition during the ladle refining have revealed that the majority of the inclusions belonged to the system Al2O3-CaO-MgO-SiO2 and showed a continuous composition change throughout the ladle refining process, from high Al2O3, via MgO-spinel to finally complex types rich in CaO and Al2O3. The final composition after vacuum treatment was found to be close to the top slag composition. Small process parameter changes and practical variations during ladle refining were proven to give large differences of the inclusion composition.

    Finally, it was concluded that equilibrium does not exist between top slag and steel bulk, with respect to oxygen, for the studied conditions. However, the equilibrium does exist between the steel bulk and inclusion.

  • 268.
    Björklund, Johan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Thermodynamic Aspects on Inclusion Composition and Oxygen Activity during Ladle Treatment2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Two industrial studies and one set of lab scale trials have been done. In addition, a theoretical study has been done. The main focus has been on non metallic inclusion composition during the ladle refining operation in industrial steel production. Sampling has been done together with careful inclusion determination. The inclusion composition is related to different variables. In the industrial trials samples have been taken at different steps during the ladle refining period. Steel and slag composition as well as temperature and oxygen activity have been determined.

    The thesis is based on five supplements with different major objectives, all related to the inclusion composition. The equilibrium top slag-steel bulk and inclusions-steel bulk were investigated by comparison between calculated and measured oxygen activity values. The oxygen activity and relation to temperature has also been discussed as well as oxygen activity and temperature gradients. The effect of vacuum pressure on inclusion composition has been evaluated in a theoretical study as well as lab scale trials. The inclusion composition has been studied during the industrial ladle treatment process. The inclusion composition was related to top slag composition and other parameters during ladle treatment.

    The major findings in the thesis are the lack of equilibrium conditions with respect to top-slag and steel bulk before vacuum treatment. The inclusions have been found to be closer to equilibrium with the steel bulk. Al/Al2O3 equilibrium has been found to control the oxygen activity after Al-deoxidation. Evaluation of inclusion composition during the ladle refining has revealed that the majority of the inclusions showed a continuous composition change throughout the ladle refining process, from high Al2O3, via MgO-spinel to finally complex types rich in CaO and Al2O3. The final inclusion composition after vacuum treatment was found to be close to the top slag composition. Vacuum pressure has been found to have a theoretical effect on inclusion composition at very low pressures.

  • 269.
    Björklund, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Andersson, Margareta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Equilibrium between slag, steel and inclusions during ladle treatment: comparison with production data2007In: Ironmaking & steelmaking, ISSN 0301-9233, Vol. 34, no 4, 312-324 p.Article in journal (Refereed)
    Abstract [en]

    The primary purpose of the investigation was to determine whether equilibrium conditions exist between slag and steel and inclusions and steel after silicon deoxidation and aluminium deoxidation. In doing so, the performance of three different models for predicting oxide component activities was also evaluated. The results from the oxide activity models were used to calculate oxygen activities in the steel melt. Industrial data such as steel, slag and inclusion component concentrations, as well as temperature, were used as input to the calculations. One general conclusion drawn was that although the results from the different models showed similar trends, the models did not predict the same actual values for specific calculations. Predicted theoretical equilibrium oxygen activity values were compared with plant measurements of oxygen activity. Here, it was found that the oxygen activity values pertaining to the equilibrium between steel and inclusions were higher than corresponding measured values. The calculations for the equilibrium between the top slag and steel melt, however, resulted in theoretical oxygen activity values considerably lower than corresponding measurements. It was thus concluded that equilibrium conditions did not exist between the top slag and the steel bulk with respect to oxygen. Overall, the models proved useful in predicting oxide activities, but the lack of equilibrium between top slag and molten steel made the calculation of oxygen activity difficult.

  • 270.
    Björklund, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Andersson, Margareta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    The Influence of Vacuum Treatment on Inclusion Composition: Laboratory Study2010In: High Temperature Materials and Processes, ISSN 0334-6455, Vol. 29, no 3, 189-202 p.Article in journal (Refereed)
    Abstract [en]

    A series of lab scale trials have been carried out with the aim of investigating the effect of vacuum treatment on inclusion chemistry. A ball bearing steel grade (1.47 wt% Cr, 0.96 wt% C) has been melted in a controlled atmosphere in magnesia and alumina crucibles. A laboratory vacuum furnace, which makes it possible to carry out sampling during vacuum treatment, was used. Samples were taken before and during vacuum treatment. Thereafter, the inclusion compositions in the samples were determined using SEM in combination with EDS. The inclusions found were mainly sulphides containing both manganese and chromium. In addition to these, MgO-Al2O3 oxides were found with varying contents of calcium. Furthermore, a few, calcium sulphides were found. Additionally, it was possible to find a small difference in the average inclusion composition in the samples taken before and during vacuum. More specifically, it was seen that the composition of the inclusions becomes more sulphide-rich during vacuum treatment. The change of average inclusion composition was not as large as suggested from theoretical computations and oxides were found at the same extent during vacuum as before. Another finding was that the inclusions from the trial where an alumina crucible was used contained no magnesia, but that the inclusions contained magnesia when a magnesia crucible was used. Even though the effect of vacuum treatment on the inclusion compositions was found to be small, it was concluded that vacuum treatment could not to be neglected when studying inclusions influenced by top slag/metal reactions.

  • 271.
    Björklund, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Andersson, Margareta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    The Influence of Vacuum Treatment on Inclusion Composition: Theoretical Study2010In: High Temperature Materials and Processes, ISSN 0334-6455, Vol. 29, no 3, 179-187 p.Article in journal (Refereed)
    Abstract [en]

    A theoretical study has been conducted into how inclusion composition is influenced by vacuum treatment. Software for computational thermodynamics has been used to simulate how the conditions in a steel melt changed as a result of a decreased pressure. A case study was made on a low sulphur bearing steel (1.4% Cr, 1.0%C). The calculations show the effect of sulphur, oxygen, carbon and temperature on precipitated phases in the steel melt. The result shows that at low pressure, formation of carbon monoxide takes place. For 5 ppm O and 10 ppm S the CO-gas becomes thermodynamically stable below 40 torr. Oxide phases will be reduced and CaS will be the stable phase.

  • 272.
    Björklund, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Andersson, Margareta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Nzotta, Mselly
    Uddeholm Tooling AB.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The Effect of Ladle Treatment on Inclusion Composition in Tool Steel Production2008In: Steel Research International, ISSN 1611-3683, Vol. 79, no 4, 261-270 p.Article in journal (Refereed)
    Abstract [en]

    An in-depth SEM-investigation of the inclusion composition change in the ladle refining process during tool steel production was done. Plant trials were carried out at Uddeholm Tooling AB in Hagfors, Sweden. A series of samples was taken during ladle refining, from deslagging through vacuum treatment. The goal was evaluating the effects of the top slag and other process parameters on the inclusion composition during ladle refining. The main conclusion was that normal variations in the process have a large influence on inclusion composition. Furthermore, it was concluded that the MgO content in the top slag had a large influence on the inclusion, composition throughout the whole ladle refining process. Also, the SiO2 content in the ladle slag originating from the EAF-slag, had a noticeable effect on the inclusions. The inclusions belonging to the system Al2O3-CaO-MgO-SiO2 showed a continuous composition change throughout the ladle refining process, from high Al2O3, via MgO-spinel to finally complex types rich in CaO and Al2O3.

  • 273.
    Björklund, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Miki, Takahiro
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Andersson, Margareta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effect of Temperature on Oxygen Activity during Ladle Treatment2008In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 48, no 4, 438-445 p.Article in journal (Refereed)
    Abstract [en]

    The effect of temperature on oxygen activity in steel was studied in plant trials where temperature and oxygen activity were measured at two depths and at the same time during different parts of ladle refining. The results show that large temperature gradients exist towards the surface of the steel melt for the sampling occasion when no slag is present on the steel surface, as can be expected. It was also observed that the oxygen activity is higher in the lower measurement position than in the upper during the majority of the ladle refining. This is explained by the oxygen activity's temperature dependence. By using the data from this study and previously reported plant trials it was shown that Si-SiO2 or Al-Al2O3 equilibrium controls the oxygen activity.

  • 274.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Activity: European Slag Conference; Euroslag 20102010Conference paper (Other (popular science, discussion, etc.))
  • 275.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Djupförvar av högaktivt avfall: miljö och säkerhet1994Report (Other academic)
  • 276.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    MIMER, minerals and materials recycling research centre: pågående och planerade forskningsaktiviteter1996In: Konferens i mineralteknik: Luleå 13-14 february 1996 / [ed] Marianne Thomaeus; Eric Forssberg, MinFo , 1996, 17-32 p.Conference paper (Other academic)
  • 277.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Thermodynamic modelling1988In: Technological advances in metallurgy: proceedings, September 20-21, 1988, Luleå Sweden, Luleå: MEFOS , 1988Conference paper (Refereed)
  • 278.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Degerstedt, U.
    Lindblom, Bo
    Luleå tekniska universitet.
    Samuelsson, Caisa
    Kinetics of Impurity Elimination During Roasting1994In: Extraction and processing for the treatment and minimization of wastes, 1994: Proceedings of an International Symposium [on Extraction and Processing for the Treatment and Minimization of Wastes] / [ed] Johm P. Hager, Warrendale, Pa: Minerals, Metals & Materials Society, 1994, 825-842 p.Conference paper (Refereed)
    Abstract [en]

    Four different arsenic containing dusts from the Boliden plant, Boliden Mineral AB, Sweden have been examined. A kinetic study of the arsenic elimination was performed in a laboratory scale roasting furnace for roasting furnace ESP dust and smelting furnace ESP dust. Characterisation and thermodynamic calculations were carried out to determine the mineralogy, and the stability of compounds in the dusts studied. The characterisation methods used were chemical analysis, X-ray diffraction analysis and microprobe analysis. It was found in the experiments that a high degree of As elimination was obtained for roasting furnace ESP dust and a low degree for smelting furnace ESP dust. Derived kinetic models are given. A prediction of the As-elimination for settling furnace dust and converter ventilation dust is presented

  • 279.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Eriksson, Johan
    Luleå tekniska universitet.
    Nedar, Lotta
    Luleå tekniska universitet.
    Samuelsson, Caisa
    Waste reduction through process optimization and development: overview1996In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 48, no 3, 45-49 p.Article in journal (Refereed)
    Abstract [en]

    In this article, the possibilities of optimizing metallurgical processes based on minimization for waste reduction and application requirements for the reuse of waste products are discussed together with the possibilities of treating existing waste in direct connection with the process involved. Some results from ongoing projects on controlled dust generation and an outline of an ongoing research program are also described.

  • 280.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Holmström, Åke
    Luleå tekniska universitet.
    A Quantitative Comparison of the Impurity Capacity in Some Copper Making Routes1989In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 18, no 1, 2-11 p.Article in journal (Refereed)
    Abstract [en]

    A metallurgical comparison of alternatives to increase the capacity to treat contaminated raw materials was made. The comparison was made by calculating the material balances at different Cu contents in mattes during Cu making and considering the effects of removal of impure intermediate products like dusts and slag for separate treatment. The most efficient methods included the removal of dust from the smelting furnace and the avoidance of reducing conditions in the matte smelting operation. By separating dust and slag produced in the Cu converters, an improved capacity could also be obtained. The removal of impurities made it possible to significantly increase the use of contaminated raw materials but, to drastically increase the impurity capacity, the introduction of pretreatment processes like roasting or leaching was necessary

  • 281. Björkman, Bo
    et al.
    Jacobsson, E.
    Boliden Metall AB.
    New thermodynamic tools1986In: Scaninject IV: 4th International Conference on Injection Metallurgy, Luleå, Sweden, June 11-13, 1986, Luleå: MEFOS , 1986, Vol. 1Conference paper (Refereed)
  • 282.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Lindblom, Bo
    Luleå tekniska universitet.
    Toppslagg: avskiljning av desoxiadationsprodukter1993Report (Other academic)
  • 283.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Menad, Nourreddine
    Thermodynamic conditions for the reduction of dioxins during combustion of the organic parts contained in electronic wastes1999In: REWAS '99: Global Symposium on Recycling, Waste Treatment and Clean Technology ; proceedings of the "REWAS'99: Global Symposium on Recycling, Waste Treatment and Clean Technology", held in San Sebastián, Spain, September 5 - 9, 1999 ; TMS Fall 1999 Extraction and Process Metallurgy Meeting / [ed] I. Gaballah, 1999, 937-648 p.Conference paper (Refereed)
    Abstract [en]

    Electric and Electronic scrap contains about 30% plastics which are treated with halogenated flame retardants. During the combustion of these wastes, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. Their reduction can be performed by optimization of combustion parameters e.g. temperature in the combustion chamber, concentration of oxygen, temperature of flue gas at exit, residence time in the cooler, and HCl and H2O mixed in secondary air. The thermodynamic calculations show that, with an oxygen content of 0.1 mole, the total amount of dioxins/furans starts to reduce at 700°C and no formation of these isomers can be observed at 1000°C. However, these molecules are formed even at high temperature and the influence of chlorine on their reduction is negligible with an oxygen content of 1E-5 mole. On the other hand, the presence of SO2 in the gas mixture minimizes the dioxin emissions and the high concentration of water reduces the ratio of dioxins and furans in a given system

  • 284.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Samuelsson, Caisa
    Dust forming mechanisms in the copper converting process1996In: Second International Symposium on Extraction and Processing for the Treatment and Minimization of Wastes, 1996: proceedings of an international symposium /c sponsored by the Extraction and Processing Division (EPD) of TMS, and held in Scottsdale, Arizona, October 27-30, 1996 / [ed] V. Ramachandran; C.C. Nesbitt, Warrendale, Pa: Minerals, Metals & Materials Society, 1996, 105-114 p.Conference paper (Refereed)
    Abstract [en]

    A controlled dust generation whereby the dust generated would be enriched with specific metals would considerably facilitate the possibilities of recovering metals from such dusts. A basic understanding of the dust forming mechanisms is of fundamental importance to achieve a controlled dust generation. The present study deals with dust formation in a copper converting process. Dust samples collected from various places in the gas cleaning system were characterised for chemical and mineralogical composition using chemical analysis as well as microprobe analysis. Thermodynamic calculations were used to predict the formation of chemically formed dust at various temperatures and amounts of leakage air to the gas system. The results show that a separation of mechanically formed dust, e.g. SiO sub 2 , Cu and chemically formed dust, e.g. Pb, Zn, As, Bi, could, to some extent, be obtained due to their different particle sizes. A selective condensation of Pb, Zn and As at a various temperatures could, according to thermodynamic calculations, be possible at high temperature. A selective condensation of metals requires an airtight gas cleaning system or a gas cleaning system with a limited amount of leakage air in order to maintain the desired temperature level.

  • 285.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Samuelsson, Caisa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Recycling of Steel2014In: Handbook of recycling: state-of-the-art for practitioners, analysts, and scientists, Waltham, Mass: Elsevier, 2014, 65-83 p.Chapter in book (Refereed)
    Abstract [en]

    Steel is perhaps the most important construction material in the world, providing services for the well-being of mankind. An increased demand for steel services creates demand for steel consumption, and the lifetime of the products in use determines the recycling potential and the need for replacement. At the same time the steel sector contributes 9% to global energy consumption and process-related carbon emissions. This is a figure that is very much dependent on the amount of steel recycled, because production of steel from recycled material can be carried out with much less energy and CO2 emissions.Considering volume, steel is already the most recycled metal, and there is a well-functioning business structure for the recycling of steel. Currently about 40% of the steel produced comes from recycled material. If and when the increase in world consumption of steel decreases, there will be numerous possibilities of producing a large amount of the steel from recycled scrap.Based on the existing process technology for scrap sorting and steel processing and on what is known about scrap quality, possible limitations and possible actions, the chapter discusses possibilities to reach a truly sustainable steel recycling. The greatest challenge for the steel and scrap processing industry to obtain long term sustainable steel recycling is perhaps the question of scrap quality and the need to avoid quality losses when recycling steel. As the share of steel produced from ore has increased in the last decade, accumulation of tramp elements has not been an issue of high importance recently, but it is an issue that has to be tackled in the future.

  • 286.
    Björkman, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Samuelsson, Caisa
    Lindblom, Bo
    Luleå tekniska universitet.
    Kinetics of impurity elimination during roasting1993Report (Other academic)
  • 287.
    Björn, Linnéa
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Forslin, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Continuous Measurements of the Pig-Iron Temperature2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is about continuous temperature measurements of pig-iron at tapping from blast furnace 2 in Oxelösund, SSAB. Nowadays the temperature is only checked once at every tapping. The purpose of this project is to see if the process stability increases by continuously knowing the temperature and to compare the costs of this new technique with the technique used today. Possible savings due to less consumption of coke/coal if the silicon amount and the temperature are closer to their aim values will be regarded and if as little steam consumption as possible are used. The process stability can be divided into different sub goals.

    The ordinary measuring techniques were investigated as a part of the main goal; such as the ordinary measured temperature, the pig-iron and slag samples.

    The new continuous temperature measuring technique was compared with the ordinary temperature measurement and investigations of the life length were done. How representative the pig-iron and slag samples are, when taking them at the time they are today, are also looked into.

    The continuous measured temperature showed around 0,37 % higher temperature than the ordinary measured temperature. The pig-iron and slag samples should be taken as they are today, for mainly safety aspects.

    By using continuous temperature measurement, some of the sub goals can be achieved for a more stable process. The economy on the other hand has shown that large savings can be done by using this continuous temperature method due to a more stable process. This is mainly because of a decrease in steam usage in the experimental period. By regarding only the material of the methods the continuous temperature equipment is a bit more expensive, but the savings are much larger so the continuous temperature method is beneficial. With time this method could probably improve the process stability even more since the operators will deal with the information and the probe better.

  • 288. Blanter, M. S.
    et al.
    Dmitriev, V. V.
    Mogutnov, B. M.
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Interaction of interstitial atoms and configurational contribution to their thermodynamic activity in V, Nb, and Ta2017In: Physics of metals and metallography, ISSN 0031-918X, E-ISSN 1555-6190, Vol. 118, no 2, 105-112 p.Article in journal (Refereed)
    Abstract [en]

    The pairwise interaction energies of O–O and N–N in bcc metals of group VB, which were calculated earlier using first-principles methods, have been employed to analyze the effect of the interatomic interactions on the configurational contribution to the thermodynamic activity. The strong effect of interstitial- interstitial interaction has been shown. The configurational contribution grows in the row (Nb–N) → (V–N) → (Ta–N) → (Nb–O) → (V–O) → (Ta–O), which is caused by a weakening of the mutual attraction of interstitial atoms in these solid solutions. The strong repulsion that characterizes the majority of coordination shells only weakly affects the thermodynamic activity. The character of the temperature dependence of the configurational contribution is defined by the strength of the mutual attraction of the interstitial atoms, i.e., upon strong attraction, the contribution increases with increasing temperature (Nb–N, V–N, Ta–N, and Nb–O) and, upon weak attraction, it decreases (V–O and Ta–O).

  • 289. Bleskov, I. D.
    et al.
    Smirnova, E. A.
    Vekilov, Y. K.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Katsnelson, M.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Abrikosov, I. A.
    Isaev, E. I.
    Ab initio calculations of elastic properties of Ru1-xNixAl superalloys2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 94, no 16Article in journal (Refereed)
    Abstract [en]

    Ab initio total energy calculations based on the exact muffin-tin orbitals method, combined with the coherent potential approximation, have been used to study the thermodynamical and elastic properties of substitutional refractory Ru1-xNixAl alloys. We have found that the elastic constants C' and C11 exhibit pronounced peculiarities near the concentration of about 40 at. % Ni, which we ascribe to electronic topological transitions. Our suggestion is supported by the Fermi surface calculations in the whole concentration range. Results of our calculations show that one can design Ru-Ni-Al alloys substituting Ru by Ni (up to 40 at. %) with almost invariable elastic constants and reduced density.

  • 290.
    Bocko, Jozef
    et al.
    Technical University of Košice, Slovakia.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Nohajová, Viera
    Technical University of Košice, Slovakia.
    Application of Evolutionary Algorithm in Elasticity2015In: Applied Mechanics and Materials, ISSN 1660-9336, E-ISSN 1662-7482, Vol. 816, 363-368 p.Article in journal (Refereed)
    Abstract [en]

    This article introduces evolutionary algorithms and their utilization in mechanicalengineering. First part of this work describes evolutionary algorithms and their characteristics. Themain body of evolutionary algorithms, the selection methods for parents and the types ofreproduction are explained in the next part of this article. Termination conditions are also discussed.Finally, the application of evolutionary algorithms to a problem in mechanical engineering isdescribed. Thereby, the material parameters for a Bodner-Partom model describing viscoelastoplasticmaterial behavior are determined by fitting data from experiments on Aluminum testsamples under tension load.

  • 291.
    Boeije, M. F. J.
    et al.
    Delft Univ Technol, Fundamental Aspects Mat & Energy, Fac Sci Appl, Mekelweg 15, NL-2629 JB Delft, Netherlands..
    Delczeg-Czirjak, Erna Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    van Dijk, N. H.
    Delft Univ Technol, Fundamental Aspects Mat & Energy, Fac Sci Appl, Mekelweg 15, NL-2629 JB Delft, Netherlands..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bruck, E.
    Delft Univ Technol, Fundamental Aspects Mat & Energy, Fac Sci Appl, Mekelweg 15, NL-2629 JB Delft, Netherlands..
    On the phase stability of CaCu5-type compounds2017In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 722, 549-554 p.Article in journal (Refereed)
    Abstract [en]

    We present a hybrid method to inspect the phase stability of compounds having a CaCu5-type crystal structure. This is done using 2D stability plots using the Miedema parameters that are based on the work function and electron density of the constituent elements. Stable compounds are separated from unstable binary compounds, with a probability of 94%. For stable compounds, a linear relation is found, showing a constant ratio of charge transfer and electron density mismatch. DFT calculations show the same trend. Elements from the s, d, f-block are all reliably represented, elements from the p-block are still challenging.

  • 292.
    Bogdanoff, Toni
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Development of aluminium-silicon alloys with improved properties at elevated temperature2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Aluminium-silicon alloys have gained increasing market share in the automotive and aerospace industry because of increased environmental demands. These alloys have a high strength-to-weight ratio, good corrosion resistance, castability and recycling potential. However, variations in properties and limited performance at elevated temperature are restricting these alloys from use at elevated temperatures. During the last decades, researchers have investigated ways to improve the properties at elevated temperatures. However, the effect of some transition elements is not well understood. The aim of this work is to investigate the aluminium-silicon alloys with addition of cobalt and nickel for high temperature applications. Tensile testing and hardness testing were conducted on samples produced by directional solidification in a Bridgman furnace with condition generating a microstructure corresponding to that obtained in high pressure die casting, i.e. SDAS ~ 10 µm. The results show that cobalt and nickel improve the tensile properties up to 230 °C.

  • 293.
    Bogdanoff, Toni
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Dahle, Arne K.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Effect of Co and Ni Addition on the Microstructure and Mechanical Properties at Room and Elevated Temperature of an Al–7%Si Alloy2017In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Article in journal (Refereed)
    Abstract [en]

    Increasing environmental demands are forcing the automotive industry to reduce vehicle emissions by producing more light-weight and fuel efficient vehicles. Al–Si alloys are commonly used in automotive applications because of excellent castability, high thermal conductivity, good wear properties and high strength-to-weight ratio. However, most of the aluminium alloys on the market exhibit significantly reduced strength at temperatures above 200 °C. This paper presents results of a study of the effects of Co and Ni in a hypoeutectic Al–Si alloy on microstructure and mechanical properties at room and elevated temperature. Tensile test specimens with microstructures comparable to those obtained in high-pressure die casting, i.e. SDAS ~ 10 µm, were produced by directional solidification in a Bridgman furnace. The results show an improvement in tensile properties up to 230 °C.

  • 294.
    Bogdanoff, Toni
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Dahle, Arne K.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    The effect of SI content on microstructure and mechanical properties of Al-Si alloy2016In: La Metallurgia Italiana, ISSN 0026-0843, Vol. 108, no 6Article in journal (Refereed)
    Abstract [en]

    Al-Si alloys are the most popular casting alloys due to their excellent castability combined with high strengthto-weight ratio. This paper investigates the role of Si content in the range of 6.5 wt. % to 14.4 wt. % on the microstructure and mechanical properties of Al-Si-Mg casting alloys. All alloys were modified with 90-150 ppm Sr. No grain refiner was added. The samples were produced by directional solidification providing a microstructure that corresponds to microstructures found in die castings. From the phase diagram and coupled zone, increasing the Si level up to 14.4 wt. % is expected to start a competition between formation of α- dendrites and a fully eutectic microstructure. However, it is known that Sr-modification shifts the eutectic to higher Si contents. For the lower Si contents, the microstructure of the samples consisted of α-dendrites and a modified Al-Si eutectic. At 12.4 wt. % Si and above, a cellular eutectic microstructure was observed. No primary Si was observed even at 14.4 wt. % Si. The mechanical properties in terms of yield and tensile strength did not vary remarkably as a function of the Si level unlike the elongation to failure that dropped from 12 % at 6.5 wt. % Si to nearly 6 % at 14.4 wt. % Si; but still the material is exhibiting an elongation to failure that is far higher than normally expected.

  • 295. Bogdanov, V. I.
    et al.
    Popov, V. A.
    Portnoi, V. K.
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Chemical and deformational interactions in solid solution of carbon in nickel2012In: Physics of metals and metallography, ISSN 0031-918X, Vol. 113, no 9, 831-835 p.Article in journal (Refereed)
    Abstract [en]

    A first-principles stuy of ordering phenomena in hcp interstitial solid solutions of oxygen and nitrogen in Ti, Zr and Hf has demonstrated that the dominant contributions to the interaction energy of interstitial atoms are of chemical nature; thus, it is necessary to modify the previously established concepts about the priority role of deformational interactions in interstitial solutions. We have continued studies of the role of chemical and deformational interactions of interstitial atoms by the example of solid solutions of carbon in nickel. The results obtained also confirm a significant role of chemical interactions between carbon atoms in these solid solutions. The results were compared with the experimental data on the enthalpy of carbon dissolution in nickel and on the coefficient of solutal expansion of the lattice.

  • 296. Bogdanov, V. I.
    et al.
    Popov, V. A.
    Portnoi, V. K.
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    First-principles investigations of interatomic interactions in Ni3Al alloyed by interstitial and substitutional impurities2013In: Physics of metals and metallography, ISSN 0031-918X, Vol. 114, no 3, 191-196 p.Article in journal (Refereed)
    Abstract [en]

    First-principles calculations of the total energy of interstitial and substitutional solid solutions in intermetallic compound Ni3Al were performed based on methods using Vienna ab-initio simulation package (VASP). The results of the calculations for interstitial solutions of carbon in Ni3Al confirmed the priority role of chemical interactions over deformational ones for the nearest neighbors. We attempted to use first-principles methods of calculation of the deformation interaction and continuum approaching in the theory of solutions to calculate coefficients of the concentration changes of the lattice spacing. Comparison of the calculation results with experimental data of substitutional impurities in Ni3Al has shown that the proposed method can aid in the study of the distribution of impurity atoms on the sublattices of the ordered phases, intermetallic compounds. We have proposed a method of calculating the partial molar volume of impurity in interstitial solid solutions.

  • 297.
    Bojestig, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Adhesion of CVD coatings on new cemeted carbides2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Steel turning inserts cemented carbides have a binder phase consisting of cobalt (Co). However, in recent years a study from the United States National Toxicity Program (NTP) found that cobalt powder is carcinogenic upon inhalation. The European Union's REACH have therefore also classified cobalt powder as carcinogenic upon inhalation. The worldwide search to find a replacement has therefore lately intensified. It is important that the alternative binder phase has no negative effects on the properties of the insert. In this thesis the adhesion between a multilayer ceramic chemical vapor deposition (CVD) coating and a cemented carbide with the alternative binder phases consisting of iron (Fe), nickel (Ni) and cobalt (Co) has been studied.

    First of all, the fracture surfaces showed that the CVD coating was able to grow on all cemented carbides, regardless of which binder phase. To evaluate the adhesion, scratch tests were performed on all samples. The results from the scratch tests were not as expected. No chipping of the coating down to the cemented carbide occurred on any of the samples and the samples with the hardest cemented carbide did not get the highest critical load, which it should according to the literature if all other parameters were the same. Instead the sample with the binder phase consisting of 73 wt% iron and 27 wt% nickel had the highest critical load. This is thought to be due to that during the scratch test the binder phase in this cemented carbide would most likely transform into deformation martensite.

  • 298.
    Bolelli, G.
    et al.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Berger, L. -M
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, D-01277 Dresden, Germany.
    Börner, T.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Koivuluoto, H.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, FI-33720 Tampere, Finland.
    Lusvarghi, L.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Lyphout, Christophe
    University West, Department of Engineering Science, Division of Production Engineering.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Production Engineering.
    Matikainen, V.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, FI-33720 Tampere, Finland.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Sassatelli, P.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Trache, R.
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, D-01277 Dresden, Germany.
    Vuoristo, P.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, FI-33720 Tampere, Finland.
    Tribology of HVOF- and HVAF-sprayed WC-10Co4Cr hardmetal coatings: A comparative assessment2015In: Surface and Coatings Technology, ISSN 0257-8972, Vol. 265, 125-144 p.Article in journal (Refereed)
    Abstract [en]

    his paper provides a comprehensive assessment of the sliding and abrasive wear behaviour of WC–10Co4Cr hardmetal coatings, representative of the existing state-of-the-art. A commercial feedstock powder with two different particle size distributions was sprayed onto carbon steel substrates using two HVOF and two HVAF spray processes.Mild wear rates of < 10-7 mm3/(Nm) and friction coefficients of ≈ 0.5 were obtained for all samples in ball-on-disk sliding wear tests at room temperature against Al2O3 counterparts. WC–10Co4Cr coatings definitely outperform a reference electrolytic hard chromium coating under these test conditions. Their wear mechanisms include extrusion and removal of the binder matrix, with the formation of a wavy surface morphology, and brittle cracking. The balance of such phenomena is closely related to intra-lamellar features, and rather independent of those properties (e.g. indentation fracture toughness, elastic modulus) which mainly reflect large-scale inter-lamellar cohesion, as quantitatively confirmed by a principal component analysis. Intra-lamellar dissolution of WC into the matrix indeed increases the incidence of brittle cracking, resulting in slightly higher wear rates. At 400 °C, some of the hardmetal coatings fail because of the superposition between tensile residual stresses and thermal expansion mismatch stresses (due to the difference between the thermal expansion coefficients of the steel substrate and of the hardmetal coating). Those which do not fail, on account of lower residual stresses, exhibit higher wear rates than at room temperature, due to oxidation of the WC grains.The resistance of the coatings against abrasive wear, assessed by dry sand–rubber wheel testing, is related to inter-lamellar cohesion, as proven by a principal component analysis of the collected dataset. Therefore, coatings deposited from coarse feedstock powders suffer higher wear loss than those obtained from fine powders, as brittle inter-lamellar detachment is caused by their weaker interparticle cohesion, witnessed by their systematically lower fracture toughness as well.

  • 299.
    Bolin, Nils Johan
    Luleå tekniska universitet.
    Flotation: en studie i några förutsättningar för selektiv flotation1983Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The zeta potential for oxide- and silicate minerals has been measured in different pulp liquids and a comparison has been made concerning the results of the flotation. The results show that the surface charge of the mineral particles reflect the condition of the dispersion of the pulp, and guiding the surface charge is a way of increasing the selectivity when concentrating by flotation. The results also show that the zeta potential indicates how easily amino reagents are adsorbed on silicate minerals. A successful dispersion is a condition for good selectivity with the exception of selective flocculation. Selective flocculation can be used in flotation in a case of for example quartz flotation with amine as the collector, the iron mineral being flocculated with dextrin. An example is given of selective flocculation of baryte and flotation of baryte.

  • 300.
    Bolin, Nils Johan
    Luleå tekniska universitet.
    Study of muscovite flotation from a pegmatite ore1983In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 12, no 3, 117-120 p.Article in journal (Refereed)
    Abstract [en]

    The article shows the relationship between the iron ion content of the flotation pulp and the selectivity of mica flotation of a granitic pegmatite from Limbergsbo, Sweden which contains 40% albite, 20% microcline, 30-35% quartz and 4% muscovite. The results of comparative experiments involving flotation in stainless steel and iron-rich environments show that selectivity with respect to microcline and quartz is better when an iron mill is used for grinding

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