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  • 1. Abas, R. Abdul
    et al.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Thermal diffusivity of sintered stainless steel-alumina composites2006In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 37, no 4, 513-518 p.Article in journal (Refereed)
    Abstract [en]

    Thermal diffusivity measurements were carried out as a function of temperature on sintered AISI 304 stainless steel-alumina composites having various compositions (0.001, 0.01, 0, 1, 1, 2, 3, 5, 7, 8, and 10 wt pct Al2O3). The measurements were carried out between room temperature and 1473 K. The thermal diffusivity and the thermal conductivity were found to increase with temperature in all the composite specimens. The thermal diffusivity was found to decrease with increasing weight fraction of alumina. This tendency can clearly be seen at temperatures above 755 K. The experimental results are in good agreement with the simple rule of mixture, the Eucken equation, and the Ohm's law model developed by Hayashi et al. at weight fractions of alumina below 5 wt pct. Beyond this composition, the thermal diffusivity/conductivity shows a large discrepancy from the models. This could probably be attributed to the accumulation of alumina particles during cooled pressing and sintering.

  • 2. Abbasalizadeh, A.
    et al.
    Teng, Lidong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Sietsma, J.
    Yang, Y.
    Rare Earth Extraction from NdFeB Magnets and Rare Earth Oxides Using Aluminum Chloride/Fluoride Molten Salts2015In: Rare Earths Industry: Technological, Economic, and Environmental Implications, Elsevier, 2015, 357-373 p.Chapter in book (Other academic)
    Abstract [en]

    In the current research, the feasibility of the recovery of neodymium and dysprosium from spent NdFeB magnets (about 6wt% Dy) was investigated using molten salt processes. The salt bath consisted of a eutectic composition of an NaCl-KCl-LiCl mixture. To enable the efficient dissolution of metal in the molten salt phase, AlCl3 was used as a chlorinating agent. Iron-free electrodeposition was carried out successfully. Energy-dispersive spectroscopic analysis of the electrodeposit revealed that co-deposition of the dysprosium occurs along with neodymium at the cathode. The process shows that this method is well suited for recovering rare earth metals from magnetic scrap containing these metals.Furthermore, the setup design for recovery of neodymium and dysprosium from their oxides was investigated with regard to previous studies on the neodymium magnets. The stability of different fluoride and chloride salts was studied by means of thermodynamic calculation. Aluminum fluoride-based molten salt systems were studied in detail as the electrolyte for electrochemical extraction of rare earth oxides into rare earth metal elements with Al.

  • 3.
    Abbasalizadeh, Aida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Teng, Lidong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Sridhar, Seetharaman
    Grinder, Olle
    Izumi, Yukari
    Barati, Mansoor
    Highlights of the Salt Extraction Process2013In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 65, no 11, 1552-1558 p.Article in journal (Refereed)
    Abstract [en]

    This article presents the salient features of a new process for the recovery of metal values from secondary sources and waste materials such as slag and flue dusts. It is also feasible in extracting metals such as nickel and cobalt from ores that normally are difficult to enrich and process metallurgically. The salt extraction process is based on extraction of the metals from the raw materials by a molten salt bath consisting of NaCl, LiCl, and KCl corresponding to the eutectic composition with AlCl3 as the chlorinating agent. The process is operated in the temperature range 973 K (700 degrees C) to 1173 K (900 degrees C). The process was shown to be successful in extracting Cr and Fe from electric arc furnace (EAF) slag. Electrolytic copper could be produced from copper concentrate based on chalcopyrite in a single step. Conducting the process in oxygen-free atmosphere, sulfur could be captured in the elemental form. The method proved to be successful in extracting lead from spent cathode ray tubes. In order to prevent the loss of AlCl3 in the vapor form and also chlorine gas emission at the cathode during the electrolysis, liquid aluminum was used. The process was shown to be successful in extracting Nd and Dy from magnetic scrap. The method is a highly promising process route for the recovery of strategic metals. It also has the added advantage of being environmentally friendly.

  • 4.
    Abbasalizadeh, Aida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Teng, Lidong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, S.
    Dysprosium extraction using molten salt process2014In: Rare metal technology 2014: proceedings of a symposium sponsored by The Minerals, Metals & Materials Society (TMS) held during TMS 2014, 143rd Annual Meeting & Exhibition, February 16-20, 2014, San Diego Convention Center, San Diego, California, USA, 2014, 207-208 p.Conference paper (Refereed)
  • 5.
    Abbasalizadeh, Aida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Teng, Lidong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Sridhar, S.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Neodymium extraction using salt extraction process2015In: Transactions of the Institution of Mining and Metallurgy Section C - Mineral Processing and Extractive Metallurgy, ISSN 0371-9553, E-ISSN 1743-2855, Vol. 124, no 4, 191-198 p.Article in journal (Refereed)
    Abstract [en]

    The present paper deals with the feasibility of the neodymium recovery from spent Nd-Fe-B magnets using molten salt electrodeposition method. The salt bath consisted of a mixture of LiCl- KCl-NaCl corresponding to the eutectic composition. The experimental set-up with its salient features is presented. AlCl3 was used as flux and graphite rods dipped in the salt bath served as electrodes. The voltage for the electrolysis was chosen on the basis of the decomposition potential of NdCl3. The reaction sequence can be described as Iron-free neodymium deposition could be carried out successfully. In view of the proximity of the electrode potentials, the co-deposition of the aluminium and neodymium was observed to occur at the cathode, as revealed by SEM/EDS and XRD analyses of the electrodeposit.

  • 6.
    Abdul Abas, Riad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Hayashi, M.iyuki
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Thermal Diffusivity measurement of CMSX-4 alloy by Laser flash method2007In: International journal of thermophysics, ISSN 0195-928X, E-ISSN 1572-9567, Vol. 28, no 1, 109-122 p.Article in journal (Refereed)
    Abstract [en]

    In the present work, thermal diffusivity measurements have been carried out on industrial samples of CMSX-4 nickel-base superalloy using the laser-flash method with emphasis on studying the effect of temperature and microstructure on the thermal diffusivity. The measurements were performed in the temperature range from 298 to 1623 K covering both solid as well as liquid ranges. Below 1253 K, the thermal-diffusivity values were found to increase with increasing temperature. Microstructural investigations of quenched samples revealed that below 1253 K, an ordered phase, usually referred to as the -phase was present together with the disordered fcc phase, often referred to as the γ phase. Between 1253 K and the solidus temperature, the phase was found to dissolve in the matrix alloy causing an increase in the disordering of the alloy, and thereby a small decrease in the thermal-diffusivity values. The thermal-diffusivity values of samples pre-annealed at 1573 K exhibited constancy in the temperature range from 1277 to 1513 K, which is attributed to the attainment of thermodynamic equilibrium. These equilibrium values were found to be lower than the results for samples not subjected to annealing. The thermal-diffusivity values of the alloy in the liquid state were found to be independent of temperature.

  • 7.
    Abdul Abas, Riad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Hayashi, Miyuki
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Thermal Diffusivity Measurements of some Industrially Important Alloys by a Laser Flash Method2007In: International journal of materials reseach, ISSN 1862-5282, Vol. 98, no 6, 535-540 p.Article in journal (Refereed)
    Abstract [en]

    In the present work, thermal diffusivity measurements of three industrially significant alloys, viz. 90Ti.6Al.4V, stainless steel with 25Cr and 6Ni as well as plain carbon steel with 0.7 % carbon have been carried out as a function of temperature. The aim of this work is to study the effect of temperature and microstructure on the thermal diffusivities of these alloys. For the 90Ti.6Al.4V alloy, thermal diffusivity increases with temperature below 1225 K. Above this temperature, the values started decreasing probably due to the dissolution of Ti3Al intermediate phase in the matrix, which would result in an increase in the disorder of the structure. For 25Cr: 6Ni stainless steel, the thermal diffusivity is nearly constant up to about 700 K. Above this, there is an increase in the thermal diffusivities with temperature during the heating cycle, which was reproducible during thermal cycling. On the other hand, the slope of the curve increases above 950 K.

    In the case of the 0.7 % carbon steel, the thermal diffusivity shows a decreasing trend with temperature below the Curie point for the alloy, where the alloy consists of bcc + fcc phases. Above this point, only the fcc phase is prevalent and the thermal diffusivity was found to increase with temperature. Heat transfer is carried out by lattice vibration (phonons) as well as electrons. The contribution of electrons varies depending upon the type of alloy. In this study, the highest electron contribution was found in 0.7 % carbon steel, while the lowest was in stainless steel. The thermal conductivity values of these alloys are in good agreement with the calculated values using the model proposed by Mills.

  • 8.
    Ahmed, Hesham M.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Investigations of the Kinetics of Reduction and Reduction/Carburization of NiO-WO3 Precursors.2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Kinetic studies of reduction of the mixtures of NiO and WO3 having different Ni/(Ni+W) molar ratios in flowing hydrogen gas were investigated by means of Thermo Gravimetric Analysis (TGA), Fluidized Bed (FB) technique as well as Thermal diffusivity measurements under isothermal conditions. In the case of TGA, the reaction progress was monitored by mass loss, while evolved gas analysis by a gas chromatograph was the indicator of the reaction progress in the case of FB. The results indicate that the reduction reaction proceeds through three consecutive steps, viz.

    NiO-WO3 Ni-WO3 Ni-WO2 Ni-W

    The present results show that the fluidized bed technique can be successfully utilized in bulk production of intermetallics containing W and a transition metal (or a composite material) wherein the process conditions would have a strong impact on the particle size of the end product.

    During the investigations, it was found that there was a delay in the reaction during the hydrogen reduction of NiO-WO3 mixed oxides in a fluidized bed reactor. In order to understand the same, a theoretical model was developed to estimate the apparent reaction rate constant for the reduction reaction from the intrinsic chemical reaction rate constant. Appropriate differential mass balance equations based on intrinsic chemical reaction rate constants and thermodynamic equilibria were developed. The proposed model was successfully applied in predicting the overall reaction kinetics of a fluidized bed reactor. This model is also suitable for scale-up calculations.

    SEM images showed that the particle size of the final product was dependent on the Ni/(Ni+W) molar ratio; smaller particles were formed at higher nickel contents. X-ray diffractions of the reduced precursors exhibited slight shift of Ni peaks from the standard one indicating the dissolution of W into Ni.

    A new method for studying kinetics of the hydrogen reduction of NiO-WO3 precursors was developed in which the reaction progress was monitored by following the change of thermal diffusivity of the precursors. Activation energies of reduction as well as sintering were calculated. This method is considered unique as it provides information regarding the physical changes like sintering, change of porosity and agglomeration along with the chemical changes occurring during the gas/solid reaction.

    As a continuation of the kinetic studies, Ni-W-C ternary carbides were synthesized by simultaneous reduction–carburization of Ni-W-O system using H2-CH4 gas mixtures by TGA. The results showed that the reduction of the oxide mixture was complete before the carburization took place. The nascent particles of the metals formed by reduction could react with the gas mixture with well-defined carbon potential to form a uniform product of Ni-W-C. The above-mentioned experiments were conducted in such a way to ensure that the reaction was controlled by the chemical reaction. The activation energies of the reduction as well as carburization processes at different stages were calculated accordingly.

    The present dissertation demonstrates the potential of the investigations of gas/solid reactions towards tailoring the process towards materials with optimized properties as for example introduction of interstitials. The present process design is extremely environment-friendly with reduced number of unit processes and the product being H2O.

  • 9.
    Ahmed, Hesham M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    El-Geassy, A. H. A.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Kinetics of Reduction of NiO-WO3 Mixtures by Hydrogen2010In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 41, no 1, 161-172 p.Article in journal (Refereed)
    Abstract [en]

    The kinetics of reduction of the oxide mixtures of Ni-W with different Ni/(Ni-W) molar ratios within the range of 923 K to 1173 K in flowing hydrogen gas was investigated by means of thermogravimetric analysis under isothermal conditions. The products were examined by X-ray diffraction, scanning electron microscope (SEM), and electron dispersion spectroscopy (EDS) analyses. Five different oxide mixtures apart from the pure oxides were studied in the present work. The results indicate that the reduction reaction proceeds through three consecutive steps that are as follows: NiO-WO3 -> Ni-WO3 -> Ni-WO2 -> Ni-W From the experimental results, the Arrhenius activation energies of the three steps were evaluated for all of the studied compositions. The activation energy for the first step was calculated to be approximately 18 kJ/mol. For the second and third stages, the activation energy values varied from 62 to 38 kJ/mol for the second stage and 51 to 34 kJ/mol for the third stage depending on the Ni/(Ni + W) molar ratio in the precursors; the activation energy increased with increasing ratios. SEM images showed that the grain size of the final product was dependent on the Ni/(Ni + W) molar ratio; smaller grains were formed at higher nickel contents.

  • 10.
    Ahmed, Hesham M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    El-Geassy, Abdel-Hady
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Kinetic Studies of the Hydrogen Reduction of NiO-WO3 precursors in a Fluidized-bed reactorIn: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916Article in journal (Other academic)
  • 11.
    Ahmed, Hesham M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Reduction-Carburization of NiO-WO3 Under Isothermal Conditions Using H2-CH4 Gas Mixture2010In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 41, no 1, 173-181 p.Article in journal (Refereed)
    Abstract [en]

    Ni-W-C ternary carbides were synthesized by simultaneous reduction–carburization of NiO-WO3 oxide precursors using H2-CH4 gas mixtures in the temperature range of 973 to 1273 K. The kinetics of the gas–solid reaction were followed closely by monitoring the mass changes using the thermogravimetric method (TGA). As a thin bed of the precursors were used, each particle was in direct contact with the gas mixture. The results showed that the hydrogen reduction of the oxide mixture was complete before the carburization took place. The nascent particles of the metals formed by reduction could react with the gas mixture with well-defined carbon potential to form a uniform product of Ni-W-C. Consequently, the reaction rate could be conceived as being controlled by the chemical reaction. From the reaction rate, Arrhenius activation energies for reduction and carburization were evaluated. Characterization of the carbides produced was carried out using X-ray diffraction and a scanning electron microscope (SEM) combined with electron dispersion spectroscopy (SEM-EDS) analyses. The grain sizes also were determined. The process parameters, such as the temperature of the reduction–carburization reaction and the composition of the gas mixture, had a strong impact on the carbide composition as well as on the grain size. The results are discussed in light of the reduction kinetics of the oxides and the thermodynamic constraints.

  • 12.
    Ahmed, Hesham M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Viswanathan, N. N.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    On The Kinetics of Hydrogen Reduction of NiO-WO3 Precursors in Fluidized Bed- A Modeling Approach2011In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 51, no 9, 1383-1391 p.Article in journal (Refereed)
    Abstract [en]

    In the present work, Fluidized bed reduction of NiO-WO3 precursors was investigated isothermally at temperatures 973-1 273 K. The reaction progress was monitored by analysis of H2O evolved during the reaction process using a gas chromatograph instrument. A theoretical model based on intrinsic chemical reaction rate constants and thermodynamic equilibria was developed to estimate the apparent reaction rate constant for the reduction reaction. In developing the model, the particles are considered to be in a completely mixed condition and gas flow is described as plug flow. The proposed model is also suitable for scale-up calculations. The interfacial chemical reaction model was found to fit the experimental results. The apparent activation energy values of the reduction process at different stages were calculated accordingly. The present investigation proved that the fluidized bed technique can be successfully utilized in bulk production of intermetallics containing W and a transition metal (or a composite material) wherein the process conditions would have a strong impact on the particle size of the end product.

  • 13.
    Akhtar, Shahid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Shaikh, Md. Robiul Haque
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Micro Porosity Development in Directionally Solidified A356 Castings Doped with Anodized Plates and Sintered Aluminium2011In: European Congress and Exhibition on Advanced Materials and Processes (EUROMAT) 2011, Symposium C52: Processing and characterizing techniques, 2011Conference paper (Refereed)
  • 14.
    Albertsson, Galina
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Abatement of Chromium Emissions from Steelmaking Slags - Cr Stabilization by Phase Separation2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Chromium is an important alloying element in stainless steel but also environmentally harmful element. A number of mineralogical phases present in the slag matrix can contain chromium and lead to chromium leaching. Chromium in slag if not stabilized, could oxidize to the cancerogenic hexavalent state, and leach out if exposed to acidic and oxygen rich environment. Other environmental concerns are slag dusting and chromium escape to the atmosphere. Despite the fact that there is a certain risk of Cr-emission from slags at operating conditions, still very little is known regarding the emission of the oxides of chromium during the slag tapping. Spinel phase is known to be important for controlling the leaching properties of chromium from the slag. The objective of the present study was to get an understanding of the phase relationships and chromium partition in the chromium-containing industrial slags and synthetic slags with a view to control the chromium stabilization in spinel phase. The impact of slag basicity, heat treatment, oxygen partial pressure and Al2O3 addition, on the phase relationships and chromium partition has been determined. The experimental results were compared with the phase equilibrium calculations. It was found that the oxygen partial pressure in the gas phase had a strong impact on chromium partition. The experimental results show that the impact of the slag basicity on chromium partition at lower oxygen partial pressures was negligible in contrast to that in air. The amount of spinel phase was found to increase with increased Al2O3 content. Slow cooling of slag and soaking at low oxygen partial pressure would improve the spinel phase precipitation. This treatment will also lead to less Cr dissolved in the unstable matrix phases. Chromium oxide was found to be emitted when chromium containing slags were exposed to oxidizing atmosphere. The results indicate that chromium oxide evaporation increases with increase in temperature and oxygen partial pressure, but decreases with slag basicity and sample thickness.

  • 15.
    Albertsson, Galina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Teng, Lidong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Björkman, Bo
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Engström, Fredrik
    Effect of Low Oxygen Partial Pressure on the Chromium Partition in CaO-MgO-SiO2-Cr2O3-Al2O3 Synthetic Slag at Elevated Temperatures2013In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 84, no 7, 670-679 p.Article in journal (Refereed)
    Abstract [en]

    The objective of the present work is to get an understanding of the impact of Al2O3 addition on the phase relationships in the CaO-MgO-Al2O3-SiO2-Cr2O3 slags at low oxygen partial pressures (P-O2 = 10(-4) Pa), with a view to control the precipitation of Cr-spinel in the slag. The equilibrium phases in CaO-MgO-Al2O3-SiO2-Cr2O3 slag system in the range on 1673-1873 K have been investigated. The compositions close to the industrial slag systems were chosen. The Cr2O3 content was fixed at 6 wt% and MgO at 8 wt%. Al2O3 contents in the slag were varied in the range of 3-12 wt%. The basicity (CaO/SiO2) of slag was set to 1.6. Gas/slag equilibrium technique was adopted. The samples were heated to 1873 K and soaked at this temperature for 24 h. The samples were then slow cooled to 1673 K and equilibrated for an additional 24 h. The oxygen partial pressure was kept at 10(-4) Pa. A gas mixture of CO/CO2 was used to control the oxygen partial pressure. After the equilibration, the samples were quenched in water. The chromium distribution and phase compositions in the quenched slags were studied using SEM-WDS and XRD techniques. The results were compared with the phase equilibrium calculations obtained from FACTSAGE software and the samples equilibrated in air. The size of spinel crystals increased drastically after slow cooling followed by annealing compared to samples being quenched after soaking at 1873 K. It was also found that low oxygen partial pressure had a strong impact on chromium partition. The amount of spinel phase increases with increased Al2O3 content.

  • 16. Andersson, G.
    et al.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    "Steel eco-cycle" - A Swedish cross-pollination environmental research program2013In: Materials Science and Technology Conference and Exhibition 2013, MS and T 2013, Warrendale , 2013, 1784-1791 p.Conference paper (Refereed)
    Abstract [en]

    In 2004, Swedish steel industry launched the first truly holistic research program in one of the world's most energy intensive industries with the aim to drastically increase the energy and resource efficiency by governing and reinforce (closing) the loop in the steel life cycle. The inter-disciplinary approach of the program has led to a significant cross-pollination in environmental steel technology and related areas apart from the impact in the educational field. The program, alongside the development of resource-efficient production of steel, has led to offshoots in aluminium remelting industry, recovery of rare earths from magnetic scrap and recovery of lead from CRT glasses. The research efforts led to the successful recovery of vanadium and magnetically important manganese nanoferrites from (waste) steel slags. The results, in fact, even provide insights into declarations of human attitudes, future raw material prognoses, process optimizations and pilot plant trials along with instrument and model developments.

  • 17.
    Arzpeima, Minoodokht
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Björling, Gunilla
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Antimicrobial Efficacy and Degradation Route of Silver-Based Coated Endotracheal Tubes2012Conference paper (Refereed)
  • 18.
    Arzpeima, Minoodokht
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Rosén, Annika
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sanchez, Javier
    Björling, Gunilla
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Chemotherapy-Induced Surface Degradation and Thrombogenicity of Intravascular Catheters: A Preliminary In-Vitro Study with Focus on Breast Cancer2012Conference paper (Refereed)
  • 19.
    Aune, Ragnhild E.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Battezzati, L.
    Egry, I.
    Etay, J.
    Fecht, H. J.
    Giuranno, D.
    Novakovic, R.
    Passerone, A.
    Ricci, E.
    Schmidt-Hohagen, F.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Wunderlich, R.
    Surface tension measurements of Al-Ni based alloys from ground-based and parabolic flight experiments: Results from the ThermoLab project2006In: Microgravity, science and technology, ISSN 0938-0108, E-ISSN 1875-0494, Vol. 18, no 3-4, 73-76 p.Article in journal (Refereed)
    Abstract [en]

    Surface tension measurements of different alloys of the Al-Ni system, performed both under reduced gravity conditions in parabolic flights and on ground by conventional techniques, are presented. The alloys compositions were selected on the basis of the intrinsic compound forming tendency with the aim to allow a sensitive test of model predictions.

  • 20.
    Aune, Ragnhild E.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Hayashi, M.
    Sridhar, S.
    Thermodynamic approach to physical properties of silicate melts2005In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 32, no 2, 141-150 p.Article in journal (Refereed)
    Abstract [en]

    The thermophysical properties of silicate melts are strongly structure dependent. It is well known that the viscosity of slags increases with increasing degree of polymerisation of the silicate anion. Even the thermodynamic properties of slags are dependent on the species type and population in the melt. Thus, a link between the thermophysical and thermochemical properties of silicate melts is logically expected. The present paper elucidates the salient features of Darken's excess stability approach to the Gibbs energy of solution as applied to the viscosities of silicate melts. It is demonstrated that the second derivatives of the viscosities of binary silicate melts with respect to composition indicate maxima corresponding to the existence of stable compounds in these systems. The concept has been successfully applied to the following systems: Al2O3-SiO2, CaO-SiO2, FeO-SiO2, MgO-SiO2 and MnO-SiO2. In all cases, the second derivative plots of viscosities with respect to composition show peaks corresponding to the metasilicates. The second derivatives of the activation energies of viscous flow with respect to temperature have earlier been shown to reflect the formation of associates/embryos in homogeneous silicate melts, indicating the readiness of the melt to separate a solid phase. Thermodynamic coupling of thermal diffusivities in the case of the CaO-Al2O3-SiO2 system from laser flash measurements of these slags, as a function of temperature, has been examined as part of the present study. Densities have been estimated from integral molar enthalpies in the case of silicate systems, and the results are presented.

  • 21.
    Aune, Ragnhild Elizabeth
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Heikkinen, E. -P.
    Koponen, J.
    Samuelsson, C.
    Heiskanen, K.
    Progress report by the Nordic International Masters Platform (NIMP) Operative group2006Report (Other academic)
  • 22.
    Aune, Ragnhild Elizabeth
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Kekkonen, Marko
    Proceedings of the Symposium in Honour of Professor Lauri E. Holappa of the Helsinki University of Technology: Metal Separation Technologies III2004Conference proceedings (editor) (Refereed)
  • 23.
    Aune, Ragnhild Elizabeth
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Experimental designs toward an understanding of process phenomena in steelmaking2006In: Iron and Steel Technology, ISSN 1547-0423, Vol. 3, no 12, 137-146 p.Article in journal (Refereed)
    Abstract [en]

    Various experimental studies towards the understanding of different process phenomena in iron and steelmaking were presented. Thermal diffusivity measurement was carried out at various temperature to monitor the structural changes occurring in coke. X-ray diffraction measurements were carried out to determine the average crystallite size of graphite along the structural c-axis and in the structural ab plane. It was observed that the apparent thermal diffusivity during the cooling cycle is larger than the heating cycle. Many experiments were also conducted in a high-temperature x-ray diffraction unit, to study the rate of graphitization at any given temperature for a given coke sample. An experimental design for the investigation of the mechanism of reduction in the blast furnace shaft, and the role of coke by dynamic x-ray photography was also carried out. The heating and melting of a mold flux during continuous casting were also simulated in specially designed laboratory.

  • 24.
    Aune, Ragnhild Elizabeth
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Experimental designs towards an understanding of process phenomena in steel making2005In: ICS 2005: Proceedings of the 3rd International Congress on the Science and Technology of Steelmaking, 2005, 381-392 p.Conference paper (Refereed)
  • 25.
    Aune, Ragnhild Elizabeth
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Experimental Designs towards an Understanding of Process Phenomena in Steel Making2006In: Iron & Steel Technology, ISSN 1547-0423, Vol. 3, no 12, 137-146 p.Article in journal (Refereed)
  • 26.
    Aune, Ragnhild Elizabeth
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Thermodynamic Aspects of Metals Processing2005In: Fundamentals of Metallurgy / [ed] Seshadri Seetharaman, Woodhead Publishing Limited, 2005, 38-81 p.Chapter in book (Refereed)
  • 27. Basu, S.
    et al.
    Lahiri, A. K.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Activity of Ferric Oxide in Steelmaking Slag2010In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 41, no 2, 414-419 p.Article in journal (Refereed)
    Abstract [en]

    Refining reactions in steelmaking primarily involve oxidation of impurity element(s). The oxidation potential of the slag and the activity of oxygen in the metal (h(O)) are the major factors controlling these chemical reactions. In turn, the oxidation potential of the slag is influenced strongly by the equilibrium distribution of oxygen between ferrous and ferric oxides. We recently investigated the activity coefficient of FeO in steelmaking slag and the effect of chemical composition thereon. This work is focused on estimation of the activity coefficient of Fe2O3.

  • 28. Basu, S.
    et al.
    Lahiri, A. K.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Activity of iron oxide in steelmaking slag2008In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 39, no 3, 447-456 p.Article in journal (Refereed)
    Abstract [en]

    Most refining reactions in steelmaking involve oxidation of impurity element(s). The product(s) of oxidation either dissolve in the slag or escape as gaseous phase. The activities of oxygen in the metal (h (O)), and that of "FeO" in slag (a (FeO)), are major factors controlling these chemical reactions. The activities of oxygen and "FeO" are thermodynamically related, provided equilibrium distribution of oxygen between the slag and the metal is attained. This enables direct estimation of one parameter from the other. A thorough knowledge of the variation in activity of FeO, and factors affecting the same, is therefore of great importance in the process metallurgy of steelmaking. The present work experimentally measures the activity of FeO in steelmaking slags and attempts to develop a correlation for estimation of gamma(FeO) as a function of temperature and chemical composition of the slag.

  • 29. Basu, S.
    et al.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Lahiri, A. K.
    Thermodynamics of Phosphorus and Sulphur Removal during Basic Oxygen Steelmaking2010In: STEEL RESEARCH INTERNATIONAL    , 2010, Vol. 81, no 11, 932-939 p.Conference paper (Refereed)
    Abstract [en]

    Removal of impurity elements from hot metal is essential in basic oxygen steelmaking. Oxidation of phosphorus from hot metal has been studied by several authors since the early days of steelmaking. Influence of different parameters on the distribution of phosphorus, seen during the recent work of the authors, differs somewhat from that reported earlier. On the other hand, removal of sulphur during steelmaking has drawn much less attention. This may be due to the magnitude of desulphurisation in oxygen steelmaking being relatively low and desulphurisation during hot metal pre-treatment or in the ladle furnace offering better commercial viability Further, it is normally accepted that sulphur is removed to steelmaking slag in the form of sulphide only However, recent investigations have indicated that a significant amount of sulphur removed during basic oxygen steelmaking can exist in the form of sulphate in the slag under oxidising conditions. The distribution of sulphur during steelmaking becomes more important in the event of carry-over of sulphur-rich blast-furnace slag, which increases sulphur load in the BOF. The chemical nature of sulphur in this slag undergoes a gradual transition from sulphide to sulphate as the oxidative refining progresses.

  • 30.
    Basu, Somnath
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Lahiri, Ashok Kumar
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    A model for activity coefficient of P2O5 in BOF slag and phosphorus distribution between liquid steel and slag2007In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 47, no 8, 1236-1238 p.Article in journal (Refereed)
  • 31.
    Basu, Somnath
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Lahiri, Ashok Kumar
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Phosphorus partition between liquid steel and CaO-SiO2-FeOx-P2O5-MgO slag containing 15-25 %FeO2007In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 38, no 4, 623-630 p.Article in journal (Refereed)
    Abstract [en]

    CaO-SiO2-FeO2-P2O5-MgO bearing slags are typically used in the basic oxygen steelmaking (BOS) process. The partition ratio of phosphorus between slag and steel is an index of the phosphorus holding capacity of the slag, which determines the phosphorus content achievable in the finished steel. The influence of factors such as FeO content and basicity on the phosphorus partition ratio was investigated at two different temperatures. The partition ratio initially increased with basicity but remained constant beyond a basicity of 2.5 to 2.6. An increase in the FeO content up to 18 to 20 mass pct was beneficial for the phosphorus partition at a basicity level of 2 to 3, but a higher concentration of FeO resulted in a decrease in the phosphorus partition ratio; the FeO concentration corresponding to this transition varied with basicity and temperature. At even lower basicities, however, the equilibrium phosphorus partition showed either no change, or a marginally decreasing trend, with an increase in the FeO content.

  • 32.
    Basu, Somnath
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Lahiri, Ashok Kumar
    KTH.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Phosphorus partition between liquid steel and CaO-SiO2-P2O5-MgO slag containing low FeO2007In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 38, no 3, 357-366 p.Article in journal (Refereed)
    Abstract [en]

    CaO-SiO2-FeOx-P2O5-MgO bearing slags are typical in the basic oxygen steelmaking (BOS) process. The partition ratio of phosphorus between slag and steel is an index of the phosphorus holding capacity of the slag, which determines the phosphorus content achievable in the finished steel. The influences of FeO concentration and basicity on the equilibrium phosphorus partition ratios were experimentally determined at temperatures of 1873 and 1923 K, for conditions of MgO saturation. The partition ratio initially increased with basicity but attained a constant value beyond basicity of 2.5. An increase in FeO concentration up to approximately 13 to 14 mass pet was beneficial for phosphorus partition.

  • 33.
    Basu, Somnath
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Lahiri, Ashok Kumar
    KTH.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Halder, Jayanta
    Change in phosphorus partition during blowing in a commercial BOF2007In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 47, no 5, 766-768 p.Article in journal (Refereed)
  • 34.
    Beheshti, Reza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Akhtar, Shahid
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Heat treatment of black dross for the production of a value added material - a preliminary study2012In: EPD Congress 2012, John Wiley & Sons, 2012, 353-360 p.Conference paper (Refereed)
    Abstract [en]

    The potential use of Black Dross (BD) as a raw material for the production of refractories, fluxing agents and glasses is the main motivation of the present study. Heat treatment experiments were carried out in Ar, and under reduced pressure (20 Pa), to evaluate the salt removal efficiency. The chemical composition of the BD after heat treatment was investigated by SEM-EDS and XRD analyses. Based on the present results, it is established that the salt starts to evaporate at ≈1273 K in Ar, and under reduced pressure. The salt removal efficiency in a 20 g sample was found to increase in both cases as a function of time and temperature. Moreover, in Ar the chlorine concentration was lowered to 0.3 wt% after heat treatment at 1523 K for 10 hours. Under reduced pressure, however, 0.2 wt% residual chlorine was obtained after 8 hours at 1473 K.

  • 35. Björling, Gunilla
    et al.
    Arzpeima, Minoodokht
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Considerations in Tube Selection2011Conference paper (Refereed)
  • 36. Björling, Gunilla
    et al.
    Axelsson, Sara
    Johansson, Unn-Britt
    Lysdahl, Michael
    Aune, Ragnhild Elizabeth
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Frostell, Claes
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Long-Term Tracheostomy: Aspects on Tube Change and Material Wear2007Conference paper (Refereed)
    Abstract [en]
    • The tracheostomy tubes in use are exposed not only to bacteria but also the lining fluids, which are a first defence against toxicity in inhaled gases. It contains several antioxidants. The complex bacteriological environment in the trachea, as well as the formation of a biofilm on the tube surface through colonization of bacteria, is believed to affect the mechanical and chemical properties of the tube material. The study was conducted at the National Respiratory Centre (NRC) at Danderyd Hospital in collaboration with the Royal Institute of Technology and Sophiahemmet University College in Stockholm, Sweden.
  • 37. Björling, Gunilla
    et al.
    Axelsson, Sara
    Johansson, Unn-Britt
    Lysdahl, Michael
    Markström, Agneta
    Schedin, Ulla
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Frostell, Claes
    Karlsson, Sigbritt
    Clinical use and material wear of polymeric tracheostomy tubes2007In: The Laryngoscope, ISSN 0023-852X, E-ISSN 1531-4995, Vol. 117, no 9, 1552-1559 p.Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: The objectives were to compare the duration of use of polymeric tracheostomy tubes, i.e., silicone (Si), polyvinyl chloride (PVC), and polyurethane (PU), and to determine whether surface changes in the materials could be observed after 30 days of patient use. METHODS: Data were collected from patient and technical records for all tracheostomized patients attending the National Respiratory Center in Sweden. In the surface study, 19 patients with long-term tracheostomy were included: six with Bivona TTS Si tubes, eight with Shiley PVC tubes, and five with Trachoe Twist PU tubes. All tubes were exposed in the trachea for 30 days before being analyzed by scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). New tubes and tubes exposed in phosphate-buffered saline were used as reference. RESULTS: Si tubes are used for longer periods of time than those made of PVC (P < .0001) and PU (P = .021). In general, all polymeric tubes were used longer than the recommended 30-day period. Eighteen of the 19 tubes exposed in patients demonstrated, in one or more areas of the tube, evident surface changes. The morphologic changes identified by SEM correlate well with the results obtained by ATR-FTIR. CONCLUSIONS: Si tracheostomy tubes are in general used longer than those made of PVC and PU. Most of the tubes exposed in the trachea for 30 days suffered evident surface changes, with degradation of the polymeric chains as a result.

  • 38. Björling, Gunilla
    et al.
    Lysdahl, Michael
    Markström, Agneta
    Schedin, Ulla
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Frostell, Claes
    Johansson, Unn-Britt
    Health-Related Quality of Life and Patient Experiences of Long-Term Tracheostomy2009Conference paper (Refereed)
  • 39. Brillo, J.
    et al.
    Egry, I.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Density and surface tension of liquid ternary Ni-Cu-Fe alloys2006In: International journal of thermophysics, ISSN 0195-928X, E-ISSN 1572-9567, Vol. 27, no 6, 1778-1791 p.Article in journal (Refereed)
    Abstract [en]

    The density and surface tension of liquid Ni-Cu-Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electromagnetic levitator equipped with facilities for optical densitometry and oscillating drop tensiometry. At temperatures above and below the liquidus point, the density and surface tension are linear functions of temperature. The concentration dependence of the density is significantly influenced by a third-order (ternary) parameter in the excess volume. The surface tensions are rather insensitive to substitution of the two transition metals Ni, Fe against each other and depend only on the copper concentration. By numerically solving the Butler equation, the surface tension of the ternary system can be derived from the thermodynamic potentials (E)G of the binary phases (Ni-Cu, Fe-Cu, Ni-Fe) alone.

  • 40. Brillo, J.
    et al.
    Egry, I.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Density and surface tension of liquid ternary Ni-Cu-Fe alloys2006In: Zeitschrift für Metallkunde, ISSN 0044-3093, Vol. 97, no 1, 28-34 p.Article in journal (Refereed)
    Abstract [en]

    Density and surface tension of liquid Ni-Cu-Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electromagnetic levitator, an optical densitometer, and an oscillating drop tensiometer. At temperatures above and below the liquidus point, density and surface tension are linear functions of temperature. The concentration dependence of the density is significantly influenced by a third-order (ternary) parameter in the volume, while the surface tensions can be derived from the thermodynamic potentials (E)G of the binary phases alone.

  • 41. Brillo, Juergen
    et al.
    Egry, Ivan
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Density and excess volumes of liquid copper, cobalt, iron and their binary and ternary alloys2006In: International Journal of Materials Research, ISSN 1862-5282, Vol. 97, no 11, 1526-1532 p.Article in journal (Refereed)
    Abstract [en]

    The densities of liquid copper, cobalt, and iron, their binary and ternary alloys have been measured over a temperature range including the undercooled regime. A non-contact technique was used, consisting of electromagnetic levitation combined with optical dilatometry. For all samples, the density was a linear function of temperature. The concentration dependence was studied by means of the excess volume which was negligible for Co-Fe and positive for Cu-Fe, Cu-Co, and Cu-Co-Fe. The density of the ternary alloy could be predicted from the excess volumes of the binary phases without the need to introduce any ternary interactions.

  • 42. Brooks, R.
    et al.
    Egry, I.
    Ricci, E.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Wunderlich, R.
    Thermophysical property measurements of high-temperature liquid metallic alloys - State of the art2006In: High Temperature Materials and Processes, ISSN 0334-6455, E-ISSN 2191-0324, Vol. 25, no 06-maj, 303-322 p.Article in journal (Refereed)
    Abstract [en]

    In this report, a survey is presented about state-of-the-art thermophysical property measurements of liquid metallic: alloys at high temperatures. Methods for measuring both caloric quantities, like specific heat and thermal conductivity, and thermophysical properties, like density, surface tension and viscosity, are described in detail. Measurement techniques discussed include container-based as well as containerless techniques. Strengths and potential pitfalls in applying these methods are pointed out and recommendations for best-practice are given.

  • 43.
    Cao, Weimin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Theoretical and experimental studies of surface and interfacial phenomena involving steel surfaces2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present work was initiated to investigate the surface- and interfacial phenomena for iron and slag/iron systems. The aim was to understand the mechanism of the effect of surface active elements on surface and interfacial properties. In the present work, the adsorption of oxygen and sulfur on iron surface as well as adatom surface movements were studied based on the ab initio method. BCC iron melting phenomena and sulfur diffusion in molten iron were investigated by Monte Carlo simulations. The impact of oxygen potential on interfacial mass transfer was carried out by X-ray sessile drop method.

    Firstly, the structural, electronic and magnetic properties as well as thermodynamic stability were studied by Density functional theory (DFT). The hollow site was found to be the most stable adsorption site both for oxygen and sulfur adsorbed on iron (100) surface, which is in agreement with the experiment. The relaxation geometries and difference charge density of the different adsorption systems were calculated to analyze the interaction and bonding properties between Fe and O/S. It can be found that the charge redistribution was related to the geometry relaxation. In addition, the sulfur coverage is considered from a quarter of one monolayer (1ML) to a full monolayer. It was found that the work function and its change Δφ increased with S coverage, in very good agreement with experiment. Due to a recent discussion regarding the influence of charge transfer on Δφ, it is shown in the present work that the increase in Δφ can be explained by the increasing surface dipole moment as a function of S coverage. S strongly interacts with the surface Fe layer and decreases the surface magnetic moment as the S coverage increases.

    Secondly, a two dimensional (2D) gas model based on density functional calculations combined with thermodynamics and statistical physics, was proposed to simulate the movement of the surface active elements, viz. oxygen and sulfur atoms on the Fe(100) surface. The average velocity of oxygen and sulfur atoms was found to be related to the vibration frequencies and energy barrier in the final expression developed. The calculated results were based on the density function and thermodynamics & statistical physics theories. In addition, this 2D gas model can be used to simulate and give an atomic view of the complex interfacial phenomena in the steelmaking refining process.

    A distance dependent atomistic Monte Carlo model was developed for studying the iron melting phenomenon as well as effect of sulfur on molten iron surface. The effect of boundary conditions on the melting process of an ensemble of bcc iron atoms has been investigated using a Lennard-Jones distance dependent pair potential. The stability of melting process was energetically and spatially analyzed under fixed wall and free surface conditions and the effects of short and long-range interactions were discussed. The role of boundary conditions was significantly reduced when long-range interactions were used in the simulation. This model was further developed for investigating the effect of sulfur on molten iron surface. A combination of fixed wall and free surface boundary condition was found to well-represent the molten bath configuration while considering the second nearest neighbor interactions. Calculations concerning the diffusion of sulfur on molten surface were carried out as a function of temperature and sulfur concentration. Our results show that sulfur atoms tended to diffuse away from the surface into the liquid bulk and the diffusion rate increased by increasing temperature.

    Finally, impact of oxygen potential on sulfur mass transfer at slag/metal interface, was carried out by X-ray sessile drop method. The movement of sulfur at the slag/metal interface was monitored in dynamic mode at temperature 1873 K under non-equilibrium conditions. The experiments were carried out with pure iron and CaO-SiO2-Al2O3-FeO slag (alumina saturated at the experimental temperature) contained in alumina crucibles with well-controlled partial pressures of oxygen and sulfur. As the partial pressure of oxygen increased, it was found that interfacial velocity as well as the oscillation amplitude increased. The thermo-physical and thermo-chemical properties of slag were also found to influence interfacial velocity.

     

  • 44.
    Cao, Weimin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Using and validation of the DFT method for oxygen adsorbed on the iron (100) surface2010In: Transactions of the Institution of Mining and Metallurgy Section C - Mineral Processing and Extractive Metallurgy, ISSN 0371-9553, E-ISSN 1743-2855, Vol. 119, no 2, 67-70 p.Article in journal (Refereed)
    Abstract [en]

    Electronic and structural properties of atomic oxygen adsorbed on the iron (100) surface are examined using density functional theory calculations. The oxygen adsorbed on the iron (100) surface is investigated at the three adsorption sites top, bridge and hollow sites respectively. Adsorption energy, work function and surface geometries were calculated, the hollow site was found to be the most stable adsorption site, which is in agreement with the experiment. In addition, the difference charge density of the different adsorption system was calculated to analyse the interaction and bonding properties between Fe and O. It can be found out that the charge redistribution was related to the geometry relaxation. The calculated results are compared with the experimental and other theoretical results.

  • 45.
    Cao, Weimin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Delin, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Theoretical investigation of sulfur adsorption on FE (100)2009In: TMS 2009 138TH ANNUAL MEETING & EXHIBITION - SUPPLEMENTAL PROCEEDINGS, VOL 3: GENERAL PAPER SELECTIONS, WARRENDALE: MINERALS, METALS & MATERIALS SOC , 2009, 523-528 p.Conference paper (Refereed)
    Abstract [en]

    The electronic and structural properties of atomic sulfur adsorbed on the iron surface (100) are examined by using density functional theory (DFT). The sulfur coverage is considered from a quarter of one monolayer (ML) to a full monolayer, and the adsorption energy and work function are calculated for three different adsorption sites of sulfur. Our calculated results indicate that the most likely site for S adsorption is the hollow site on Fe (100), which is agreement with experiment. In addition, at 1 ML coverage, the work function increased after the S adsorption on the Fe (100) surface, which implies that charge transfer from the surface to sulfur has taken place. The results are in agreement with previous theoretical work.

  • 46.
    Cao, Weimin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Delin, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Calculation of Oxygen and Sulfur Average Velocity on the Iron Surface: A Two-dimensional Gas Model Study2010In: Steel Research International, ISSN 1611-3683, Vol. 81, no 11, 949-952 p.Article in journal (Refereed)
    Abstract [en]

    In the present work, a two-dimensional (2D) gas model is derived and used to simulate the average velocity of individual atoms of the surface active elements oxygen and sulfur on the Fe(100) surface. The average velocity of oxygen and sulfur atoms was found to be related to the vibration frequencies and minimal energy barrier. The calculated results are based on data from density functional calculations combined with thermodynamics and statistical physics. The calculated average velocity of oxygen on the Fe (100) is lower than that of sulphur. This is because of the stronger interaction between oxygen and the first iron layer. We conclude that our simple 2D gas model may be useful for simulating and understanding the complex interfacial phenomena in the steelmaking refining process from an atomic point of view.

  • 47.
    Cao, Weimin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Delin, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Effect of electronic structure and magnetism on S adsorption on Fe (100) from first principlesIn: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215Article in journal (Other academic)
  • 48.
    Cao, Weimin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Khanna, R.
    Mahjoub, R.
    Sahajwalla, V.
    An atomistic Monte Carlo investigation on the influence of sulfur on molten iron surface at high temperatureArticle in journal (Other academic)
  • 49.
    Cao, Weimin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Muhmood, Luckman
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Sulfur Transfer at Slag/Metal Interface-Impact of Oxygen Potential2012In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 43, no 2, 363-369 p.Article in journal (Refereed)
    Abstract [en]

    In the present work, the interfacial movement resulting from sulfur mass transfer at the slag/metal interface was monitored by X-ray sessile drop method in dynamic mode at temperature 1873 K (1600 A degrees C) under nonequilibrium conditions. The experiments were carried out with pure iron and CaO-SiO2-Al2O3-FeO slag (alumina saturated at the experimental temperature) contained in alumina crucibles with well-controlled partial pressures of oxygen and sulfur. The impact of oxygen potential on the droplet oscillation as sulfur from the gas phase reaches the metal drop through the intermediate slag phase was monitored. The interfacial velocity was investigated. It was found that the increases of interfacial velocity and the maximum oscillation time were mainly attributed to the partial pressure of oxygen increases. The experiment results were explained by previous ab initio calculations. The thermo-physical and thermo-chemical properties of slag were also found to influence interfacial velocity.

  • 50.
    Chychko, Andrei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Energy and environmental optimization of some aspects of EAF practice with novel process solutions2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of the present thesis is to optimize the electric arc furnace (EAF) practice from an environmental view point. Two aspects that meet the requirements of the secondary steelmaking industries today, viz. Mo alloying with maximum retainment of the alloying element in molten steel and optimization of foaming by carbonate addition with a view to optimize the energy need of the process. Both these aspects would also have a significant impact on the process economy.

    Iron molybdate (Fe2MoO4) has been synthesized from commercial grade materials and proposed as a new potential precursor for steel alloying with Mo. The thermal stabilities of different molybdates, viz. Fe2MoO4, CaMoO4 and MgMoO4, were studied using thermogravimetry analysis (TGA). It was found that Fe2MoO4 is the most stable one and doesn’t evaporate in Ar atmosphere when heating up to 1573 K.

    The synthesis of Fe2MoO4 requires high temperature (1373 K) and long holding time (up to 16 hours). In a view of this, the possibilities for in-situ formation of Fe2MoO4 and CaMoO4 from their precursor mixtures were studied with the aid of high-temperature X-ray diffraction (XRD) and TGA analysis. Laboratory and industrial trials on steel alloying with Mo were conducted using precursor mixtures as sources of Mo. It was found that the mixture, which contains FeOx, MoO3 and C (Fe2MoO4 precursor), can provide the Mo yield up to 98 % at both the laboratory as well as industrial trials. The Mo yields even in the case of C+MoO3 and C+MoO3+CaO mixtures were around 93 % in these trials. The higher yield for the MoO3+C+FeOx mixture was attributed to the stabilization of Mo in the precursor (marked by the decrease in the Gibbs energy of Mo) and the readiness to dissolve in the steel bath.

    The heat effect of the slag foaming with carbonates addition was studied at 1623 and 1673 K with the aid of thermal analysis technique with a new crucible design. Experiments were conducted by adding limestone and dolomite pieces of defined shapes (together with iron sinkers) in molten slag and monitoring the temperature changes accompanying the decomposition of carbonates. It was found that the decomposition energies for dolomite and limestone for the studied slag composition are in the range 56-79 % of theoretical values, which is linked to the energy saving effect of slag foaming. No influence of sample shape on decomposition energy was found both for limestone and dolomite.

    The kinetics of slag foaming by limestone particles was studied at 1773 K with the aid of X-ray imaging system. A model was proposed to describe the decrease in foam height with time on the basis of CaO shell formation during decomposition reaction.

    The energy impact of limestone and raw dolomite addition was examined in a 100-ton EAF. It was found that, in the case of addition of carbonates after the scrap is completely molten; the endothermic heat effects for limestone and dolomite (2255 and 2264 kJ/kg respectively) were only 70 % from theoretical values. This is indicative of the resistance to heat transfer due to increased foaming.

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