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  • 301.
    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, p. 825-842Conference 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

  • 302.
    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, p. 45-49Article 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.

  • 303.
    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, p. 2-11Article 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

  • 304. 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)
  • 305.
    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)
  • 306.
    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, p. 937-648Conference 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

  • 307.
    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, p. 105-114Conference 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.

  • 308.
    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, p. 65-83Chapter 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.

  • 309.
    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)
  • 310.
    Björkvall, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Studie om dynamiken i en pilotrullkrets med rulltrumma2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Luossavaara-Kiirunavaara AB (LKAB) produce pellets from magnetite iron ore. Pellets are formed by balling moist iron ore concentrate to green pellets, which are then burned to pellets. The green pellets are formed in balling circuits consisting of balling drums and roller decks for screening. In 2017 a pilot scale balling circuit with a drum was completed in LKAB's agglomeration laboratory in Malmberget. The purpose of the pilot balling circuit is to predict the dynamics in a full scale balling circuit under different conditions.

    This master degree project is an initial attempt to study the response in LKAB's pilot circuit in terms of green pellet quality and dynamics in the circuit. The goal was to determine an effective way to run experiments and to investigate whether the pilot circuit can predict the dynamics of balling in large-scale circuits. Pelletizing production is within LKAB's core competence, and therefore the origin and character of the reagents, as well as the design of the pilot balling drum circuit, are confidential. Code names are used for both iron ore concentrates and reagents.

    The work began by creating a test procedure with the aim of running as many different mixtures as possible in the pilot balling circuit during a normal working day. Five different mixtures could be run. Four different additives were tested: bentonite, a flotation reagent (FLOT), an organic binder (OB) and a new development product (UTV). The first experiment in the pilot balling circuit was run with varying doses of bentonite because its impact in balling is well known at LKAB. Experiment two and three, with FLOT and OB, could be compared to previous experience from large scale test runs. The fourth and last experiment was a test of how the pilot circuit predicted the behavior of a new development product UTV. Each type of experiment was performed twice.

    The pilot balling circle predicted well both dynamics and green pellet quality in all three experiments where experience from large-scale runs was available. The new, unknown, UTV product showed improved green pellet quality, without affecting adversely on the dynamics of the circuit. UTV can therefore be an interesting option for a future large scale run at LKAB.

    The developed working schedule worked very well. A "basic analysis package" has been created to facilitate planning of future experiments in the pilot balling circuit. The number of persons needed to run the circuit depends on the number of mixtures and analyzes. For smaller experiments, at least five people is required, in addition to the leader of the experiments. More advanced experiments will demand seven people.

  • 311.
    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.

  • 312. 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, p. 105-112Article 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).

  • 313. 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.

  • 314.
    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, p. 363-368Article 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.

  • 315.
    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, p. 549-554Article 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.

  • 316.
    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.

  • 317.
    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 Alloy2018In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, no 3, p. 434-440Article 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.

  • 318.
    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.

  • 319. 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, E-ISSN 1555-6190, Vol. 113, no 9, p. 831-835Article 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.

  • 320. 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, E-ISSN 1555-6190, Vol. 114, no 3, p. 191-196Article 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.

  • 321.
    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.

  • 322.
    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, p. 125-144Article 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.

  • 323.
    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.

  • 324.
    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, p. 117-120Article 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

  • 325.
    Borasi, Luciano
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Investigation of the Effect of Different “Q&P” Parameters on the Mechanical Properties of AHSS2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the present study, the influence of the quenching temperature and partitioning conditions (temperature and time) have been investigated on a 0.6%C-1.2%Mn-1.6%Si-1.75%Cr alloy. Maps of hardness, impact toughness and amount of retained austenite have been developed for three quenching temperatures as a function of partitioning temperature and partitioning time. Results demonstrate that, in this material, the carbon depletion of the martensite and the stabilization of austenite can be achieved significantly faster at high partitioning temperatures, promoting higher retained austenite fractions, lower hardness, and maximizing the energy absorbed in a Charpy V‑Notch test. In addition, the effect of the partitioning time was also analysed, presenting different behaviour at high and low partitioning temperatures. Whereas an increment of time at high partitioning temperatures (>400 ºC) leads to an austenite consumption, at low partitioning temperatures it is effective to retain a higher amount of austenite. 

    Furthermore, tensile properties are shown to be better than in conventional alloys utilized in industry. Whilst, for example, the AISI 52100 alloy achieves 2 GPa of tensile strength and 1‑2% of fracture deformation, in the present study the notable combination of 2.5 GPa of tensile strength and 5.7 % of fracture deformation was achieved in samples quenched until room temperature. Untempered martensite transformed during final cooling in samples quenched until higher temperatures was shown to be detrimental for tensile properties.

    A comparison between the Q&P process and the austempering process on this alloy has been carried out. Results reveal that the quenching and partitioning heat treatment is presented as a promising alternative to reach higher hardness (>700 HV) and similar specific wear rates in dry conditions performing a shorter heat treatment.   

    Finally, a complementary study about the effect of micro-segregation on the Q&P process and an optimization method to minimize the inhomogeneity of the structure by a correct selection of the quenching temperature were established.

  • 326.
    Borgenstam, Annika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Edmonds, D.
    Hillert, Mats
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Eutectoids with cementite as the major constituent in Fe-C-M alloys2016In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 103, p. 280-289Article in journal (Refereed)
    Abstract [en]

    The addition of a third element to hypereutectoid Fe-C alloys may cause inclusions of a minor constituent in the precipitate of cementite from austenite even if the initial austenite is supersaturated only with cementite. Cementite will often become the major constituent of this kind of microstructure. For Fe-C-Cu alloys this has been explained as the result of precipitation from supersaturated cementite. An alternative mechanism could be that the mixture of cementite and a minor constituent forms by simultaneous and cooperative growth of the two phases, i.e., by a reaction that may be regarded as eutectoid. This mechanism has already been applied to explain the occurrence of eutectoid colonies with cementite as the major constituent and a minor constituent for which there was no supersaturation initially. This phenomenon has been observed in hypereutectoid ternary Fe-C alloys with Al, Mn or Si. The necessary requirements on the ordinary isothermal phase diagram are now examined with a graphical method based on the slopes of tie-lines. It predicts the phenomenon in all cases where it has been observed, including Fe-C-Cu and not in the Fe-C-Ni and Fe-C-Cr systems where it has not been observed. The requirements become more evident when the calculated phase equilibria are plotted as an isothermal phase diagram with the alloy content as a function of the carbon activity instead of carbon content. Finally, a comparison is made with bainite in Fe-C alloys where ferrite is the major and cementite the minor constituent. The same two explanations have been proposed for that case.

  • 327.
    Borgenstam, Annika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Hillert, Mats
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Kinetics of bainite transformation in steels2012In: Phase Transformations in Steels, Elsevier, 2012, Vol. 1, p. 468-501Chapter in book (Refereed)
    Abstract [en]

    The main kinetic features of the formation of bainite are discussed, firstly in relation to two incompatible hypotheses for the growth mechanism of bainitic ferrite. One is based on diffusionless growth of bainitic ferrite but diffusional growth of Widmanstätten ferrite. The other is based on the assumption that there is only one kind of acicular ferrite and it grows under simultaneous diffusion of carbon into the interior of the parent austenite. The kinetics of the first stage of bainite formation, the growth of acicular ferrite, is treated in detail because it has been subject to the more intensive research. The kinetics of the reactions by which cementite forms and the subsequent reactions, by which the transformation to bainite is completed, have been subject to less research.

  • 328.
    Borgh, Ida
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Aspects of Structural Evolution in Cemented Carbide – Carbide Size, Shape and Stability2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cemented carbide is a composite material used in applications like cutting tools and rock drilling inserts. The material commonly consists of WC grains embedded in a Co-rich binder phase and the material properties strongly depend on the WC grain size. Hence, to tailor the properties it is important to understand the fundamental mechanisms of grain coarsening. At the same time, the higher demands on material properties today also require new solutions. In the present work, some different aspects of structural evolutions in cemented carbides have been investigated.

    The first part of the work considers WC grain coarsening by means of size, size distribution and shape. Some efforts of the work have been to evaluate the effects of C-activity and initial WC powder size and distribution on the coarsening behavior in the material using different characterization techniques, e.g. scanning electron microscopy, and electron backscattered diffraction. Additionally, two earlier developed models are used and evaluated with the experimental data. The results indicate that the C-activity will affect size, size distribution and shape of the WC grains. It was also observed that the initial WC powder size and size distribution will have a large influence on the WC grain coarsening. The statistical shape was found to fit a spherical approximation but for individual grains both faceted and non-faceted shapes was observed. Steps and planar defects were observed supporting that the nucleation of new atomic layers is the main rate limiting mechanism for grain coarsening.

    The second part of this work considers the carbide phase stability in the (Ti,Zr)C system. The phase stability was investigated after synthesizing and aging a mixed (Ti,Zr)C using X-ray diffraction and different types of electron microscopy techniques. A decomposed lamellar structure was found with a composition variation of approximately 10% between the 50-75 nm thick lamellas. The experimental investigations were supported by computational work and the results were in good agreement. Additionally, two cemented carbide related systems were studied. A miscibility gap was found in the two investigated systems, (Ti,Zr,W)(C,N)-Co or Fe-graphite, and the effect of N2-gas pressure was investigated suggesting a critical N2-gas pressure below 0.1 bar.

  • 329.
    Borgh, Ida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Blomqvist, Andreas
    Ågren, John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Odqvist, Joakim
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Synthesis and phase separation of (Ti,Zr)C2014In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 66, p. 209-218Article in journal (Refereed)
    Abstract [en]

    Synthesis and phase separation of (Ti,Zr)C were investigated in the present work. The (Ti,Zr)C phase was synthesized at 2200 C and subsequently aged at 1300 C for different times. The microstructure was investigated using X-ray diffraction and electron microscopy, and supplemented by first-principles calculations. The (Ti,Zr)C phase separates into a lamellar nanostructure with alternating Ti- and Zr-rich face-centered cubic domains as well as non-stoichiometric TiC and ZrC. The lamellar structure is a consequence of phase separation within the miscibility gap that is directionally constrained by high coherency stresses, as indicated by the first-principles calculations. Moreover, the increased hardness due to the phase separation suggests that the mixed carbide could be used as a strengthening constituent in, for example, cemented carbides.

  • 330.
    Borgh, Ida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Borgenstam, Annika
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Ågren, John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Odqvist, Joakim
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Effect of carbon activity and powder particle size on WC grain coarsening during sintering of cemented carbides2014In: International journal of refractory metals & hard materials, ISSN 0958-0611, E-ISSN 2213-3917, Vol. 42, p. 30-35Article in journal (Refereed)
    Abstract [en]

    Liquid-phase sintering is an important step in the production of cemented carbides. During sintering, the average WC grain size increases, leading to a coarser structure, which affects the performance of the final product. The coarsening occurs by dissolution of small grains and growth of large grains. In the present work, the effect of high carbon activity during sintering on the WC grain coarsening has been evaluated using electron backscattered diffraction (EBSD) and the results have been compared with a previous work where sintering was performed at a lower carbon activity. A more homogeneous grain size distribution was observed in alloys sintered at a high carbon activity. In addition, the effect of the initial powder particle size distribution was investigated. It was found that the coarsening rate of a WC powder with an initial small average grain size is significantly higher as compared to the coarsening rate for a powder with a larger initial average grain size. The results obtained emphasize the importance of considering the complete particle size distribution in order to predict coarsening.

  • 331.
    Borgh, Ida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Odqvist, Joakim
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Borgenstam, Annika
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Ågren, John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Gholinia, Ali
    Winiarski, Bartlomiej
    Withers, Philip J.
    Thompson, George E.
    Mingard, Ken
    Gee, Mark G.
    On the three-dimensional structure of WC grains in cemented carbides2013In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 61, no 13, p. 4726-4733Article in journal (Refereed)
    Abstract [en]

    In the present work, the size distribution and shape of WC grains in cemented carbides (WC-Co), with different Co contents, have been investigated in three dimensions. Direct three-dimensional (3-D) measurements, using focused ion beam serial sectioning and electron backscattered diffraction (EBSD), were performed and a 3-D microstructure was reconstructed. These measurements were supplemented by two-dimensional (2-D) EBSD and scanning electron microscopy on extracted WC grains. The data from 2-D EBSD collected on planar sections were transformed to three dimensions using a recently developed statistical method based on an iterative inverse Saltykov procedure. This stereological analysis revealed that the assumed spherical shape of WC grains during the Saltykov method is reasonable and the estimated 3-D size distribution is qualitatively in good agreement with the actual distribution measured from 3-D EBSD. Although the spherical assumption is generally fair, the WC grains have both faceted and rounded surfaces. This is a consequence of the relatively low amount of liquid phase during sintering, which makes impingements significant. Furthermore, the observed terraced surface structure of some WC grains suggests that 2-D nucleation is the chief coarsening mechanism to consider.

  • 332.
    Borgh, Ida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Persson, Tomas
    Norgren, Susanne
    Borgenstam, Annika
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Ågren, John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Odqvist, Joakim
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Microstructure, grain size distribution and grain shape in WC-Co alloys sintered at different carbon activities2014In: International Journal of Refractory Metals and Hard Materials, ISSN 0958-0611, Vol. 43, p. 205-211Article in journal (Refereed)
    Abstract [en]

    The properties of cemented carbides strongly depend on the WC grain size and it is thus crucial to control coarsening of WC during processing. The aim of this work was to study the effect of sintering at different carbon activities on the final microstructure, as well as the coarsening behavior of the WC grains, including the size distribution and the shape of WC grains. These aspects were investigated for five WC-Co alloys sintered at 1410 C for 1 h at different carbon activities in the liquid, in the range from the graphite equilibrium (carbon activity of 1) to the eta (M6C) phase equilibrium (carbon activity of 0.33). The grain size distribution was experimentally evaluated for the different alloys using EBSD (electron backscatter diffraction). In addition, the shape of the WC grains was evaluated for the different alloys. It was found that the average WC grain size increased and the grain size distribution became slightly wider with increasing carbon activity. Comparing the two three-phase (WC-Co-eta and WC-Co-graphite) alloys a shape change of the WC grains was observed with larger grains having more planar surfaces and more triangular shape for the WC-Co-graphite alloy. It was indicated that in alloys with a relatively low volume fraction of the binder phase the WC grain shape is significantly affected by impingements. Moreover, after 1 h of sintering the WC grains are at a non-equilibrium state with regards to grain morphology.

  • 333.
    Borgh, Ida
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Norgren, Susanne
    Borgenstam, Annika
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Ågren, John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Influence of nitrogen Gas pressure on the miscibility Gap in the Ti-Zr carbonitride system2012In: International Journal of Refractory Metals and Hard Materials, ISSN 0263-4368, Vol. 32, p. 11-15Article in journal (Refereed)
    Abstract [en]

    The microstructure of cemented carbides with a gradient structure at the surface consists of WC, cubic carbonitrides and a binder phase. The carbonitrides can, for example, consist of Ti(C,N)-Zr(C,N) where it is reasonable to believe that there is a miscibility gap with Ti-rich and Zr-rich carbonitrides. In the present work, the effect of the N-2-gas pressure on the equilibrium composition of the miscibility gap in the (Ti,Zr)(C,N) system has been investigated. In the study, the carbonitride system is in equilibrium with: WC, liquid binder, graphite and, N-2-gas of different pressures. Both Fe and Co are used as binder phase to study the effect of the binder phase. The results verify that there is a miscibility gap in the carbonitride system and that the region of the miscibility gap will change when N is introduced. There is a critical N-2-gas pressure lower than 0.1 bar and above that pressure the compositions of the carbonitride are rather constant as a result of the formation of a surface rim.

  • 334.
    Borkar, Hemant
    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.
    Microstructure analysis of Al-Si-Cu alloys prepared by gradient solidification technique2015In: International Journal of Modern Physics B, ISSN 0217-9792, Vol. 29, no 10-11, article id 1540015Article in journal (Refereed)
    Abstract [en]

    Al–Si–Cu alloys were cast with the unique gradient solidification technique to producealloys with two cooling rates corresponding to secondary dendrite arm spacing (SDAS) of ∼9 and ∼27 μm covering the microstructural fineness of common die cast components.The microstructure was studied with optical microscopy and scanning electronmicroscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electronbackscattered diffraction (EBSD). The alloy with higher cooling rate, lower SDAS, hasa more homogeneous microstructure with well distributed network of eutectic and intermetallicphases. The results indicate the presence of Al–Fe–Si phases, Al–Cu phases andeutectic Si particles but their type, distribution and amount varies in the two alloys withdifferent SDAS. EBSD analysis was also performed to study the crystallographic orientationrelationships in the microstructure. One of the major highlights of this study is theunderstanding of the eutectic formation mechanism achieved by studying the orientationrelationships of the aluminum in the eutectic to the surrounding primary aluminumdendrites.

  • 335.
    Brandberg Hurtig, Jenny
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Hydrogen pick-up after vacuum degassing2015In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 42, no 1, p. 49-54Article in journal (Refereed)
    Abstract [en]

    The present work aimed at determining the major source for hydrogen pick-up of the steel after vacuum degassing but before casting. Samples of slag and metal were taken at different stages during ladle treatment at SSAB. Hydrogen increase after vacuum treatment was observed. Moisture contents of the industrial slags were analysed and their water capacities were calculated. It could be seen that the hydrogen increase was correlated to the amount of moisture in the slag and the water capacity. The study showed that the slag containing most water was also the heat having the largest hydrogen increase. The slag with most water had the highest water capacity. It could be concluded that the major source for hydrogen increase after degassing was due to the slag-metal reaction.

  • 336.
    Brandtberg, Sebastian
    Linköping University, Department of Management and Engineering, Engineering Materials.
    Microstructural inhomogeneity and anisotropicproperties in IN-718 structures fabricated byElectron Beam Melting: Mikrostrukturell inhomogenitet och anisotropa egenskaper i strukturerav IN-718 tillverkade genom Electron Beam Melting2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive Manufacturing, or 3D printing, provides an opportunity to manufacture advanced 3D geometrieswith little material waste and reduced need for tooling compared to conventional methods. There are,however, challenges remaining regarding anisotropy in the mechanical properties of built components.

    The aim of this project is to investigate the anisotropy of additive manufactured material and the effect ofdifferent build directions. The material used is Inconel 718, which was manufactured by Electron BeamMelting as vertical and horizontal rods. The tests performed are microstructural investigations about thegrains, precipitates and porosities, but also include hardness testing and tensile testing. The material istested in its as-built state.

    The results show that the material consist of an anisotropic microstructure with elongated grains in thebuild direction. The build height has a bigger influence on the properties of the material than the builddirection for the specimens. The top pieces are consistently different from the others and are the leasthomogeneous. The microstructure consists of large quantities of delta-phase, and solidification pores arefound throughout the material. The hardness of the material differs from 324 HV to 408 HV depending onthe part of the build. The tensile testing shows that the vertically built specimens have a higher yieldstrength and ultimate tensile strength while the horizontally built specimens have a greater ductility.

  • 337. Breidi, A.
    et al.
    Fries, S. G.
    Palumbo, M.
    Ruban, Andrei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Materials Center Leoben Forschung GmbH, Leoben, Austria.
    First-principles modeling of energetic and mechanical properties of Ni-Cr, Ni-Re and Cr-Re random alloys2016In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 117, p. 45-53Article in journal (Refereed)
    Abstract [en]

    We apply the exact-muffin-tin-orbitals (EMTO) method to investigate structural properties, formation enthalpies, mechanical stability and polycrystalline moduli in Ni-Re, Ni-Cr and Cr-Re disordered fcc, bcc and hcp phases. Substitutional disorder is treated by using the coherent potential approximation (CPA). We predict the alloy lattice parameters in good agreement with the experiment. We find a continuous softening, as a function of Cr composition, of the tetragonal shear modulus C' in fcc Ni-Cr phase indicating mechanical instability in Cr-rich Ni-Cr alloys. On the other hand, we show that the mechanical stability of fcc Ni-Re alloys persists through the whole composition range. We observe an intriguing behaviour of the Young's modulus vs. the intrinsic ductility curve in Ni-rich Ni-Re fcc phase.

  • 338. Brennhaugen, David D. E.
    et al.
    Mao, Huahai
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Louzguine-Luzgin, Dmitri V.
    Arnberg, Lars
    Aune, Ragnhild E.
    Predictive modeling of glass forming ability in the Fe-Nb-B system using the CALPHAD approach2017In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 707, p. 120-125Article in journal (Refereed)
    Abstract [en]

    Accurate values needed for the most commonly used indicators of good Glass Forming Ability (GFA) in alloys, i.e. the liquidus (T-l), crystallization (T-x) and glass transition (T-g) temperatures, are only available after successful production of the metallic glass of interest. This has traditionally made discovery of new metallic glasses an expensive and tedious procedure, based on trial-and-error methodology. The present study aims at testing the CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) approach for predicting GFA in the Fe-Nb-B system by the use of the Thermo-Calc software and the thermodynamic database TCFE7. The melting temperatures and phase stabilities were calculated and combined with data for an atomic size mismatch factor, lambda, in order to identify and map potential high-GFA regions. Selected compositions in the identified regions were later produced by suction casting and melt spinning, and the potential success verified using X-Ray Diffraction (XRD). Differential Scanning Calorimetry (DSC) was also used to compare thermodynamic calculations for the model predictions, and evaluate standard GFA indicators. The model is found to fit well with literature data, as well as predict new bulk glassy compositions at and around Fe70.5Nb7B22.5. These results show promise in further predictive use of the model.

  • 339.
    Briland, Ida
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Reduction kinetics of regenerated iron oxide from scale with hydrogen: Reduction kinetics related to the Flash Ironmaking technology2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The possibility and the rate of reduction of regenerated iron oxide from scale related to the Flash ironmaking (FIM) technology have been studied. There are promising environmental benefits for reducing the iron oxide with FIM technology as an alternative to the BF process. There is little information about the reduction of fine powder with FIM as the technology is under development. The prospect of reducing recovered iron oxide from scale by hydrogen in FIM is attractive, for the reason that scale is a sizeable by-product of 33 million tons per year produced worldwide. The Reduction kinetics of regenerated iron oxide from scale with a particle size of 0.56 µm with hydrogen was evaluated. The material was reduced in an LFR within the temperature interval of 600-900 °C, partial pressure of H2 within 0.1-0.6 atm and residence time within 1.5-7.5 seconds. The chemical composition of the samples were analyzed with ICP-OES. Over 90 % reduction degree was achieved with a metallization degree of 94 %. It was evident that temperature, partial pressure of H2 and the residence time affected the reduction rate. The rate of reduction could be described with a nucleation and growth rate equation with an Avrami parameter of 0.5, the partial pressure dependence of 1.4 and the activation energy of 137 kJ/mol. The reduction degree met sufficient amount to determine that the FIM technology can be a reduction process for scale in the future.

  • 340.
    Broberg, Gunnar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ahlbäck, Anton
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Wirhed, Oliver
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Study of an innovative ladle shroud to decrease slag carry over due to vortex formation2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 341.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Surface crack detection in welds using thermography2013In: NDT & E international, ISSN 0963-8695, E-ISSN 1879-1174, Vol. 57, p. 69-73Article in journal (Refereed)
    Abstract [en]

    Thermography is today used within non-destructive testing for detecting several different types of defects. The possibility for using thermography for detecting surface cracks in welded metal plates has here been investigated. During testing the weld is illuminated using a high power infrared light source. Due to surface cracks acting like black bodies, they will absorb more energy than the surrounding metal and can be identified as a warmer area when imaged using an infrared camera. Notches as well as real longitudinal cold cracks in a weld are investigated using the presented method. The results show that thermography is promising as a method for detection cracks open to the surface.

  • 342.
    Broberg, Patrik
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Production System.
    Analysis algorithm for surface crack detection by thermography with UV light excitation2016In: Quantitative InfraRed Thermography 2016: Abstracts / [ed] Kaczmarek, M. & Bujnowski, A., Gdańsk, Poland: Publishing Gdańsk University of Technology , 2016, p. 144-149Conference paper (Refereed)
    Abstract [en]

    Surface crack defects can be detected by IR thermograpgy due to the high absorption of energy within the crack cavity. It is often difficult to detect the defect in the raw data, since the signal easily drowns in the background. It is therefore important to have good analysis algorithms that can reduce the background and enhance the defect. Here an analysis algorithm is presented which significantly increases the signal to noise ratio of the defects and reduces the image sequence from the camera to one image.

  • 343.
    Brusewitz Lindahl, Bonnie
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Liu, Xuan L.
    Liu, Zi-Kui
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    A thermodynamic re-assessment of Al-V toward an assessment of the ternary Al-Ti-V system2015In: Calphad, ISSN 0364-5916, E-ISSN 1873-2984, Vol. 51, p. 75-88Article in journal (Refereed)
    Abstract [en]

    Titanium alloys are highly sought after due to their excellent mechanical properties. One of the most commonly used Ti alloys is Ti-6Al-4V, which contains 6% Al and 4% V by weight. Despite the popularity of this alloy, no thermodynamic description of the ternary Al-Ti-V system has been published in the open literature. In this work an assessment procedure of the ternary Al-Ti-V system was initiated based on the binary descriptions by Witusiewitcz et al. (J. Alloys Compds. 465 (2008) 64-77 [1]) for (Al-Ti), Gong et al. (Int. J. Mater. Res. 95 (2004) 978-986 [2]) for (Al-V) and Saunders (COST 507, 2 (1998) 297-298 [3]) for (Ti-V). When combining the three binary systems and looking at the extrapolated ternary isothermal sections, it was found that there was a very large miscibility gap in the bcc phase. The origin of this miscibility gap was mainly the Al-V system and therefore it was decided to reassess this system. The Al-V system was reassessed according to available experimental data along with the enthalpies of formation of all compounds as well as the enthalpies of mixing for all terminal phases obtained by first-principles calculations based on the density functional theory. For the Al8V5 phase there are two different sets of data for the enthalpies of formation. These two sets are investigated in this work and it is found that the set not used by Gong et al. in their assessment of the Al-V binary system gives better extrapolations. The final description produced improved extrapolated ternary isothermal sections.

  • 344.
    Brämming, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    An Operational View on Foaming and Slopping Control in Top-blown BOS Vessels2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Slag formation plays a decisive role in all steelmaking processes. In top-blowing Basic Oxygen Steelmaking (BOS) i.e., in the LD process, an emulsion consisting of liquid slag, dispersed metal droplets, undissolved particles and solid precipitates will, together with process gases, form an expanding foam. Extensive research has defined the parameters that govern the foaming characteristics of BOS slag-metal emulsions. It is a well-known fact that certain process conditions in the Basic Oxygen Furnace (BOF) will lead to excessive foam growth, forcing foam out through the vessel opening (mouth). This process event is commonly known as slopping. Slopping results in loss of valuable metal, equipment damage, lost production time, unsafe work environment and pollution. A literature survey covering the slopping phenomena has been carried out, as well as a deeper investigation into the causes behind slopping on the BOF type LD/LBE at SSAB Europe, Luleå, equipped with an automatic system for slopping registration using image analysis Good slag formation and foam-growth control in order to avoid slopping is primarily accomplished by taking preventive “static” measures. The most common pre-blowing operational conditions favouring foam growth and, hence, slopping were found to be linked to oxygen lance positioning, hot metal Si and Mn contents, scrap quality and large additions of iron oxide bearing materials. Improved slopping control may be achieved by developing oxygen lance control schemes with automatic adjustment of the distance between the lance tip and the metal bath (i.e., the lance gap) according to scrap quality and ore additions. If “static” measures cannot be effectuated, a set of in-blow slopping preventive measures is needed. For such “dynamic” measures to be effective, it is necessary to have a system for slopping prediction. Trials with vessel vibration measurements for indirect foam height estimation in industrial scale BOFs, type LD/LBE, have been carried out. FFT spectrum analysis was applied in order to find the frequency band with best correlation to an estimated foam height. The results show that there is a correlation between vessel vibration and foam height which can be used for dynamic foam level and slopping control, and this during the entire blow. The vessel vibration results have been tested against what is the perhaps most commonly implemented technique for dynamic foam height estimation and slopping control, the audiometric system. Parallel vibration and audio measurements have been carried out on 130-tonne as well as on 300-tonne BOFs. The results show that during stable process conditions there is good agreement between the two methods in regard to foam height estimation and that combining the two methods will provide a powerful slopping prediction and control system. A feasibility study has been carried out with the aim to describe the possibilities and limitations of multivariate data analysis, including batch analysis, for dynamic BOS process control, mainly in regard to slopping prevention. Two principal modelling approaches were tested.A central part of this PhD work is the performed emulsion characterisation and the subsequent investigation into the influence of emulsion mineralogy and morphology on slopping in the LD process. The results are based on the study of emulsion samples from trial heats conducted in a 6-tonne pilot plant LD vessel. The main emulsion slag phase mineral species identified were di-calcium silicate, monoxides (mainly FeO, MnO and MgO), calcium ferrites and late-appearing tri-calcium silicate. The study also show that the iron oxidation state has a large influence on the emulsion mineralogy and morphology, as a higher Fe3+ content facilitates the precipitation of calcium ferrites, raising the emulsion apparent viscosity and, hence, the foam index. The same effect is caused by higher MgO contents (i.e., at saturation), resulting in the precipitation of monoxide phase. However, large volume fractions of emulsion precipitates will not always lead to slopping in the LD process. A second “requirement” for excessive foam growth is a simultaneously high gas generation rate. Vice versa; an LD heat may very well slop at low volume fractions of 2ndphase particles in the emulsion if the gas generation rate is sufficiently high. It is an indisputable fact that excessive foaming is one of the main features of the LD process, due to the practice of top-lance oxygen blowing, creating a highly oxidised slag, and heavy batch additions of basic slag formers, causing an initial formation of large quantities of precipitates. Therefore, preventing slopping is primarily a matter of tight process control, most importantly, control of the oxygen lance gap in order to reach a state of sufficiently high liquid MeO phase to minimise the emulsion apparent viscosity, but low enough to avoid over-oxidising and a high gas generation rate.

  • 345.
    Brämming, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Avoiding slopping in top-blown BOS vessels2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Slag formation plays a decisive role in all steelmaking processes. In top-blowing Basic Oxygen Steelmaking (BOS), i.e. in the LD process, an emulsion consisting of liquid slag, dispersed metal droplets and solid particles will, together with process gases, form an expanding foam. Extensive research has defined the parameters that govern the foaming characteristics of BOS slag emulsions. It is a well known fact that certain process conditions will lead to an excessive foam growth, forcing the foam out through the vessel opening (mouth). This process event is commonly known as slopping. Slopping results in loss of valuable metal, equipment damage, lost production time and pollution. A literature survey covering the slopping phenomena has been carried out, as well as a deeper investigation into the causes behind slopping on the BOS vessels, type LD/LBE, at SSAB EMEA Metallurgy Luleå, equipped with an automatic system for slopping registration using image analysis. Good slag formation and foam-growth control in order to avoid slopping is primarily accomplished by taking preventive "static" measures. Improved slopping control has been achieved by developing a new oxygen lance control scheme, featuring adjustment of the distance between the lance tip and the metal bath according to scrap quality and ore additions. If "static" measures cannot be effectuated, in-blow control measures are needed. For such "dynamic" measures to be effective, it is necessary to have a system for slopping prediction. In the early-1980s a system for foam level and slopping control, based on BOS vessel vibration, was temporarily installed and tested on one of the vessels in Luleå. Based on the experiences from these tests it was decided to re-investigate the vessel vibration measurement technique. Trials on industrial scale BOS vessels of type LD/LBE have been carried out. FFT spectrum analysis has been applied in order to find the frequency band with best correlation to an estimated foam height. The results show that there is a correlation between vessel vibration and foam height which can be used for dynamic foam level and slopping control. The vessel vibration results have been tested against perhaps the most common implemented technique for dynamic foam height estimation and slopping control, the audiometric system. Parallel vibration and audio measurements have been carried out on a 130-tonne as well as on 300-tonne BOS vessels. The results show that during stable process conditions there is good agreement between the two methods with regard to foam height estimation and that combining the two methods will provide a powerful slopping prediction and control system.

  • 346.
    Brämming, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Avoiding sloppy BOS process behavior2010In: Proceedings of the Iron & Steel Technology Conference: May 3 - 6, 2010, Pittsburgh, Pennsylvania, U.S.A / [ed] Ronald E. Ashburn, Warrendale, Pa: Association for Iron & Steel Technology , 2010, p. 1037-1047Conference paper (Refereed)
    Abstract [en]

    Extreme BOS processing conditions may sometimes lead to excessive slag foaming and slopping, resulting in considerable amounts of metallic losses, equipment damage and un-necessary production disturbances. Control of slag formation without slopping is primarily accomplished by taking preventive measures. If static control measures are not effective then in-blow control measures are required and for these to be successful, it is necessary to employ a method for predicting slopping events. Such a system, utilizing BOS vessel vibration measurement, is presently being re-introduced at SSAB's BOS plant in Luleå, Sweden. A deep study into the causes of slopping has been carried out for a 114 tonne LD/LBE vessel, equipped with an automatic system for slopping registration using image analysis. Improved slopping control was achieved by developing a novel lance control scheme, with a new approach to the adjustment of lance position according to scrap quality and ore additions

  • 347. Brämming, Mats
    et al.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Avoiding sloppy BOS process behavior2010In: Iron & Steel Technology, ISSN 1547-0423, Vol. 7, no 11, p. 66-75Article in journal (Refereed)
    Abstract [en]

    SSAB EMEA's BOS plant in Luleå, Sweden installed a new system in April 2009 for slopping registration in order to raise the level of metallurgical process control. An excellent and well-documented tool for investigating the causes behind slopping is image analysis. The system scans each received camera image (25 per second) and counts the number of light pixels above a set threshold within a designated area of the camera frame. The scanning output is a 1-second number called the slopping value (in %). A 2-second average value is stored for a period of up to 14 days. Data for a complete year of production on BOS vessel LDI (over 11,000 heats) were collected and scrutinized. The multivariate analysis showed that main static causes behind slopping are the large additions of scrap of lower quality, mainly recycled large-size skulls and pig iron, but also purchased scrap, high ratio of dolomitic fluxes and high Si content in hot metal in the case of HS blowing regime.

  • 348.
    Brämming, Mats
    et al.
    Department of Process Integration, Swerea MEFOS AB.
    Björkman, Bo
    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.
    BOF Process Control and Slopping Prediction Based on Multivariate Data Analysis2016In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, no 3, p. 301-310Article in journal (Refereed)
    Abstract [en]

    A complex industrial batch processes such as the top-blown BOF steelmaking process, it is a complicated task to monitor and act on the progress of several important control parameters in order to avoid an undesired process event such as “slopping” and to secure a successful batch completion such as a sufficiently low steel phosphorous content. It would, therefore, be of much help to have an automated tool, which simultaneously can interpret a large number of process variables, with the function to warn of any imminent deviation from the normal batch evolution and to predict the batch end result. One way to compute, interpret, and visualize this “batch evolution” is to apply multivariate data analysis (MVDA). At SSAB Europe's steel plant in Luleå, new BOF process control devices are installed with the purpose to investigate the possibility for developing a dynamic system for slopping prediction. A main feature of this system is steelmaking vessel vibration measurements and audiometry to estimate foam height. This paper describes and discusses the usefulness of the MVDA approach for static and dynamic slopping prediction, as well as for end-of-blow phosphorous content prediction.

  • 349.
    Brämming, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Samuelsson, Caisa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    BOF slopping prediction based on multivariate data analysis2012In: Scanmet IV: 4th International Conference on Process Development in Iron and Steelmaking, Luleå: MEFOS , 2012, Vol. 1, p. 461-470Conference paper (Refereed)
  • 350.
    Brämming, Mats
    et al.
    SSAB EMEA, Luleå.
    Millman, Stuart
    Tata Steel Research, D & T, Teesside Technology Centre, Middlesbrough.
    Overbosch, Aart
    Tata Steel Research, D & T, IJmuiden Technology Centre.
    Kapilashrami, Abha
    Tata Steel Research, D & T, IJmuiden Technology Centre.
    Malmberg, Donald
    Swerea MEFOS AB.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    BOS vessel vibration measurement for foam level detection2011In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 51, no 1, p. 71-79Article in journal (Refereed)
    Abstract [en]

    In the BOS process liquid slag together with dispersed metal droplets, solid particles and process gases form an expanding foam. Certain process conditions may lead to excessive foam growth, forcing foam out through the vessel mouth, an event commonly known as 'slopping'. Slopping results in loss of valuable metal, equipment damage and lost production time. In the early 1980s a system for foam level and slopping control was installed at SSAB's steel plant in Lulea, a system based on the correlation between BOS vessel vibration in a narrow low frequency band and foam development. The technique, in this case with an accelerometer mounted on the trunnion bearing housing, soon showed its usefulness, for example when adapting existing lance patterns to a change in oxygen lance design from a 3-hole to a 4-hole nozzle. Estimating the actual foam height in the BOS vessel was of great importance in the recently completed RFCS funded research project "IMPHOS" (Improving Phosphorus Refining). Based on the earlier positive experiences, it was decided to further develop the vessel vibration measurement technique. Trials on an industrial size BOS vessel type LD/LBE have been carried out, this time with a tri-axial accelerometer mounted on the vessel trunnion. FFT spectrum analysis has been used in order to find the frequency band with best correlation to the foam level development. The results show that there is a correlation between vessel vibration and foam height that can be used for dynamic foam level and slopping control

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