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  • 201.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Andersson, Mats
    SSAB Europe, Luleå.
    Mousa, Elsayed
    Swerim AB, Luleå, Sweden; Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Kullerstedt, Adeline
    Swerim AB, Luleå, Sweden.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerim AB, Luleå, Sweden.
    The Potential of Recycling the High-Zinc Fraction of Upgraded BF Sludge to the Desulfurization Plant and Basic Oxygen Furnace2018Inngår i: Metals, ISSN 2075-4701, Vol. 8, nr 12, artikkel-id 1057Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In ore-based steelmaking, blast furnace (BF) dust is generally recycled to the BF via the sinter or cold-bonded briquettes and injection. In order to recycle the BF sludge to the BF, the sludge has to be upgraded, removing zinc. The literature reports cases of recycling the low-zinc fraction of upgraded BF sludge to the BF. However, research towards recycling of the high-zinc fraction of BF sludge within the ore-based steel plant is limited. In the present paper, the high-zinc fraction of tornado-treated BF sludge was incorporated in self-reducing cold-bonded briquettes and pellets. Each type of agglomerate was individually subjected to technical-scale smelting reduction experiments aiming to study the feasibility of recycling in-plant residues to the hot metal (HM) desulfurization (deS) plant. The endothermic reactions within the briquettes decreased the heating and reduction rate leaving the briquettes unreduced and unmelted. The pellets were completely reduced within eight minutes of contact with HM but still showed melt-in problems. Cold-bonded briquettes, without BF sludge, were charged in industrial-scale trials to study the recycling potential to the HM deS plant and basic oxygen furnace (BOF). The trials illustrated a potential for the complete recycling of the high-zinc fraction of BF sludge. However, further studies were identified to be required to verify these results.

    Fulltekst (pdf)
    fulltext
  • 202.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Gullberg, Amanda
    Swerea MEFOS, Luleå, Sweden.
    Kullerstedt, Adeline
    Swerea MEFOS, Luleå, Sweden.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerea MEFOS, Luleå, Sweden.
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Upgrading of Blast Furnace Sludge and Recycling of the Low-Zinc Fraction via Cold-bonded Briquettes2019Inngår i: Journal of Sustainable Metallurgy, ISSN 2199-3823, nr 3, s. 350-361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Depending on the operation of the blast furnace (BF), the main outlet of zinc from the furnace is more or less via the BF dust and sludge. As the dust is recycled to the BF, the sludge has to be de-zinced prior to recycling to prevent the accumulation of zinc in the BF. De-zincing and recycling of the low-zinc fraction via sinter have been reported. However, no research con-cerning recycling of upgraded BF sludge via cold-bonded briquettes has been performed. In the present study, a fine-grained BF sludge with low zinc content, generated by a BF operating on a ferrous burden of 100% pellets, was upgraded using the tornado process. The process simultaneously dried and separated the BF sludge into a high-zinc and a low-zinc fraction. The feasibility of recycling the low-zinc fraction to the BF using cold-bonded briquettes was studied on a laboratory-scale BF shaft simulator. On comparison with a reference briquette, the experiments indicated that 10 wt% of the upgraded BF sludge can be added to the briquette without negatively affecting the reducibility. Higher additions were found to render the briquette less reduced compared to the reference under test conditions corresponding to the central part of the BF. The strength of the briquettes was not compromised with the addition of the upgraded BF sludge, and a decision to study the briquettes in the LKAB experimental blast furnace was made in order to evaluate the behavior under actual BF conditions.

  • 203.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Gullberg, Amanda
    Swerea MEFOS, Luleå, Sweden.
    Kullerstedt, Adeline
    Swerea MEFOS, Luleå, Sweden.
    Sandberg, Erik
    Swerea MEFOS, Luleå, Sweden.
    Andersson, Mats
    SSAB Europe, Luleå, Sweden.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerea MEFOS, Luleå, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    A Holistic and Experimentally-Based View on Recycling of Off-Gas Dust within the Integrated Steel Plant2018Inngår i: Metals, ISSN 2075-4701, Vol. 8, nr 10, artikkel-id 760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ore-based ironmaking generates a variety of residues, including slags and fines such as dust and sludges. Recycling of these residues within the integrated steel plant or in other applications is essential from a raw-material efficiency perspective. The main recycling route of off-gas dust is to the blast furnace (BF) via sinter, cold-bonded briquettes and tuyere injection. However, solely relying on the BF for recycling implicates that certain residues cannot be recycled in order to avoid build-up of unwanted elements, such as zinc. By introducing a holistic view on recycling where recycling via other process routes, such as the desulfurization (deS) station and the basic oxygen furnace (BOF), landfilling can be avoided. In the present study, process integration analyses were utilized to determine the most efficient recycling routes for off-gas dust that are currently not recycled within the integrated steel plants of Sweden. The feasibility of recycling was studied in experiments conducted in laboratory, pilot, and full-scale trials in the BF, deS station, and BOF. The process integration analyses suggested that recycling to the BF should be maximized before considering the deS station and BOF. The experiments indicated that the amount of residue that are not recycled could be minimized.

  • 204.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Gullberg, Amanda
    Swerim AB.
    Kullerstedt, Adeline
    Swerim AB.
    Wedholm, Anita
    SSAB Merox .
    Wikström, Jenny
    LKAB.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Recycling of Blast Furnace Sludge to the Blast Furnace via Cold-Bonded Briquettes: Evaluation of Feasibility and Influence on Operation2019Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 59, nr 10, s. 1786-1795Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ore-based steelmaking generates various residues including dusts, sludges, scales and slags. Recycling of these residues within the process or via other applications is essential for sustainable production of steel. In blast furnace (BF) ironmaking, the gas-cleaning equipment generally recovers the particles in the off-gas as dust and sludge. Traditionally, the dry dust is recycled via the sinter or, in the case of pellet-based BF operation, via cold-bonded briquettes and injection. As the BF sludge mainly consists of iron and carbon, this residue is of interest to recycle together with the BF dust. However, depending on how the BF is operated, these two residues are more or less the major outlet of zinc from the furnace. Thus, to limit the recycled load of zinc, both materials cannot be recycled without dezincing the sludge prior to recycling. Dezincing and recycling of the low-zinc fraction of BF sludge via sinter have been reported whereas recycling via cold-bonded briquettes has not been performed. In the present study, cold-bonded briquettes containing the low-zinc fraction of dezinced BF sludge were charged as basket samples to the LKAB Experimental Blast Furnace (EBF). The excavated basket samples from the quenched EBF suggested that additions of up to 20 wt.% of upgraded BF sludge was feasible in terms of reducibility and strength. Based on these results, BF sludge were added to cold-bonded briquettes and charged in industrial-scale trials. The trials indicated that the annual generation of BF sludge, after dezincing, could be recycled to the BF.

  • 205.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Morcel, Adeline
    Swerea MEFOS.
    Gullberg, Amanda
    Swerea MEFOS.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Helwan.
    Upgrading and Recycling of Blast Furnace Sludge2017Konferansepaper (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 206.
    Andersson, B.M.
    et al.
    Department of Physics, Umeå University.
    Sundqvist, B.
    Department of Physics, Umeå University.
    Niska, John
    Luleå tekniska universitet.
    Loberg, Bengt
    Easterling, K.
    Luleå tekniska universitet.
    Electrical transport properties of dense bulk YBa2Cu4O8 produced by hot isostatic pressing1990Inngår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 170, nr 5-6, s. 521-531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Highly dense sintered YBa2Cu4O8 has been produced by hot isostatic pressing (HIP). The electrical resistivity ρ of this material has been measured as a function of temperature T and pressure p in the range 40-650 K and 0-0.7 GPa. Both the temperature dependence and the pressure dependence of ρ are found to be well described by a model based on the standard Bloch-Grueneisen theory. It is pointed out that ρ is liner in T only under isobaric conditions, while ρ is strongly nonlinear in all high-Tc superconductors under isochoric (constant volume) conditions. The critical current density of the material is 900 A/cm2 at 4 K, while the resistivity is 630 μΩ cm at 294 K.

  • 207.
    Andersson, Britt
    et al.
    Umeå university.
    Sundqvist, Bertil
    Umeå university.
    Niska, John
    Luleå tekniska universitet.
    Loberg, Bengt
    Thermal conductivity of polycrystalline YBa2Cu4O81994Inngår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 49, nr 6, s. 4189-4198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have measured the thermal conductivity κ and the thermal diffusivity a of a dense bulk ceramic polycrystalline sample of YBa2Cu4O8 (1:2:4) in the temperature range 30-300 K. We find κ≊10 W m-1 K-1 at 100 K, significantly higher than in ceramic YBa2Cu3O7-δ (1:2:3) and approaching the in-plane value for single-crystal 1:2:3, and decreasing to 7.6 W m-1 K-1 at 300 K. The data for this sample can be described by standard theories for phonon thermal conductivity of crystalline materials with boundary, phonon, and electron scattering. The higher κ in 1:2:4 as compared to 1:2:3 is, in this model, due to the smaller point defect scattering in the former. The fitted parameters for the three scattering mechanisms all agree with independent estimates based on simple models; inserting data for electric resistivity, grain size, carrier density, and lattice properties we can predict κ and its T dependence to within about 20%. We also discuss models for the phonon and electron thermal conductivities in some detail, including some second-order effects such as inelastic electron scattering and a T-dependent carrier density.

  • 208.
    Andersson, Börje
    et al.
    Aeronautical Research Institute of Sweden.
    Sjögren, Anders
    Aeronautical Research Institute of Sweden.
    Berglund, Lars
    Luleå tekniska universitet.
    Micro- and meso-level residual stresses in glass-fiber/vinyl-ester composites2000Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 60, nr 10, s. 2011-2028Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Residual stresses in glass-fiber composites were studied on the micro and meso scales by computational and experimental methods. Transmitted polarized light images of thin sections were compared with 3D finite-element solutions of a sample containing 1410 fibers. Calculated point-wise stresses were derived from a linear thermoelastic model with negligibly small numerical errors. Regions with calculated maximum compressive stresses showed good agreement with experimentally observed optical bands. A material with poor interfacial adhesion showed weaker optical effects indicating fiber/matrix debonding. On the basis of these results it seems likely that irreversible matrix deformation and debonding can take place in the curing phase.

  • 209.
    Andersson, Charlotte
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Thermal diffusivity measurements in magnetite based iron ore pellets2011Inngår i: Proceedings: METEC InSteelCon 2011 : Düsseldorf, Germany, CCD Congress Center Düsseldorf, 27th June - 1st July, 2011 ; it unites for international congresses/conferences under one roof: ECIC, 6th European Coke and Ironmaking Congress; ECCC, 7th European Continuous Casting Conference; EECRsteel, 1st International Conference on Energy Efficiency and CO2 Reduction in the Steel Industry; STEELSIM, 4th International Conference on Modelling and Simulation of Metallurgical Processes in Steelmaking, Düsseldorf, 2011Konferansepaper (Fagfellevurdert)
  • 210. Andersson, Charlotte
    et al.
    Björkman, Bo
    Engström, Fredrik
    Mostaghel, Sina
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    The need for fundamental measurements for a sustainable extraction of metals2010Konferansepaper (Fagfellevurdert)
  • 211.
    Andersson, Charlotte
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mostaghel, Sina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    The need for fundamental measurements for a sustainable extraction of metals2011Inngår i: Transactions of the Institution of Mining and Metallurgy Section C - Mineral Processing and Extractive Metallurgy, ISSN 0371-9553, E-ISSN 1743-2855, Vol. 120, nr 2, s. 199-204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The increased need for efficient material processing and efficient utilisation of more complex raw materials and the need for recycling or reusing byproduct and waste streams, are all increased challenges in material processing. To cope with these challenges, there is a need for new basic physical and thermodynamic data. The present paper gives four examples, as well as preliminary data, of areas where increased knowledge of fundamental parameters will increase the possibility for a sustainable extraction of metals. The examples include measurement of solubility of pure individual slag minerals, determination of distribution of leachable elements between different mineralogical phases in slag, influence of alumina on liquidus temperature of a copper slag and thermal diffusivity measurements in magnetite based iron ore pellets, all important in different ways to increase the sustainability of the respective materials involved

  • 212. Andersson, Linnéa
    et al.
    Akhtar, Farid
    Department of Materials and Environmental Chemistry, Stockholm University.
    Jones, C.
    Knackstedt, M.
    Bergström, Lennart M.
    Department of Materials and Environmental Chemistry, Stockholm University.
    Tuning the permeability to fluid flow in macroporous Al2O3: A 3D study with X-ray micro-computed tomography.2010Konferansepaper (Fagfellevurdert)
  • 213. Andersson, Linnéa
    et al.
    Akhtar, Farid
    Department of Materials and Environmental Chemistry, Stockholm University.
    Jones, C.
    Knackstedt, M.
    Bergström, Lennart M.
    Department of Materials and Environmental Chemistry, Stockholm University.
    Zeolite coated alumina foam for CO2 capture2011Konferansepaper (Fagfellevurdert)
  • 214.
    Andersson, Linnéa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Akhtar, Farid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Ojuva, Arto
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Colloidal processing and CO2-capture performance of hierarchically porous Al2O3-zeolite 13X composites2012Inngår i: Journal of Ceramic Science and Technology, ISSN 2190-9385, Vol. 3, nr 1, s. 9-16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hierarchically porous composites for CO2-capture have been produced by coating the inner walls of foam-like macroporous alumina monoliths, produced by templated synthesis, with microporous zeolite 13X particles. Homogeneous and dense coatings of the particulate adsorbent were obtained when the impregnation process was performed at a pH above 9. At this pH-level the colloidally stable suspensions of the negatively charged zeolite 13X particles could fill all the voids of the highly connected pore space of the alumina supports and attach to the monolith walls, which had been pre-coated with poly(ethylene imine). A CO2-uptake as high as 5 mmol CO2/g zeolite 13X was achieved for alumina-zeolite 13X composites through minimisation of the added inorganic binder, kaolin, to only 3.0 wt% with respect to zeolite content, and through optimisation of the thermal treatment.

  • 215.
    Andersson, Roger
    Luleå tekniska universitet.
    Deformation characteristics of stainless steels2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the results of a theoretical and experimental investigation into the deformation characteristics of stainless steels. The title of the chapters is as follows; A new type of forming limit diagram for use with meta-stable stainless steels. A new equation to describe the microstructural transformation of meta- stable austenitic stainless steels during plastic deformation. FEM-simulation of the forming and impact behaviour of stainless steel automobile components. The development of high strain rate equations for stainless steels. The metallurgy and mechanical properties of laser welds between stainless and carbon steels.

    Fulltekst (pdf)
    FULLTEXT01
  • 216.
    Andersson, Roger
    Luleå tekniska universitet.
    Effects of composition and the production process on formability of austenitic stainless steels1999Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Formability of austenitic stainless steels is strongly influenced by the chemical composition, the internal texture and the deformation conditions. The purpose of this study is to determine how small variations in chemical composition and minor variations in the production process are influencing the formability of type 304 and 316 austenitic stainless steels. In this study, the formability of ten sub-grades of type 316 austenitic stainless steel and four sub-grades of type 304 austenitic stainless steel were investigated. These investigations are expected to have significant impact for both stainless steel producers and users. If the influence of the chemistry on the formability and the influence of different paths in the cold-rolling plant on the anisotropy are better understood, then manufacturers will be able to design processes which optimise the limiting strains.

  • 217.
    Andersson, Roger
    Luleå tekniska universitet.
    Virtuell verifiering av plåtformning: en undersökning av funktionalitet hos några av de vanligaste programvarorna och intresset bland några svenska företag2001Rapport (Annet vitenskapelig)
    Abstract [sv]

    En sammanfattning av befintliga programvaror inom virtuell verifiering av plåtformningsverktyg

    Fulltekst (pdf)
    FULLTEXT01
  • 218.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Schedin, Erik
    Luleå tekniska universitet.
    Using stainless steel for energy absorbing components in automobiles2001Inngår i: Innovations in processing and manufacturing of sheet materials: proceedings / the Second Global Symposium on Innovations in Materials Processing and Manufacturing: Sheet Materials, held at the 2001 TMS annual meeting, February 11 - 15, 2001, New Orleans, Louisiana / [ed] Mahmoud Y. Demeri, Warrendale, Pa: Minerals, Metals & Materials Society, 2001, s. 97-110Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To increase the crash performance in automobiles it is necessary to use new techniques and materials. To produce energy absorbing components the material should have high yield strength, high elongation to fracture and strong work hardening. The total work a component absorbs during impact is the area under the stress-strain curve for unit material volume. This has lead to an interest in high strength stainless steels as crash safety components in automobiles due to their excellent material properties. The material performance of different stainless grades has been evaluated through intrinsic and simulative tests. A stainless steel bumper beam has been optimised for a VOLVO car and comparisons have been made with the present application. Simulations have been done and verified by experiments.

  • 219.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Magnusson, Claes
    Fem-simulation of forming and subsequently impact behaviour of a stainless steel component2005Inngår i: Proceedings of the 8th ESAFORM Conference on Material Forming / [ed] Dorel Banabic, Bucharest: The Romanian Academy Publishing House , 2005, Vol. 1, s. 265-268Konferansepaper (Fagfellevurdert)
  • 220. Andersson, Roger
    et al.
    Schedin, Erik
    Magnusson, Claes
    Ocklund, J.
    Persson, A.
    Stainless steel components in automotive vehicles2004Inngår i: Stainless Steel World, ISSN 1383-7184, Vol. 16, nr 1, s. 34-37Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Components linked to crash safety in automotive vehicles are required to transmit or absorb energy. The energy absorbing capability of a given component depends on a combination of geometry, material properties and loading conditions. Increased crash performance can be obtained by using materials with higher yield strength and relatively high elongation to fracture. These demands have led to increasing interest in the use of high strength stainless steels due to their relatively high elongation to fracture and good formability. To increase knowledge of the formability and forming behaviour of these materials, several components from current and prototype vehicles have been made using high strength stainless steels at Volvo Cars Body Components, Olofstrom, Sweden. These were subsequently analysed in close collaboration with the Division of Manufacturing Systems Engineering at Lulea University of Technology, Sweden.

  • 221.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Schedin, Erik
    AvestaPolarit Inc..
    Magnusson, Claes
    Ocklund, Jonny
    Volvo Car Corporation.
    Persson, Arne
    Volvo Car Corporation.
    The applicability of stainless steels for crash absorbing components2002Inngår i: ACOM : Avesta Sheffield corrosion management and application engineering, ISSN 1101-0681, Vol. 3-4, s. 7-12Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    To increase crash performance in automotive vehicles it is necessary to use new techniques and materials. Components linked to crash safety should transmit or absorb energy. The energy absorbing capability of a specific component is a combination of geometry and material properties. For these components the chosen material should have high yield strength and relatively high elongation to fracture. These demands have led to increasing interest in the use of high strength stainless steels. The relative performance of three high strength carbon steels and two high strength stainless steel grades was evaluated through intrinsic and simulative tests. The rear bumper for a Volvo Car model in current production was manufactured using the five sheets tested to verify formability and behaviour under load. The bumpers were clamped in a rig that allowed quasi-static impact tests to be made. The energy absorbing capabilities were evaluated by measuring force versus displacement during the impact test.

  • 222.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Syk, M.
    Powell, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Magnusson, Claes
    Formability behaviour of meta-stable stainless steels2005Inngår i: Proceedings of the 8th ESAFORM Conference on Material Forming / [ed] Dorel Banabic, Bucharest: The Romanian Academy Publishing House , 2005, Vol. 1, s. 359-362Konferansepaper (Fagfellevurdert)
  • 223. Andersson, Urban
    et al.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Gustavsson, Håkan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Karlsson, Rolf
    Vattenfall Research & Development.
    The Turbine-99 workshops - conclusions and recommendations2004Inngår i: 22nd IAHR Symposium on Hydraulic Machinery and Systems, Stockholm, Sweden, June 29 - July 2, 2004, Stockholm: IAHR , 2004Konferansepaper (Annet vitenskapelig)
  • 224. Andreasson, Johanna
    High density ferroelectric Na0.5K0.5NbO3 ceramics: preparation and applications2002Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the production of high density ferroelectric Na0.5K0.5NbO3-ceramics (NKN). The main steps in the production are milling, calcination, pressing and sintering. To produce a full dense ceramic material several of these steps have to be considered. In milling the main concern is to produce a powder with small grains and a normally distributed range of grain size. This is done to achieve an optimal packing arrangement with a minimum of porosity. Several different milling techniques and milling parameters such as milling additives and milling media are also discussed. Sintering of the ceramics may be performed in a conventional furnace with or without special atmosphere, so called pressureless sintering. Another method is hot isostatic pressing which is a combination of high isostatic pressure and high temperature; this gives a more efficient sintering. Both methods are discussed here. Paper I describes sintering conditions of NKN produced with different sintering techniques, the results show high density and good ferroelectric properties. Paper II describes the production and properties of thin films laser deposited on different substrates from high dense ceramic targets. Paper III also describes properties of laser deposited thin films on different substrates.

  • 225.
    André, Alann
    et al.
    Swerea SICOMP AB, Mölndal.
    Kliger, Robert
    Division of Structural Engineering, Chalmers University of Technology.
    Asp, Leif
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Compression failure mechanism in small scale timber specimens2014Inngår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 50, s. 130-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding the failure mechanism of wood loaded in compression parallel to the grain has been shown to be an important parameter in the design of timber beams strengthened with fibre-reinforced plastics (FRP). In this paper, a constitutive relationship for wood under uniaxial compression load parallel to the grain was determined experimentally. Several parameters, such as silviculture, moisture content and radial position in the log in relation to the pith from where the specimen was sawn, were considered. Small clear-wood specimens were used. The strain localisation in the failure region (kinkband) was monitored using the digital image correlation method. The results show that silviculture and moisture content are two very important parameters which influence the compression failure mechanism. Furthermore, there is a significant difference in behaviour between specimens from the juvenile region of the log and specimens from mature wood. Based on experimental results, two numerical models were built, considering either a global or a local constitutive relationship. It was demonstrated that both numerical models yield accurate results and that, depending on the experimental equipment available, a constitutive relationship could be extracted and used as input in these numerical models.

  • 226.
    André, Alann
    et al.
    Swerea SICOMP AB.
    Nilsson, Sören
    Swerea SICOMP AB.
    Asp, Leif
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Finite element delamination study of a notched composite plate under flexural loads2009Inngår i: ICCM 17, Edinburgh: 17th International Conference on Composite Materials ; 27 Jul 2009 - 31 Jul 2009, Edinburgh International Convention Centre, Edinburgh, UK, London: IOM Communications , 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The delamination process in notched composite plates under flexural loading has been investigated using finite element analysis. Cohesive elements implemented in the commercial finite element package ABAQUS have been used in the region around the drilled-hole, and positioned between layers where delamination was observed during experiments presented in an accompanying paper. The delamination initiation and subsequent propagation was studied between the layers at the tension side separately and simultaneously. For all FE models, the load displacement curve was in good agreement with the one from experiments. However, the amount of damage reported from the fractography study was more extensive than that predicted by the models. Finally, it was shown that the models with only one cohesive layer show significantly different results to that of the model with four cohesive layers in terms of size of the degradation area.

    Fulltekst (pdf)
    FULLTEXT01
  • 227.
    Ansari, Farhan
    et al.
    Department of Fiber and Polymer Technology, KTH Royal Institute of Technology.
    Granda, Luis A.
    Laboratory of Paper Engineering and Polymer Materials (LEPAMAP) Group, Department of Chemical Engineering, University of Girona.
    Joffe, Roberts
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Berglund, Lars A.
    Department of Fiber and Polymer Technology, KTH Royal Institute of Technology.
    Vilaseca, Fabiola
    Department of Fiber and Polymer Technology, KTH Royal Institute of Technology.
    Experimental evaluation of anisotropy in injection molded polypropylene/wood fiber biocomposites2017Inngår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 96, s. 147-154Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although the anisotropy of wood fibers is reasonably well established, the anisotropy of injection molded wood fiber composites is not well understood. This work focuses on chemo-thermomechanical pulp (CTMP) reinforced polypropylene (PP) composites. A kinetic mixer (Gelimat) is used for compounding CTMP/PP composites, followed by injection molding. Effects from processing induced orientation on mechanical properties are investigated. For this purpose, a film gate mold was designed to inject composites in the shape of plates so that specimens in different directions to the flow could be evaluated in tensile tests. Observations from tensile tests were complemented by performing flexural tests (in different directions) on discs cut from the injected plates. SEM was used to qualitatively observe the fiber orientation in the composites. At high fiber content, both modulus and tensile strength could differ by as much as 40% along the flow and transverse to the flow. The fiber orientation was strongly increased at the highest fiber content, as concluded from theoretical analysis.

  • 228.
    Antti, Britt-Marie
    Luleå tekniska universitet.
    Pulpkemi och kalcitflotation1986Inngår i: Workshop i mineralteknik: Luleå 11-12 februari 1986 / [ed] Börje Sköld; Eric Forssberg, MinFo , 1986, s. 81-104Konferansepaper (Annet vitenskapelig)
  • 229.
    Antti, Britt-Marie
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Pulp chemistry in calcite flotation.: Modelling of oleate adsorption using theoretical equilibrium calculations1989Inngår i: Mining engineering, ISSN 0026-5187, Vol. 2, nr 1, s. 93-109Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers the conditions required for direct flotation of calcite. Flotation experiments have been performed with oleate as the collector reagent and water glass as the dispersant and modifier. To be able to explain what happens in the flotation, solubility and adsorption experiments have been conducted parallel to, and under the same conditions as, the flotation experiments. Theoretical equilibrium calculations have been made with the help of data from the practical experiments for the purpose of modelling the adsorption experiments. With theoretical equilibrium calculations it is possible to predict that silicate ions will form complexes with calcium ions at the mineral surface.

  • 230.
    Antti, Britt-Marie
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Pulp chemistry in industrial mineral flotation: Studies of surface complex on calcite and apatite surfaces using FTIR spectroscopy1989Inngår i: Mining engineering, ISSN 0026-5187, Vol. 2, nr 2, s. 217-227Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Flotation experiments in a Hallimond tube have been performed on calcite and apatite at pH levels and oleate concentrations judged to be interesting from the point of view of adsorption isotherms. For the calcite system, adsorption isotherms indicate precipitation of calcium oleate after monolayer formation at pH 9, 10 and 11. In the apatite system, a double layer of oleate is formed. This means that apatite, unlike calcite, is sensitive to collector reagent overdosage. With the aid of FTIR techniques it is possible to demonstrate the existence of a surface complex in the apatite system with a calcium-oleate ratio of 1:1 at monolayer coverage of the surface. In conditions corresponding to bulk precipitation of calcium oleate, this compound can be detected by FTIR analysis of unfloated material.

  • 231.
    Antti, Marta-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    All-oxide ceramic matrix composites2001Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This work has concerned the preparation and properties of all-oxide composites. The most common examples of such materials are composites of oxide particles in an oxide matrix, continuous oxide fibres in an oxide matrix and layered composites consisting of alternate layers of different oxides. In the case of continuous fibre composites, the matrix and fibres can be of the same oxide since the mechanical properties of the composite are to a large extent influenced by the interface between the two. All-oxide composites are of interest as possible high temperature materials since they are inherently oxidation resistant. The emphasis of the thesis is on continuous fibre composites. The thesis, consisting of an extensive introductory review and six appended papers (listed in appendix 2), covers a number of aspects of these composites including the properties of candidate oxide constituents, methods of composite preparation, microstructure and mechanical properties. The first paper describes attempts made to prepare alumina composites reinforced with monocrystalline (sapphire) fibres using hot isostatic pressing. The second paper reports on the thermal expansion behaviour of candidate oxides and the consequences of differences in thermal expansion of composite constituents with respect to residual thermal stresses in the composite. Paper VI reports measurements made of the stress-strain and fracture behaviour of experimental sapphire fibre/alumina matrix composites. The materials studied included both unidirectional and 0/90° cross-ply composites, all with a thin layer of zirconia at the fibre/matrix interface designed to adjust the interfacial properties to provide optimum composite stress-strain behaviour. The results could be linked to measurements made of interfacial properties. Papers III, IV and V concern the stress strain behaviour of a commercial all-oxide composite consisting of fine-diameter, polycrystalline oxide fibres in a porous, aluminosilicate matrix. In these composites the fibres were woven in a 0/90° geometry and tested in both the 0/90° and ±45° orientation. The emphasis of the study was on the notch-sensitivity of test specimens containing a central circular hole. Aspects studied included failure mechanisms, the effects of notch size and the effects of high temperature thermal exposure on microstructure and strength degradation. The observed behaviour could be described successfully in terms of a simple model based on fracture mechanics.

    Fulltekst (pdf)
    FULLTEXT01
  • 232.
    Antti, Marta-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Preparation and properties of sapphire/alumina long fibre composites1999Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The research described in the thesis concerns the preparation and properties of oxide/oxide composites and in particular composites consisting of an oxide matrix reinforced with continuous oxide fibres and intended for use as structural materials at very high temperatures. For this application particular attention must be paid to the behaviour of the fibre/matrix interface and to the properties of the fibre. The research has involved two main aspects (i) a thorough review of the physical and mechanical properties of candidate oxides with emphasis on elastic properties and creep properties and (ii) the experimental development of methods to produce continuous fibre reinforced oxide/oxide composites.

    Fulltekst (pdf)
    fulltext
  • 233.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Babushkin, O
    Luleå tekniska universitet.
    Shen, Z
    Nygren, M
    Warren, R
    Thermal expansion behaviour of high melting point oxides1999Inngår i: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 164-165, s. 279-282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The thermal expansion characteristics of the reinforcement and matrix constituents in ceramic composites have a strong influence on a number of aspects of the composite performance. Thus the toughness and strength of the composite can be influenced by local residual stresses due to the thermal expansion mismatch of different phases. Moreover, in individual polycrystalline phases, local stress variations from grain to grain, generated as a result of anisotropy of thermal expansion in combination with anisotropy of elasticity can influence strength and toughness in similar ways. In the present study, reported data on the thermal expansion coefficients of oxides having potential as constituents in high temperature composites are reviewed and complemented with additional measurements made using high temperature X-ray diffraction

  • 234.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Cheng, Y-B
    Monash University, Melbourne, VIC.
    Odén, Magnus
    Synthesis and phase development in the Ct-Al-N system2009Inngår i: Mechanical properties and processing of ceramic binary, ternary and composite systems: a collection of papers presented at the 32nd International Conference on Advanced Ceramics and Composites, January 27-February 1, 2008, Daytona Beach, Florida / [ed] Jonathan Salem; Greg Hilmas; William Fahrenholtz, Hoboken, NJ: John Wiley & Sons, 2009, s. 3-12Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The ternary nitride system Cr-Al-N has been investigated by sintering different powder compositions. The powder compositions belong to four groups, AIN- + Cr-powder (5 compositions between 20-90 molar% AlN), Al- + Cr 2N-powder (5 compositions between 15-80 molar% Cr2N), AlN-+ Cr2N-powder (50- and 90 molar% Cr2N) and Al- + Cr-powder. The powders were dry mixed and pressed into pellets by uniaxial pressing followed by cold isostatic pressing (ClP). Sintering took place in a graphite lined reaction bonding furnace under nitrogen atmosphere at three different temperatures, 1350°C, 1500°C and 1800°C and in an alumina tube furnace in order to avoid access to carbon. Holding times were varied, from 2 hours up to 72 hours. The phase development was evaluated by thermal analysis and XRD. CrAlN was formed at 1350°C but decomposed at higher temperatures. Both pure Al and Cr-powder were prone to react with carbon in the graphite furnace. Thermal analysis showed a sublimation of Cr2N at temperatures around 1050°C and nitridation of pure Al-powder between 680-750°C and of pure Cr-powder between 610-1080°C. Samples with pure Al-powder showed a very large expansion due to melting of aluminium in combination with nitridation. AIN was found to be more stable than Cr 2N at higher temperatures and longer holding times. The mixtures of Al-+Cr-powder produced an intermediate Al-Cr-phase.

  • 235.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Frisk, Lars
    Warren, Richard
    Luleå tekniska universitet.
    P, P Vincenzini
    Synthesising of a model composite in the oxide/oxide system: alumina fibre reinforced alumina matrix1999Inngår i: Advanced structural fiber composites, TECHNA Srl , 1999Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Ceramic matrix composites have attracted big interest as potential material for high temperature applications. To avoid one of the main problems, namely oxidation at higher temperatures, interest has increased for systems where both reinforcement and matrix material are ceramic oxides. This work presents a possible method of producing long fibre reinforced ceramic matrix composites. The method was applied to single crystal aluminium oxide fibres in a polycrystalline alumina matrix and involves cladding individual fibres with the matrix material in the form of pre-sintered tubes with appropriately small diameter. The composite is then hot isostatically pressed (HIP), by putting several fibre-tube pairs in a container of required diameter. A HIP cycle was found that led to full densification of the composite without visual damage to the fibres. The method produces composites with an ideal uniform fibre spacing; samples of cylindrical shape suitable, for example, for uniaxial testing can be produced

  • 236.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Kero, Ida
    Cheng, Y-B
    Monash University, Melbourne, VIC.
    Tegman, Ragnar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Phase reactions in a hot pressed TiC/Si powder mixture2012Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 38, nr 3, s. 1999-2003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work investigated the possibility of producing dense Ti3SiC2 by hot pressing TiC/Si powders. A hot press with graphite heating elements was used for densification and the phase reactions of some hot pressed samples were further evaluated by pressureless heating in a dilatometer. The density and phase composition of the heat treated samples were evaluated using Archimedes principle and by x-ray diffractometry respectively. Hot pressing resulted in a low Ti3SiC2 yield; the main phases were TiC and TiSi2 regardless of starting powder composition, temperature, holding time or pressure. A second heating without pressure resulted in Ti3SiC2 formation, but only in samples initially hot pressed at 1300 °C or lower. At higher hot pressing temperatures, thin oxide layers on particle surfaces were locked into the structure. Acting as diffusion barriers, they prevented the Ti3SiC2 forming reaction. In hot pressed samples the density was significantly higher than in samples sintered without pressure

  • 237.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Lara-Curzio, E.
    Effect of notches, specimen size, and fiber orientation on the monotonic tensile behavior of composites at ambient and elevated temperatures2001Inngår i: Ceramic Engineering and Science Proceedings, ISSN 0196-6219, E-ISSN 1940-6339, Vol. 22, nr 3, s. 643-650Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of circular central holes on the monotonic tensile stress-strain behaviour and strength of a continuous fibre-reinforced oxide/oxide composite was investigated. The material used consisted of 12 layers of un-coated plain weave fabric of Nextel 720, with either 0/90 or plus or minus 45 degrees fibre orientation with respect to the loading direction, embedded in an aluminosilicate matrix. 100 and 200-mm long straight-sided specimens with central holes were tested for ratios of hole diameter to width (a/w) between 0.1 and 0.4, and width values between 3 mm and 25 mm. It was found that as-processed specimens with both fibre architectures were notch insensitive at ambient temperature, but exhibited mild notch sensitivity at elevated temperatures. It was also found that the strength of the material was retained after heat treatments at 1000 C, but that it decreased significantly after exposures at 100 C for periods of time of 20 and 100 h. The strength of test specimens with 0/90 fibre orientation was found to decrease with increasing width, but no size effects on strength were observed for specimens with plus or minus 45 degrees fibre orientation. These results are discussed in relation to the microstructure of the material and its evolution at elevated temperatures.

  • 238.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Lara-Curzio, E.
    Ferber, M K
    Analysis of damage evolution in continuous fiber-reinforced oxide /oxide composites under cyclic loading, using infrared thermography2001Inngår i: Ceramic Engineering and Science Proceedings, ISSN 0196-6219, E-ISSN 1940-6339, Vol. 22, nr 3, s. 711-716Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The evolution of damage in continuous fiber-reinforced oxide/oxide matrix composites was investigated at ambient temperature using an infra-red camera and a servohydraulic testing machine. The material used in this study consisted of 12 layers of un-coated fabric of Nextel 720 (either 0/90 or plus/minus45 deg fiber orientation with respect to the loading direction) and an aluminosilicate matrix. Straight-sided specimens 100 mm long and 12.5 mm wide with center holes were tested for a/w between 0.1 and 0.4. It was possible to record the onset of "necking", the propagation of cracks in the matrix, and the rotation of fiber bundles during matrix crack growth. These processes were recorded using a fast-speed digital image recorder/analyzer, and the sequence of events is presented.

  • 239.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Lara-Curzio, E.
    Oak Ridge National Laboratory.
    Warren, R
    Malmö University.
    Thermal degradation of an oxide fibre (Nextel 720)/aluminosilicate composite2004Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 24, nr 3, s. 565-578Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of thermal exposure on the microstructure and tensile stress-strain behaviour has been investigated for composites of woven continuous oxide fibres (Nextel 720) in a porous aluminosilicate matrix. The tensile tests were carried out on straight-sided, centre hole notched plates with 0/90° and ±45° orientations. The as-received material was slightly notch sensitive in that the net section fracture stress decreased somewhat with increasing hole diameter but much less than predicted for an ideally elastic, fully notch-sensitive material. After exposure at 1100°C and for long time at 1000°C in air the composite was embrittled. In the 0/90 composite this resulted in a reduced fracture strength, a reduced strain to failure as well as a reduced fracture toughness and damage zone size. After exposure for 100 h at 1100 °C (the most extreme exposure applied) the material also became significantly more notch sensitive and had failure characteristics similar to those of a monolithic ceramic. The ±45 composite was also embrittled which resulted in a reduced strain to failure but an increase in fracture strength. Density measurements and observations on the microstructure and fracture surfaces indicated that the embrittlement was due mainly to localised densification of the matrix and an increase in fibre/matrix bonding.

  • 240.
    Antti, Marta-Lena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    LePagne, D
    Holmqvist, M.
    Paquien, J-N
    Warren, Richard
    Micromechanics of failure in an alumina fibre reinforced alumina matrix composite2000Inngår i: Composites - from fundamentals to exploitation: [the premier composites conference in Europe ; proceedings] / ECCM9, 4 - 7 June 2000, Brighton Conference Centre, UK, London: Institute of Materials , 2000Konferansepaper (Fagfellevurdert)
  • 241.
    Antzutkin, Oleg
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Kota, Hanumantha Rao
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Ikumapayi, Fatai
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Gunneriusson, Lars
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Johansson, Björn
    New Boliden AB.
    Berggren, Andreas
    New Boliden AB.
    Larsson, Anna-Carin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Bhuiyan, Iftekhar Uddin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forsmo, Seija
    LKAB.
    Interactions in multi-component mineral systems2011Konferansepaper (Annet vitenskapelig)
    Fulltekst (pdf)
    FULLTEXT01
  • 242.
    Antzutkin, Oleg
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Kota, Hanumantha Rao
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Ikumapayi, Fatai
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Johansson, Björn
    New Boliden AB.
    Berggren, Andreas
    New Boliden AB.
    Larsson, Anna-Carin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Holmgren, Allan
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Bhuiyan, Iftekhar Uddin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forsmo, Seija
    LKAB.
    Interactions in multi-component mineral systems2010Konferansepaper (Annet vitenskapelig)
    Fulltekst (pdf)
    FULLTEXT01
  • 243. Arab, A.
    et al.
    Stommel, M.
    Wallström, Lennart
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rack, A.
    Investigation of fibre degradation in natural fibre reinforced biocomposites2013Inngår i: Proceedings of the 5th International Conference on Sustainable Materials, Polymers and Composites: Ecocomp 2013, 2013, s. 174-185Konferansepaper (Fagfellevurdert)
  • 244. Arab, A.
    et al.
    Stommel, M.
    Wallström, Lennart
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Varna, Janis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Stiffness prediction in green composites using homogenization techniques2013Inngår i: Proceedings of the 19th International Conference on Composite Materials: ICCM 2013, Montreal (Canada), 2013, s. 1214-1222Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    FULLTEXT01
  • 245.
    Arab, Asghar
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Stommel, L.
    Saarland University.
    Wallström, Lennart
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Fibre Orientation Investigation in Short Natural Fibre Reinforced Composites Using Synchrotron Imaging2013Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    FULLTEXT01
  • 246.
    Ardakani, M.G.
    et al.
    Imperial College of Science Technology and Medicine.
    McLean, M.
    Shollock, B.A.
    Luleå tekniska universitet.
    Twin formation during creep in single crystals of nickel-based superalloys1999Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 47, nr 9, s. 2593-2602Artikkel i tidsskrift (Fagfellevurdert)
  • 247.
    Ari, Vidyadhar
    Luleå tekniska universitet.
    Flotation of silicate minerals: physico-chemical studies in the presence of alkylamines and mixed (cationic/anionic/non-ionic) collectors2001Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The mechanism of adsorption of long chain alkyl primary amines and, co-adsorption of amines and alcohols on silicate minerals (quartz and feldspar) were studied using FTIR (DRIFT and IRRAS) and XPS spectroscopy methods. The spectroscopy data were correlated with zeta-potential and Hallimond flotation results. The effect of alkyl chain length of mixed collectors in adsorption at solid/water interface is also examined. In addition, the underlying mechanism of the reported mixed cationic/anionic collector scheme for selective feldspar flotation from quartz is delineated through flotation, zeta-potential and infrared spectroscopy studies. Furthermore, the mixed collector system is applied for a successful separation of albite from Greek Stefania feldspar ore. For the first time, it was shown from infrared spectra that the amine cation forms strong hydrogen bonds with the surface silanol groups. The XPS spectra revealed the presence of molecular amine together with the protonated amine on silicate surface. Based on these observations, a model of successive two-dimensional and three-dimensional precipitation was suggested to explain amine adsorption on a silicate surface. The co-adsorption of long chain alcohols or sulfonates with amine cations leads to formation of a closer packed surface layer with synergistic enhancement of amine adsorption. The enhanced adsorption and hence higher flotation recoveries is discussed in the light of our experimental results.

    Fulltekst (pdf)
    FULLTEXT01
  • 248.
    Artz, E.
    et al.
    Max-Planck-Institut für Metallforschung.
    Ashby, M. F.
    University of Cambridge.
    Easterling, K. E.
    Luleå tekniska universitet.
    Practical applications of hotisostatic pressing diagrams: four case studies1983Inngår i: Metallurgical Transactions. A, Physical Metallurgy and Materials Science, ISSN 0360-2133, Vol. 14, nr 1, s. 211-221Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The construction of mechanism maps for hot-isostatic pressing is described. Maps are constructed for a number of materials of commercial and scientific interest: a tool steel, a superalloy, Al2O3, and ice. They allow the processes involved in hot-isostatic pressing to be examined, and suggest ways of picking optimum combinations of pressure, temperature, and time to give maximum density.

  • 249.
    Arvidsson, Edwin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Studie av inneslutningsbeteende under tillverkningsprocessen av götgjutet verktygsstål2019Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    En undersökning av inneslutningsbeteende under tillverkningsprocessen av götgjutet verktygsstål har utförts på Uddeholm i Hagfors. Med hjälp av OES med PDA och SEM med INCA feature undersöktes sammansättningen, antalet, storleken, fördelningen, koncentrationen och formen av inneslutningar före och efter vakuumbehandlingen samt i kokill.  

    Fyra typer av inneslutningar kunde identifieras i olika skeden i processen. Al2O3-MgO spineller i flytande CaO- Al2O3 lösning, CaO-Al2O3 flytande inneslutning, Al2O3-MgO Spineller och Al2O3-SiO2 i fastform. 

    Vakuumbehandlingen påverkar typen, formen, storleken och antalet inneslutningar. Den induktiva omrörningen påverkar antalet och storleken av inneslutningarna. Vid avgjutningen utskiljs Al2O3-SiO2 som med stor sannolikhet beror på provtagningen.  

    Fulltekst (pdf)
    fulltext
  • 250.
    Arwidson, Claes
    Luleå tekniska universitet.
    Numerical simulation of sheet metal forming for high strength steels2005Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    New demands for passenger safety, vehicle performance and fuel economy have led to an increase in the use of advanced high strength steel. An increase in strength decreases the formability of the material and increases the spring back behaviour. Recently the development of high strength steel has rapidly advanced, requiring verification of earlier material models suitable for describing the plasticity behaviour in sheet metal forming. The aim of the here conducted numerical simulations is to verify the deep drawing process and the shape of the final component of a simple hat profile geometry for studying spring-back of high strength steels. Four advanced high strength steels were selected for detailed investigation, namely the dual phase steels DP600 and DP750, the triple phase steel TRIP700 and the stainless steel HYTENS800. The plastic properties of these steels have been assessed through intrinsic and simulative tests, leading to verification and comparison at different levels. The hat profile serves as a simple test geometry for deep drawing due to elimination of the lateral dimension in first order. The corresponding simpler plasticity behaviour in space facilitates systematic analysis Experiments and simulations were carried out, leading to comparison of the resulting draw in, strain, thinning, final shape and spring-back. The verification and analysis concerns the friction coefficient, two software codes, Finite Element properties and the two material models Hill48 and Hill90. The simulation provides a good qualitative coincidence with experimental results, which enables to develop a process theory and to study the individual mechanisms involved. The friction coefficient, varied from 0 to 0.1, shows very low sensitivity on the process. The simulation underestimates the spring-back by 8-12° at the flange edge. Among the four materials studied basically the stainless steel HYTENS800 shows the largest deviations during comparison. In general the results partially reveal distinct quantitative discrepancies, in particular in the critical bending regions, demanding for improved material models and better knowledge of the boundary conditions.

    Fulltekst (pdf)
    FULLTEXT01
2345678 201 - 250 of 3816
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