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  • 1.
    Abadei, S.
    et al.
    Department of Microelectronics, Chalmers University of Technology, Gothenburg, Sweden.
    Gevorgian, S
    Department of Microelectronics, Chalmers University of Technology, Gothenburg, Sweden;Core Unit Research Center, Ericsson Microwave Systems, Mölndal, Sweden.
    Cho, C.-R
    Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm, Sweden.
    Grishin, A.
    Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm, Sweden.
    Andreasson, Johanna
    Luleå University of Technology.
    Lindbäck, Ture
    Luleå University of Technology.
    DC field dependent properties of Na0.5 K0.5 NbO3/SiO2/Si structures at millimeter-wave frequencies2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 13, p. 1900-1902Article in journal (Refereed)
    Abstract [en]

    Dielectric properties of laser-ablated 0.5-μm-thick c-axis epitaxial Na0.5K0.5NbO3 films on high-resistivity (7.7 Ω cm) silicon SiO2/Si substrate are studied experimentally at frequencies up to 40 GHz. For measurements, planar 0.5-μm-thick gold electrodes (interdigital and straight slot) are photolithography defined on the top surface of Na0.5K0.5NbO3 films. The slot width between the electrodes is 2 or 4 μm. 13% capacitance change at 40 V dc bias and Q factor more than 15 are observed at 40 GHz, which makes the structure useful for applications in electrically tunable millimeter-wave devices

  • 2.
    Abadei, S.
    et al.
    Chalmers University of Technology, Department of Microelectronics.
    Gevorgian, S.
    Chalmers University of Technology, Department of Microelectronics.
    Kugler, V.
    Department of Physics, Linköping University.
    Helmersson, U.
    Department of Physics, Linköping University.
    Andreasson, Johanna
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Microwave properties of tunable capacitors basee on magnetron sputtered ferroelectric Na0.5K0.5NbO3 film on low and high resistivity silicon substrates2001In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 39, no 1-4, p. 359-366Article in journal (Refereed)
    Abstract [en]

    In this work, small signal DC voltage dependent dielectric permittivity, loss tangent, and tuneability of magnetron sputtered epitaxial Na0.5K0.5NO3 films are studied experimentally. (100)-oriented Na0.5K0.5NbO3 films are deposited onto SiO2-buffered CMOS grade low resistivity (p = 10-20 cm) and high resistivity (p = 15-45 kcm) silicon substrates. Planar capacitors with 2 or 4 m gaps between electrodes have been fabricated on top of ferroelectric films. These devices have been characterized in the frequency range 1.0 MHz to 50 GHz at temperatures 30 - 300K. Na0.5K0.5NbO3/SiO2/Si structures on high resistivity silicon substrate exhibit C-V performances typical for Metal-Insulator- Semiconductor (MIS) capacitors. At low frequencies, f 1.0 GHz, the large tuneability and large losses are associated with the MIS structure, while at higher microwave frequencies the tuneability is mainly associated with the ferroelectric, film. At 1.0 MHz and room temperature, the tuneability of Na0.5K0.5NbO3/SiO2/Si structures more than 90%, reducing to 10-15 % at 50 GHz. The losses decrease with increasing the DC bias and frequency. A Q-factor more than 15 at 50 GHz is observed. The dielectric permittivity of the Na0.5K0.5NbO3 film is in the range 50-150 at frequencies 0.045-50 GHz. On low resistivity substrate the performance of Na0.5K0.5NbO3 films is completely screened by the high losses in silicon, and the tuneability is negligible

  • 3.
    Abali, Bilen Emek
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics. Univ Nat Resources & Life Sci, Christian Doppler Lab LiCRoFast, Peter Jordan Str 82, A-1190 Vienna, Austria.
    Zecchini, Michele
    Univ Nat Resources & Life Sci, Christian Doppler Lab LiCRoFast, Peter Jordan Str 82, A-1190 Vienna, Austria.
    Daissè, Gilda
    Univ Nat Resources & Life Sci, Christian Doppler Lab LiCRoFast, Peter Jordan Str 82, A-1190 Vienna, Austria.
    Czabany, Ivana
    BOKU Univ Nat Resources & Life Sci, Dept Mat Sci & Proc Engn, Inst Wood Technol & Renewable Mat, Konrad Lorenz Str 24, A-3430 Tulln, Austria.
    Gindl-Altmutter, Wolfgang
    BOKU Univ Nat Resources & Life Sci, Dept Mat Sci & Proc Engn, Inst Wood Technol & Renewable Mat, Konrad Lorenz Str 24, A-3430 Tulln, Austria.
    Wan-Wendner, Roman
    Univ Nat Resources & Life Sci, Christian Doppler Lab LiCRoFast, Peter Jordan Str 82, A-1190 Vienna, Austria; Univ Ghent, Dept Struct Engn & Bldg Mat, Magnel Lab, Technol Pk Zwijnaarde 60, B-9052 Ghent, Belgium.
    Cure Kinetics and Inverse Analysis of Epoxy-Amine Based Adhesive Used for Fastening Systems2021In: Materials, E-ISSN 1996-1944, Vol. 14, no 14, article id 3853Article in journal (Refereed)
    Abstract [en]

    Thermosetting polymers are used in building materials, for example adhesives in fastening systems. They harden in environmental conditions with a daily temperature depending on the season and location. This curing process takes hours or even days effected by the relatively low ambient temperature necessary for a fast and complete curing. As material properties depend on the degree of cure, its accurate estimation is of paramount interest and the main objective in this work. Thus, we develop an approach for modeling the curing process for epoxy based thermosetting polymers. Specifically, we perform experiments and demonstrate an inverse analysis for determining parameters in the curing model. By using calorimetry measurements and implementing an inverse analysis algorithm by using open-source packages, we obtain 10 material parameters describing the curing process. We present the methodology for two commercial, epoxy based products, where a statistical analysis provides independence of material parameters leading to the conclusion that the material equation is adequately describing the material response.

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  • 4. Abbasalizadeh, A.
    et al.
    Sridar, S.
    Chen, Z.
    Sluiter, M.
    Yang, Y.
    Sietsma, J.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Hari Kumar, K. C.
    Experimental investigation and thermodynamic modelling of LiF-NdF3-DyF3 system2018In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 753, p. 388-394Article in journal (Refereed)
    Abstract [en]

    Electrolysis of molten fluorides is one of the promising methods for the recovery and recycling of rare earth metals from used magnets. Due to the dearth of phase equilibria data for molten fluoride systems, thermodynamic modelling of LiF-DyF3-NdF3 system using the CALPHAD approach was carried out. Gibbs energy modelling for LiF-NdF3 and LiF-DyF3 systems was performed using the constitutional data from literature. Ab initio calculations were used to obtain enthalpy of reaction of LiDyF4, an intermediate phase that is found to exist in the LiF-DyF3 system. Differential thermal analysis was carried out for selected compositions in the NdF3-DyF3 system, in order to determine liquidus and solidus temperatures. The Gibbs energy parameters for the limiting binaries determined in this work is used for modelling the Gibbs energy functions of equilibrium phases in the ternary system. Selected compositions of LiF-NdF3-DyF3 were subjected to DTA in order to validate the calculated phase temperatures involving melt.

  • 5.
    Abbasi, Saeed
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Characterisation of airborne particles from rail traffic2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since the investigation of wear particles in rail transport started in late-1910s, the high mass concentration of these particles has raised worries among researchers concerned with air quality. However, effective action has yet to be taken because of lack of relevant knowledge. This thesis provides applicable information for the airborne wear particles in rail transport. Some aspects of their characteristics such as diameter size, mass concentration, number concentration, and morphology of particles were investigated in field tests and laboratory tests.The effects on particle characterisations from different operational conditions in the field tests, and applying different braking materials, conducting tests in different applied loads or sliding velocities in the laboratory tests were studied. The main advantage of conducting laboratory tests was to focus on studying particles from one source. The possibility of repetition, using high sensitive instruments and conducting tests at low costs are the other advantages of laboratory studies. Paper A describes how a pin-on-disc machine was used to reproduce similar real operational conditions during mechanical braking in a train. The results were validated by comparing the field tests results with the laboratory studies. The particles morphology and size distribution were also studied.Paper B presents a summary of field tests results. The effects of curve negotiating and applying braking in different real conditions were investigated with an on-board measurement.The element composition of the particles and their potential sources were also investigated outside of the particles morphologies.Paper C presents comprehensive results from laboratory studies on airborne particles from different braking materials. The differences in the particle characteristics in similar test conditions were attributable to different material compositions and dominant wear mechanisms. A new index was introduced in this paper and is suggested to be used as a qualitative factor with regard to the airborne wear particle emission rate.Paper D is a review of the recent studies of exhaust emission and non-exhaust emission from rail vehicles. A summary of results, measurements, adverse health effects, and proposed or applied solutions are reviewed in this paper.

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  • 6.
    Abbaspour, Benjamin
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Art History, Conservation.
    Isoleringsegenskaper hos frodvuxen gran: En studie av dess värmeledningsförmåga och funktion2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study investigates the potential of fast-grown spruce (Picea abies) as an insulation material in historic buildings, aiming to evaluate the relationship between density and thermal conductivity. The background of the study lies in the need for sustainable and efficient insulation materials that can be used to improve the energy performance of buildings while preserving their historical character and aesthetic value. Fast-grown spruce has a lower density then the lowest available in the Swedish standard for materials heat conductivity. 

    The methodology included both laboratory analyses and field studies. In the laboratory part, a hot-disk instrument was used to measure thermal conductivity, followed by calculations of density and moisture content. The field studies were conducted to identify practical applications and challenges in using fast-grown spruce as a construction material. These studies involved inspections of buildings constructed with fast-grown spruce and interviews with those responsible for their construction to investigate its potential functionality as a construction material. 

    The main results from the laboratory analyses showed a strong correlation between density and thermal conductivity, indicating that fast-grown spruce, with its lower density, has improved insulation properties compared to slow-grown spruce. The field studies confirmed that fast-grown spruce can be used as a construction material in buildings, but also pointed out its tendency to exhibit greater movement during drying, which can be accounted for to prevent issues during the drying process. 

    The conclusions suggest that fast-grown spruce can be a valuable addition to existing insulation materials due to its improved insulation performance. The study recommends further research to examine long-term degradation effects and the material's moisture properties, which are critical for its practical use in buildings. Additionally, further research should investigate the ability of fast-grown spruce to serve as a substrate for plaster, both for clay and lime-based plasters, to determine the wood's compatibility with these materials. 

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    Frodvuxen gran värmeledning
  • 7.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Assiut University, Egypt; The British University in Egypt (BUE), Egypt.
    Sultan, Sahar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Wallenberg Wood Science Center, Sweden.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Wallenberg Wood Science Center, Sweden.
    Three-Dimensional Printing of Cellulose/Covalent Organic Frameworks (CelloCOFs) for CO2 Adsorption and Water Treatment2023In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 15, no 51, p. 59795-59805Article in journal (Refereed)
    Abstract [en]

    The development of porous organic polymers, specifically covalent organic frameworks (COFs), has facilitated the advancement of numerous applications. Nevertheless, the limited availability of COFs solely in powder form imposes constraints on their potential applications. Furthermore, it is worth noting that COFs tend to undergo aggregation, leading to a decrease in the number of active sites available within the material. This work presents a comprehensive methodology for the transformation of a COF into three-dimensional (3D) scaffolds using the technique of 3D printing. As part of the 3D printing process, a composite material called CelloCOF was created by combining cellulose nanofibrils (CNF), sodium alginate, and COF materials (i.e., COF-1 and COF-2). The intervention successfully mitigated the agglomeration of the COF nanoparticles, resulting in the creation of abundant active sites that can be effectively utilized for adsorption purposes. The method of 3D printing can be described as a simple and basic procedure that can be adapted to accommodate hierarchical porous materials with distinct micro- and macropore regimes. This technology demonstrates versatility in its use across a range of COF materials. The adsorption capacities of 3D CelloCOF materials were evaluated for three different adsorbates: carbon dioxide (CO2), heavy metal ions, and perfluorooctanesulfonic acid (PFOS). The results showed that the materials exhibited adsorption capabilities of 19.9, 7.4–34, and 118.5–410.8 mg/g for CO2, PFOS, and heavy metals, respectively. The adsorption properties of the material were found to be outstanding, exhibiting a high degree of recyclability and exceptional selectivity. Based on our research findings, it is conceivable that the utilization of custom-designed composites based on COFs could present new opportunities in the realm of water and air purification.

  • 8.
    AbdElKhalek, Y. M.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Awad, M. I.
    Abd El Munim, H. E.
    Maged, S. A.
    Trajectory-based fast ball detection and tracking for an autonomous industrial robot system2021In: International Journal of Intelligent Systems Technologies and Applications, ISSN 1740-8865, E-ISSN 1740-8873, Vol. 20, no 2, p. 126-145Article in journal (Refereed)
    Abstract [en]

    Autonomising industrial robots is the main goal in this paper; imagine humanoid robots that have several degrees of freedom (DOF) mechanisms as their arms. What if the humanoid's arms could be programmed to be responsive to their surrounding environment, without any hard-coding assigned? This paper presents the idea of an autonomous system, where the system observes the surrounding environment and takes action on its observation. The application here is that of rebuffing an object that is thrown towards a robotic arm's workspace. This application mimics the idea of high dynamic responsiveness of a robot's arm. This paper will present a trajectory generation framework for rebuffing incoming flying objects. The framework bases its assumptions on inputs acquired through image processing and object detection. After extensive testing, it can be said that the proposed framework managed to fulfil the real-time system requirements for this application, with an 80% successful rebuffing rate. 

  • 9.
    Abdollahifakhr, Hamon
    et al.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Computer Supported Engineering Design.
    Sengul, Ceyhun
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Computer Supported Engineering Design.
    AUTOMATIC DESIGN OF WIRING PATTERN FOR CAR SEAT HEATERS2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This projects aims to develop design automation in product development. Design automation causes increase in producibility and decrease in product cost and manufacturing lead time.

    The study at hand is proposed to provide a new method and to introduce procedure to the design of wiring pattern for a car seat heater for Kongsberg Automotive, KA. KA is a Norwegian company and a global provider of engineering, design, and manufacture for seat comfort, driver and motion control systems, fluid assemblies, and industrial driver interface products. The method that currently is used in the company to create a wiring pattern is neither sufficient enough nor automated.

    In order to design the wiring pattern, at first procedure is handled by the designer. Secondly, car seat heater 2D layout is imported and then, the dimensions of the elements are defined as constraints. Then VBA codes are opened and the program is run. The result will be a wiring pattern in different 2D layouts. To make the design process easier, we have modeled five different layouts; wiring pattern of one element, two elements, three elements, five elements (with two back sides) and one element trapezoidal 2D layout.

    The algorithm written in VBA (Visual basic for application) creates the pattern according to the dimensions of the elements which are used as inputs to define constrained parameters. The created macros are simple to use and easy to modify, independent from the programming knowledge. The user is only responsible with parameter input and running the program. The solution gives wiring pattern for a car seat heater.

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  • 10.
    Abiri, Olufunminiyi
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Non-local models in manufacturing simulations2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ductile fracture presents challenges with respect to material modelling andnumerical simulations of localization. The strain and damage localization maybe unwanted as it indicates a failure in the process or, as in the case ofmachining and cutting, a wanted phenomenon to be controlled. The latterrequires a higher accuracy regarding the modelling of the underlying coupledplastic and fracturing/damage behaviour of the material, metal in the currentcontext as well as the stability and robustness of the simulation procedure.This aim of this work is to develop, evaluate and implement formulations thatcan efficiently and reliably handle localization problems in machiningsimulations. The focus is on non-local models. The non-local models extendthe standard continuum mechanics theory by using non-local continuumtheory in order to achieve mesh independent results when simulating fractureor shear localization.The non-local damage model is implemented and various formulations areevaluated in a Matlab™ based finite element code. The chosen algorithm wasthen implemented in commercial software. The implementations remedy themesh sensitivity problem and gives convergent solution for metal cuttingsimulations with reasonable cost. The length scale associated with the nonlocalmodels are in the current context considered as a numericalregularization parameter. The model has been applied in machiningsimulations and compared with measurements from industry.Keywords: Finite element simulation; Non-local damage; Plasticity; Machining

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  • 11.
    Abiri, Olufunminiyi
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Simplifications of non-local damage models2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ductile fracture presents challenges with respect to material modelling and numerical simulations of localization. The strain and damage localization may be unwanted as it indicates a failure in the process or, as in the case of machining and cutting, a wanted phenomenon to be controlled. The latter requires a higher accuracy regarding the modelling of the underlying coupled plastic and fracturing/damage behaviour of the material, metal in the current context as well as the robustness of the simulation procedure. The focus of this thesis is on efficient and reliable finite element solution of the localization problem through the non-local damage model. The non-local damage model extends the standard continuum mechanics theory by using non-local continuum theory in order to achieve mesh independent results when simulating fracture or shear localization. In this work, the non-local damage model and its various simplifications are evaluated in an in-house finite element code developed using Matlab™. The accuracy, robustness, efficiency and costs of the models are investigated and also compared to a general multi-length scale finite element formulation. A numerical study versus published data is used to demonstrate the validity of the model. The explicit non-local damage variant will be implemented in a commercial finite element code for use in machining simulation

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  • 12.
    Abiri, Olufunminiyi
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Non-local damage models in manufacturing simulations2013Conference paper (Refereed)
    Abstract [en]

    Localisation of deformation is a problem in several manufacturing processes. Machining is an exception where it is a wanted feature. However, it is always a problem in finite element modelling of these processes due to mesh sensitivity of the computed results. The remedy is to incorporate a length scale into the numerical formulations in order to achieve convergent solutions. Different simplifications in the implementation of a non-local damage model are evaluated with respect to temporal and spatial discretisation to show the effect of different approximations on accuracy and convergence.

  • 13.
    Abiri, Olufunminiyi
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Non-local damage models in manufacturing simulations2015In: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 49, p. 548-560Article in journal (Refereed)
    Abstract [en]

    Localisation of deformation is a problem in several manufacturing processes. Machining is an exception where it is a wanted feature. However, it is always a problem in finite element modelling of these processes due to mesh sensitivity of the computed results. The remedy is to incorporate a length scale into the numerical formulations in order to achieve convergent solutions. Different simplifications in the implementation of a non-local damage model are evaluated with respect to temporal and spatial discretisation to show the effect of different approximations on accuracy and convergence.

  • 14.
    Abiri, Olufunminiyi
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Qin, Hao
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Comparison of Multiresolution Continuum Theory and Nonlocal Dame model for use in Simulation of Manufacutring Processes2016In: International Journal for Multiscale Computational Engineering, ISSN 1543-1649, Vol. 14, no 1, p. 81-94Article in journal (Refereed)
    Abstract [en]

    Modelling and simulation of manufacturing processes may require the capability to account for localization behavior, often associated with damage/fracture. It may be unwanted localization indicating a failure in the process or, as in the case of machining and cutting, a wanted phenomenon to be controlled. The latter requires a higher accuracy regarding the modelling of the underlying physics, as well as the robustness of the simulation procedure. Two different approaches for achieving mesh-independent solutions are compared in this paper. They are the multiresolution continuum theory (MRCT) and nonlocal damage model. The MRCT theory is a general multilength-scale finite element formulation, while the nonlocal damage model is a specialized method using a weighted averaging of softening internal variables over a spatial neighborhood of the material point. Both approaches result in a converged finite element solution of the localization problem upon mesh refinement. This study compares the accuracy and robustness of their numerical schemes in implicit finite element codes for the plane strain shear deformation test case. Final remarks concerning ease of implementation of the methods in commercial finite element packages are also given.

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  • 15.
    Abiri, Olufunminiyi
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials. National Mathematical Centre, Gwagwalada, Abuja, Nigeria.
    Svoboda, Ales
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Wedberg, Dan
    AB Sandvik Coromant, Sandviken, Sweden.
    Controlling Thermal Softening Using Non-Local Temperature Field in Modelling2016In: Journal of Machining and Forming Technologies, ISSN 1947-4369, Vol. 8, no 1-2, p. 13-28Article in journal (Refereed)
    Abstract [en]

    One of the aims of this work is to show that thermal softening due to the reduced flow strength of a material with increasing temperature may cause chip serrations to form during machining. The other purpose, the main focus of the paper, is to demonstrate that a non-local temperature field can be used to control these serrations. The non-local temperature is a weighted average of the temperature field in the region surrounding an integration point. Its size is determined by a length scale. This length scale may be based on the physics of the process but is taken here as a regularization parameter.

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  • 16.
    Abiri, Olufunminiyi
    et al.
    Institute of Intelligent Systems, University of Johannesburg.
    Wedberg, Dan
    AB Sandvik Coromant.
    Svoboda, Ales
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Non-Local Modelling of Strain Softening in Machining Simulations2017In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 225, article id 012053Article in journal (Refereed)
    Abstract [en]

    Non-local damage model for strain softening in a machining simulation is presented in this paper. The coupled damage-plasticity model consists of a physically based dislocation density model and a damage model driven by plastic straining in combination with the stress state. The predicted chip serration is highly consistent with the measurement results. 

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  • 17.
    Abuhussain, Mohammed Awad
    et al.
    Architectural Engineering Department, College of Engineering, Najran University, Najran, Saudi Arabia.
    Ahmad, Ayaz
    Department of Civil Engineering, COMSATS University Islamabad, Abbottabad 22060, Pakistan.
    Amin, Muhammad Nasir
    Department of Civil and Environmental Engineering, College of Engineering, King Faisal University, Al-Ahsa 31982, Saudi Arabia.
    Althoey, Fadi
    Department of Civil Engineering, College of Engineering, Najran University, Najran, Saudi Arabia.
    Gamil, Yaser
    Department of Civil Engineering, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, 47500 Bandar Sunway, Selangor, Malaysia.
    Najeh, Taoufik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Data-driven approaches for strength prediction of alkali-activated composites2024In: Case Studies in Construction Materials, E-ISSN 2214-5095, Vol. 20, article id e02920Article in journal (Refereed)
    Abstract [en]

    Alkali-activated composites (AACs) have attracted considerable interest as a promising alternative to reduce CO2 emissions from Portland cement production and advance the decarbonisation of concrete construction. This study describes the data-driven predictive modelling to anticipate the compressive strength (CS) of AACs. Four different modelling techniques have been chosen to forecast the CS of AACs using the selected data set. The decision tree (DT), multi-layer perceptron (MLP), bagging regressor (BR), and AdaBoost regressor (AR) were employed to investigate the precision level of each model. When it comes to predicting the CS of AACs, the results show that the AR model performs better than the BR model, the MLP model, and the DT model by providing a higher value for the coefficient of determination, which is equal to 0.91, and a lower MAPE value, which is equal to 13.35%. However, the accuracy level of the BR model was very near to that of the AR model, with the R2 value suggesting a value of 0.90 and the MAPE value indicating a value of 14.43%. Moreover, the graphical user interface has also been developed for the strength prediction of alkali-activated composites, making it easy to get the required output from the selected inputs.

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  • 18.
    Adamopoulos, Stergios
    TEI Thessaly, Greece.
    Recovery and utilization of wood and rubber at the end of their lifespan to produce innovative products2014In: Development and Business Prospects in Thessaly by Symbiotic Utilization of Agricultural and Industrial Solid Waste to Produce Materials and Energy, November 24, Larissa, Greece, 2014Conference paper (Other academic)
  • 19.
    Addassi, Mouadh
    et al.
    Technical University of Denmark, Denmark.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Wadsö, Lars
    Lund University, Sweden.
    Inverse analyses of effective diffusion parameters relevant for a two-phase moisture model of cementitious materials2018In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 106, p. 117-129Article in journal (Refereed)
    Abstract [en]

    Here we present an inverse analyses approach to determining the two-phase moisture transport properties re-levant to concrete durability modeling. The purposed moisture transport model was based on a continuumapproach with two truly separate equations for the liquid and gas phase being connected by the sorption ki-netics. The moisture properties of ten binder-systems containingfly ash, calcined clay, burnt shale and graymicro-filler, were investigated experimentally. The experiments used were, (i) sorption test (moisturefixation),(ii) cup test in two different relative humidity intervals, (iii) drying test, and, (iv) capillary suction test. Masschange over time, as obtained from the drying test, the two different cup test intervals and the capillary suctiontest, was used to obtain the effective diffusion parameters using the proposed inverse analyses approach. Themoisture properties obtained with the proposed inverse analyses method provide a good description of the testperiod for the ten different binder-systems.

  • 20.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthesis of reactive soybean oils for use as thermoset resins in composites.2007Conference paper (Refereed)
  • 21.
    Adolfi, Sofia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Slag inclusion formation during solidification of steel alloys and in cast iron2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis explores the formation of segregation and inclusions during solidification of steel and cast iron. A better understanding of the formation mechanism should result in decreasing fraction of defects during solidification of ingot and strand material.

    Density driven macrosegregation was studied both experimentally and theoretically to see the effect of channel segregation on the total segregation. Formation of these pencil-like segregations is due to natural convection in the solidifying metal caused by liquid enrichment of elements with lower density compared to the bulk. It is suggested to change the composition to compensate for this density difference.

    Inclusion precipitation can be finite by limitations in segregation. Saturated liquid is found in the last solidified areas, often between dendrites. Here the enrichment of the liquid is possible due to microsegregation. Meanwhile crystals form and solidify the elements with low solubility in the solid is pushed out in the remaining liquid. Soon the liquid is saturated to the level where spontaneous formation of inclusions occurs. Microstructure studies by aid of SEM and micro-probe measurements are analysed to find at what point during solidification process the inclusions start to form. In steel making this formation has a detrimental effect on the mechanical properties in contrary to the production of nodular cast iron where the inclusions have a beneficial effect on the graphite formation.

    Inoculation of cast iron aims at reaching higher number density of graphite nodules, nodule morphology modification and control of nodule distribution during solidification. Late precipitation of nucleation sites has shown to have a positive impact on preventing chill. To find the most potent inoculation agent different additives were tested. Special effort has been made to analyse the effect of oxides and sulphides as nucleation sites.

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  • 22.
    Adolfsson, Robin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Jönsson, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Är SundaHus materialklassning kompatibel med Miljöbyggnads, BREEAMs och LEEDs materialkrav?: En studie om SundaHus miljöklassningar.2015Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    We live in a society where there is a shortage of housing and the demand for new and sustainable buildings is growing. The houses that are being built today are focused on being energy efficient to save resources. Something that is forgotten is the choice of materials to house constructions. Materials can affect nature and people from the cradle to the grave by for example material hazardous components. The certification systems Miljöbyggnad, BREEAM and LEED have been checked and their material criteria have been defined. Through a selection of construction materials taken from SundaHus a review has been made of these materials towards the certification systems´ criteria on materials to see if they are compatible. The minority of the criteria were reviewed to separate materials and could be verified in SundaHus. Almost all materials passed the criteria that could be used of Miljöbyggnad and BREEAM regardless of classification in SundaHus. None of the LEED criteria were compatible with SundaHus for separate materials. The fact that the worse classifications in SundaHus could pass the criteria that were reviewed indicates that the requirements in environmental certification systems are too low. Higher and more demands should be made on individual materials and the hazardous substances in them.

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  • 23.
    Afshar, R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Stjärnesund, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Gamstedt, E. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Girlanda, O.
    Hitachi Energy Res Sweden, Västerås, Sweden.
    Sahlen, F.
    ABB Corp Res, Västerås, Sweden.
    Tjahjanto, D.
    NKT HV Cables Abtechnol Consulting, Västerås, Sweden.
    A micro-CT investigation of densification in pressboard due to compression2023In: Strain, ISSN 0039-2103, E-ISSN 1475-1305, Vol. 59, no 4, article id 12442Article in journal (Refereed)
    Abstract [en]

    As a non-destructive inspection method, micro-computed tomography has been employed for determining local properties of a cellulose-based product, specifically pressboard. Furthermore, by utilizing the determined properties in a detailed numerical model, by means of a finite element analysis, we demonstrate a continuum anisotropic viscoelastic-viscoplastic model. Through such a combination of non-invasive experiments with accurate computations in mechanics, we attain a better understanding of materials and its structural integrity at a pre-production stage increasing the success of the first prototype. In detail, this combination of micro-computed tomography and finite element analysis improves accuracy in predicting materials response by taking into account the local material variations. Specifically, we have performed indentation tests and scanned the internal structure of the specimen for analysing the densification patterns within the material. Subsequently, we have used a developed material model for predicting the response of material to indentation. We have computed the indentation test itself by simulating the mechanical response of high-density cellulose-based materials. In the end, we have observed that pressboard, having initially a heterogeneous density distribution through the thickness, shows a shift in the densification to the more porous part after indentation. The densification maps of the simulated results are presented by comparing with the experimental results. A reasonable agreement is observed between the experimental and the simulated densifications patterns, which suggests that the proposed methodology can be used to predict densification also for other fibre-based materials during manufacturing or in service loading.

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  • 24.
    Afshar, Reza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics. Uppsala University.
    Cheylan, Matthieu
    École Nationale Supérieure de Mécanique et des Microtechniques, Besançon.
    Almkvist, Gunnar
    Department of Molecular Sciences, Swedish University of Agricultural Sciences.
    Ahlgren, Anders
    The Swedish National Maritime and Transport Museums, The Vasa Museum.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics. Uppsala University.
    Creep in oak material from the Vasa ship:: verification of linear viscoelasticity and identification of stress thresholds2020In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 78, no 6, p. 1095-1103Article in journal (Refereed)
    Abstract [en]

    Creep deformation is a general problem for large wooden structures, and in particular for shipwrecks in museums. In this study, experimental creep data on the wooden cubic samples from the Vasa ship have been analysed to confrm the linearity of the viscoelastic response in the directions where creep was detectable (T and R directions). Isochronous stress–strain curves were derived for relevant uniaxial compressive stresses within reasonable time spans. These curves and the associated creep compliance values justify that it is reasonable to assume a linear viscoelastic behaviour within the tested ranges, given the high degree of general variability. Furthermore, the creep curves were ftted with a one-dimensional standard linear solid model, and although the rheological parameters show a fair amount of scatter, they are candidates as input parameters in a numerical model to predict creep deformations. The isochronous stress–strain relationships were used to defne a creep threshold stress below which only negligible creep is expected. These thresholds ranges were 0.3–0.5 MPa in the R direction and 0.05–0.2 MPa in the T direction.

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  • 25.
    Afshari, Davood
    et al.
    Univ Zanjan, Zanjan 4537138791, Iran..
    Mirzaahamdi, Soheil
    Univ Zanjan, Zanjan 4537138791, Iran..
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Residual Stresses in Resistance Spot Welded AZ61 Mg Alloy2019In: CMES - Computer Modeling in Engineering & Sciences, ISSN 1526-1492, E-ISSN 1526-1506, Vol. 118, no 2, p. 275-290Article in journal (Refereed)
    Abstract [en]

    The use of magnesium alloys has been rapidly increased due to their ability to maintain high strengths at light weights. However weldability of steels and aluminum alloys by using resistance spot weld (RSW) process is a major issue, because it cannot be directly utilized for magnesium alloys. In this study, a structural-thermal-electrical finite element (FE) model has been developed to predict the distribution of residual stresses in RSW AZ61 magnesium alloy. Thermophysical and thermomechanical properties of AZ61 magnesium alloy have been experimentally determined, and have been used in FE model to increase the accuracy of the model. X-ray diffraction (XRD) technique has been utilized to measure the residual stresses in welded samples, and its results have been used to validate the FE model. Comparison study shows that the results obtained by using FE model have a good agreement with the experimental XRD data. In specific, the results show that the maximum tensile residual stress occurs at the weld center while decreases towards the nugget edge. In addition, the effects of welding parameters such as electrical current, welding time, and electrode force have been investigated on the maximum tensile residual stress. The results show that the tensile residual stress in welded joints rises by increasing the electrical current; however, it declines by prolonging the welding time as well as increasing the electrode force.

  • 26.
    Agde Tjernlund, Jessica
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Length-scale effects in yielding and damage development in polymer materials2005Licentiate thesis, comprehensive summary (Other scientific)
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  • 27.
    Agde Tjernlund, Jessica
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Gamstedt, Kristofer
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Gudmundson, Peter
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Length-scale effects on damage development in tensile loading of glass-sphere filled epoxy2006In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 43, no 24, p. 7337-7357Article in journal (Refereed)
    Abstract [en]

    Particle-reinforced polymers are widely used in load-carrying applications. The effect of particle size on damage development in the polymer is still relatively unexplored. In this study, the effect of glass-sphere size on the damage development in tensile loaded epoxy has been investigated. The diameter of the glass spheres ranged from approximately 0.5-50 mu m. The first type of damage observed was debonding at the sphere poles, which subsequently grew along the interface between the glass spheres and epoxy matrix. These cracks were observed to kink out into the matrix in the radial direction perpendicular to the applied load. The debonding stresses increased with decreasing sphere diameter, whereas the length to diameter ratio of the resulting matrix cracks increased with increasing sphere diameter. These effects could not be explained by elastic stress analysis and linear-elastic fracture mechanics. Possible explanations are that a thin interphase shell may form in the epoxy close to the glass spheres, and that there is a length-scale effect in the yield process which depends on the strain gradients. Cohesive fracture processes can contribute to the influence of sphere size on matrix-crack length. Better knowledge on these underlying size-dependent mechanisms that control damage development in polymers and polymer composites is useful in development of stronger materials. From a methodology point of view, the glass-sphere composite test can be used as an alternative technique (although still in a qualitative way) to hardness vs. indentation depth to quantify length-scale effects in inelastic deformation of polymers.

  • 28.
    Agde Tjernlund, Jessica
    et al.
    KTH, Superseded Departments (pre-2005), Solid Mechanics.
    Gamstedt, Kristofer
    KTH, Superseded Departments (pre-2005), Solid Mechanics.
    Xu, Zhi-Hui
    KTH, Superseded Departments (pre-2005), Materials Science and Engineering.
    Influence of molecular weight on strain-gradient yielding in polystyrene2004In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 44, no 10, p. 1987-1997Article in journal (Refereed)
    Abstract [en]

    Experimental observations have indicated that the presence of strain gradients has an influence on the inelastic behavior of polymers as well as in other materials such as ceramics and metals. The present study has experimentally quantified length-scale effects in inelastic deformations of the polymer material polystyrene (PS) with respect to the molecular length. The experimental technique that has been used is nano-indentation to various depths with a Berkovich indenter. The hardness has been calculated with the method by Oliver and Pharr, and also by direct measurements of the area from atomic force microscopy. The experiments showed that the length-scale effects in inelastic deformations exist in polystyrene at ambient conditions. The direct method gave a smaller hardness than the Oliver-Pharr method. It was also shown that the length-scale parameter according to Nix and Gao increases with increasing molecular weight. For high molecular weights above a critical value of entanglement, there was no pertinent increase in the length-scale parameter. The length-scale parameter for strain-gradient plasticity has a size of around 0.1 μm for polystyrene.

  • 29.
    Agelet de Saracibar, Carlos
    et al.
    ETS Ingenieros de Caminos, Canales y Puertos, Universidad Politécnica de Cataluña, Barcelona Tech, Barcelona, Spain; International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Chiumenti, Michele
    ETS Ingenieros de Caminos, Canales y Puertos, Universidad Politécnica de Cataluña, Barcelona Tech, Barcelona, Spain; International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
    Cervera, Miguel
    ETS Ingenieros de Caminos, Canales y Puertos, Universidad Politécnica de Cataluña, Barcelona Tech, Barcelona, Spain; International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
    Shaped Metal Deposition Processes2014In: Encyclopedia of Thermal Stresses, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 4347-4355Chapter in book (Refereed)
    Abstract [en]

    The shaped metal deposition (SMD) process is a novel manufacturing technology which is similar to the multi-pass welding used for building features such as lugs and flanges on components [1–7]. This innovative technique is of great interest due to the possibility of employing standard welding equipment without the need for extensive new investment [8, 9]. The numerical simulation of SMD processes has been one of the research topics of great interest over the last years and requires a fully coupled thermo-mechanical formulation, including phase-change phenomena defined in terms of both latent heat release and shrinkage effects [1–6]. It is shown how computational welding mechanics models can be used to model SMD for prediction of temperature evolution, transient, as well as residual stresses and distortions due to the successive welding layers deposited. Material behavior is characterized by a thermo-elasto-viscoplastic constitutive model coupled with a metallurgical model [6]. Two different materials, nickel superalloy 718 [6] and titanium Ti-6Al-4 V [7], are considered in this work. Both heat convection and heat radiation models are introduced to dissipate heat through the boundaries of the component. The in-house-developed coupled thermo-mechanical finite element (FE) software COMET [10] is used to deal with the numerical simulation, and an ad hoc activation methodology is formulated to simulate the deposition of the different layers of filler material.

  • 30.
    Aghda, Soheil Karimi
    et al.
    Rhein Westfal TH Aachen, Germany.
    Bogdanovski, Dimitri
    Rhein Westfal TH Aachen, Germany.
    Lo, Lukas
    Sua, Heng Han
    Rhein Westfal TH Aachen, Germany.
    Patterer, Lena
    Rhein Westfal TH Aachen, Germany.
    Holzapfel, Damian M.
    Rhein Westfal TH Aachen, Germany.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hans, Marcus
    Rhein Westfal TH Aachen, Germany.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Germany.
    Valence electron concentration- and N vacancy-induced elasticity in cubic early transition metal nitrides2023In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 255, article id 119078Article in journal (Refereed)
    Abstract [en]

    Motivated by frequently reported deviations from stoichiometry in cubic transition metal nitride (TMNx) thin films, the effect of N-vacancy concentration on the elastic properties of cubic TiNx, ZrNx, VNx, NbNx, and MoNx (0.72 & LE; x & LE; 1.00) is systematically studied by density functional theory (DFT) calculations. The predictions are validated experimentally for VNx (0.77 & LE; x & LE; 0.97). The DFT results indicate that the elastic behavior of the TMNx depends on both the N-vacancy concentration and the valence electron concentration (VEC) of the transition metal: While TiNx and ZrNx exhibit vacancy-induced reductions in elastic modulus, VNx and NbNx show an increase. These trends can be rationalized by considering vacancy-induced changes in elastic anisotropy and bonding. While introduction of N-vacancies in TiNx results in a significant reduction of elastic modulus along all directions and a lower average bond strength of Ti-N, the vacancy-induced reduction in [001] direction of VNx is overcompensated by the higher stiffness along [011] and [111] directions, resulting in a higher average bond strength of V-N. To validate the predicted vacancy-induced changes in elasticity experimentally, close-to-singlecrystal VNx (0.77 & LE; x & LE; 0.97) are grown on MgO(001) substrates. As the N-content is reduced, the relaxed lattice parameter a0, as probed by X-ray diffraction, decreases from 4.128 & ANGS; to 4.096 & ANGS;. This reduction in lattice parameter is accompanied by an anomalous 11% increase in elastic modulus, as determined by nanoindentation. As the experimental data agree with the predictions, the elasticity enhancement in VNx upon N-vacancy formation can be understood based on the concomitant changes in elastic anisotropy and bonding.

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  • 31.
    Aghdam, Araz Sheibani
    et al.
    Sabanci Univ, Fac Engn & Nat Sci, TR-34956 Istanbul, Turkey..
    Ghorbani, Morteza
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems. Sabanci Univ, Fac Engn & Nat Sci, Mechatron Engn Program, TR-34956 Istanbul, Turkey;Sabanci Univ, Ctr Excellence Funct Surfaces & Interfaces NanoDi, TR-34956 Istanbul, Turkey..
    Deprem, Gokberk
    Sabanci Univ, Fac Engn & Nat Sci, Mechatron Engn Program, TR-34956 Istanbul, Turkey..
    Cebeci, Fevzi Cakmak
    Sabanci Univ, Fac Engn & Nat Sci, TR-34956 Istanbul, Turkey.;Sabanci Univ, SUNUM Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey..
    Kosar, Ali
    Sabanci Univ, Fac Engn & Nat Sci, Mechatron Engn Program, TR-34956 Istanbul, Turkey.;Sabanci Univ, Ctr Excellence Funct Surfaces & Interfaces NanoDi, TR-34956 Istanbul, Turkey.;Sabanci Univ, SUNUM Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey..
    A New Method for Intense Cavitation Bubble Generation on Layer-by-Layer Assembled SLIPS2019In: Scientific Reports, E-ISSN 2045-2322, Vol. 9, article id 11600Article in journal (Refereed)
    Abstract [en]

    The importance of surface topology for the generation of cavitating flows in micro scale has been emphasized during the last decade. In this regard, the utilization of surface roughness elements is not only beneficial in promoting mass transportation mechanisms, but also in improving the surface characteristics by offering new interacting surface areas. Therefore, it is possible to increase the performance of microfluidic systems involving multiphase flows via modifying the surface. In this study, we aim to enhance generation and intensification of cavitating flows inside microfluidic devices by developing artificial roughness elements and trapping hydrophobic fluorinated lubricants. For this, we employed different microfluidic devices with various hydraulic diameters, while roughness structures with different lengths were formed on the side walls of microchannel configurations. The surface roughness of these devices was developed by assembling various sizes of silica nanoparticles using the layer-by-layer technique (D2). In addition, to compare the cavitating flow intensity with regular devices having plain surfaces (D1), highly fluorinated oil was trapped within the pores of the existing thin films in the configuration D2 via providing the Slippery Liquid-Infused Porous Surface (D3). The microfluidic devices housing the short microchannel and the extended channel were exposed to upstream pressures varying from 1 to 7.23 MPa. Cavitation inception and supercavitation condition occured at much lower upstream pressures for the configurations of D2 and D3. Interestingly, hydraulic flip, which rarely appears in the conventional conical nozzles at high pressures, was observed at moderate upstream pressures for the configuration D2 proving the air passage existence along one side of the channel wall.

  • 32.
    Aguilar Sánchez, Andrea
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Jalvo, Blanca
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nano-cellulose coatings for antifouling polyethersulfone (PES) membranes2019Conference paper (Refereed)
  • 33.
    Aguilar-Mamani, Wilson
    et al.
    Department of Chemistry, Faculty of Science and Technology, San Simon University, UMSS, Cochabamba.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment2018In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 487, p. 57-64Article in journal (Refereed)
    Abstract [en]

    The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.

  • 34.
    Aguilar-Sánchez, Andrea
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Jalvo, Blanca
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nano-cellulose coatings for antifouling and mechanically enhanced polyethersulfone (PES) membranes2019In: Nordic Polymer Days 2019: Book of Abstracts / [ed] Rita de Sousa Dias, Sulalit Bandyopadhyay, 2019, p. 92-92Conference paper (Refereed)
    Abstract [en]

    Membrane technology is commonly used for filtration processes of industrial wastewater. Using membranes for water filtration is a safe and energy efficient solution. One of the main problems that arises during the usage of membranes is the fouling effects. Fouling increases the membrane separation resistance, reduces productivity due to a flux decline and affect membrane selectivity. These effects can be avoid by modifying the surface of the membranes using bio-based materials such as nano-cellulose. Nano-cellulose is a great example of a material obtained from renewable resources, which provides high reinforcement and antifouling properties to membranes.

    The aim of this work was the development of coatings with cellulose nano-crystals (CNC) and Tempooxidized cellulose nano-fribrils (T-CNF) using polyvinyl-alcohol (PVOH), as binding phase to enhance mechanical and antifouling properties over pure commercial PES membranes. The coatings were chemically crosslinked to increase mechanical properties and to improve stability of the coating and avoid swelling. It is expected that by avoiding swelling, permeability remains stable through time. All coating formulations remained stable after 10 hours of crossflow filtration. Mechanical properties of the coated membranes were improved in both dry and wet conditions, showing higher values of tensile strenght and E modulus compared to the uncoated ones. In addition, coated membranes showed high hydrophilicity and low adherence of bovine serum albumin (BSA).

    The coatings developed showed stability over PES membranes and provide them with a nanostructured surface which showed an extended durability in use. The modified surface membranes presented good mechanical properties in dry and wet conditions, high flux, high hydrophilicity, resistance to BSA fouling and to different pH environments. Moreover, these modified membranes showed promising results for fast upscaling at industrial level due to the simplicity of the coating process and the availability of the materials in the market.

  • 35.
    Ahmadkhaniha, Donya
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Huang, Y.
    University of Southampton, Southampton, UK.
    Jaskari, M.
    University of Oulu, Nivala, Finland.
    Järvenpää, A.
    University of Oulu, Nivala, Finland.
    Heydarzadeh Sohi, M.
    University of Tehran, Tehran, Iran.
    Zanella, Caterina
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Karjalainen, L.P.
    University of Oulu, Oulu, Finland.
    Langdon, T.G.
    University of Southampton, Southampton, UK..
    Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg2017Conference paper (Refereed)
    Abstract [en]

    High-pressure torsion (HPT) processing was applied to cast pure Mg pieces and its effects on microstructure, hardness and tensile properties as well as corrosion resistance were evaluated. The microstructure of the processed samples was examined by electron backscatter diffraction (EBSD) and the mechanical properties were determined by microhardness and tensile tests. Corrosion resistance of the samples was studied via electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results showed that HPT refined the grain size of Mg very effectively from millimeters in the cast structure to a few micrometers homogeneously through the thickness and created a basal texture on the surface. One or five turns of HPT produced no significant difference in the grain size of the processed Mg but the hardness was a maximum after one turn. The yield strength of the cast Mg was increased by seven times whereas the corrosion resistance was not affected by the HPT processing.

  • 36.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Hansson, Lars
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Distribution of preservatives in thermally modified Scots pine and Norway spruce sapwood2013In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 47, no 3, p. 499-513Article in journal (Refereed)
    Abstract [en]

    Studying the impregnation and distribution of oil-based preservative in dried wood is complicated as wood is a nonhomogeneous, hygroscopic and porous material, and especially of anisotropic nature. However, this study is important since it has influence on the durability of wood. To enhance the durability of thermally modified wood, a new method for preservative impregnation is introduced, avoiding the need for external pressure or vacuum. This article presents a study on preservative distribution in thermally treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) sapwood using computed tomography scanning, light microscopy, and scanning electron microscopy. Secondary treatment of thermally modified wood was performed on a laboratory scale by impregnation with two types of preservatives, viz. Elit Träskydd (Beckers) and pine tar (tar), to evaluate their distribution in the wood cells. Preservative solutions were impregnated in the wood using a simple and effective method. Samples were preheated to 170 °C in a drying oven and immediately submerged in preservative solutions for simultaneous impregnation and cooling. Tar penetration was found higher than Beckers, and their distribution decreased with increasing sample length. Owing to some anatomical properties, uptake of preservatives was low in spruce. Besides, dry-induced interstitial spaces, which are proven important flow paths for seasoned wood, were not observed in this species.

  • 37.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology, Sweden.
    Morén, Tom
    Luleå University of Technology, Sweden.
    Moisture properties of heat-treated Scots pine and Norway spruce sapwood impregnated with wood preservatives2012In: Wood and Fiber Science, ISSN 0735-6161, Vol. 44, no 1, p. 85-93Article in journal (Refereed)
    Abstract [en]

    An experiment was conducted on commercially heat-treated (HT) Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst.) sapwood collected from Ht Wood AB, Arvidsjaur, Sweden. Secondary treatment on HT wood was performed in laboratory scale by impregnating with water-repellent preservatives (a commercial one and pine tar) to evaluate their retention and different moisture-related properties. Preservative solutions were impregnated using a simple and effective method. Wood samples were heated at 170°C in a dry oven and were immediately immersed in preservative solutions. Considerable retention was observed in HT wood, particularly in pine. Moisture adsorption properties were measured after conditioning in a high-humidity environmental chamber (4°C and 84% RH). Experimental results showed that secondary treatment enhanced moisture excluding efficiencies by decreasing equilibrium moisture content, suggesting better hydrophobicity. Soaking test in water showed that antiswelling and water repellence efficiencies improved, especially in tar-treated wood. In addition, this type of treatment significantly decreased water absorption. It was also possible to decrease volumetric swellings. Thus, secondary treatment of HT wood with preservative, in particular with tar, improved dimensional stability and water repellency.

  • 38.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Hansson, Lars
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Evaluation of preservative distribution in thermally modified European aspen and birch boards using computed tomography and scanning electron microscopy2013In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 59, no 1, p. 57-66Article in journal (Refereed)
    Abstract [en]

    The aim of this experiment was to impregnate thermally modified wood using an easy and cost-effective method. Industrially processed thermally modified European aspen (Populus tremula L.) and birch (Betula pubescens Ehrh.) were collected and secondarily treated at the laboratory scale with the preservatives tung oil, pine tar and Elit Träskydd (Beckers) using a simple and effective method. Preservative uptake and distribution in sample boards were evaluated using computed tomography (CT) and scanning electron microscopy (SEM) techniques. Preservative uptake and treatability in terms of void volume filled were found the highest in Beckers and the lowest in tung oil-treated samples. Thermally modified samples had lower treatability than their counterpart control samples. More structural changes after thermal modification, especially in birch, significantly reduced the preservative uptake and distribution. The differences of preservatives uptake near the end grain were high and then decreased near the mid position of the samples length as compared with similar type of wood sample. Non-destructive evaluation by CT scanning provided a very useful method to locate the preservative gradients throughout the sample length. SEM analysis enabled the visualization of the preservative deposits in wood cells at the microstructural level.

  • 39.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Karlsson, Olov
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Uneven distribution of preservative in kiln-dried sapwood lumber of Scots pine: Impact of wood structure and resin allocation2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 2, p. 251-258Article in journal (Refereed)
    Abstract [en]

    Scots pine (Pinus sylvestris L.) sapwood lumber was collected after kiln drying and preservative treatment with Celcure AC 800 (a copper-amine wood preservative). Distribution of the preservative throughout the lumber was visually examined. Not all, but some samples showed specific localized areas without any preservative distribution throughout their entire length. Those samples were assessed further for anatomical properties, specifically in impregnated and unimpregnated areas. Additional study was conducted on the morphological nature and redistribution of lipophilic extractives using three different histochemical staining methods. Intrinsic wood properties – especially the frequency of axial resin canals and the percentage of canals blocked – were found to be responsible for the irregular distribution of the preservative. Furthermore, the inability to create continuous and frequent interstitial spaces due to the collapse of thin-walled ray cells throughout the lumber resulted in un-even distribution of preservatives. Staining techniques were useful to localize places with more or less abundance of extractives (e.g., fats) in impregnated and unimpregnated wood, which varied considerably. Histochemical observations revealed information pertaining to the kiln dry specific distribution and redistribution of extractives between the areas. Moreover, resin reallocation and modification in ray parenchyma and resin canals induced by kiln drying would be another reason for the impregnation anomalies.

  • 40.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Yang, Qian
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Accelerated Mold Test on Dried Pine Sapwood Boards: Impact of Contact Heat Treatment2013In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 33, no 3, p. 174-187Article in journal (Refereed)
    Abstract [en]

    We test the hypothesis that the combination of kiln drying of double-stacked boards and contact heat treatment will reduce the susceptibility of treated boards to colonization by mold fungi. Winter-felled Scots pine (Pinus sylvestris L.) sapwood boards were double-stacked in an industrial kiln in ''sapwood out'' and ''sapwood in'' positions. Dried samples were then contact heat-treated using a hot press at three different temperatures (140°C, 170°C, and 200°C) for three different periods (1, 3, and 10 min). An accelerated mold test was performed in a climate chamber where naturally mold-infected samples were used as a source of mold inocula. Contact heat treatment degraded the saccharides that accumulated at dried surfaces, and reduced the mold growth. The threshold temperature and time for inhibiting mold growth were 170°C for 10 min. However, for industrial application, the most feasible combination of temperature and time would be 200°C for 3 min. We concluded that double stacking/contact heat treatment used is an environmentally friendly alternative to chemicals for reducing mold on Scots pine sapwood boards.

  • 41.
    Aid, Graham
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Environmental Technology and Management. Ragn-sells, Sweden.
    Kihl, Anders
    Ragn Sells AB.
    Driving forces and inhibitors of secondary stock extraction2014Conference paper (Other academic)
    Abstract [en]

    Even though it’s well known to mankind that our common resources are limited and that recycling is a key for a sustainable future; in reality we see few examples of true recycling where virgin raw material is substituted by waste. There are endless number of examples where waste is utilized to some extent without solving the core issue: reducing the need of extracting virgin raw materials. This article analyses some of the driving forces and inhibitors that explains why it’s so difficult establish secondary stock extraction although technology is available. The authors discuss and suggest possible ways for reducing the some of the main barriers.

    Download full text (pdf)
    fulltext
  • 42.
    Aijaz, Asim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ion induced stress relaxation in dense sputter-deposited DLC thin films2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 111, no 5, article id 051902Article in journal (Refereed)
    Abstract [en]

    Deposition of high-density and low-stress hydrogen-free diamond like carbon (DLC) thin films is demonstrated using a pulsed ionized sputtering process. This process is based on high power impulse magnetron sputtering, and high C ionization is achieved using Ne as the sputtering gas. The intrinsic compressive stress and its evolution with respect to ion energy and ion flux are explained in terms of the compressive stress based subplantation model for DLC growth by Davis. The highest mass density was similar to 2.7 g/cm(3), and the compressive stresses did not exceed similar to 2.5 GPa. The resulting film stresses are substantially lower than those achieved for the films exhibiting similar mass densities grown by filtered cathodic vacuum arc and pulsed laser deposition methods. This unique combination of high mass density and low compressive stress is attributed to the ion induced stress relaxation during the pulse-off time which corresponds to the post thermal spike relaxation timescales. We therefore propose that the temporal ion flux variations determine the magnitude of the compressive stress observed in our films. Published by AIP Publishing.

  • 43. Ajay, A.
    et al.
    Raja, V. S.
    Sivakumar, G.
    Joshi, Shrikant V.
    Hot corrosion behavior of solution precursor and atmospheric plasma sprayed thermal barrier coatings2015In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 98, p. 271-279Article in journal (Refereed)
    Abstract [en]

    Hot corrosion behavior of solution precursor plasma spray (SPPS) thermal barrier coating (TBC) in molten salt mixtures of 90wt.% Na<inf>2</inf>SO<inf>4</inf>+5wt.% V<inf>2</inf>O<inf>5</inf>+5wt.% NaCl and 50wt.% Na<inf>2</inf>SO<inf>4</inf>+50wt.% V<inf>2</inf>O<inf>5</inf> at 900°C is compared vis-à-vis atmospheric plasma spray (APS) coating. APS TBCs show better hot corrosion resistance than SPPS TBCs in both the salt mixtures. The vertical cracks in SPPS coatings, meant for strain tolerance and high thermal cycling life, serve as channels for transporting salts across the coating to bond coat/top coat interface and accelerate failure. © 2015 Elsevier Ltd.

  • 44.
    Akbarnejad, Shahin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Investigation on static strength of welded joints2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Although high strength steels represent yield strength up to 1300 MPa, welded structures reveal lowerstrength values. The strongest commercially available electrode provides the yield strength of about900 MPa. Therefore, in welded steels with strength above this type of filler metal, achieving anacceptable global strength is a crucial issue.

    In this master thesis, affects of different welding procedures on static strength of welded jointsof Weldox 960 and Weldox 1100 steels, were studied. These steels are produced by SSAB inOxelösund. Meanwhile, finite element method analyses were applied in order to investigatethe static strength behavior of such weldments under uniaxial tension.

    The welding parameters which were selected as variables are:

    •  Heat input
    • Weld joint geometry
    • Filler metal

    When weld metal is undermatching in strength levels than the base material, by applyingtension the soft weld metal begins to deform before parent metal. At that point thedeformation of resulted soft zone, including the weld metal and the heat affected zone, ishindered by high strength parent metal. Thus, uniaxial stress caused by uniaxial load isconverted to multiaxial stress. This conversion in tension results in increase in the staticstrength of weldment. The increase in strength is emphasized by increase in the width of thewelded joint while the thickness of the plate is kept as constant.

    After experiments and performing FEM studies, it was revealed that the static strength ofWeldox 960 welded joints approaches towards the tensile strength of parent metal by increasein the width of the weldment. In Weldox 1100 joints; a slight increase in tensile properties ofthe weldments, when the width of the sample increases, was observed.

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    Investigation on static strength of welded joints
  • 45.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kennedy, M. W.
    Fritzsch, R.
    Aune, R. E.
    An Investigation on Permeability of Ceramic Foam Filters (CFF)2015In: Light Metals 2015, Wiley , 2015, p. 949-954Chapter in book (Other academic)
    Abstract [en]

    CFF s are used to filter liquid metal in the aluminum industry. CFFs are classified in grades or pores per inch (PPI), ranging froml0-100 PPI. Their properties vary in everything from pore and strut size to window size. CFFs of 80-100 PPI are generally not practical for use by industry, as priming of the filters by gravitational forces requires an excessive metal head. Recently, co-authors have invented a method to prime such filters using electromagnetic Lorentz forces, thus allowing filters to be primed with a low metal head. In the continuation of this research work, an improved experimental setup was developed in the present study to validate previous results and to measure the permeability of different filters, as well as a stack of filters. The study of permeability facilitates estimation of the required pressure drop to prime the filters and the head required to generate a given casting rate.

  • 46.
    Akhtar, Farid
    Institute of Powder Metallurgy, University of Science & Technology, Beijing.
    A new method to process high strength TiCN stainless steel matrix composites2007In: Powder Metallurgy, ISSN 0032-5899, E-ISSN 1743-2901, Vol. 50, no 3, p. 250-254Article in journal (Refereed)
    Abstract [en]

    Layered composites of Ti(C, N) reinforcements and stainless steel have been prepared successfully by powder technology. The layer composite consisted of two layers. The upper layer consisted of TiCN reinforcements and stainless steel as binder material. The lower layer was entirely of binder material (stainless steel). The micro structural study revealed that the upper layer (TiCN/465 stainless steel) showed core–rim microstructure of conventional cermets and the lower layer showed the structure of sintered steel. An intermediate layer was formed due to diffusion reaction of upper and lower layers. This intermediate layer showed a gradient microstructure. The bending strength of the layered material measured was remarkably higher. Ninety per cent increase in the bending strength in the case of 50 wt-% reinforcement in the upper layer was found. The fracture morphologies of upper, lower and intermediate layers are also reported

  • 47.
    Akhtar, Farid
    Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore.
    An investigation on the solid state sintering of mechanically alloyed nano-structured 90W--Ni--Fe tungsten heavy alloy2008In: International journal of refractory metals & hard materials, ISSN 0263-4368, Vol. 26, no 3, p. 145-151Article in journal (Refereed)
    Abstract [en]

    In this study, 90W–7Ni–3Fe heavy alloy was investigated for its microstructure development, mechanical properties and fracture behavior after solid state sintering. The nano-sized powders were synthesized by mechanical alloying (MA). The microstructure of solid state sintered heavy alloys consisted of tungsten matrix. The average tungsten grain size in the range of 1.7–3.0 μm was obtained. It was found that the grain size largely affected the mechanical properties. Tensile strength more than 1200 MPa was achieved at a sintering temperature of 1350 °C. Fracture mechanisms based on microscopical observations on the fracture surfaces were studied. Matrix failure, tungsten-intergranular cleavage and tungsten–matrix interfacial separation were found to be the possible failure mechanisms.

  • 48.
    Akhtar, Farid
    Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore.
    Carbide reinforced steel matrix composites2009In: Recent Research Developments in Materials Science, Research Signpost, 2009Chapter in book (Refereed)
  • 49.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ceramic reinforced high modulus steel composites: processing, microstructure and properties2014In: Canadian metallurgical quarterly, ISSN 0008-4433, E-ISSN 1879-1395, Vol. 53, no 3, p. 253-263Article in journal (Refereed)
    Abstract [en]

    Ceramic reinforced steel matrix composites are materials for automotive, aerospace, wear and cutting applications. Such metal matrix composites (MMCs) combine attractive physical, mechanical and wear properties with ease of fabrication and low cost. The review focuses on the current state of the art of producing these metal matrix composites, ceramics reinforcements, composition of steel matrix, microstructure evolution and parameters influencing the mechanical and wear properties. Processing methods to fabricate ceramic reinforced steel matrix composites are discussed to produce these composites with low number of defects, homogeneous microstructure and high mechanical and wear performance. The influence of chemical nature of ceramic reinforcements and composition of steel matrix on the microstructure, mechanical and wear properties is presented. The strengthening mechanisms and parameters controlling wear performance of steel MMCs are described as a function of the content of ceramic reinforcements, microstructural design and structure of the steel matrix. Keeping in view the stability of ceramics in steels, suitable ceramic reinforcements and steel matrix materials are discussed. Moreover, the importance of microstructure and interface between ceramic reinforcement and steel matrix in controlling the mechanical properties of steel MMCs is highlighted. The review identifies area of research for development to fully appreciate and tailor the properties of these industrially important composites.

  • 50.
    Akhtar, Farid
    Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore.
    Effect of additive Cu-10Sn alloy on sintering Behavior of elemental powders in composition of 465 stainless steel2007In: Journal of Iron and Steel Research International, ISSN 1006-706X, E-ISSN 2210-3988, Vol. 14, no 4, p. 61-74Article in journal (Refereed)
    Abstract [en]

    The addition of Cu-10Sn alloy for developing the high strength 465 maraging stainless steel from elemental powders was studied. The sintering parameters investigated include the sintering temperature, the sintering time, and the mass percent of Cu-10Sn. For vacuum sintering, effective sintering occurs at temperature between 1250°C and 1300°C. The maximum sintered density was achieved at 1300°C for 60 min with 3% (in mass percent) Cu-10Sn alloy. More than 3% (in mass percent) Cu-10Sn content and temperature above 1300°C caused slumping of the samples. A maximum density of 7.4 g/cm3 was achieved with 3% (in mass percent) Cu-10Sn content at a sintering temperature of 1300°C for 60 min. A maximum ultimate tensile strength (UTS) of 517 MPa was achieved with 3% (in mass percent) Cu-10Sn content. With content higher than 2% (in mass percent) Cu-10Sn, a maximum increase in the density was observed. The fracture morphologies of the sintered samples are also reported.

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