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  • 1.
    Falk, Joel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hannl, Thomas Karl
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-90187 Umeå, Sweden; BEST−Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, AT-8010 Graz, Austria; Institute of Chemical, Environmental & Bioscience Engineering, TU Vienna, AT-1060 Vienna, Austria.
    Ash Transformation during Fixed-Bed Co-combustion of Sewage Sludge and Agricultural Residues with a Focus on Phosphorus2023In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 14, p. 13162-13176Article in journal (Refereed)
    Abstract [en]

    This work investigates the ash transformation during fixed-bed co-combustion of sewage sludge mixtures with the agricultural residues wheat straw and sunflower husks, focusing on the fate of phosphorus (P) in the resulting ash fractions. The study aims to determine suitable process parameters for fixed-bed combustion of fuels previously investigated in single-pellet experiments. The pure fuels and fuel mixtures were combusted in a 20 kWth residential pellet burner while monitoring the flue gas composition, temperature, and particulate matter formation. Subsequently, the different ash fractions were collected and characterized by CHN, SEM/EDS, and XRD analysis. The results showed that co-combustion of sewage sludge and agricultural residues reduced the formation of particulate matter as well as the formation of slag. Co-combustion of sewage sludge with either agricultural residue resulted in a change in phosphate speciation, displaying higher shares of Ca and lower shares of Fe and Al in the formed orthophosphates as well as amorphous phases containing higher shares of K. The formation of K-bearing phosphates was hindered by the spatial association of P with Ca and Fe in the sewage sludge, the incorporation of available K in K-Al silicates, and the depletion of K in the P-rich melt phase. Compared to mono-combustion, co-combustion experiments showed the potential for improving the combustion performance and reducing the risk of slag formation. The outcome suggests that co-combustion is a feasible path to integrate waste streams in fixed-bed energy conversion with simultaneous formation of phosphates enabling P recovery.

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  • 2.
    Forouzan, Farnoosh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gunasekaran, Suresh
    Department for Materials Science, Functional Materials, Saarland University.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mücklich, Frank
    Department for Materials Science, Functional Materials, Saarland University.
    Microstructure analysis and mechanical properties of Low alloy High strength Quenched and Partitioned Steel2016In: MSMF 2016: Materials Structure & Micromechanics of Fracture, 2016Conference paper (Refereed)
  • 3.
    Forouzan, Farnoosh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gunasekaran, Suresh
    Luleå University of Technology.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mücklich, Frank
    Department for Materials Science, Functional Materials, Saarland University, D-66041 Saarbrücken, Germany.
    Microstructure analysis and mechanical properties of Low alloy High strength Quenched and Partitioned Steel2017In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 258, p. 574-578Article in journal (Refereed)
    Abstract [en]

    Gleeble study of the quenching and partitioning (Q&P) process has been performed onDomex 960 steel (Fe, 0.08 %C, 1.79 %Mn, 0.23 %Si, 0.184 %Ti, and 0.038 %Al). The effect ofdifferent Q&P conditions on microstructure and mechanical properties were investigated. The aimof the process is to produce a fine grained microstructure for better ductility and controlled amountsof different micro-constituents to increase the strength and toughness simultaneously. Threedifferent quenching temperatures, three partitioning temperatures and three partitioning times havebeen selected to process the 27 specimens by Gleeble® 1500. The specimens were characterized bymeans of OM, SEM, XRD, hardness and impact tests. It was found that, fine lath martensite withretained austenite is achievable without high amount of Si or Al in the composition although lack ofthese elements may cause the formation of carbides and decrease the available amount of carbon forpartitioning into the austenite. The hardness increases as the quenching temperature is decreased,however, at highest partitioning temperature (640◦C) the hardness increases sharply due to extensiveprecipitate formation.

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  • 4.
    Forouzan, Farnoosh
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Processing of Nano/Submicron Grained Stainless Steel 304L by an Advanced Thermomechanical Process2012In: International Journal of Modern Physics, Conference Series, ISSN 2010-1945, Vol. 5, p. 383-390Article in journal (Refereed)
    Abstract [en]

    Nano/Submicron crystalline grains of about 250 nm were obtained in a metastable austenitic stainless steel AISI304L by an advanced thermomechanical process consisting of heavy conventional cold rolling and annealing. Effects of cold thickness reduction and temperature and time of the reversion treatment on microstructure and mechanical properties of the steel were investigated. The nano-structured austenitic steel exhibited not only high strength (above 1 GPa) but also good elongation (above 50%).

  • 5.
    Forouzan, Farnoosh
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Processing of Nano/Submicron Grained Stainless Steel 304L by an Advanced Thermomechanical Process2009Conference paper (Refereed)
  • 6.
    Forouzan, Farnoosh
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Artificial neural network models for production of nano-grained structure in AISI 304L stainless steel by predicting thermo-mechanical parameters2009In: International Journal of Iron & Steel Society, Vol. 6, no 2, p. 6-13Article in journal (Refereed)
    Abstract [en]

    An artificial neural network (ANN) model is developed for the analysis, simulation, and prediction of the austenite reversion in the thermo-mechanical treatment of 304L austenitic stainless steel. The results of the ANN model are in good agreement with the experimental data. The model is used to predict an appropriate annealing condition for austenite reversion through the martensite to austenite transformation. This model can also be used as a guide for further grain refining and to improve mechanical properties of the AISI 304L stainless steel.

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  • 7.
    Forouzan, Farnoosh
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Optimization of the Thermomechanical Parameters to AISI 304L Stainless Steel using Neural Network2009In: International Journal of Iron & Steel Society of Iran, Vol. 6Article in journal (Refereed)
  • 8.
    Forouzan, Farnoosh
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Simulation of mechanical properties and obtaining nano/submicron AISI 304L stainless steel through the martensite reversion process by using naural network2010Conference paper (Refereed)
  • 9.
    Forouzan, Farnoosh
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Surkialiabad, Roohallah
    Department of Materials Engineering, Isfahan University of Technology.
    Production of nano/submicron grained AISI 304L stainless steel through the martensite reversion process2010In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 527, no 27-28, p. 7334-7339Article in journal (Refereed)
    Abstract [en]

    Production of nano/submicron grained AISI 304L austenitic stainless steel through formation of strain-induced martensite and its reversion to austenite are studied in this paper. The effects of annealing parameters on the microstructural development and mechanical properties are also investigated. Heavily cold rolling at 0 °C is employed to induce the formation of martensite in the metastable austenitic material, followed by reversion treatment at the temperature range of 700-900 °C for 0.5-300. min. Microstructural evolutions are analyzed using Feritscope, X-ray diffraction, and scanning electron microscopy, whereas the mechanical properties are determined by hardness and tensile tests. The smallest grain size (about 135. nm) is obtained in the specimen annealed at 700 °C for 20. min. The resultant nano/submicron grained steel not only exhibits a high strength level (about 1010. MPa) but also a desirable elongation of about 40%. Moreover, an annealing map is developed which indicates the appropriate range of annealing parameters for grain refinement of AISI 304L stainless steel through the martensite reversion process.

  • 10.
    Forouzan, Farnoosh
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmed
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Simulation of mechanical properties and obtaining nano/submicron AISI 304L stainless steel through the martensite reversion process by using naural network2010Conference paper (Refereed)
  • 11.
    Forouzan, Farnoosh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Surki Aliabad, Roohallah
    Materials and Mechanical Engineering, University of Oulu, Oulu, 90014, Finland.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hosseini, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Maawad, Emad
    Helmholtz-Zentrum Hereon, Institute of Materials Physics, Max-Planck-Straße 1, Geesthacht, 21502, Germany.
    Blasco, Nuria
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Kinetics of Carbon Enrichment in Austenite during Partitioning Stage Studied via In-Situ Synchrotron XRD2023In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 16, no 4, article id 1557Article in journal (Refereed)
    Abstract [en]

    The present study reveals the microstructural evolution and corresponding mechanisms occurring during different stages of quenching and partitioning (Q&P) conducted on 0.6C-1.5Si steel using in-situ High Energy X-Ray Diffraction (HEXRD) and high-resolution dilatometry methods. The results support that the symmetry of ferrite is not cubic when first formed since it is fully supersaturated with carbon at the early stages of partitioning. Moreover, by increasing partitioning temperature, the dominant carbon source for austenite enrichment changes from ongoing bainitic ferrite transformation during the partitioning stage to initial martensite formed in the quenching stage. At low partitioning temperatures, a bimodal distribution of low- and high-carbon austenite, 0.6 and 1.9 wt.% carbon, is detected. At higher temperatures, a better distribution of carbon occurs, approaching full homogenization. An initial martensite content of around 11.5 wt.% after partitioning at 280 °C via bainitic ferrite transformation results in higher carbon enrichment of austenite and increased retained austenite amount by approximately 4% in comparison with partitioning at 500 °C. In comparison with austempering heat treatment with no prior martensite, the presence of initial martensite in the Q&P microstructure accelerates the subsequent low-temperature bainitic transformation.

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  • 12. Forouzan, M. R
    et al.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Forouzan, Farnoosh
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Jalali, M. R
    Numerical Simulation of Temperature History and Phase Transformations during Submerged Direct Seam Welded Pipes of steel X702009Conference paper (Refereed)
  • 13. Haerian, B
    et al.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    The effect of cold deformation: annealing process on grain size of austenitic stainless steel AISI 3042008Conference paper (Refereed)
  • 14.
    Hannl, Thomas Karl
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Häggström, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden; Institute of Chemical, Environmental & Bioscience Engineering, TU Wien, AT-1060 Vienna, Austria; BEST - Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, AT-8010 Graz, Austria.
    Kuba, Matthias
    Institute of Chemical, Environmental & Bioscience Engineering, TU Wien, AT-1060 Vienna, Austria; BEST - Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, AT-8010 Graz, Austria.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ash transformation during single-pellet gasification of sewage sludge and mixtures with agricultural residues with a focus on phosphorus2022In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 227, article id 107102Article in journal (Refereed)
    Abstract [en]

    The recovery of phosphorus (P) from sewage sludge ashes has been the focus of recent research due to the initiatives for the use of biogenic resources and resource recovery. This study investigates the ash transformation chemistry of P in sewage sludge ash during the co-gasification with the K-Si- and K-rich agricultural residues wheat straw and sunflower husks, respectively, at temperatures relevant for fluidized bed technology, namely 800 °C and 950 °C. The residual ash was analyzed by ICP­AES, SEM/EDS, and XRD, and the results were compared to results of thermochemical equilibrium calculations. More than 90% of P and K in the fuels were retained in the residual ash fraction, and significant interaction phenomena occurred between the P-rich sewage sludge and the K-rich ash fractions. Around 45–65% of P was incorporated in crystalline K-bearing phosphates, i.e., K-whitlockite and CaKPO4, in the residual ashes with 85–90 wt% agricultural residue in the fuel mixture. In residual ashes of sewage sludge and mixtures with 60–70 wt% agricultural residue, P was mainly found in Ca(Mg,Fe)-whitlockites and AlPO4. Up to about 40% of P was in amorphous or unidentified phases. The results show that gasification provides a potential for the formation of K-bearing phosphates similar to combustion processes.

  • 15.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ash transformation in single-pellet combustion and gasification of biomass with special focus on phosphorus2020Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The utilization of different biomass feedstocks in thermal conversion systems can contribute towards mitigation of global warming. However, the formation of different ash fractions (i.e., bottom ash, and fly ash) during thermal conversionof biomass can cause several ash-related problems such as deposit formation, slagging, and particle emissions, all of which may limit its usage as an energy source. It has been found that phosphorus (P), even in relatively low concentrations, can play a vitalrole in the abovementioned ash-related problems. However, the ash transformation reactions occurring in the thermal conversion of P-bearing biomass assortments are not fully understood and rarely described in the literature. Therefore, an understanding ofthe phenomena associated with ash transformations with a special focus on P is crucial.

    The overall objective was to determine the ash transformation and release of P duringsingle-pelletthermochemical conversion ofdifferent types of agricultural and forest fuelsin the low to medium temperature range (600-950 °C). Different agricultural biomasses (poplar, wheat straw, grass, and wheat grain residues), as well as forest residues (bark, twigs, and a mixture of bark and twigs) were used. Thebark and poplar fuels represent a fuel rich in K and Ca with minor P contents. The wheat straw, grass, and twigs represent a typical Si- and K-rich fuel with minor and moderate P contents. The wheat grain residues represent a typical K- and P-rich fuel witha considerable amount of Mg. The produced residual materials, i.e. chars and ashes, were characterized by SEM-EDS, XRD, and ICP-OES. The experimental results were interpreted with support from thermodynamic equilibrium calculations (TECs).

    The overall findings are that the majority of P (>80%) in all the studied fuels remained in the final condensed residues, and that the main fraction of P release occurred during the devolatilization stage. The chemical form of P in the residuesis strongly dependent on the relative concentrations of other major ash-forming elements such as K, Ca, and Si, as well as the type of association of P in the pure fuel. For woody-based fuels rich in Ca and K (poplar, bark, and twigs in this study), P in theash is generally found in the form of crystalline hydroxyapatite. For herbaceous fuels rich in Si and K (wheat straw and grass), P in the ash is generally found in Ca5(PO4)3OH, Ca15(PO4)2(SiO4),KCaPO4, and K-Ca/Mg phosphosilicate melts. For wheat grain residues rich in P, K, and Mg, P in the ash is found in crystalline forms K4Mg4(P2O7)3, K2MgP2O7,K2CaP2O7, and KMgPO4, as well as amorphous K-Mg/Ca phosphates.

    The obtained new knowledge can be used to find practical measures to mitigate ash-related problems during thermochemical conversion of P-bearing biomass fuels. It can also be used to find optimal pyrolysis process conditions to obtain biocharsuitable as alternative fuels and reducing agents in the metallurgical industry.

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  • 16.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ash transformation in thermochemical conversion of different biomass resources with special focus on phosphorus2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A great potential exists for increasing the use of bioenergy in thermochemical processes by utilizing agricultural biomass, forest residues, and sewage sludge that have high availability. Many of these biomass assortments have high ash contents with relatively high concentrations of ash-forming elements such as potassium (K), calcium (Ca), silicon (Si), and phosphorus (P). These elements can, during thermal conversion, cause several ash-related problems, such as deposit formation, slagging, and particle emissions. In particular, P has been found to play a vital role in such ash-related problems even at relatively low concentrations. In addition, ashes obtained from these biomass assortments could be an important source of valuable elements such as P and K. Therefore, detailed knowledge about the ash transformation and fate of P during thermal conversion of these opportunity biomass resources is of immense importance to mitigate ash-related problems and to recover valuable nutrient elements from the ash. 

    The overall objective of this work was to determine the ash transformation and fate of P during single-pellet and fixed-bed combustion/gasification of different opportunity biomass fuels in the process temperature range of 600-1250°C. Different agricultural biomasses (poplar, wheat straw, grass, and wheat grain residues), forest residues (bark and twigs), and sewage sludge (pure and in mixtures with agricultural residues) were used. These fuels cover a wide range of overall ash compositions and different chemical associations of P in the fuel. The bark and poplar represent fuels rich in K and Ca with minor P content. The wheat straw, grass, and twigs represent typical Si- and K-rich fuels with minor to moderate P contents. The wheat grain residues (WGR) represent typical K- and P-rich fuels with a significant amount of Mg. The produced residual materials, i.e., char, different ash fractions and fine flue gas particles, were morphologically and chemically characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography. The interpretation of the results was supported by thermodynamic equilibrium calculations.  

    For all fuels, a major part of the P (> 80%) was found in coarse ash fractions because the studied process conditions favored the formation of stable condensed phosphates. The thermal conversion atmosphere (i.e., gasification/combustion) only caused small effects on the P release and the speciation of the P-compounds formed. Ash transformation pathways generally lead to the formation of orthophosphates (PO43-) such as Ca5(PO₄)3(OH), CaKPO4, and Ca3(PO4)2 with the partial substitution of Ca by some cation forming elements (Fe, Mg, and/or K), as the main P containing crystalline phases. Crystalline pyrophosphate (P2O74-) compounds were also found in the residual ashes from the seed-based fuel (WGR), where P originates from phytate in the biomass. For the fuels containing a certain (sufficient) amount of Si, orthophosphates interact with silicate phases to form both amorphous and crystalline phosphosilicates. For the sewage sludge mixtures, a surplus of available K was needed to form K-bearing phosphates due to side reactions of K with Si and Al.  

    The chemical form of P in the formed ash residues is thus strongly dependent on both the type of P association in the fuel and the relative concentrations of other major ash-forming elements, such as K, Ca, Si, and Al. For the fuels with a high (Ca+Mg)/P molar ratio (AER), i.e., for the typical wood-derived fuels bark and poplar, hydroxyapatite was the main P-containing crystalline phase found in the ash. For the studied fuels/fuel mixtures with moderate AER and a high (K+Na)/(Si+Al) molar ratio (AR), e.g., twigs, grass, wheat straw, and sewage sludge with high mixtures of agricultural residues, there was also a possibility to form alkali-bearing phosphates such CaKPO4 and K-Mg whitlockite, besides hydroxyapatite. Since these fuels contain a high amount of Si, the P can be found in both amorphous phases, i.e. phosphosilicate, and Si substituted crystalline phases, i.e. Ca10(SiO4)x(PO4)6-XOH2-x and Ca15(PO4)2(SiO4)6. For fuels with moderate AER and low AR, e.g., pure sewage sludge and sewage sludge with low mixtures of agricultural residues, K-bearing phosphates were not formed. Instead, P was found in phases such as whitlockite and phosphosilicates. For the WGR fuel with relatively low AER and high AR, K-bearing phosphates were formed in the ashes, where the P was found in crystalline K-Mg/Ca pyrophosphates and K-Mg orthophosphate, as well as amorphous K-Mg-Ca phosphates. 

    The produced knowledge can potentially be used to, e.g., i) suggest efficient measures to mitigate ash-related problems associated with P during thermochemical conversion of opportunity biomass fuels, ii) suggest potential pathways to form plant-available phosphates directly in the thermal conversion process to enable recovery of P and K from the obtained ashes, and iii) find optimal thermal conversion process conditions to obtain bio charcoals that are suitable as alternative fuels and reducing agents in the metallurgical industry. 

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  • 17.
    Hedayati, Ali
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Asghari, S
    Alinoori, A.
    An Investigation on Corrosion properties and contact resistance of TiN coating on AISI 316L stainless steel as bipolar plate in proton exchange membrane fuel cell2012Conference paper (Refereed)
  • 18.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Department of Materials Engineering, Isfahan University of Technology.
    Asghari, S
    Alinouri, A
    An Investigation on contact resistance and corrosion properties of AISI 316L stainless steel as bipolar plate in proton exchange membrane fuel cell2012Conference paper (Refereed)
  • 19.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Asghari, Saeed
    Institute of Materials and Energy, Iranian Space Research Cente.
    Alinoori, Amir Hosein
    Institute of Materials and Energy, Iranian Space Research Cente.
    Koosha, Morteza
    Institute of Materials and Energy, Iranian Space Research Cente.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Effects of coating thickness on corrosion and contact resistance behavior of TiN coated AISI 316L as bipolar plates for PEMFC2016In: Iranian Journal of Hydrogen & Fuel Cell, ISSN 2383-1618, Vol. 3, no 2, p. 137-149Article in journal (Refereed)
    Abstract [en]

    In the polymer electrolyte membrane fuel cells (PEMFCs), low corrosion resistance and high interfacial contact resistance (ICR) are two controversial issues in usage of AISI 316L stainless steel as a metallic bipolar plate. For solving these problems, investigation and development of different coatings and/or surface treatments are inevitable. Corrosion behavior and ICR of AISI 316L specimens coated with 1, 2, and 3 µm thick TiN were investigated. Potentiodynamic (PD), potentiostatic (PS) and electrochemical impedance spectroscopy (EIS) tests were conducted at 80 °C in pH3 H2SO4+2 ppm HF solution purged with either O2 or H2 under both simulated cathodic and anodic conditions. The PS corrosion test results revealed that the current densities of the specimens were below 1 µA cm−2. In the simulated cathodic condition, an increase of coating thickness from 1 to 3 µm led to a relatively large decrease of the current density from 0.76 to 0.43 µA cm−2. Furthermore, the ICR values of the coated specimens after the PS test were lower than that of the uncoated specimen before the PS. In general, the TiN coating decreases the ICR, and has enough corrosion resistance in simulated PEMFC conditions. However, none of the coatings achieved the DOE ICR targets.

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  • 20.
    Hedayati, Ali
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Asghari, Saeed
    Alinouri, Amirhossein
    Corrosion behavior and interfacial contact resistance of TiN coated type 316L stainless steel as bipolar plate for proton exchange membrane fuel cell2013Conference paper (Refereed)
  • 21.
    Hedayati, Ali
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Asghari, Saeed
    Faghilhimmani, Bagher
    Koosha, Morteza
    A coating with highcorrosion resistance and low interfacial contact resistance for metallic bipolar plates of PEMfuel cells2013Patent (Other (popular science, discussion, etc.))
  • 22.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Falk, Joel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Borén, Eleonora
    Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden; Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Lindgren, Robert
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Skoglund, Nils
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Boman, Christoffer
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ash Transformation during Fixed-Bed Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus2022In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 36, no 7, p. 3640-3653Article in journal (Refereed)
    Abstract [en]

    In this study, ash transformation during fixed-bed combustion of different agricultural opportunity fuels was investigated with a special focus on potassium (K) and phosphorus (P). The fuel pellets were combusted in an underfed fixed-bed pellet burner. Residual ashes (bottom ash and slag) and particulate matter were collected and characterized by scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography. The interpretation of the results was supported by thermodynamic equilibrium calculations. For all fuels, almost all P (>97%) was found in residual-/coarse ash fractions, while K showed different degrees of volatilization, depending on fuel composition. During combustion of poplar, which represents Ca–K-rich fuels, a carbonate melt rich in K and Ca decomposed into CaO, CO2, and gaseous K species at sufficiently high temperatures. Ca5(PO4)3OH was the main P-containing crystalline phase in the bottom ash. For wheat straw and grass, representing Si–K-rich fuels, a lower degree of K volatilization was observed than for poplar. P was found here in amorphous phosphosilicates and CaKPO4. For wheat grain residues, representing P–K-rich fuels, a high degree of both K and P retention was observed due to the interaction of K and P with the fuel-bed constituents, i.e., char, ash, and slag. The residual ash was almost completely melted and rich in P, K, and Mg. P was found in amorphous phosphates and different crystalline phases such as KMgPO4, K2CaP2O7, K2MgP2O7, and K4Mg4(P2O7)3. In general, the results therefore imply that an interaction between ash-forming elements in a single burning fuel particle and the surrounding bed ash or slag is important for the overall retention of P and K during fuel conversion in fixed-bed combustion of agricultural biomass fuels.

  • 23.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Forouzan, Farnoosh
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Kermanpur, Ahmad
    Surki Aliabadi, Rouhallah
    The process to produce a new generation of AISI 304L Austenitic Stainless Steel with High Strength & Good Elongation by the creation of Nano Grain Size Structure2010Patent (Other (popular science, discussion, etc.))
  • 24.
    Hedayati, Ali
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Forouzan, Farnoosh
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    An Advanced Thermomechanical Process to Obtain Nano/Submicron Grain Sizes in a Metastable Austenitic Stainless Steel2008Conference paper (Refereed)
  • 25.
    Hedayati, Ali
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Forouzan, Farnoosh
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Surki Aliabadi, Rouhallah
    Department of Materials Engineering, Isfahan University of Technology.
    The process to produce a new generation of AISI 304L Austenitic Stainless Steelwith High Strength & Good Elongation by the creation of Nano Grain Size Structure2010Patent (Other (popular science, discussion, etc.))
  • 26.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Department of Materials Engineering, Isfahan University of Technology.
    Forouzan, Farnoosh
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Surki, R
    Effect of Cold Work Percent on Mechanical Properties of AISI 304L Stainless Steel2009Conference paper (Refereed)
    Abstract [en]

    This article investigates the effect of various degrees of plastic deformation introduced by cold rolling at zero temperature on the mechanical properties of AISI 304L stainless steel. microstructural and ferromagnetic studies were also conducted. The material was evaluated up to 90% reduction in thickness. For this purpose, magnetic measurements, optical metallography, hardness and Tensile test, were used. Results show that by increasing the amount of rolling strain, transformation of austenite to martensite generally increases. The regime of this increase depends on the amount of the plastic deformation and temperature. The tensile strength and hardness were found to increase with the increase of cold rolling percentage (%CR) up to 90%.The results indicate that the formation of strain-induced martensite evidently led to a significant strengthening of the steel.

  • 27.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lestander, Torbjörn A.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden.
    Rudolfsson, Magnus
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden.
    Thyrel, Mikael
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Fate of phosphorus and potassium in single-pellet thermal conversion of forest residues with a focus on the char composition2021In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 150, article id 106124Article in journal (Refereed)
    Abstract [en]

    The phosphorus and potassium contents of the char obtained from thermal conversion of forest residues can limit its utilization as an alternative fuel and reducing agent to substitute coal/coke in the steelmaking industry. In this study, ash transformation and release of K and P during single-pellet thermal conversion of different types of forest residues (i.e., bark, twigs, and bark+twigs) were investigated with the aid of a vertical tube furnace (Macro-TGA) at different temperatures (i.e., 600, 800, and 950 °C) and within and after different fuel conversion stages, i.e., devolatilization and char gasification. The residual char before and after full devolatilization, and ash after char gasification were characterized by SEM-EDS, XRD, and ICP-OES with the support of thermochemical equilibrium calculations. The concentrations of K (7970–19500 mg/kg) and P (1440–4925 mg/kg) in the char produced after devolatilization were more than four times higher than in coke and pulverized coal frequently used in metallurgical processes. A low amount of P and K (≤15%) were released from all fuels. K and P were evenly distributed within the char residues, and no crystalline compounds containing K and P were found. In ash residues of bark, K was found in K2Ca2(CO3)3, and K2Ca(CO3)2. K in ash residues from twigs and bark+twigs was mainly found in the amorphous part of ash, most likely in the form of K-Ca rich silicates. Apatite was found as the main P crystalline compound in all ashes at all temperatures. Estimations show that a release of more than 80% is needed for the studied forest residual assortments to reach K and P concentrations typical of blast furnace coals and cokes.

  • 28.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lindgren, Robert
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Skoglund, Nils
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Boman, Christoffer
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Kienzl, Norbert
    BEST—Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, A 8010 Graz, Austria.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ash Transformation during Single-Pellet Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus2021In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 35, no 2, p. 1449-1464Article in journal (Refereed)
    Abstract [en]

    In this study, ash transformation and release of critical ash-forming elements during single-pellet combustion of different types of agricultural opportunity fuels were investigated. The work focused on potassium (K) and phosphorus (P). Single pellets of poplar, wheat straw, grass, and wheat grain residues were combusted in a macro-thermogravimetric analysis reactor at three different furnace temperatures (600, 800, and 950 °C). In order to study the transformation of inorganic matters at different stages of the thermal conversion process, the residues were collected before and after full devolatilization, as well as after complete char conversion. The residual char/ash was characterized by scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography, and the interpretation of results was supported by thermodynamic equilibrium calculations. During combustion of poplar, representing a Ca–K-rich woody energy crop, the main fraction of K remained in the residual ash primarily in the form of K2Ca(CO3)2 at lower temperatures and in a K–Ca-rich carbonate melt at higher temperatures. Almost all P retained in the ash and was mainly present in the form of hydroxyapatite. For the Si–K-rich agricultural biomass fuels with a minor (wheat straw) or moderate (grass) P content, the main fraction of K remained in the residual ash mostly in K–Ca-rich silicates. In general, almost all P was retained in the residual ash both in K–Ca–P–Si-rich amorphous structures, possibly in phosphosilicate-rich melts, and in crystalline forms as hydroxyapatite, CaKPO4, and calcium phosphate silicate. For the wheat grain, representing a K–P-rich fuel, the main fraction of K and P remained in the residual ash in the form of K–Mg-rich phosphates. The results showed that in general for all studied fuels, the main release of P occurred during the devolatilization stage, while the main release of K occurred during char combustion. Furthermore, less than 20% of P and 35% of K was released at the highest furnace temperature for all fuels.

  • 29.
    Hedayati, Ali
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Forouzan, Farnoosh
    Department of Materials Engineering, Isfahan University of Technology.
    Submicron Microstructure Achieved by Thermomechanical Process in Metastable Austenitic Stainless Steel AISI 304L2009Conference paper (Refereed)
  • 30.
    Hedayati, Ali
    et al.
    Department of Materials Engineering, Isfahan University of Technology.
    Najafizadeh, Abbas
    Department of Materials Engineering, Isfahan University of Technology.
    Kermanpur, Ahmad
    Department of Materials Engineering, Isfahan University of Technology.
    Forouzan, Farnoosh
    Department of Materials Engineering, Isfahan University of Technology.
    The effect of cold rolling regime on microstructure and mechanical properties of AISI 304L stainless steel2010In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 210, no 8, p. 1017-1022Article in journal (Refereed)
    Abstract [en]

    In this paper, the effect of different thickness reductions by cold rolling on the microstructure and mechanical properties of AISI 304L austenitic stainless steel were investigated. The hot rolled steel strips were subjected to cold rolling at 0 °C from 10 to 90% thickness reduction. Microstructures, strain-induced martensitic transformation and mechanical properties of the cold-rolled specimens were characterized by X-ray diffraction, Feritscope measurements, optical metallography, hardness and tensile tests. The resulting transformation curve showed a sigmoidal shape with the saturation value of strain-induced martensite of approximately 100%. A good agreement was found between the experimental results and the Olsen-Cohen model. The results indicated that formation of strain-induced martensite clearly resulted in a significant strengthening of the steel

  • 31.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Sefidari, Hamid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. RISE ETC (Energy Technology Centre) AB, Box 726, SE-941 28 Piteå, Sweden.
    Boman, Christoffer
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Skoglund, Nils
    Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden.
    Kienzl, Norbert
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, A 8010 Graz, Austria.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ash transformation during single-pellet gasification of agricultural biomass with focus on potassium and phosphorus2021In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 217, article id 106805Article in journal (Refereed)
    Abstract [en]

    Agricultural biomasses and residues can play an important role in the global bioenergy system but their potential is limited by the risk of several ash-related problems such as deposit formation, slagging, and particle emissions during their thermal conversion. Therefore, a thorough understanding of the ash transformation reactions is required for this type of fuels. The present work investigates ash transformation reactions and the release of critical ash-forming elements with a special focus on K and P during the single-pellet gasification of different types of agricultural biomass fuels, namely, poplar, grass, and wheat grain residues. Each fuel was gasified as a single pellet at three different temperatures (600, 800, and 950 °C) in a Macro-TGA reactor. The residues from different stages of fuel conversion were collected to study the gradual ash transformation. Characterization of the residual char and ash was performed employing SEM-EDS, XRD, and ICP with the support of thermodynamic equilibrium calculations (TECs). The results showed that the K and P present in the fuels were primarily found in the residual char and ash in all cases for all studied fuels. While the main part of the K release occurred during the char conversion stage, the main part of the P release occurred during the devolatilization stage. The highest releases – less than 18% of P and 35% of K – were observed at the highest studied temperature for all fuels. These elements were present in the residual ashes as K2Ca(CO3)2 and Ca5(PO4)3OH for poplar; K-Ca-rich silicates and phosphosilicates in mainly amorphous ash for grass; and an amorphous phase rich in K-Mg-phosphates for wheat grain residues.

  • 32. Hoseyni, M.
    et al.
    Salekbafghi, M.
    Shamanian, M.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Coating of MoSi2 on the plain steel substrates by TIG Cladding2008Conference paper (Refereed)
  • 33.
    Häggström, Gustav
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hannl, Thomas Karl
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Kuba, M.
    BEST-Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, AT-8010, Austria; Institute of Chemical, Environmental and Bioscience Engineering, Tu Vienna, Vienna, AT-1060, Austria.
    Skoglund, Nils
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. BEST-Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, AT-8010, Austria; Institute of Chemical, Environmental and Bioscience Engineering, Tu Vienna, Vienna, AT-1060, Austria.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Single Pellet Combustion of Sewage Sludge and Agricultural Residues with a Focus on Phosphorus2021In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 35, no 12, p. 10009-10022Article in journal (Refereed)
    Abstract [en]

    Recycling of phosphorus in combination with increased utilization of bioenergy can mitigate material and global warming challenges. In addition, co-combustion of different fuels can alleviate ash-related problems in thermal conversion of biomass. The aim of this study is to investigate the ash transformation reactions of mainly P in co-combustion of P-rich sewage sludge (SS) with K-rich sunflower husks (SH) and K-And Si-rich wheat straw (WS). Single pellets of 4 mixtures (10 and 30 wt % SS in WS and 15 and 40 wt % SS in SH) and pure SS were combusted in an electrically heated furnace at process temperatures relevant for fluidized bed combustion (800 and 950 °C). Collected ash fractions were analyzed by inductively coupled plasma techniques, ion chromatography, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and X-ray diffraction. Thermodynamic equilibrium calculations were performed to interpret the results. Over 90% of K and P was found to be captured within the residual ash with 30-70% P in crystalline K-bearing phosphates for mixtures with low amounts of SS (WSS10 and SHS15). The significant share of K and P in the amorphous material could be important for P recovery. For the lower percentage mixtures of SS (WSS10 and SHS15), P in crystalline phases was mainly found in K-whitlockite and CaKPO4. For the higher percentage SS mixtures, most of P was found in whitlockites associated with Fe and Mg, and no crystalline phosphates containing K were detected. For P recovery, co-combustion of the lower SS mixtures is favorable, and they are suggested to be further studied concerning the suitability for plant growth.

  • 34.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Material Science and Environmental Engineering, Tampere University, FI-33720 Tampere, Finland.
    Vila, Ricardo
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kienzl, Norbert
    BEST─Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, 8010 Graz, Austria.
    Wang, Liang
    SINTEF Energy Research, P.O. Box 4761 Torgarden, 7465 Trondheim, Norway.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Broström, Marcus
    Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory, Umeå University, SE-901 87 Umeå, Sweden.
    Ramser, Kerstin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Engvall, Klas
    Department of Chemical Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Skreiberg, Øyvind
    SINTEF Energy Research, P.O. Box 4761 Torgarden, 7465 Trondheim, Norway.
    Robinson, Ryan
    Global Technology, Höganäs AB, SE-263 83 Höganäs, Sweden.
    Umeki, Kentaro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    CO2 Gasification Reactivity of Char from High-Ash Biomass2021In: ACS Omega, E-ISSN 2470-1343, Vol. 6, no 49, p. 34115-34128Article in journal (Refereed)
    Abstract [en]

    Biomass char produced from pyrolysis processes is of great interest to be utilized as renewable solid fuels or materials. Forest byproducts and agricultural wastes are low-cost and sustainable biomass feedstocks. These biomasses generally contain high amounts of ash-forming elements, generally leading to high char reactivity. This study elaborates in detail how chemical and physical properties affect CO2 gasification rates of high-ash biomass char, and it also targets the interactions between these properties. Char produced from pine bark, forest residue, and corncobs (particle size 4–30 mm) were included, and all contained different relative compositions of ash-forming elements. Acid leaching was applied to further investigate the influence of inorganic elements in these biomasses. The char properties relevant to the gasification rate were analyzed, that is, elemental composition, specific surface area, and carbon structure. Gasification rates were measured at an isothermal condition of 800 °C with 20% (vol.) of CO2 in N2. The results showed that the inorganic content, particularly K, had a stronger effect on gasification reactivity than specific surface area and aromatic cluster size of the char. At the gasification condition utilized in this study, K could volatilize and mobilize through the char surface, resulting in high gasification reactivity. Meanwhile, the mobilization of Ca did not occur at the low temperature applied, thus resulting in its low catalytic effect. This implies that the dispersion of these inorganic elements through char particles is an important reason behind their catalytic activity. Upon leaching by diluted acetic acid, the K content of these biomasses substantially decreased, while most of the Ca remained in the biomasses. With a low K content in leached biomass char, char reactivity was determined by the active carbon surface area.

  • 35. Schodek, Daniel L
    et al.
    Ferreira, Paulo
    Ashby, Michael F
    Hedayati, Ali (Translator)
    Forouzan, Farnoosh (Translator)
    Soroor, Ghaziof (Translator)
    Nanomaterials, nanotechnologies and design: an introduction for engineers and architects2016Book (Other academic)
  • 36.
    Suopajärvi, Hannu
    et al.
    Process Metallurgy Research Unit, University of Oulu.
    Umeki, Kentaro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Mousa, Elsayed
    Swerea MEFOS, Process Integration Department.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Romar, Henrik
    Research Unit of Sustainable Chemistry, University of Oulu.
    Kemppainen, Antti
    Process Metallurgy Research Unit, University of Oulu.
    Wang, Chuan
    Swerea MEFOS, Process Integration Department.
    Phounglamcheik, Aekjuthon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Tuomikoski, Sari
    Research Unit of Sustainable Chemistry, University of Oulu.
    Norberg, Nicklas
    Future Eco North Sweden AB.
    Andefors, Alf
    Future Eco North Sweden AB.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lassi, Ulla
    Research Unit of Sustainable Chemistry, University of Oulu.
    Fabritius, Timo
    Process Metallurgy Research Unit, University of Oulu.
    Use of biomass in integrated steelmaking: Status quo, future needs and comparison to other low-CO2 steel production technologies2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 213, p. 384-407Article in journal (Refereed)
    Abstract [en]

    This paper provides a fundamental and critical review of biomass application as a reducing agent and fuel in integrated steelmaking. The basis for the review is derived from the current process and product quality requirements that also biomass-derived fuels should fulfill. The availability and characteristics of different sources of biomass are discussed and suitable pretreatment technologies for their upgrading are evaluated. The existing literature concerning biomass application in bio-coke making, blast furnace injection, iron ore sintering and production of carbon composite agglomerates is reviewed and research gaps filled by providing insights and recommendations to the unresolved challenges. Several possibilities to integrate the production of biomass-based reducing agents with existing industrial infrastructures to lower the cost and increase the total efficiency are given. A comparison of technical challenges and CO2 emission reduction potential between biomass-based steelmaking and other emerging technologies to produce low-CO2 steel is made.

  • 37. Surki, R
    et al.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Temperature dependency of strain induced martensitic transformation in metastable austenitic stainless steels2012Conference paper (Refereed)
  • 38.
    Surkialiabad, Roohallah
    et al.
    Department of Materials Engineering, Isfahan University of Technology, Engineering Faculty, Ferdowsi Uniersity of Mashhad.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Similar tendency to strain-induced martensite transformation in different austenitic stainless steels2013In: Materials Performance and Characterization, ISSN 2379-1365, E-ISSN 2165-3992, Vol. 2, no 1, p. 206-213Article in journal (Refereed)
    Abstract [en]

    The formation of strain-induced martensite in metastable austenitic stainless steels depends on many parameters; the most well known and highly investigated of these is temperature. In this work, we suggest a new relationship between Md30/50, deformation temperature (DT), and martensite content based on data gathered from other studies and our experimental findings. For this purpose we rolled an AISI 304L stainless steel in different strains at 25°C, 0°C, and - 15°C; then we characterized the steel via x-ray diffraction and Ferritescope studies to identify different phases and calculate their contents. According to the results, the relationship is as follows: If the delta value (DT - Md30/50) is the same for different austenitic stainless steels, they will form equal amounts of martensite under similar strain conditions. Moreover, both the delta value and the true strain have a strong effect on the formation of martensite.

  • 39.
    Surkialiabad, Roohallah
    et al.
    Department of Materials Engineering, Isfahan University of Technology, Materials Group, Engineering Faculty, Ferdowsi University of Mashhad.
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Alam, Ali Saheb
    Materials Group, Engineering Faculty, Ferdowsi University of Mashhad.
    Monitoring of Martensitic Transformation in Cold-Rolled 304L Austenitic Stainless Steel by Eddy Current Method2013In: e-Jounral of Nondestructive Testing, ISSN 1435-4934, Vol. 1, no 10Article in journal (Refereed)
    Abstract [en]

    With measuring the volume fraction of martensite, the destruction of the samples would be considered. In this work a 304L AISI austenitic stainless steel was rolled from 10 to 80 % reduction then the formation of martensite phase was monitored by X-ray diffraction, image analysis of optical, SEM microscopy and eddy current investigation. Also eddy current was carried out in the wide range of frequencies from 50 to 10000 Hz to figure out the effect of it on structural changes then the outputs were calibrated by XRD. By comparing the data of these methods relationship between them was found to be a function of exponential regression. In spite, some researchers have previouslyreported a linear relationship.

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  • 40. Torabpour, A
    et al.
    Khorasani, M. R
    Asghari, S
    Hedayati, Ali
    Department of Materials Engineering, Isfahan University of Technology.
    Review process to manufacture metallic bipolar plates in proton exchange membrane fuel cell2012Conference paper (Refereed)
  • 41.
    Vuorinen, Esa
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Heino, V.
    Tampere University of Technology, Department of Materials Science.
    Ojala, N.
    Tampere University of Technology, Department of Materials Science.
    Haiko, O.
    University of Oulu, Faculty of Technology, Materials Engineering.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Erosive-abrasive wear behavior of carbide-free bainitic and boron steels compared in simulated field conditions2018In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 232, no 1, p. 3-13Article in journal (Refereed)
    Abstract [en]

    The wear resistance of carbide-free bainitic microstructures have recently shown to be excellent in sliding, sliding-rolling, and erosive-abrasive wear. Boron steels are often an economically favorable alternative for similar applications. In this study, the erosive-abrasive wear performance of the carbide-free bainitic and boron steels with different heat treatments was studied in mining-related conditions. The aim was to compare these steels and to study the microstructural features affecting wear rates. The mining-related condition was simulated with an application oriented wear test method utilizing dry abrasive bed of 8–10 mm granite particles. Different wear mechanisms were found; in boron steels, micro-cutting and micro-ploughing were dominating mechanisms, while in the carbide-free bainitic steels, also impact craters with thin platelets were observed. Moreover, the carbide-free bainitic steels had better wear performance, which can be explained by the different microstructure. The carbide-free bainitic steels had fine ferritic-austenitic microstructure, whereas in boron steels microstructure was martensitic. The level of retained austenite was quite high in the carbide-free bainitic steels and that was one of the factors improving the wear performance of these steels. The hardness gradients with orientation of the deformation zone on the wear surfaces were one of the main affecting factors as well. Smoother work hardened hardness profiles were considered beneficial in these erosive-abrasive wear conditions.

  • 42.
    Vuorinen, Esa
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Heino, V.
    Tampere University of Technology, Department of Materials Science.
    Ojala, N.
    Tampere University of Technology, Department of Materials Science.
    Haiko, O.
    University of Oulu, Faculty of Technology, Materials Engineering.
    Hedayati, Ali
    The effects of microstructure on erosive-abrasive wear behavior of carbide free bainitic and boron steels2016In: Nordic Symposium on Tribology - NORDTRIB 2016, 2016Conference paper (Refereed)
  • 43.
    Vuorinen, Esa
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hosseini, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hedayati, Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Kornacker, Eva
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Fernandez, Maria Teresa
    CIDAUT Foundation, Boecillo, Spain.
    Sanz, Javier
    CIDAUT Foundation, Boecillo, Spain.
    Gonzalez, Manuel I.
    CIDAUT Foundation, Boecillo, Spain.
    Cañibano, Esteban
    CIDAUT Foundation, Boecillo, Spain.
    Mechanical and microstructural evaluation of high performance steel (S700MC) for road restraint systems2020In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 108, article id 104251Article in journal (Refereed)
    Abstract [en]

    The suitability of using high performance steel (S700MC) for road restraint systems (RRS) under very high containment level was evaluated in this study. To investigate the influence of the crash on the mechanical behaviour of the steel, different test pieces were tested by tensile and hardness testing, and examined by scanning electron microscopy (SEM). The tensile test results of S700MC showed a noticeable increase in yield strength at 0.2% elongation (Rp0.2) from 744 to 935 MPa, and ultimate tensile strength (UTS) from 810 to 1017 MPa, before and after crash tests (BC and AC, respectively). S700MC showed ~9% lower elongation at fracture value in comparison with S275JR and S355JR steels. Besides, fracture toughness, was significantly higher for S700MC (133 and 148 MJ/m3 for BC and AC, respectively) compared to conventional mild steels (108–118 MJ/m3). Microstructural observations of head-part of all S700MC samples revealed equi-axed grains. The fracture surface of tensile tested samples before crash, showed elongated grains accompanied by pore formation. Among after crash samples, one test piece showed intergranular cracks while no intergranular cracks were observed for the other crashed pieces which resulted in the lower Rp0.2 (813 MPa) and UTS strength (847 MPa) and fracture toughness (125 MJ/m3). The results showed that although RRS manufactured with S700MC undergoes severe mechanical deformation, the risk of brittle fracture is very low and this is beneficial from industrial as well as social point of view.

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