3D numerical simulation with experimental validation of a traveling magnetic field stirring generated by a Bitter coil for silicon directional solidification processHiba, B; Nouri, Ab; Hachani, L; Zaidat, K
doi: 10.1088/1757-899x/1223/1/012001pmid: N/A
Silicon is the most widely used raw material in photovoltaic industry; however, the quality of the silicon photovoltaic solar cells depends on the quality of the raw material (i.e. metallurgical silicon or poly-silicon) and the solidification methods used for the production of the silicon ingot from which the solar cells are produced. This study is related to how improve the quality of the final ingot in the directional solidification process; it is necessary to control the impurity segregation of silicon raw material during the processing. This control can be accomplished by adding an electromagnetic Bitter coil which can generate an external traveling magnetic field (TMF) stirring to control the hydrodynamic flow of silicon melt during the solidification process without contaminating it. To carry out this study, we used a Bridgman vertical directional solidification furnace, equipped with a cylindrical Bitter coil stirrer used in order to have the control of the silicon melt convection on the principal parameters of the solidification process, such as the growth rate, the thermal gradient and the natural convection of silicon melt. For the electromagnetic, heat exchange and silicon melt flow modelling, we used 3D numerical Multiphysics coupled models. Parallel to the numerical results we carried out experimental investigations relating to the characterization of the electromagnetic parameters. This study shows a promising effect of the applied traveling magnetic field on the final ingot quality; indeed, we have the ability to control the silicon melt flow which can affect the thermal configuration, the solidification interface shape and the segregation of impurities by changing the electric current input configuration of the Bitter coil stirrer.
Twenty Years’ Research on Microwave Application to Metal Production and RecyclingYoshikawa, Noboru
doi: 10.1088/1757-899x/1223/1/012006pmid: N/A
Ever since discovery of microwave heating in 1946, its application has been developed in various fields. Our research group has performed intensive studies on microwave heating application to metal production and recycling for these twenty years. In this article, it is intended to introduce our attempts having made for different projects. They are 1. Microwave processing of Ti bearing blast furnace slag, microstructural alteration and comminution. 2. Microwave carbo-thermic reduction of valuable metals from various oxides. 3. Microwave drying and dehydration of wet wastes. 4. Vapor de-phosphorization by microwave rapid heating. It is to be emphasized that we utilized a single mode microwave applicator for the purpose of clarification on the heating mechanisms of various metallurgical matters and compounds, and it was intended to discuss the reaction kinetics excited by microwave heating.
Peer review declarationdoi: 10.1088/1757-899x/1223/1/011002pmid: N/A
All papers published in this volume of Electromagnetic Processing of Materials (EPM 2021) conference special issue have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.Type of peer review: Single-blind / Double-blind / Triple-blind / Open / Other (please describe) All articles were sent to independent reviewer, which is the expert in the field. After review, the reviewers form was sent back to authors. Corrected article was sent to reviewer again to check if corrections are implemented. Review processes were anonymous and all communication between reviewers and authors were carried out by conference e-mail. Reviewer form were used (see attached).• Conference submission management system: https://www.epm2021.lu.lv/(Review invitations and communication with authors were carried out via e-mail)• Number of submissions received: 7• Number of submissions sent for review: 7• Number of submissions accepted: 6Acceptance Rate (Number of Submissions Accepted / Number of Submissions Received X 100): 86Average number of reviews per paper: 1.5 (Half of the accepted papers were accepted after one review round and minor revisions, half of the papers were sent to the reviewer two times, because reviewer still have some suggestions after corrections suggested in the first review)• Total number of reviewers involved: 9• Any additional info on review process: No• Contact person for queries: [email protected]
Dynamic transitions of the magnetized spherical Couette flow between its base state and the return flow instabilityOgbonna, J; Garcia, F; Gundrum, T; Seilmayer, M; Stefani, F
doi: 10.1088/1757-899x/1223/1/012004pmid: N/A
The transition between the stable base state of the magnetized spherical Couette (MSC) flow and the return flow instability is experimentally investigated. The experiments are conducted using an MSC setup consisting of insulating spheres with the ratio of the inner to the outer radii ri/ro = 0.5, Reynolds number Re = 1000 and Hartmann number Ha ∈ [25, 29]. The transition is characterized by changes in the power spectra of the azimuthal modes in the flow as Ha is dynamically changed. The transition occurs in the interval Ha ∈ [26.5, 27.5]. The evolution of the power spectra of the azimuthal modes exhibits hysteretic effect depending on whether Ha is increased or decreased within the experimental interval. The power spectra in the azimuthal modes m ∈ {3, 4} increases and remains dominant as Ha is increased, while the power spectra in m ∈ {2, 4} are dominant while the flow is time dependent due to return flow instability as Ha is decreased.
Design of induction tempering of surface hardened componentsBaldan, Marco; Nacke, Bernard
doi: 10.1088/1757-899x/1223/1/012005pmid: N/A
Induction hardening is a well-known heat treatment in the automotive and aerospace industries. Very often it is accompanied by tempering that is conventionally performed in ovens. However, induction tempering is getting more popular and this introduces the chance of using numerical simulations and optimization in the design stage. In this paper, based on a real case study, we will describe how to model and choose the regime parameters in both induction hardening and tempering.
Model experiments for Czochralski crystal growth processes using inductive and resistive heatingEnders-Seidlitz, A; Pal, J; Dadzis, K
doi: 10.1088/1757-899x/1223/1/012003pmid: N/A
The Czochralski (CZ) growth technique is widely applied in crystal growth, using both induction and resistance heaters. In this work, a novel model experiment platform with comprehensive in-situ measurement capability is introduced. Growth experiments with the model material tin applying both heating concepts are performed and analyzed, e.g., in terms of the maximum achievable crystal diameter. Strong asymmetries in the magnetic field of the induction heater are measured and temperature distribution on the resistance heater is found to be non-uniform. Furthermore, significant losses are observed in the power supplies of the resistance heater. The heating efficiency of both concepts is compared considering different insulation geometries. The obtained results show the capability of model experiments for design optimization and will provide valuable input for further validation of numerical simulations.
Preface to IOP conference series issue Electromagnetic Processing of Materials (EPM2021), June 14-17 (Online)doi: 10.1088/1757-899x/1223/1/011001pmid: N/A
Special issue editors: Imants Kaldre, Arturs BrekisElectromagnetic Processing of Materials (EPM) is a branch of research about the possibilities to improve various physical processes with electric or magnetic fields.Where some benefit could be attained from an electromagnetic influence on the process. This covers traditional areas such as liquid metal processing, metal casting and solidification, induction heating, but also crystal growth from the melt, plasma processes, recycling, separation. The series of EPM conferences was initiated in 1994 by S. Asai (Japan) and M. Garnier (France). It takes place every three years alternating between Europa and Asia (Nagoya 1994, Paris 1997, Nagoya 2000, Lyon 2003, Sendai 2006, Dresden 2009, Beijing 2012, Cannes 2015, Hyogo 2018). The conference is open for any kind of materials processing involving electric or magnetic fields. It intends to bring together people from academic institutions, industry and related equipment manufacturers.June 13-17, 2021Riga, Latvia, University of Latvia, Jelgavas street 3, LV-1004Due to the travel and public event restrictions EPM2021 was held online in Zoom platform. We decided to keep the announced dates and make online event rather than postpone event to unknown time. It would be difficult to find good time slot for this conference between other postponed related conferences.We attach the conference program. Time limits for each presenter were 30 minutes for Keynote and 20 minutes for regular report. Short discussion after each speech.Participants from more than 10 countries. More than 50 scientific reports, more than 100 unique participants listening. Each session was chaired by two recognized scientists. We experienced very little technical difficulties during the conference.