WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Institution Author: search.filters.institutionAuthor.Gökelma, MertolPublisher: search.filters.publisher.Springer

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Now showing 1 - 5 of 5
  • Article
    Citation - WoS: 10
    Citation - Scopus: 7
    Assessment of Melt Cleanliness of Secondary 5000 Aluminum Alloy Via Non-Metallic Inclusions Characterization
    (Springer, 2023) Li, Cong; Dang, Thien; Huang, Jinxian; Huang, Chunfa; Li, Jianguo; Friedrich, Bernd; Gökelma, Mertol
    The extensive energy consumption of primary aluminum production stimulates increasing need of producing primary-quality alloys with secondary sources, during which process amount of non-metallic inclusions (NMIs) in the alloy must be strictly controlled. In the present study funded by AMAP Open Innovation Research Cluster, NMIs generated during remelting a 5000 Al-Mg alloy was investigated to offer benchmarking characters of NMIs with respect to type, morphology, size, composition, and concentration. Under different remelting conditions NMIs formed in the melt ahead of solidification were concentrated using Porous Disc Filtration Apparatus (PoDFA) and characterized microstructurally and quantitatively. Investigated conditions included heating cycle, organic contaminations, and refractory materials. Results suggested oxide films and cuboid particles as typical oxides with, respectively, different compositions. The amount of formed oxides declined with the increase of heating rate. With respect to aluminum carbide (Al4C3), organic contaminations were confirmed to lead to an increased amount of its formation. The carbon-containing refractory material contributed more significantly than organic contaminations on the formation of Al4C3 at melt temperatures over 760 & DEG;C. Formulas were derived based on trial results to enable translation of NMIs PoDFA value [mm(2)/kg] into their mass fraction [ppm] in the melt.
  • Conference Object
    Pre-Study of the Dissolution Behavior of Silicon Kerf Residue in Steel
    (Springer, 2022) Lazou, Adamantia; Nilssen, David; Gökelma, Mertol; Wallin, Maria; Tranell, Gabriella
    Silicon kerf residue is generated during the wafering process of pure silicon in the photovoltaic value chain. The generated by-product has a high volume, and the particle size is typically below 1 μm. Although the fine particles are partly oxidized, the material may be beneficial in different metallurgical applications such as grain refining and alloy composition adjustments. This work studies the dissolution behavior of silicon kerf in low alloy steel melts with the aim to upcycle the kerf material in the steel industry for different purposes. In this study, a steel alloy and the kerf residue were melted (at 1580 °C) in an alumina crucible placed in an induction furnace. The amount of added kerf residue was varied. The behavior of the particles in the solidified alloy was characterized by using an optical microscope, electron probe microscope (EPMA), and wavelength-dispersive X-ray spectroscopy (WDS) in order to study the dissolution behavior of the Si-kerf residue in the steel.
  • Article
    Citation - WoS: 10
    Citation - Scopus: 11
    Behavior of Al4c3 Particles During Flotation and Sedimentation in Aluminum Melts
    (Springer, 2021) Gökelma, Mertol; Storm Aarnaes, Trygve; Maier, Juergen; Renkel, Maria F.; Ekstrom, Kai Erik; Friedrich, Bernd; Tranell, Gabriella
    Al4C3 particles form during the primary production of aluminum via molten salt electrolysis due to the carbon solubility and direct contact between bath, metal, and carbon anodes. Additional Al4C3 may form during melt processing through direct contact between the melt and carbonaceous materials. As a result of their small size and similar density to aluminum, removal of aluminum carbide particles can be challenging. If not removed, carbides can produce inclusion defects or poor surface condition in aluminum products. The current work studies the removal and behavior of Al4C3 particles during flotation with different gas mixtures, as well as sedimentation. The interaction between carbide particles and Al2O3 films during the melt treatment processes was also studied and reported. Factsage thermochemical software was used to model the interactions at the interface of inclusions and bubbles covered by films. The highest degree of carbide removal was obtained after flotation with an H2O-containing argon gas mixture, where the carbide concentration dropped below the measured solubility limit of carbon at the corresponding temperature. Strong interaction between Al4C3 particles and Al2O3 films was observed during sedimentation which worked as an efficient removal method for the particles. Oxidation of carbides and formation of oxycarbides were suggested as the mechanisms promoting the attachment of carbides on oxide films.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Rewas 2022: Developing Tomorrow's Technical Cycles
    (Springer, 2021) Fleuriault, Camille; Gökelma, Mertol; Anderson, Alexandra; Olivetti, Elsa A.
    REWAS, a sustainability driven conference within The Minerals, Metals & Materials Society (TMS), has a long history of bringing together academia and industry to exchange and reflect on the latest technology developments in the process optimization and waste management fields. The first edition of REWAS (REcycling and WASte symposium) took place in 1999. The scope of the conference has since then broadened to include environmental sustainability, resource management and manufacturing efficiency, liaising these developments to the metallurgical industry in a broader societal and systemic context. The 2022 edition of REWAS which will be hosted at the TMS 2022 Annual Meeting & Exhibition in Anaheim, California, provides a resolute outlook towards Developing Tomorrow's Technical Cycles. Within the metals and materials industry, technical cycles refer to the ensemble of strategies and processes applied to the development of sustainable product loops with the intent to eliminate waste and instead rethink, reuse and upcycle products. The success of technical cycles requires strengthening our circular approach for product life cycle design by providing guidelines and implementation examples to the developers, designers, policy makers and business managers. REWAS promotes such strategies within a priority sector identified for Circular Economy enablement: raw materials supply and management. REWAS 2022 consists of six symposia, and abstract submissions are expected in summer 2021. Topics include recycling and sustainability within the aluminum industry, specifically on casting technologies, recovery of metals from complex products and systems, decarbonization of the metallurgical and manufacturing industry, sustainable production and development perspectives, as well as automatization and digitalization for advanced manufacturing. REWAS 2022 will also include an honorary symposium for Dr. Diran Apelian, whose contributions in metals processing, aluminum and battery recycling, sustainability, education in materials science and more have shaped the path for sustainable materials processing.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 1
    The Influence of the Casting Speed in Horizontal Continuous Casting of Aluminium Alloy En Aw 6082
    (Springer, 2021) Obalı, Akın; Dilek, Kerem Ahmet; Akdi, Seracettin; Ürk, Deniz Kavrar; Gökelma, Mertol
    Vertical direct chill (VDC) casting is commonly used to produce slabs and billets from wrought aluminium alloys. The fact that the VDC is not a continuous process and moulds must be prepared for the next batch decreases the productivity of the process. Alternatively, horizontal direct chill (HDC) casting simplifies the process and allows a continuous production. The casting speed in the HDC casting is easier to control and can be optimized for different alloys by changing the speed. This study focuses on investigating the effects of casting speed on the macrostructure of 6082 aluminium billets with 60 mm diameter. A demo-scale casting unit was used and the casting speed was changed from 310 to 385 mm/min. Changes in surface condition, macrocracks, microporosity, and diameter of the billets were investigated. Surface quality of the billets became better with the increasing casting speed, while diameter of the billet expands. Furthermore, centreline cracks appear at the casting speed of 355 mm/min. © 2021, The Minerals, Metals & Materials Society.