Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
Browse
5 results
Search Results
Article Citation - WoS: 1Citation - Scopus: 1Effect of Compaction and Fluoride Content on the Remelting Efficiency of Pure Magnesium Chips(Taylor & Francis, 2023) Yörük, Pınar; Gökelma, Mertol; Derin, BoraMagnesium is widely used in industries, such as automotive, aerospace, and medical fields. The demand on magnesium has been growing, although the production and melt treatment is complex due to strong oxidation tendency. Recycling of magnesium scraps is crucial due to the criticality of magnesium-containing raw materials in Europe as well as increasing environmental concerns. Remelting of magnesium is typically conducted under a salt flux which absorbs the impurities and protects the melt against oxidation. This study investigates the effect of compaction, fused salt flux, and salt composition on remelting behavior of magnesium chips. Metal yield and coagulation efficiency were calculated after remelting, and samples were characterized by using Scanning Electron Microscope and X-ray Diffraction. The liquidus temperature and density of fluxes were analyzed by FactSage software. Remelting of compacted chips under a fused salt flux with 5 wt.% CaF2 showed the highest magnesium recovery with a yield of 97.7%. Le magnesium est largement utilise dans une variete d'industries, telles que les domaines de l'automobile, de l'aerospatiale et de la medecine. La demande en magnesium s'est accrue, bien que la production et le traitement du bain soient complexes en raison de sa forte tendance a l'oxydation. Le recyclage des dechets de magnesium est crucial en raison de la criticite des matieres premieres contenant du magnesium en Europe ainsi que des preoccupations environnementales croissantes. La refusion du magnesium est effectuee typiquement sous un flux de sel qui absorbe les impuretes et protege le bain contre l'oxydation. Cette etude examine l'effet du compactage, du flux de sel fondu et de la composition du sel sur le comportement a la refusion des copeaux de magnesium. On a calcule le rendement en metal et l'efficacite de la coagulation apres des experiences de refusion, et l'on a caracterise les echantillons a l'aide d'un microscope electronique a balayage et de la diffraction des rayons X. On a analyse la temperature du liquidus (Tliq) et la densite des flux de sel avec le logiciel FactSage. La refusion des copeaux compactes sous un flux de sel fondu avec 5% en poids de CaF2 a montre la recuperation de magnesium la plus elevee avec un rendement de 97.7%Article Citation - WoS: 3Citation - Scopus: 4Partial Austenitisation and Tbf Steel Composed of Ferrite, Bainitic Ferrite, and Austenite(Taylor & Francis, 2022) Erişir, Ersoy; Bilir, Oğuz Gürkan; Sözer, Yunus Emre; Ararat, Özge; Davut, KemalA TRIP-aided bainitic-ferritic (TBF) steel with a chemical composition of Fe-0.19C-1.7Mn-1.09Si-0.51Al-0.05Nb (wt-%) was partially austenitised from a hot-rolled martensitic initial microstructure. After the hot rolling, the martensitic specimens were reheated to different intercritical temperatures and then austempered at 350 degrees C. Thus, the effect of the initial microstructure of TBF steel on intercritical austenite formation during partial austenitisation was studied. The microstructures were investigated by scanning electron microscopy and electron backscatter diffraction (EBSD), and the tensile properties were tested. Microstructural observations revealed that a final microstructure of fine ferrite, bainitic ferrite, and retained austenite can be obtained. The steel partial austenitised at 770 degrees C showed a good combination of ultimate tensile strength and total elongation.Article Citation - WoS: 3Citation - Scopus: 5Temperature Dependent Electrical and Electrocaloric Properties of Textured 0.72pmn-0.28pt Ceramics*(Taylor & Francis, 2021) Böbrek, İrem; Berksoy Yavuz, Ayşe; Kaya, M. Yunus; Alkoy, Sedat; Okatan, Mahmut Barış; Mısırlıoğlu, İbrahim Burç; Mensur Alkoy, EbruLead magnesium niobate (PMN) - lead titanate (PT) solid solution ceramics in the ratio of 0.72PMN-0.28PT was produced by a combination of tape-casting in ⟨001⟩(pc) textured and random forms. The Lotgering factor, f, of textured ceramics was approximately calculated as 80%. Modified Curie-Weiss analysis indicated relaxor dominant behavior for both the random and textured ceramics. Development of texture led to an enhancement in the electromechanical properties with converse piezoelectric charge coefficient (d(33)*) under 20 kV/cm electric field reaching 545 pm/V for the textured ceramic. Electrocaloric (EC) behavior of random and textured ceramics were obtained from indirect measurements using temperature dependent polarization vs. electric field hysteresis loops. An EC temperature change (Delta T-EC) of similar to 0.5 K was calculated from the PMN-28PT ceramics at around 80 degrees C under an electric field of 60 kV/cm. Development of texture was demonstrated to have led to an anisotropy in the EC response.Article Citation - WoS: 1Citation - Scopus: 1Investigating Triple Superphosphate for Lead Removal From Aqueous Solutions(Taylor & Francis, 2022) Souley Garba, Mahamane Chapiou; Kaya, Erol; Gökelma, Mertol; Seyrankaya, AbdullahThe aim of this research is to investigate monocalcium phosphate monohydrate [Ca(H2PO4)2. H2O] also called triple superphosphate (TSP) for the removal of lead (Pb) from aqueous solutions. In this study, TSP was selected amongst various phosphate-based materials and fertilizers to act as the source of orthophosphate (PO43-) which is a powerful tool for metal fixation in soil and water. Thermodynamic equilibrium dissolution-precipitation relationships for the systems of Pb-H2O and Pb-PO43--H2O were drawn with the aid of Eh-pH stability diagrams to determine the predominance areas of different species. The lead phosphate compounds, identified through the stability area diagrams, were verified with the batch precipitation tests performed with standard solutions of lead and TSP at different conditions. It was observed that, depending upon solution conditions, TSP can precipitate 99.9% of the lead from the solution. Lead precipitates, analyzed by x-ray diffraction, showed the formation of lead phosphate compounds. The mechanism of TSP for the removal of lead from aqueous solutions is discussed.Article Citation - WoS: 13Citation - Scopus: 14Landau, Ginzburg, Devonshire and Others(Taylor & Francis, 2020) Levanyuk, Arkady P.; Mısırlıoğlu, İbrahim Burç; Barış Okatan, MahmutMacroscopic modeling of ferroelectric properties refers usually to Landau-Ginzburg-Devonshire theory. This paper questions the meaningfulness of this term, discussing contributions of the three authors in the title to what is supposed to be a theory. The limitations of every contribution are analysed. In the main text and, to more extent in the Supplementary Material, the Landau theory is presented from an unusual perspective starting from simple mechanical models of spontaneous symmetry breaking and finishing by the Ising model. The aim of the presentation is to emphasize along with the qualitative breakthroughs the approximate character of macroscopic modeling associated with the above three authors. © 2020 Taylor & Francis Group, LLC.