Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2026Scopus SJRQ2/r/munzur/1345
  Simultaneous Leaching and Kinetics of Cu and Zn from Malachite Ore in NH3-NH4NO3 Solutions

  Bakici, Zümra; Baysar, Ahmet; Demİrkiran, Nİzamettİn

  The simultaneous leaching behavior and kinetics of copper and zinc from malachite were investigated in NH3-NH4NO3 buffer solutions at pH 9.8. The effects of solution concentration, temperature, stirring speed, average particle size, and solid to liquid ratio on the leaching rate were examined. It was observed that the leaching rate of copper and zinc increased with an increase in the solution concentration, temperature, stirring speed, and with a decrease in the solid to liquid ratio and particle size. The findings showed that copper was leached nearly completely depending on the experimental conditions while zinc was dissolved partially. While the concentration of NH3-NH4NO3, temperature, stirring speed, average particle size, solid to liquid ratio, and time were 0.38/0.11 M, 40°C, 500 rpm, 214 µm, 5/500 g/mL, and 240 min, respectively, and the amount of the leached copper and zinc was calculated to be 83.0% and 43.4%, respectively. It was determined that the leaching kinetics fit a mixed-kinetic model. The activation energy values were found to be identical for both copper and zinc leaching (16.22 kJ/mol). The process was determined to be weakly dependent on temperature, with diffusion playing a significant role in the overall leaching process.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/751
  Engineering Superior Soft Magnetic Properties Through FeCo/Cr and FeCo/Fe Nanocrystalline Architectures

  Yüzüak, Gizem Durak

  Soft magnetic materials are integral to various technologies, including high-frequency transformers, spintronic devices, and magnetic sensors, because of their low coercivity (HC) and high magnetization. This study investigates nanocrystalline Fe70Co30(100 nm)/Cr(2-10 nm) and Fe70Co30(100 nm)/Fe(2-10 nm) thin films, deposited via magnetron sputtering. X-ray diffraction analysis reveals that Fe70Co30 films without buffer layers crystallize in a body-centered cubic phase. The Cr and Fe buffer layers enhance it by minimizing lattice mismatch and promoting a uniform crystalline growth of the Fe70Co30 layer. The most significant particle size variations observed were approximately 24% for the Cr buffer and 31% for the Fe buffer. Microstructural characterization using atomic force microscopy and scanning electron microscopy identified nanograins with an average size of 30–80 nm. Magnetic characterization with a vibrating sample magnetometer showed a marked reduction in HC. Additionally, the remanence-to-saturation magnetization ratio remains nearly constant at 0.95 across all Fe-buffered films, whereas it increases from 0.80 to 0.92 in Cr-buffered films as the Cr thickness increases. The results highlight the importance of buffer layer engineering in enhancing the microstructural and magnetic properties of FeCo thin films, thereby increasing their suitability for advanced magnetic technologies.

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• MakaleYalnız künye2026Scopus SJRQ2/r/munzur/707
  Lithium Recovery from Boron Processing Wastes via Mechanical Activation-Assisted Water Leaching: Application of Planetary Milling

  Boylu, F.; Obuz Teker, Gülsen; Ersever Angur, Gafure; Ozdemir, O.; Çelik, M.S.

  In this study, a more sustainable, cost-effective, and environmentally friendly approach for selective lithium extraction via water leach assisted by planetary mill mechanical activation was applied on clayey wastes of the Kırka Boron Plant. A detailed systematic study on wastes was performed to optimize both mechanical activation and leaching conditions and to characterize the active powders by XRD, FTIR and EDS/EDX. The results show that lithium can be recovered at relatively low leach temperatures of 50–60°C and short leach times of 3–5 min, achieving leach recoveries of 44.71 (without salt addition) and 57.71% (with 20% salt addition, w/w) without the need for pre-concentration of the waste. Despite relatively low lithium recoveries, water leaching of activated powder produced remarkably low concentrations of co-leached ionic impurities less than 10 ppm Mg, 20 ppm Ca, and 250 ppm K, compared to significantly higher concentrations observed during 1 M acid leaching (9422 ppm Mg, 564.5 Ca, and 72.5 ppm K, upon 1 M acid leaching, respectively). The presence of Mg ions, in particular, is known to be highly detrimental competing ion in metal recovery processes. Therefore, the proposed method offers both economic and environmental advantages by enabling higher purity lithium recovery under much milder conditions.

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  AtıfScopus1·OpenAlex1

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/691
  Production and Thermal–Structural Characterization of Nano-Oxide-Doped Paraffin-Based Phase Change Composite Materials for Thermal Storage Applications

  Yücel, Halit Lutfi; Özdemir, Osman; Kahraman, Gökhan

  Paraffin-based composite phase change materials (PCMs) have been synthesized for thermal energy storage applications to enhance thermal conductivity and stability while maintaining latent heat storage capacity. In this study, RT42 paraffin was modified with inorganic nano-oxides (Al2O3, CuO, SiO2, and ZnO) in the presence of sodium dodecyl sulfate (SDS) as a surfactant. The incorporation of SDS improved nanoparticle dispersion and reduced agglomeration, resulting in enhanced phase-change behavior and improved structural homogeneity. Differential scanning calorimetry (DSC) analysis revealed slight variations in melting and crystallization temperatures, while the ZnO-doped composite retained up to 92% of the latent heat storage capacity of pure RT42. Among all the investigated composites, the Al2O3-doped sample exhibited the highest thermal conductivity and specific heat capacity. Thermogravimetric analysis (TGA) indicated an increase of approximately 15–20°C in the decomposition temperature, demonstrating enhanced thermal stability. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the preservation of the crystalline structure and improved microstructural uniformity. The developed SDS-assisted nano-oxide/RT42 composites exhibit significant potential for passive thermal regulation in renewable energy and building applications.

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  AtıfScopus1·WoS1·OpenAlex1

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/1313
  Role of Rare-Earth Cerium in Martensitic Transformation and Magnetic Properties of Cu-Al-Mn Alloys

  Özkul, İskender; Kalay, Ece; Karaduman, Oktay; Kizilgün, Yasİn; Güler, Ömer; Canbay, Canan Aksu

  This study investigates the effects of different cerium additions on the properties of Cu-Al-Mn high-temperature shape memory alloy (HTSMA), such as the characteristic martensitic transformation temperatures, transformational kinetic parameters, and martensitic microstructures which are related to its shape memory mechanism and also to its magnetic behavior. Polycrystalline alloys with a base composition of Cu77.32Al21.02Mn1.67 (at.%) were synthesized, and varying concentrations of cerium (Ce-1 to Ce-4) were added for comparison. Differential scanning calorimetry tests revealed notable increments in transformation temperatures with cerium additions. Specifically, the austenite start temperature of the reference alloy increased from 143.75 °C to 194.88 °C by 0.05 at.% of Ce addition (Ce-3 alloy), corresponding to the formation of CeCu5 and Mn1.15Cu3.85Ce phases. However, excessive Ce addition in Ce-4 led to the over-stabilization of secondary phases, reducing the transformation temperatures. Microstructural analysis indicated that Ce addition of refined grains changed the crystallite size of the martensite structure and reduced lattice strain (from 0.72% to 0.34%). Magnetic characterization demonstrated that Ce addition shifted the alloy towards paramagnetic behavior, with M-H curves showing no significant coercive field or remanent magnetization across the studied alloy samples. These findings suggest that cerium can enhance the high-temperature performance of Cu-Al-Mn HTSMAs, with potential applications in environments requiring both shape memory and magnetic properties.

  AtıfScopus3·WoS3

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/1064
  Comprehensive Computational Assessment of Al-Based High-Entropy Superalloys: Thermodynamic, Mechanical, and Radiation Shielding Characterization for Nuclear Applications

  ALMisned, Ghada; Güler, Ömer; Özkul, İskender; Baykal, Duygu Sen; Alkarrani, Hessa; Kilic, G.; Mesbahi, A.; Tekin, H.O.

  This study investigates the radiation shielding properties of aluminum-based superalloy high-entropy alloys (HEAs) for potential use in advanced nuclear reactor applications. These HEAs, composed of five or more metals in equimolar or near-equimolar ratios, were evaluated for their thermodynamic stability, mechanical strength, and radiation attenuation capabilities. Key parameters such as entropy of mixing (ΔSmix), enthalpy of mixing (ΔHmix), valence electron concentration (VEC), and atomic size difference (δ) were analyzed. Radiation shielding properties, including mass attenuation coefficients (MAC), half-value layer (HVL), effective atomic number (Zeff), and exposure buildup factor (EBF), were assessed using various simulations. Alloy 12, with its superior MAC, lowest HVL, and high ΣR value, demonstrated exceptional effectiveness in gamma and neutron attenuation. These findings underscore the potential of aluminum-based HEAs, particularly Alloy 12, to enhance the operational capabilities and longevity of nuclear reactors, paving the way for the development of next-generation materials for high-radiation environments.

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/771
  Removal of Impurities from Sepiolite by Gravity/Sizing Methods for Better Viscosity Development

  Angur, G. Ersever; Çınar, M.; Çelik, M.S.

  Sepiolite, a natural strategic clay mineral within the phyllosilicate group, is utilized in numerous applications because of its physical, and rheological properties. In particular, outstanding rheological properties are utilized in areas including drilling mud, paint, cosmetics, adhesives, etc. Several studies have been performed for the purification of clays, such as air classification, calcination, hydrocyclone, and flotation, for different purposes. In this study, relatively easy physical upgrading methods involving hydroxyclone, Falcon, and shaking table have been tested with the aim of obtaining a high-viscosity sepiolite product for rheological applications. It is shown that dispersion time, particle size, and pH are the most critical parameters in the viscosity development of sepiolite. The results indicate that, depending on the dispersion time of the raw HS1 sepiolite sample used in this study, the highest quality rheological material remains in the size range of – 2 mm to + 1 mm. Below – 0.1 mm, the viscosity value of the sepiolite sample decreased to its lowest value of 6000 cP. The pH-dependent viscosity measurements of a raw HS1 sepiolite sample exhibited the highest viscosity value of 13,000 cP at its natural pH of 8.5. Polyacrylic acid sodium salt (PAA) is the most effective dispersing agent in the decantation process for the enrichment of HS1 sepiolite samples. Among the three gravity/sizing beneficiation techniques tested, the middlings product of the shaking table achieved the highest quality sepiolite product of 17,000 cP with 49.2 wt.% using the size range of – 2.83 mm to + 1 mm; this material is suitable for high-grade rheological applications.

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