Sürdürülebilir Kalkınma Amaçları

• 1
• 1

• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/1499
  Impact of hybrid Er2O3 and B4C additions on structural characteristics and experimental gamma-ray transmission behavior of Ni–Co–Fe–Cr–Mo high-entropy alloys

  Özkul, İskender; Güler, Ömer; Durmus, Hasan; Camgoz, Berkay; ALMisned, G.; Yaprak, Gunseli; Tekin, H.O.

  This study examines how Er2O3 and B4C additions affect the structural, microstructural, mechanical, and gamma-ray attenuation behaviour of Ni–Co–Fe–Cr–Mo high-entropy alloy composites. Five samples, labelled S0–S4, were produced by vacuum arc melting with different single and combined reinforcement contents. Thermodynamic calculations showed that the metallic matrix meets the general conditions expected for solid-solution HEA formation. XRD results indicated that an FCC-based matrix remained dominant in all samples. Reflections related to Er2O3 were identified in the Er2O3-containing compositions, while several weak secondary reflections could not be assigned with certainty because of their low intensity and peak overlap. SEM-EDS analysis confirmed the presence of Er-, O-, B-, and C-containing regions and also revealed local compositional variations within the microstructure. The reinforcement additions produced a clear increase in microhardness, with the highest value of 693 ± 51 HV0.5 obtained for the hybrid-reinforced S3 sample. Gamma-ray attenuation was measured at 276, 302, 356, and 383 keV using a high-purity germanium (HPGe) detector under narrow-beam condition. S4 showed the lowest nominal transmission factor at most energies at its actual sample thickness. However, after correcting for thickness using the Beer-Lambert relationship, S2 generally showed the highest nominal linear attenuation coefficient, while S4 gave closely comparable values at several energies. Some of the differences between samples were within the propagated counting uncertainties and were therefore interpreted with caution. Overall, the results show that the composition giving the highest hardness does not necessarily provide the strongest thickness-normalized gamma-ray attenuation. The attenuation behaviour is influenced by several factors, including reinforcement composition, sample thickness, density, phase distribution, microstructural heterogeneity, and measurement uncertainty. These findings highlight the need to optimize reinforced HEA composites according to the specific mechanical and radiation-related property being targeted.

  İncele
• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/1358
  Effect of Y2O3 rare earth oxide on the microstructure and growth kinetics of TiO2-based ceramic coatings fabricated by micro arc oxidation

  Ayday, Aysun; Duru, Erhan; Kırsever, Derya; Doğan, Fatih

  This study investigates the influence of Y2O3 addition on the microstructure, growth kinetics, and mechanical properties of TiO2-based ceramic coatings formed on Ti–6Al–4V alloy through the Micro Arc Oxidation (MAO) process. The experiments were carried out using Ti–6Al–4V plates coated in silicate-based electrolytes, with and without 1 g/L Y2O3, under a constant current density of 5 A/dm2 and a voltage of 360 ± 20 V for different treatment times (1, 3, 7, and 10 min). The coatings were evaluated by weight gain measurements, SEM/EDS analyses, X-ray diffraction (XRD), and constant load scratch testing supported by profilometry. Results revealed that Y2O3 significantly accelerated coating growth during the initial stages, leading to higher weight gains and denser, less porous morphologies compared to Y2O3-free coatings. XRD analysis indicated amorphous TiO2 and anatase phases at short durations, while rutile formation became dominant with longer treatments. Kinetic modeling demonstrated that both coatings initially followed a linear reaction-controlled mechanism (n ≈ 1), with calculated growth constants of 3.44 × 10⁻4 mg/mm2·s for Ti-MAO and 7.45 × 10⁻4 mg/mm2 s for Ti–Y2O3–MAO. However, after approximately 420 s, the Y2O3 coatings exhibited a marked reduction in growth rate due to electrical insulation effects of the thickened ceramic layer, resulting in multi-stage kinetics. Constant load scratch testing showed that Y2O3 incorporation reduced groove depth and width by nearly 45%, improving adhesion strength and mechanical durability. These findings confirm that rare-earth oxide addition is an effective strategy for enhancing the performance of MAO coatings on titanium alloys.

  AtıfScopus2·WoS1·OpenAlex2

  İncele
• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/996
  Evaluation of electrical properties of poly(NIPA-co-St) composites containing neodymium and yttrium

  Cetinkaya, Ebru; Karaaslan Ayhan, Nagihan; Torgut, Gulben

  In this study, firstly, to obtain neodymium (Nd) and yttrium (Y)-containing composite materials, poly(N-isopropylacrylamide-copolymer-styrene) (poly(NIPA-co-St)) copolymer was synthesized by free radical polymerization method using N-isopropylacrylamide (NIPA) and styrene (St) monomers. Secondly, new composite materials were obtained by adding neodymium and yttrium to this copolymer at different weight ratios (10% and 20%). Structural and morphological characterizations of poly(NIPA-co-St) copolymer, poly(NIPA-co-St)-10%Nd, poly(NIPA-co-St)-20%Nd, poly(NIPA-co-St)-10%Y and poly(NIPA-co-St)-20%Y composite materials were carried out. The electrical properties of the copolymer and composite materials were evaluated by considering the frequency dependence of the dielectric constant (έ), dielectric loss (ε″) and electrical conductivity (σac) properties. At 100 Hz, the έ, ε″, and σac values of the copolymer were 5.12, 0.05, and 2.29 × 10−10 S/cm, respectively. With the addition of 10% Nd, the έ, ε″, and σac values at 100 Hz were calculated as 6.57, 0.10, and 1.79 × 10−9 S/cm, respectively, while with the addition of 20% Nd, these values were calculated as 8.39, 0.15, and 4.78 × 10−8 S/cm at 100 Hz. With the addition of 10% Y, the έ, ε″, and σac values at 100 Hz were calculated as 6.56, 0.053, and 1.81 × 10−9 S/cm, respectively, while with the addition of 20% Y, these values were calculated as 8.57, 0.0058, and 3.70 × 10−8 S/cm at 100 Hz. It can be stated that as the amount of Nd and Y additives to the poly(NIPA-co-St) copolymer increases, the έ, ε″, and σac values increase, indicating an improvement in electrical properties with the addition of Nd and Y elements.

  AtıfOpenAlex1

  İncele
• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/863
  Assessment of microstructure and tribological performance of ZrO2-reinforced MAO coatings on 7075 aluminum alloy using grey relational analysis

  Yıldıztaş, Mesut; Ayday, Aysun; Candan, Gökçe; Duru, Erhan; Doğan, Fatih

  In this study, micro-arc oxidation (MAO) coatings containing different concentrations of ZrO2 were fabricated on 7075 Al alloy in a silicate-based electrolyte to evaluate their microstructural evolution, surface characteristics, and tribological performance. The coatings were produced at 390 V for 30 min in an electrolyte containing 10 g/L Na2SiO3 with ZrO2 additions of 0, 3, 6, and 9 g/L. Surface and cross-sectional morphologies were examined by SEM/EDS, while surface topography and wear track profiles were characterized by profilometry. Tribological behavior was evaluated under dry sliding conditions using a reciprocating tribometer. The results revealed that ZrO2 incorporation markedly influenced the coating growth behavior and surface morphology. The Zr0-MAO coating exhibited a rough and porous structure with large discharge channels, whereas the addition of ZrO2 led to a more compact and homogeneous morphology with reduced porosity. Among the coated samples, Zr6-MAO exhibited the most refined microstructure and the lowest surface roughness (Ra = 4.24 µm). This sample also showed the best tribological performance, with the lowest coefficient of friction (0.27), wear volume (0.0065 mm3), and wear rate (1.63 × 10−4 mm3/N·m). To provide a comprehensive multi-criteria assessment, grey relational analysis (GRA) was employed by simultaneously considering coating thickness, surface roughness, friction coefficient, wear volume, and wear rate. The GRA results were consistent with the experimental findings and identified Zr6-MAO as the optimum coating condition. These findings demonstrate that a moderate ZrO2 addition is highly effective in improving the compactness and wear resistance of MAO-coated 7075 Al alloy.

  İncele
• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/818
  Thermodynamic assessment of an equiatomic FeNiCoCrMn precursor for a spinel high-entropy oxide produced via mechano-oxidation with structure–radiation interaction correlation

  Güler, Ömer; Güler, Seval Hale; Özkul, İskender; ALMisned, Ghada; Sen Baykal, Duygu; Tekin, H.O.

  Spinel high-entropy oxides (HEOs) can stabilize multiple transition-metal cations within a single lattice, yet their radiation-interaction behavior is scarcely explored. Here, a (FeNiCoCrMn)3O4 spinel HEO was produced via an alloy-to-oxide route: 40 h mechanical alloying of equiatomic FeNiCoCrMn powders followed by mechano-oxidation (1000 °C/3 h) and high-energy grinding. HEA-derived thermodynamic metrics were used to rationalize the stability of the equiatomic metallic precursor prior to mechano-oxidation, rather than to directly predict the formation of the final oxide phase. XRD evidenced progressive amorphization of the HEA and its conversion to a crystalline spinel oxide, while SEM–EDS confirmed homogeneous elemental distribution. XPS indicated a defect-rich, multivalent surface (Co2+/Co3+, Cr3+/Cr6+, Fe3+, mixed Mn states, Ni2+) with lattice oxygen and vacancy-related components. Moreover, the spinel oxide showed higher linear attenuation coefficients than 316L stainless steel, Inconel-718, and several lightweight Al-based entropy alloys, yielding lower HVL values, especially at low energies. Zeff exhibited the expected energy dependence and exceeded Al-dominant alloys across the spectrum. EBF/EABF at 1 and 40 mfp displayed Compton-region peaks and strong depth effects, consistent with attenuation behavior. It can be concluded that a (FeNiCoCrMn)3O4 spinel high-entropy oxide, produced via an alloy-to-oxide transformation route, exhibits structurally stable and compositionally homogeneous characteristics together with favorable gamma-ray attenuation behavior.

  İncele
• MakaleAçık Erişim2024Scopus SJRQ1/r/munzur/2329
  Mechanical, wear and thermal properties of natural fiber-reinforced epoxy composite: cotton, sisal, coir and wool fibers

  Tasgin, Yahya; Demircan, Gokhan; Kandemir, Seckin; Acikgoz, Abuzer

  Natural fiber-reinforced epoxy composites (NFRCs) have gained significant attention in recent years due to their potential as environmentally friendly and sustainable materials. These composites combine natural fibers, derived from plants, with epoxy resins to create a material with enhanced properties. The objective of this study is to investigate the mechanical, wear and thermal properties of NFRCs incorporating cotton, sisal, coir and wool fibers. The vacuum-assisted resin transfer molding (VARTM) technique was employed to produce composite plates, followed by conducting tests on tensile, wear and thermal properties. The cotton composite showcased the highest tensile strength, reaching 52.81 MPa, while the coir composite exhibited the lowest, measuring 15.34 MPa. Sisal composite exhibited a moderate wear rate (1.423 mm3/Nm) and a lower coefficient of friction (0.233), implying smoother relative motion. Coir composite presented the highest wear rate (4.615 mm3/Nm), attributed to its coarse fiber nature. Thermal conductivity is highest at cotton composite (1.017 W/mK) and is lowest at coir composite (0.187 W/mK). Additionally, the highest specific heat was observed in the coir composite (26.313 MJ/m3K). Cotton demonstrated potential for efficient heat transfer, while wool outperformed in insulation. Sisal displayed versatility for structural applications. Coir emerged as an effective insulator with energy-saving applications.

  • 
  AtıfScopus101·WoS83·OpenAlex102

  İncele
• MakaleYalnız künye2024Scopus SJRQ1/r/munzur/1862
  Effect of Zr content on microstructure and wear behavior of Al-Si-Cu-Ni Mg-Zrx alloy

  Taşgın, Yahya; Gök, Mehmet

  In this study, the effect of zirconium addition (1, 1.5, 2 wt%) on the microstructural morphology and wear behavior of Al-Si-Cu-Ni-Mg alloys, known as light metals in which intermediate phases solidify rapidly at high temperatures, was investigated. The study aimed to obtain a stronger material by modifying the Al81Si12Cu4Ni2Mg alloy. It was observed that the Zr added to the alloy was homogeneously distributed throughout the samples. Aluminum and silicon formed compounds with zirconium (Al3Zr and ZrSi2), leading to the formation of a thinner and stronger structure. With the heat treatment applied to the aluminum alloys, the structure became more ductile. Additionally, as a result of Zr addition, microhardness increased, and wear values improved. Graphical abstract: (Figure presented.)

  AtıfScopus2·WoS2·OpenAlex5

  İncele
• MakaleAçık Erişim2024Scopus SJRQ1/r/munzur/1600
  Enhanced photocatalytic abilities of innovative NbTaZrMoW high-entropy alloys (HEAs): a comparative analysis with its high entropy oxide (HEO) counterpart

  Zakir, O.; Guler, O.; Idouhli, R.; Nayad, A.; Khadiri, M.E.; Guler, S.H.; Abouelfida, A.; Dikici, B.

  The photocatalytic performance of high entropy alloy (HEA) and its oxide form (high entropy oxide, HEO) have been evaluated in this study. The HEA, composed of Nb, Ta, Zr, Mo, and W powders, was synthesized through a mechanical alloying process for 120 h. This process was carried out under a high-purity Ar atmosphere to prevent oxidation. Subsequently, the HEA was converted into HEO via a mechano-thermal oxidation method 900 °C for 12 h. The photocatalytic activity of both oxidized and non-oxidized samples was systematically evaluated by degradation of methyl blue (MB) under UV irradiation. Electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to investigate the structural and chemical features of the alloys. Furthermore, BET surface area analysis and Zeta potential measurements were conducted to understand the alloys’ surface properties and stability in aqueous solutions. The results showed that the HEA has a remarkable photodegradation performance of around 58.77% which is two times higher than that observed with the HEO. Graphical abstract: (Figure presented.)

  AtıfScopus31·WoS30·OpenAlex28

  İncele
• MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/3073
  Graphene reinforced hybrid-bioceramic coatings on porous-Ti6Al4V for biomedical applications: morphology, corrosion resistance, and cell viability

  Aslan, N.; Aksakal, B.; Dikici, B.; Sinirlioglu, Z.A.

  The effect of Hydroxyapatite (HA)-based coatings reinforced with reduced graphene oxide (rGO) on porous-Ti6Al4V (P-Ti6Al4V) alloys in terms of electrochemical corrosion and cell viability for potential biomedical applications was investigated in this study. The scaffold-porous surfaces of P-Ti6Al4V were coated by the biocomposite structure of HA and reduced graphene oxide (rGO) at various porosity rates (40, 50, and 60%) by using the sol–gel dip-coating method. The results of 0.5, 1.0, and 1.5 wt% rGO-HA coatings were compared to coatings that contained only HA (free-rGO). Raman spectroscopy, X-ray diffractometer, and scanning electron microscopy were used for structural and morphological characterizations. The coatings in vitro corrosion susceptibilities were tested in simulated body fluid at 37 °C. Compared to free-rGO coatings, the results showed that rGO reinforcements phases reduced the corrosion rate of the scaffolds. The corrosion rate increased as the porosity content of the scaffolds increased. In vitro cell viability tests revealed that samples of 0.5 and 1.0 wt% rGO-HA coating groups performed better than the control and 1.5 wt% rGO-HA samples. Graphical abstract: [Figure not available: see fulltext.]

  • 
  AtıfScopus8·WoS7·OpenAlex6

  İncele