Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Güler, Ömer(8)
- Özkul, İskender(7)
- Aslan, Naim(6)
- Aksakal, B.(5)
- Artuğer, Fırat(5)
- Aslan, N.(5)
- Kahraman, Gökhan(5)
- Say, Yakup(5)
- Tekin, H.O.(5)
- Canbay, Canan Aksu(4)
- Danabas, Durali(4)
- Dikici, B.(4)
- Gul, Muhammet(4)
- Ince, Muharrem(4)
- Kaplan Ince, Olcay(4)
- Karaduman, Oktay(4)
- Koç, Mümin Mehmet(4)
- Kutlu, Banu(4)
- Taşgın, Yahya(4)
- ALMisned, Ghada(3)
- Ates, Mehmet(3)
- Aşkin, A.(3)
- Baykal, Duygu Sen(3)
- Cihangir, Salih(3)
- Doğan, Fatih(3)
- Güler, Seval Hale(3)
- Imak, Andaç(3)
- Karaaslan Ayhan, Nagihan(3)
- Kök, Mediha(3)
- Topal, Murat(3)
- Torğut, Gülben(3)
- Yucesan, Melih(3)
- Özkaynak, Fatih(3)
- Akkurt, Nevzat(2)
- Aksoy, M.E.(2)
- Aksu, Onder(2)
- Alkarrani, Hessa(2)
- Alp Dal, Nursel(2)
- Arslan Topal, E. Işıl(2)
- Arslan, Zikri(2)
Yayınlar
- MakaleYalnız künye2026Scopus SJRQ3Impact of ZnF2 and PbF2 on the radiation attenuation performance of the fluoride-based bismuth borate glass system
Aşkın, A.
Among the various types of glasses, fluoride-based glasses stand out due to their chemical and mechanical stability, low refractive indices, low phonon energies, and low transition temperatures. In this study, key radiation shielding parameters, including the mass attenuation coefficient (µm), half-value thickness (HVL), mean free path (MFP), transmission fraction (T), effective atomic number (Zeff), exposure build-up factors (EBF) and fast neutron removal cross-section (∑R), of the newly developed fluoride-based glass system, xZnF2—(25-x)PbF2—25Bi2O3—49.8B2O3—0.2Cr2O3 (where x is between 0, and 25 mol%), were evaluated. The data was gathered through Monte Carlo simulations, utilizing the Geant4 framework for a germanium detector and the PHY-X/PSD software. The parameters were assessed for gamma-ray energies ranging from 0.284 to 1.33 MeV across all glass samples. The results clearly show that the presence of PbF2 significantly enhances radiation shielding, owing to the high atomic number (Z) of lead. The highest µm and Zeff values were found to be highest and MFP, HVL, and T values were found to be lowest for the glass sample with the highest PbF2 content. Furthermore, the ∑R values of the glasses were observed to decrease as the PbF2 content reduced, highlighting the importance of high-Z elements in neutron absorption. Therefore, gamma and neutron shielding abilities of the studied glasses improve with the addition of PbF2 into the glass structure and glass system containing 25% mole PbF2 exhibits superior gamma and neutron shielding performance compared to shielding concrete.
AtıfScopus1WoS1
İncele - MakaleYalnız künye2026Scopus SJRQ1Impact 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.
- MakaleYalnız künye2026Scopus SJRQ1From trash to technology: Ai-driven waste classification with hybrid CNN-transformer approach for sustainable recycling
Utku, Anil
The increasing amount of waste globally requires more efficient recycling processes and increases the importance of intelligent, automatic classification systems. Since traditional waste separation methods are time-consuming and have high error rates, artificial intelligence-based solutions have great potential in this area. In this study, the effectiveness of deep learning-based waste classification models was investigated, and nine different waste types were classified using DenseNet121, EfficientNetB0, ResNet50, ViT, DenseNet121-ViT, EfficientNetB0-ViT, ResNet50-ViT. Experimental results show that hybrid CNN-ViT models achieved the highest accuracy rates. Mainly, the EfficientNetB0-ViT model exhibited the best performance with a 95% accuracy rate and made a balanced classification for all waste types. The model can optimize recycling processes by ensuring the correct separation of wastes and contribute to environmental sustainability by reducing misclassification. Artificial intelligence-supported waste management systems offer an effective solution in critical areas such as reducing greenhouse gas emissions, saving energy, and supporting environmentally friendly urban planning. The findings of this study reveal that deep learning-based artificial intelligence models are an important tool for sustainable environmental management.
AtıfScopus1WoS1OpenAlex3İncele - MakaleAçık Erişim2026Scopus SJRQ1Effect 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.
AtıfScopus2WoS1OpenAlex2İncele - MakaleYalnız künye2026Scopus SJRQ2Simultaneous 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.
- MakaleAçık Erişim2026Scopus SJRQ2Effects of Magnetic Abrasive Finishing Process Parameters on the Inner Surface Machining of AISI 304 Austenitic Stainless Steel Pipes
Sarıçiçek, İzel; Çaydaş, Alparslan Ulaş; Cihangir, Salih; Say, Yakup
In this study, the effects of SiC abrasive ratio, size of magnetic Fe particles and the machining time parameters on the surface roughness, material removal rate, roundness of the holes and corrosion resistance in magnetic abrasive inner surface finishing (MAF) of the AISI 304 austenitic stainless steel pipes were experimentally investigated. A Taguchi L9 orthogonal array was used for the experiments. The surface roughness and the characteristics of the machined surfaces were examined by using the3D surface topography method. The characteristics of the abrasive and magnetic powders before and after machining operations were investigated under scanning electron microscope (SEM) and x-ray diffraction analysis (XRD) techniques. The electrochemical corrosion measurements were performed in 3.5 wt.% NaCl solutions in a typical three-electrode electrochemical cell. An analysis of variance (ANOVA) method was also applied to the study in order to determine the statistical effects of each factor on the measured responses. Consequently, AISI 304 samples machined with MAF technique revealed better results for corrosion performance, surface quality, material removal rate and the hole dimensional tolerances.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2026Scopus SJRQ2Drying temperature-dependent changes in grape seed bioactives and oxidative status: integrated HPLC/GC and multivariate analysis
Karaca Sanyürek, Nesrin
Abstract: Drying temperature (40–80 °C) critically influences the stability of bioactive compounds in grape seeds and their functional responses. In this study, we evaluated the vitamin and phytosterol content of Boğazkere grape seeds using high-performance liquid chromatography (HPLC) and the fatty acid content using gas chromatography (GC). Antioxidant capacity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and the oxidative stress marker, malondialdehyde (MDA). Temperature-dependent and compound-specific alterations were observed: while selected vitamins and phytosterols showed distinct thermal susceptibilities, fatty acid profiles exhibited measurable remodeling. Antioxidant activity revealed non-linear dose- and temperature-dependent patterns, whereas MDA consistently decreased with increasing temperature, reflecting the reduced oxidative metabolism in dehydrated tissues. Multivariate analysis, including principal component analysis (PCA) and heatmap visualization, effectively discriminated temperature treatments and revealed correlations between compositional and functional parameters. The combined use of univariate and multivariate analyses revealed that the drying temperature reshaped not only individual bioactive compounds but also the overall biochemical profile of grape seeds. These findings establish a mechanistic link between thermal processing and bioactive stability, providing a chemical basis for optimizing grape seed valorization in food systems.
- MakaleYalnız künye2026Scopus SJRQ2Influence of Low-SiC Content on the Tribological and Electrical Properties of Cu Composites Produced by Spark Plasma Sintering
Çelik, Ertuğrul
In this study, copper matrix composites reinforced with varying silicon carbide (SiC) contents (0.25, 0.5, 0.75, and 1 wt.%) were fabricated using spark plasma sintering (SPS). The effects of SiC reinforcement on the microstructure, hardness, porosity, electrical conductivity, and tribological performance were systematically investigated. Brinell hardness values increased with higher SiC content, reaching up to 76 HB for the 1 wt.% SiC composite. This improvement was accompanied by a gradual increase in porosity from 0.6 to 2.1%. Electrical conductivity decreased from 93% IACS to 66% IACS with increasing SiC content. Tribological tests revealed that the specific wear rate was significantly reduced, reaching as low as 1.1 × 10−4 mm3/N m at 15 N due to the formation of a protective tribolayer. These results demonstrate that incorporating small amounts of SiC can substantially improve hardness and wear resistance, while maintaining acceptable electrical performance, making Cu-SiC composites promising candidates for durable electrical contact applications.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2026Scopus SJRQ1Hydrogeochemical controls on chromium speciation and potential human health risks in surface waters of an ultramafic mining watershed
Kutlu, Banu; Baydar, Tarık; Yıldırım, Vesile; Konurhan, Zekeriya
Accurate assessment of chromium contamination in mining-influenced watersheds requires distinguishing between the environmentally contrasting Cr(III) and Cr(VI) species, yet environmental monitoring and risk assessments still rely predominantly on total chromium concentrations. This study evaluated whether chromium speciation provides additional information beyond operational total chromium for assessing chromium occurrence and potential human health risks in an ultramafic, mining-influenced watershed. Surface-water samples were collected from 28 sampling stations across the Pülümür and Ovacık regions of the Eastern Anatolia Basin (Türkiye) between March 2025 and February 2026. Chromium speciation was determined using species-specific UV–Visible spectrophotometric methods and integrated with hydrochemical characterization, multivariate statistical analyses, mineralogical investigations (XRD, SEM–EDS, and FTIR), and deterministic and empirical-bootstrap human health risk assessments. Operational total chromium, defined as the sum of separately measured Cr(III) and Cr(VI), ranged from below the detection limit to 578.13 µg L−1. For contextual screening, this calculated value exceeded World Health Organization (WHO) drinking-water guideline for total chromium at 14 stations; however, it was not an independently measured total-Cr concentration. The highest Cr(VI) concentration occurred at a localized hotspot, whereas Cr(III) predominated throughout most of the watershed. Nevertheless, Cr(VI)-based screening thresholds were exceeded at multiple stations under the assumed untreated drinking-water ingestion scenario, indicating that operational total chromium alone did not consistently identify the spatial distribution of Cr(VI)-related potential risk. Screening-level hazard quotient (HQ) estimates were higher for children than for adults; however, direct untreated consumption of the sampled surface waters was not verified. Mining-influenced stations generally exhibited higher chromium concentrations, although the relative contributions of geogenic weathering and mining-related mobilization could not be quantitatively apportioned. Overall, chromium speciation provided additional environmentally and toxicologically relevant information beyond operational total chromium for evaluating chromium mobility and screening-level potential human health risks in this ultramafic watershed.
- MakaleAçık Erişim2026Scopus SJRQ2Investigation of the Mechanical and Metallographic Effects of Adding 2-3% Al-Ti-Mo Elements to High-Entropy CoCrFeNi Alloys
Dilek, İlhan; Taşgın, Yahya; Kanca, Muhammed Sait; Kök, Mediha; Güler, Ömer
Recently, high-entropy alloys (HEAs) have attracted significant attention due to their unique multicomponent composition and exceptional mechanical properties, such as high wear and corrosion resistance, making them superior to conventional alloys for advanced engineering applications. The effects of Al, Ti, and Mo addition on the microstructural and mechanical properties of CoCrFeNi-based HEAs were investigated. The alloys were produced via powder metallurgy and vacuum arc melting, with the addition of 2 and 3% Al, Ti, and Mo, respectively. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) were used to perform microstructural characterization, while microhardness and wear tests were used to evaluate mechanical performance. The addition of Al and Ti enhanced the face-centered cubic phase stability and increased the hardness by improving the lattice structure. In contrast, the addition of Mo contributed to solid solution and precipitation hardening, resulting in a simpler microstructure and superior tribological performance. Among all compositions, the alloy with 3% Mo addition exhibited the highest hardness value (≈ 233.8 HV) and the lowest mass loss (4.3 mg) was observed, indicating a significant improvement in the wear resistance and mechanical strength. In conclusion, the addition of Ti and Mo to CoCrFeNi HEAs promotes solid solution, precipitation, and grain boundary hardening mechanisms, thereby enhancing microstructural integrity, hardness, and wear resistance. These findings suggest that such alloys are promising candidates for use as next-generation structural and tribological materials under demanding operational conditions.
- MakaleYalnız künye2026Scopus SJRQ2The Turkish Version of the Self Evaluation of Breathing Questionnaire: Cross-cultural Adaptation, Validity and Reliability
Ataş, Kübra; Kızmaz, Erhan; Mutlu, Ebru Kaya
Investigating the validity and reliability of the Turkish version of the Breathing Self-Assessment Questionnaire (SEBQ), a tool for measuring dysfunctional breathing. Ninety-two healthy adults (mean (range) age 29.4 (19–56) years; 39 males) were analysed. The SEBQ was translated and adapted into Turkish. At baseline, data were collected using the SEBQ, Nijmegen Questionnaire (NQ), breath-holding time, and Short Form 36 (SF-36). The SEBQ was repeated within 7–14 days. SEBQ validity was assessed through content, structural, and convergent/divergent validity analyses, while reliability was evaluated for internal consistency, stability, and reproducibility. One item was removed based on exploratory factor analysis. The SEBQ has a two-factor structure and explains 50.1% of total variance, confirmed by confirmatory factor analysis. It has a positive correlation with the NQ and a negative correlation with SF-36 subscales, but not with breath-holding time and general health. The Cronbach’s alpha coefficient was 0.931, and the intraclass correlation coefficient was 0.814. The Standard Error of Measurement and Smallest Real Difference were 5.06 and 15.03, respectively. The SEBQ is well-structured, valid, internally consistent, stable, and reproducible for assessing subjective unexplained respiratory symptoms in the Turkish population.
AtıfScopus1WoS1OpenAlex3
İncele - MakaleAçık Erişim2026Scopus SJRQ1Evaluation 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.
AtıfOpenAlex1İncele - MakaleAçık Erişim2026Scopus SJRQ2Structural and optical properties of Bi- and Sn-doped Sb2Se3 thin films prepared by thermal evaporation
Kök, Mediha; Öztürk, Yunus; Sait Kanca, M.
In this study, Sb2Se3-based semiconductor thin films, both pure Sb2Se3 and those doped with Bi and Sn, were produced using the thermal evaporation method. The structural, morphological, and optical properties of the obtained films were investigated using XRD, SEM, and UV–Vis spectroscopy. While films without annealing exhibited an amorphous structure, significant crystallization was observed after annealing at 350 °C, especially at high doping levels. SEM analyses showed significant changes in surface morphology and grain structure depending on the doping level. Optical measurements revealed that absorption increased and the band gap changed with increasing doping level. The band gap for the undoped Sb2Se3 thin film was found to be 1.54 eV. An increase due to the Burstein–Moss effect was observed at low additive ratios, while band narrowing was observed at high additive ratios. The results obtained indicate that Bi and Sn additives improve the optoelectronic properties of Sb2Se3 thin films and hold potential for photovoltaic applications.
- MakaleAçık Erişim2026Scopus SJRQ1A new key generator algorithm based on sine map and SHA-3 for image encryption
Artuğer, Fırat; Özkaynak, Fatih
In recent years, the need for secure cryptographic keys for various purposes has been constantly increasing. One of these areas is undoubtedly image encryption. In this study, a new key generation algorithm has been developed for use in image encryption algorithms. The proposed generator has a hybrid structure based on the chaotic sine map and the SHA-3 algorithm. It is aimed to produce strong keys by using the benefits of these two structures. To do this, first, bit sequences of the desired length are generated using the basic parameters of the sine map. Then, bit sequences of the same length are obtained using the SHA-3 algorithm. These two bit sequences are then subjected to an XOR operation to generate key values of the desired length. With this structure, 3 different bit sequences of 1 million length were produced. All of these bit sequences successfully passed NIST SP 800 − 22 tests. This key value obtained in this study has been successfully applied to a new image encryption algorithm. The results of the study demonstrate that the proposed algorithm meets important cryptographic criteria such as information entropy, correlation-histogram analysis, NPCR, and UACI values. In addition, the simple and fast structure of the algorithm in key generation was the most important difference from other studies.
AtıfScopus3OpenAlex2İncele - MakaleYalnız künye2026Scopus SJRQ2Influence of Boron Addition on the Microstructure, Mechanical, and Corrosion Behavior of NiCrBSi Alloys Prepared by Spark Plasma Sintering
Çelik, Ertuğrul
This study investigates the effect of boron addition on the microstructural, mechanical, and corrosion properties of NiCrBSi alloy fabricated by the spark plasma sintering (SPS) method. Boron was added at levels of 1.5, 3, and 4.5 wt.%, and sintering was conducted at 950 °C for 5 min. Microstructural characterization was carried out using SEM–EDS and XRD analyses, hardness was measured by the Vickers method, and densities were determined according to Archimedes’ principle. The transverse rupture strength (TRS) was obtained by three-point bending tests, while wear performance was evaluated in a reciprocating wear mode. Corrosion behavior was examined through potentiodynamic polarization in a 0.1 M HCl solution. Increasing boron content promoted the formation of nickel and chromium boride phases, enhancing hardness (up to 675 HV0.5) and wear resistance but reducing TRS values due to brittle intermetallic formation. Furthermore, corrosion protection efficiency improved, reaching about 65.9% at 4.5 wt.% B addition.
- MakaleYalnız künye2026Scopus SJRQ1Assessment 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.
- MakaleAçık Erişim2026Scopus SJRQ1The Role of Graphene on Microstructural, Mechanical, and Tribological Properties of Cu–AlCrFeCuNi Metal Matrix Composites Fabricated via Spark Plasma Sintering
Yanar, Harun; Çelebİ, Müslİm; Sekban, Dursun Murat; Özkaya, Serdar; Karabacak, Abdullah Hasan; Çelİk, Ertuğrul
In this study, Cu-based AlCrFeCuNi high-entropy alloy (HEA) composites reinforced with graphene were fabricated using a mechanical-alloying-assisted spark plasma sintering (SPS) technique. The HEA reinforcement content was kept constant at 20 wt pct for all samples, while the graphene content was varied at 0, 0.5, 1.0, and 2.0 wt pct to investigate its influence on the microstructure, hardness, and tribological performance. The results indicate that both the HEA particles and graphene exhibit an almost homogeneous distribution within the matrix; however, increasing graphene content led to noticeable graphene accumulation along grain boundaries. With higher graphene fractions, the relative density decreased from 97.51 to 94.92 pct, whereas the hardness increased up to the 1.0 wt pct graphene addition, reaching 134.16 HB, followed by a slight decrease to 129.25 HB at 2.0 wt pct. Furthermore, graphene reinforcement significantly improved the tribological behavior of the composites, providing a substantial reduction in wear. The addition of graphene significantly decreased the coefficient of friction from about ~ 0.70 in the Cu–HEA alloy to 0.08 at 2.0 wt pct graphene. Graphene also suppressed the pronounced frictional fluctuations observed in the base alloy, leading to a much more stable sliding behavior. As a result, wear loss was reduced by nearly 99 pct, primarily due to the formation of a continuous lubricating tribofilm on the contact surface.
AtıfScopus3WoS4OpenAlex4İncele - MakaleYalnız künye2026Scopus SJRQ1Thermodynamic 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.
- MakaleYalnız künye2026Scopus SJRQ2Oxide Dispersion, Microstructure, and Functional Evolution in La2O3 Modified Cu-Al-Mn-Fe Shape Memory Alloys
Karaduman, Oktay; Doğan, Fatih; Dehghanpour, Heydar; Yüzüak, Gizem Durak; Yüzüak, Ercüment; Canbay, Canan Aksu
Cu-Al-Mn-Fe high-temperature shape memory alloys containing 0-1.0 wt.% La2O3 were fabricated by vacuum arc remelting to investigate oxide-dispersion effects on microstructure, martensitic transformation, wear, and corrosion behavior. XRD and SEM analyses revealed that low La2O3 additions (0.2-0.4 wt.%) promoted β1′ martensite refinement and enhanced crystallinity, while higher contents induced structural heterogeneity. The alloy with 0.4 wt.% La2O3 exhibited the highest transformation enthalpy (7.49 J g−1), reduced friction coefficient (~0.55), and the narrowest wear scar (~501 µm). Electrochemical tests in 3.5 wt.% NaCl showed a fivefold decrease in corrosion current density and increased charge-transfer resistance (2512 Ω cm2) for the same composition. Excessive La2O3 led to performance degradation due to particle agglomeration and interfacial defects. The results demonstrated that controlled La2O3 addition enabled microstructural refinement and multifunctional performance enhancement in Cu-based shape memory alloys.
- MakaleAçık Erişim2026Scopus SJRQ2Engineering 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.