Sürdürülebilir Kalkınma Amaçları

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• 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.

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• 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.

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• MakaleYalnız künye2026Scopus SJRQ2/r/munzur/800
  Oxide 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.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/761
  Corrosion behavior and constant load scratch adhesion properties of CeO2 doped ceramic composite layer via micro arc oxidation on Al 1050 alloy

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

  In this study, CeO2-doped ceramic coatings were produced on Al 1050 alloy by micro-arc oxidation (MAO) using a silicate-alkaline electrolyte containing 0, 0.5, 1, and 2% CeO2. The aim was to investigate the effect of CeO2 addition on the microstructure, phase composition, corrosion behavior, and constant-load scratch adhesion performance of the coatings. Surface characterization was carried out by SEM, EDS, XRD, and 3D profilometry, while corrosion performance was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5 wt% NaCl solution. Scratch tests were also performed to assess the mechanical integrity of the coatings. The results showed that increasing CeO2 content improved coating uniformity, reduced surface roughness and porosity, and promoted the formation of a denser oxide structure. XRD analysis confirmed that γ-Al2O3 was the predominant alumina phase in all coatings, while Ce-containing species were incorporated into the oxide layer without forming additional detectable phases. Electrochemical results revealed that CeO2 addition significantly improved corrosion resistance by lowering the corrosion current density and increasing the polarization resistance. Scratch test results further showed improved adhesion-related behavior with reduced crack formation and surface damage. Overall, CeO2 addition effectively enhanced both the corrosion protection and mechanical performance of MAO coatings on Al 1050 alloy.

  AtıfScopus1·OpenAlex1

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• MakaleAçık Erişim2023/r/munzur/5791
  Experimental investigation of engineering properties of silica sand filled mortars containing high doses of SWCNT

  Subaşı, Serkan; Dehghanpour, Heydar; Maraşlı, Muhammed; Doğan, Fatih

  Recently, great efforts have been made by researchers on the mixture of electrically conductive concretes that have been developed for different purposes. In this study, an experimental research was carried out on electrically conductive mortar mixtures especially for shell elements produced for building facade cladding. Six different mixtures were produced, including the non-conductive reference mixture. Single-walled carbon nanotube (SWCNT) was used as nano-sized conductive additive material. SWCNT was added at 0.2% and 0.3% of cement weight. SF was added to the same mixtures as another group at the rate of 4% by total weight. 2, 14, 28, 90 and 180 days electrical resistivities of the obtained conductive mortar samples were measured. As a non-destructive method, dynamic resonance testing was performed and the 28-day damping rates of the samples were determined. Ultrasonic pulse velocity (UPV) and Leeb hardness tests were performed, respectively, by using other non-destructive testing methods to obtain information about the internal structure voids and surface hardness of the samples. SWCNT, which causes low machinability and therefore internal structure voids, caused a decrease in compressive strength and flexural strength, as well as a significant increase in electrical conductivity.

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