Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026Scopus SJRQ2Microstructure and Dry-Sliding Tribology of HVOF-Sprayed NiCrBSi/WC-Co Coatings on AZ91D
Gürgenç, Turan; Macit, Cevher Kürşat; Sömer, Medeni; Aksakal, Bünyamin; Ayık, Merve; Say, Yakup
High-velocity oxy-fuel (HVOF)-sprayed NiCrBSi coatings containing 0, 10, 30, and 50 wt.% WC-Co were evaluated on AZ91D magnesium alloy to determine how the discrete reinforcement level affects surface topography, phase constitution, Vickers microhardness, dry-sliding friction, mass loss, and wear-track microchemistry. As-sprayed surfaces were characterized by three-dimensional profilometry; coating cross-sections and worn surfaces by optical microscopy and SEM/EDS; phase constitution by XRD; and mechanical response by HV0.1 indentation. Dry-sliding tests were performed at 10, 30, and 50 N over 100–1000 m. Increasing WC-Co content raised Sa from 8.8 ± 0.3 to 13.0 ± 0.5 µm and Vickers microhardness from 776 ± 4 to 959 ± 5 HV0.1. XRD indicated a γ-Ni-based matrix containing boride/carbide constituents, while WC, W2C, and Co became increasingly prominent in the reinforced coatings. Boride assignments are based on diffraction evidence, whereas B and C EDS signals were treated semi-quantitatively. The 50 wt.% WC-Co coating exhibited the lowest mass loss and mean coefficient of friction at every load. Its mean friction coefficients were 0.31, 0.35, and 0.41 at 10, 30, and 50 N, corresponding to reductions of 40.1%, 38.9%, and 36.2% relative to AZ91D. At 1000 m, its mass-normalized wear rate indices were 9.0 × 10−4, 4.0 × 10−4, and 5.3 × 10−4 mg N−1 m−1, respectively. Post-wear mapping showed the largest field-scale W-Co-rich fraction in the 50 wt.% coating; however, isolated spectra containing more than 94 wt.% Mg are compatible with local coating penetration/substrate exposure and/or Mg-rich debris. The 50 wt.% composition therefore provided the best combined response among the four tested levels, while intermediate compositions are required to identify a continuous-composition optimum.
- MakaleAçık Erişim2026Scopus SJRQ2Multi-functional GeAg- and TiO2-modified diamond-like carbon thin film device: structure, surface properties, photoresponse, photosensitivity, and biological performance
Aslan, Naim; Şükrü Kurt, Mustafa; Mehmet Koç, Mümin; Yilmazer, Yasemin; Coskun, Burhan; Aksakal, Bünyamin
DLC films represent a promising class of materials that can be used in various applications due to their optical, optoelectronic, tribological, and biomedical characteristics. In this work, GeAg- and TiO2-modified DLC thin films were prepared using the magnetron sputtering method under ultrahigh vacuum conditions. DLC thin film characteristics and addition of GeAg and TiO2 into the DLC structure were confirmed and subsequently assessed via scanning electron microscopy (SEM), atomic force microscopy, energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy. DLC thin film thicknesses were determined via SEM and found to be 235 nm and 380 nm for DLC/TiO2 and DLC/GeAg thin films, respectively. Contact angle and surface wettability analyses were performed for uncoated glass, GeAg- and TiO2-modified DLC thin films. The antibacterial properties of the DLC films were assessed for E. coli and S. aureus. The biocompatibility of these same films was confirmed using the L929 cell line, where no toxic effect was evidenced. To elucidate the optical characteristics of the thin films, a UV–vis spectrum was obtained, and band gap energies were proposed using these data. Photoresponse characteristics of the DLC thin films were assessed under varying illumination using current–time plots. It could be seen that DLC thin films’ responsiveness to light was dependent on illumination intensity. The results demonstrate that nanostructures are good candidates for multifunctional applications exhibiting good antibacterial and photoresponsive characteristics with outstanding biocompatibility.
- MakaleAçık Erişim2026Scopus SJRQ2Thickness- and Binder-Chemistry-Dependent Structural, Mechanical, and Tribological Performance of HVOF-Sprayed WC-Co and WC-Co-Cr Coatings on High-Speed Steel
Macit, Cevher Kursat; Aksakal, Bünyamin; Ayık, Merve; Gürgenç, Turan; Aslan, Naim
High-velocity oxy-fuel (HVOF) spraying was used to deposit WC-Co and WC-Co-Cr coatings on high-speed steel in order to determine how binder chemistry and coating thickness jointly control load support, friction, and dry sliding wear resistance. Nominal 50 and 100 µm coatings were compared within the same substrate framework by XRD, FT-IR, SEM/EDX, cross-sectional image analysis, Vickers hardness testing, dry sliding wear testing, and post-wear SEM/EDX. The coatings retained WC as the dominant crystalline phase, while weak overlapping features were associated with binder-rich regions and limited decarburization products. Cross-sectional observations confirmed continuous coating build-up close to the nominal thicknesses and low apparent dark-feature/porosity fractions. All WC-based coatings increased the effective hardness and reduced mass loss relative to uncoated HSS. Among the tested conditions, WC-Co-Cr-100 provided the highest effective hardness and the lowest mass loss after 1000 m sliding, whereas WC-Co-100 produced the lowest mean coefficient of friction. The results show that low friction and high wear resistance are not governed by identical mechanisms: WC-Co favours interfacial shear reduction, while the thicker Cr-containing coating provides superior resistance to material removal through improved carbide retention, binder stability, and coating-scale load support.
- MakaleAçık Erişim2025Scopus SJRQ2Effects of ZrN and DLC coatings on morphostructural, corrosion, cell viability, and antibacterial properties of Ti6Al4V scaffolds
Aslan, Naim; Aksakal, Bünyamin; Cihangir, Salih; Fidan, Ferzan; Yilmazer, Yasemin
Lightweight and functional metallic materials are consistently favored and attract significant attention in the biomedical field. This study investigates the influence of ZrN and DLC coatings on Ti6Al4V scaffolds with varying porosities (40%, 50%, 60%) for biomedical applications. PVD-deposited coatings exhibited distinct growth mechanisms: High-resolution SEM-FIB analyses revealed columnar ZrN structures due to limited adatom mobility, while DLC formed conformal, amorphous layers via high-energy carbon species. Corrosion resistance decreased in 40% porous DLC and 60% porous ZrN-coated samples, likely due to coating defects and increased electrolyte access through open pores. ZrN coatings showed superior antibacterial activity and attributed to surface reactivity and potential ion release. In contrast, the uncoated 60% porous scaffolds demonstrated highest cell viability, suggesting that excessive coating on highly porous structures may hinder cell–material interactions. Furthermore, the cytotoxicity evaluations indicated that uncoated scaffolds exhibited the highest cell viability (77.51%) at 60% porosity after 48 hours, with ZrN coatings demonstrating better efficacy compared to DLC in the 50% and 60% porosity groups.
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İncele - MakaleAçık Erişim2023Scopus SJRQ2ZrN and ta-C coatings on titanium for biomedical applications: Improved adhesion, corrosion, antibacterial activity, and cytotoxicity properties
Aslan, Naim; Aksakal, Bünyamin; Cihangir, Salih; Cetin, Fadime; Yilmazer, Yasemin
Commercially pure titanium (CP-Ti) is extensively used in biomedical applications. However, numerous qualities, including mechanical strength, corrosion resistance, and wear resistance, must be established for long-term performance as an implant material. This study investigates the enhancement of surface properties of CP-Ti through physical vapor deposition (PVD) with ZrN and ta-C (tetrahedral amorphous carbon). Among the coatings, ZrN revealed best overall results, such as adhesion, corrosion, microhardness, and wettability, excluding cell viability when compared to ta-C. E. coli and S. aureus were employed for antibacterial activity and MTS cell viability experiments. Compared to α-titanium, hardness tests revealed 91% increase in ZrN coating, and %22 increase in ta-C coating. Super-hydrophobicity and excellent antibacterial activity were found for ZrN coatings in comparison to ta-C. These findings emphasize the potential of ZrN and ta-C coatings to improve the surface properties of titanium, encouraging it to be used in biomedical devices. Graphical abstract: [Figure not available: see fulltext.].
AtıfScopus16WoS16OpenAlex19İncele - MakaleAçık Erişim2019Scopus SJRQ2Electrical characterization of solar sensitive zinc oxide doped-amorphous carbon photodiode
Koç, Mümin Mehmet; Aslan, Naim; Erkovan, Mustafa; Aksakal, Bünyamin; Uzun, Orhan; Farooq, W. Aslam; Yakuphanoğlu, Fahrettin
A new solar-sensitive zinc oxide doped-amorphous carbon diode was fabricated using the electrochemical deposition technique. The current-voltage characteristics of the fabricated Al/ZnO-a:C/p-Si/Al diode were investigated under dark and various lighting intensities using both I-V and C-V methods. The fabricated diode was characterized by XRD, SEM-EDS, FTIR and XPS analysis. Through the analysis, it was determined that the photocurrents increased with increasing intensity of incident light. The capacitance-voltage (C-V) characteristics revealed that the capacitance of the diode depended on voltage, frequency and illumination, indicating the existence of a continuous distribution of interface states. It was found that the capacitance changed drastically with changing frequency and separation was observed in different frequencies, as identified in the reverse bias region. The ideality factor obtained was found to be higher than unity, with the average barrier height and ideality factor of the diode were found to be 0.528 ± 0.0069 eV and 5.24 ± 0.39, respectively. The newly fabricated ZnO-doped amorphous carbon (Al/ZnO-a:C/p-Si/Al) photodiode exhibited good solar sensitivity. The overall results indicated that the fabricated Al/ZnO-a:C/p-Si can be used as a solar sensitive diode in optoelectronic device applications as an alternative to graphene-based materials.
AtıfScopus41OpenAlex46İncele - MakaleYalnız künye2017Scopus SJRQ2The effect and characterization of newly synthesized SrBr2 reinforced bone grafts on structure and cell viability
Demirel, Mehtap; Aksakal, Bünyamin; Kaya, Ali İhsan
Abstract: In this study, a highly durable SrBr2 compound was added to Ca(NO3)2·4H2O, KOH, NaNO3, P2O5, and urea (CO(NH2)2) compounds at different ratios (wt 10–30%); biografts were synthesized in different compositions using the sol gel method They were characterized using X-ray diffraction, Fourier transform infrared spectrometer, scanning electron microscope, and mechanical tests e.g. hardness and compression. Structural, mechanical properties and cell viabilities of the synthesized biografts were comparatively examined. Fourier transform infrared spectrometer and X-ray diffraction analysis results showed that, including SrBr2, hydroxyapatite had formed in the biografts. Also, hardness and compression tests revealed that compressive stress and hardness values of the grafts increased as the amount of SrBr2 increased. The cell viability ratios also enhanced with the amount of SrBr2 increased in the synthesized biografts. Graphical Abstract: [InlineMediaObject not available: see fulltext.]
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