Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1513
  Microstructure 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.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1455
  Comparative Microstructural, Mechanical, and Tribological Evaluation of Cu Matrix Composites Reinforced with B4C, B, Cr, Co, Al2O3, and Graphite via Powder Metallurgy

  Macit, Cevher Kursat; Gürgenç, Turan; Aksakal, Bunyamin; Aslan, Naim

  Copper and its alloys are widely used in electrical, automotive, aerospace, and energy applications because of their excellent thermal and electrical conductivity. However, the low hardness and poor wear resistance of pure Cu limit its use under tribologically demanding sliding conditions. In this study, Cu matrix composites reinforced with 1 wt.% boron carbide (B4C), boron (B), chromium (Cr), cobalt (Co), alumina (Al2O3), and graphite (Gr) were fabricated by powder metallurgy and comparatively evaluated under identical processing and testing conditions. Phase constitution and microstructural characteristics were analyzed by XRD, SEM, and EDS, while mechanical and tribological behavior was assessed by Vickers hardness and dry sliding wear tests. All reinforcements improved the hardness of the Cu matrix compared with unreinforced Cu. The hardness increase followed the order Cu–B4C (68.91%) > Cu–B (66.43%) > Cu–Gr (63.97%) > Cu–Al2O3 (61.79%) > Cu–Cr (42.69%) > Cu–Co (36.04%). Dry sliding wear tests, performed under a 10 N normal load, 0.05 m s−1 sliding speed, and 1000 m sliding distance against a 316L stainless-steel ball, showed that all reinforced composites exhibited lower mass loss and more stable sliding behavior than pure Cu. Among all samples, Cu–B4C displayed the best wear performance, with a 154.8% improvement in wear resistance relative to pure Cu. SEM analysis of the worn surfaces revealed that reinforcement addition reduced severe plastic deformation, groove formation, and delamination, leading to a more stable wear regime. Graphite- and boron-containing composites benefited from interfacial lubrication and contact stabilization, whereas B4C and Al2O3 improved wear resistance through rigid-particle strengthening and enhanced load-bearing capacity. By comparing ceramic, metalloid, metallic, oxide, and solid-lubricating reinforcements at the same low addition level and under identical processing and testing conditions, this study provides a reinforcement-selection framework for Cu-based composites requiring improved hardness and dry-sliding durability.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1325
  Multi-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.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1129
  Thickness- 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.

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/1000
  Effects 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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  AtıfScopus3·WoS3·OpenAlex3

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• DüzeltmeAçık Erişim2024Scopus SJRQ1/r/munzur/2103
  Correction to: Influence of Plastic Deformation and Hydroxyapatite Coating on Structure, Mechanical, Corrosion, Antibacterial and Cell Viability Properties of Zinc Based Biodegradable Alloys (Metals and Materials International, (2024), 30, 12, (3320-3337), 10.1007/s12540-024-01710-z)

  Aksakal, B.; Isın, Ege; Aslan, N.; Cihangir, S.; Sezek, S.; Yilmazer, Yasemin

  In the original version of this article, co-author ‘Yasemin Yilmazer’ name was missed to add in the author group. The correct order of author names should read as ‘B. Aksakal · Ege Isın · N. Aslan · S. Cihangir · S. Sezek, Y. Yilmazer’. The affiliation details of Yasemin Yilmazer are ‘Department of Molecular Biology and Genetics Sabahattin Zaim University, Istanbul, Turkey yaseminyilmazer14@gmail.com’. The original article has been corrected.

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• MakaleAçık Erişim2024Scopus SJRQ2/r/munzur/1830
  The influence of cold rolling and hydroxyapatite coating on the mechanostructure, corrosion resistance, cell viability, and antibacterial activity of ZnCu biodegradable implants

  Aksakal, B.; Karadogan, S.A.; Aslan, N.; Fidan, F.; Yilmazer, Y.; Sezek, S.

  Zinc (Zn) and its alloys exhibit great potential for utilization in biodegradable bone implants. Zn-1Cu biodegradable alloy was produced and were cold rolled at two different deformation rates of 47 and 61%. The samples have been bioceramic coated with the sol–gel method and microstructure-mechanical property changes, corrosion behavior and biocompatibility of the samples were investigated. They were characterized by Optical, SEM, XRD and wettability analysis. The rolled samples showed a significant increase in hardness when compared to the non-rolled samples. The unrolled and 47% rolled samples showed better corrosion resistance compared to 61% rolled samples. Antibacterial effects of the base and sol–gel-coated groups showed higher cell viability ratios than the uncoated groups. Cell viability increased significantly in 47% of the rolled samples after 24, 48, and 72 h, however decreased by up to 70% in 61% of the rolled samples. Graphical abstract: (Figure presented.).

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  AtıfScopus2·WoS2·OpenAlex2

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• MakaleAçık Erişim2024Scopus SJRQ1/r/munzur/1604
  Influence of Plastic Deformation and Hydroxyapatite Coating on Structure, Mechanical, Corrosion, Antibacterial and Cell Viability Properties of Zinc Based Biodegradable Alloys

  Aksakal, B.; Isın, Ege; Aslan, N.; Cihangir, S.; Sezek, S.; Yilmazer, Yasemin

  Zinc (Zn)-based biodegradable alloys have been at the forefront of absorbable biomaterial research in recent years due to their high biocompatibility and corrosion rates. The arc melting process was used to produce the Zn–1Cu–1Ag biodegradable alloy. The influence of different plastic deformation rates on the microstructure of the material was examined after the cold rolling at deformation rates of 47% and 61%. The undeformed and deformed alloys have been hydroxyapatite-coated using the electrophoretic deposition process to improve its surface, corrosion, and bioactivity properties. Optical, XRD, SEM, and EDS examinations were used to analyze the samples’ uncoated, coated, and rolled-unrolled forms. The nucleation of the (Ag, Cu)Zn4 secondary phase was formed during the rolling process. Hardness and compression tests were used to determine the mechanical properties of cast and rolled alloys, and in vitro corrosion tests were carried out in simulated body fluid. Antimicrobial and cell viability tests are executed to demonstrate the biocompatibility of the deformed and HA-coated Zn–1Cu–1Ag alloy. The mechanical properties were improved after the rolling process, with the highest results found in 47% of the rolled samples exhibiting a compressive strength of 412.65 ± 0.5 MPa and 61% of the rolled samples exhibiting a hardness value of 88.1 ± 0.5 HV. The samples that were rolled (61%) and coated with hydroxyapatite (HA) exhibited the highest level of corrosion resistance. The antimicrobial tests revealed that the rolled and HA coated Zn1Cu1Ag groups exhibited greater inhibition rates (47 and 61%) compared to the other groups when tested against E. coli. The HA-coated groups exhibited good cell viability ratios, with the maximum viability seen in the rolled and HA-coated group at 47%.

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• Kitap BölümüAçık Erişim2023/r/munzur/2792
  Production technique–structure relationship in bioceramic-coated scaffold applications

  Aslan, Naim; Topuz, Mehmet; Aksakal, Bunyamin; Dikici, Burak

  It is well known that the surface of metal-based implants is very resistive in aggressive body environments due to the noble oxide layer naturally formed on their surfaces. However, their osseointegration properties are very low. By the way, specific cells attached are desired on the implant surface when the surface of an implant connects with tissue in many circumstances. Thus in parallel with technological developments, biomedical engineering focuses on the growth of new tissue on the implant surface or in the porosities of the implant. The bulk properties of metallic scaffolds, especially Young’s modulus, can be controlled by the porosity ratio of the scaffold but cannot form a bond between the implant and tissue interfaces. Thus the coating of scaffold walls with a bioactive material is required. In this chapter, bioceramic coating techniques of scaffolds, mechanical and corrosion behavior, biocompatibility, and interactions of surface/tissue interface, especially considering the last published reports, were reviewed, in detail.

  AtıfScopus4·OpenAlex4

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• MakaleAçık Erişim2023Scopus SJRQ2/r/munzur/1716
  Fabrication of hydroxyapatite-based nano-gold and nano-silver-doped bioceramic bone grafts: Enhanced mechanostructure, cell viability, and nuclear abnormality properties

  Demirel, M.; Aslan, N.; Aksakal, B.; Arslan, M.E.

  In this study, nano-gold (nAu) and nano-silver (nAg) were doped at the molar ratios of Molar5–Molar30 to the Hydroxyapatite (HAp)-based bioceramic bone graft synthesized by the sol–gel method. The effects of nAu and nAg on structural, mechanical, cell viability, and nuclear abnormality of the synthesized bioceramic grafts were evaluated. The chemical and morphological properties of the bone grafts after production were examined through XRD and SEM–EDX analyses and mechanical tests. To determine the biocompatibility of the bone grafts, cell viability tests were performed using human fibroblast cells. In the cytotoxicity analyses, only HAp and HAp-nAu5 grafts did not show toxicological properties at any concentration, while HAp-nAg5 among the nAg-containing grafts gave the best results at the 200–100 μg/mL concentrations and showed significant cytotoxicity in human fibroblast cells. The other nAu-containing grafts showed toxicological properties in the concentration range of 200–50 μg/mL and nAg-containing grafts in the concentration range of 200–100 μg/mL against the negative control. The micronucleus (MN) analyses showed that the lowest total MN and L (lobbed) amounts, while the lowest total N (notched) amount, was obtained from the only HAp graft. It was found that the nAg-doped bone grafts gave higher total MN, L, and N amounts compared to the nAu-doped bone grafts. Furthermore, while the mean nuclear abnormality (NA) values of all grafts gave close results, the highest values were again obtained from the nAg-doped bone grafts.

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