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Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2026/r/gumushane/13782
  Investigation of the adhesion properties of duplex coating on AZ91 alloy surface by MAO/HiPIMS-PVD methods

  Kaplan, Emine Boynueğri; Şüküroğlu, Süleyman; Şüküroğlu, Ebru Emine

  This study focuses on enhancing the surface properties and minimizing the mechanical incompatibility between the AZ91 magnesium alloy and the coating by applying CrAlYN/CrYN gradient coatings through the HiPIMS-PVD method, combined with the enlargement of a MgO intermediate layer via the Micro Arc Oxidation (MAO) method. The duplex coating approach was designed to strengthen adhesion and structural integrity between the substrate and the coating. Coating parameters for both MAO and HiPIMS-PVD processes were optimized using a Taguchi L4 orthogonal array, and the coatings were analyzed using SEM, EDS, XRD and scratch testing. MAO coatings exhibited porous and rough surfaces with volcanic morphologies. The best adhesion performance under MAO conditions was achieved with 650 V, 700 Hz, and a Type B solution, resulting in a critical load value of Lc₂ = 24 N. CrAlYN/CrYN gradient coatings alone showed coating thicknesses from 0.83 μm to 1.66 μm with compact and homogeneous microstructures. Adhesive strength was relatively low (Lc₂ = 5–10 N). In the duplex coating configuration, CrAlYN/CrYN coatings were deposited on the MAO-formed MgO layer, significantly increasing adhesion. Critical load values (Lc₂) ranged from 90 to 110 N, with the highest adhesion achieved under low CrY target voltage and current conditions. The findings demonstrate that the MAO/HiPIMS-PVD duplex coating method substantially improves adhesion and surface characteristics of AZ91 alloy, offering a promising solution for advanced surface engineering applications.

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• MakaleAçık Erişim2026/r/gumushane/12123
  Experimental and Modeling Study of Fluidity in Ductile Iron (GGG40)

  Coşar, Mehmet; Şüküroğlu, Ebru Emine; Güngör, Kadir; Çolak, Murat

  Ductile irons (spheroidal graphite cast irons, SGI) are widely used in automotive and energy systems due to their high strength, ductility, and excellent machinability. The casting quality of these alloys largely depends on the flow and filling behavior of the molten metal, namely its fluidity. In this study, the effects of pouring temperature, filling time, and metallurgical quality on the fluidity of GGG40 ductile iron were investigated through both experimental and numerical approaches. Experimental trials were conducted at pouring temperatures of 1350 °C, 1400 °C, and 1450 °C; metallurgical quality levels of 10%, 50%, and 90%; and filling times of 5 s and 10 s. The fluidity lengths were measured and statistically evaluated. The results revealed that increasing the pouring temperature and metallurgical quality significantly improved fluidity, while shorter filling times allowed the molten metal to travel longer distances before solidification. Modeling studies performed using a commercial casting simulation software showed strong correlation with the experimental data. Microstructural examinations indicated that higher pouring temperatures and improved metallurgical quality led to a more homogeneous distribution of graphite nodules and an increased ferrite fraction in the matrix. The findings provide valuable insights into the influence of process parameters on the fluidity behavior of ductile iron and offer critical design data for enhancing casting quality and productivity in industrial foundry applications.

  İncele
• MakaleAçık Erişim2025/r/gumushane/19760
  Geçmişten Günümüze Gümüşhane’de Madencilik

  Sukuroglu, Ebru Emine; Dağ, Serhat; Alemdag, Selcuk; Saylan, Kemal; Nazir, Bayram; Ozer, Ismail; Kurucu, Muhammet; Sipahi, Ferkan; Atalan, Öznur; Zeybek, Halil

  Türkiye, madenler bakımından oldukça çeşitli ve zengin bir ülkedir. Ülkede yer alan bazı madenlerin dünya çapında önemli bir yere sahip olduğu bilinmektedir. Türkiye'nin Doğu Karadeniz bölgesinde bulunan Gümüşhane ili de madenler bakımından zengin bir çeşitliliğe sahiptir. Öyle ki, Gümüşhane’de var olan bu çeşitlilik ilk medeniyetlerin bölgeye hâkim olması ile önemli hâle gelmiş, şehirde bulunan madenlerin dışında şehrin İpek Yolu güzergâhında yer alması da bu bölgenin önemini daha da arttırmıştır. Hiç şüphesiz bu önem, Osmanlı Devleti’nin Trabzon’un fethi ile bölgeyi topraklarına katması ile devam etmiştir. Bu dönem ile birlikte şehirde madencilik faaliyetleri artmaya başlamış ve bu yönde yapılan çalışmalar ülkeye maddi anlamda katkı sağlamıştır. Bu açıdan Osmanlı Devleti, 16., 17. ve 18. yüzyıllarda bünyesinde barındırdığı başta gümüş ve altın madenleri olmak üzere diğer madenlerin varlığı nedeniyle ticari olarak canlı bir özellik gösteren Gümüşhane’ye büyük önem vermiştir. Böylece 17. yüzyılda adeta altın çağını yaşayan maden ocakları, 18. yüzyılın sonlarına kadar faaliyetlerini devam ettirmiştir. Bu yüzyıldan sonra da madenlerde yapılan üretim zamanla azalarak bölgedeki maden işletmelerinde çalışan işçiler madenleri terk etmeye başlamıştır. 19. yüzyılın ortalarına gelindiğinde maden ocaklarının işletilmesinde büyük oranda çözülme ortaya çıkmıştır. Yapılan bu çalışma; Gümüşhane şehrinin tarihî çağlar, Osmanlı Dönemi ve Cumhuriyetten günümüze kadar olan maden çalışmalarını ele alarak şehir ekonomisine birinci derecede yön veren madenlerin şehir açısından önemini ortaya koymayı amaçlamıştır. Çalışmada alan ile ilgili yapılmış çalışmalardan ve arşiv vesikalarından istifade edilmiştir.

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  İncele
• MakaleAçık Erişim2025/r/gumushane/14353
  Investigation of the Effects of Filling Speed, Casting Temperature and Metallurgical Quality on Fluidity of Lamellar Graphite Cast Iron at Different Section Thicknesses

  Köse, Sami; Çolak, Murat; Şüküroğlu, Ebru Emine

  In this study, the fluidity properties of the alloy were investigated at different casting temperatures, different section thicknesses, and varying casting parameters of lamellar graphite cast iron materials. To achieve our goal, we utilized sand molds that were created with specific parameters including pouring temperature, metallurgical quality, section thickness, and fluidity test model. These molds were used for casting. Thus, the effect of fluidity properties in changing casting conditions and liquid metal advance distances at determined section thicknesses was investigated. Modeling was carried out with FlowCast casting simulation software by determining the liquid metal advance distance depending on the section thickness in the castings made in sand molds under changing casting conditions. The fluidity and advance distance of the liquid metal was determined comparatively with experimental and modeling techniques under the changing casting conditions in the parameters determined in this study. When the outcomes were examined; it was observed that different liquid metal advance distances occur at different cross-section thicknesses depending on the changing conditions.

  İncele
• MakaleYalnız künye2025/r/gumushane/14079
  Investigation of structural and adhesion properties of ZnO and h-BN doped TiO2 coatings on Cp–Ti alloy

  Belet, Ali Kadir; Şüküroğlu, Süleyman; Şüküroğlu, Ebru Emine

  Titanium and its alloys are widely used in aircraft, automotive, chemistry, marine, and military industries owing to their superior properties such as specific strength, very low density, high melting point, high corrosion resistance, good fatigue strength and toughness, low elastic modules, and excellent biocompatibility. However, insufficient tribological properties such as high and unstable friction coefficient, low scraping wear resistance and strong adhesion tendency, and poor corrosion resistance in some aggressive corrosive environments such as severe chloride solution limits the use of titanium and its alloys in some engineering applications. For this reason, it has become quite common to change and/or improve the surface properties of titanium and its alloys. In this study, the structural properties of TiO2 coatings with zinc oxide (ZnO) added TiO2 and hexagonal boron nitride (h-BN) added TiO2 grown composite coatings, respectively, on Cp–Ti substrates by micro-arc oxidation method and the adhesion behavior between the base material and coatings were investigated.

  İncele
• MakaleYalnız künye2024/r/gumushane/16054
  Investigation of Corrosion Properties of LA-91 Alloy Coated with MAO Method

  Sukuroglu, Suleyman; Totik, Yasar; Sukuroglu, Ebru Emine; Avci, Selcuk

  LA91 magnesium alloy is a super lightweight magnesium -lithium alloy proposed for next generation materials. In addition to the advantages of these alloys such as low density, high strength-to -weight ratio, specific stiffness and brittleness, these alloys also have disadvantages such as low corrosion resistance and the oxide -carbonate film formed on the surfaces of the alloys cannot provide sufficient corrosion protection even in non-corrosive environments. In this study, micro arc oxidation, one of the coating methods, was applied to LA91 alloy. The surface morphologies of the coatings were characterized and it was aimed to increase the corrosion resistance of LA91 alloy. For this purpose, potentiodynamic polarization tests were carried out in 3.5% NaCl solution at room temperature to draw attention to the protection of the coating. As a result of the tests, it was determined that the oxide coatings raised on the surface

  İncele
• MakaleAçık Erişim2024/r/gumushane/12623
  Investigation of friction behavior of TiO2: Al2O3 composite coating formed on AA2024 alloy by micro-arc oxidation

  Boynueğri̇ Kaplan, Emine; Şüküroğlu, Ebru Emine

  In this study, an alumina (Al2O3) ceramic coating and a composite coating containing titanium dioxide (TiO2) particles were prepared on surfaces of AA2024 substrates by micro-arc oxidation (MAO) treatment. The effects of micro-sized (≈20-30 µm) TiO2 particles incorporated into electrolyte on the microstructure, phase and chemical composition, thickness, and friction behavior of the coating were investigated. The surface morphologies of the coatings were analyzed by scanning electron microscopy (SEM). The phase and chemical compositions of the coatings were evaluated by means of X-ray diffraction (XRD) and energy-dispersive X-ray spectrometry (EDS), respectively. The friction coefficient of the coatings was investigated using a pin-on-disc tribometer under condition of dry slip sliding. Moreover, the wear tracks were analyzed by SEM. Addition of TiO2 particles into the electrolyte resulted in the reduction in number of pores and formation of smaller and more uniform pores in comparison with the Al2O3 ceramic coating. XRD analyses demonstrated that the TiO2:Al2O3 composite coating was composed of anatase-TiO2 and rutile-TiO2, as well as pure aluminum, α-Al2O3 and γ-Al2O3 which are the primary phases. The friction tests showed a significant reduction in the friction coefficient of the composite coated samples which contains titanium oxide (TiO2) particles in comparison with Al2O3 coated and uncoated samples. Copyright 2021, Yıldız Technical University.

  İncele
• MakaleAçık Erişim2024/r/gumushane/12000
  Effect of micro-arc oxidation coatings with graphene oxide and graphite on osseointegration of titanium implants-an in vivo study

  Tekin, Bahar; Dundar, Serkan; Tekin, Samet; Emine Sukuroglu, Ebru; Khurshid, Zohaib; Ezgi, Yusuf; Demirci, Fatih; Faheemuddin, Muhammad

  Background: This in vivo study evaluated the effect of graphene oxide and graphite coatings, coupled with the micro-arc oxidation (MAO) surface roughening technique, known for their mechanical strength, chemical stability, and antibacterial properties. The main objective was to assess the degree of improvement in osseointegration of titanium implants resulting from these interventions. Materials and methods: In this study, 32 female rats were utilized and randomly allocated into four groups (n = 8 each): machined surface titanium implants (control), those roughened by the MAO method, those coated with graphene oxide-doped MAO, and those with a graphite-doped MAO coating. Titanium implants were surgically placed in the right tibia of the rats. Rats undergoing no additional procedures during the 4-week experimental period were sacrificed at the end. Then, the implants and surrounding bone tissues were separated and embedded in acrylic blocks for reverse torque analysis. Using a digital torque device, the rotational force was applied to all samples using a hex driver and racquet until implant separation from the bone occurred, with the corresponding values recorded on the digital display. Then, statistical analysis was performed to analyze the data. Results: No statistically significant difference between the groups was observed in the biomechanical bone–implant connection levels (N/cm) (P = 0.268). Post-hoc tests were not required because no discernible differences were identified between the groups. Conclusion: Within the scope of this study, implants treated with the MAO method, along with those coated with graphene oxide- and graphite-doped MAO method, did not exhibit significant superiority in terms of osseointegration compared to machined surface titanium implants.

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  İncele
• MakaleAçık Erişim2024/r/gumushane/11661
  Corrosion and adhesion properties of MAO-coated LA91 magnesium alloy

  Sukuroglu, Suleyman; Sukuroglu, Ebru Emine; Totik, Yasar; Gulten, Gokhan; Efeoglu, Ihsan; Avci, Selcuk

  Magnesium–lithium alloy is used in different areas of industry and is known as a super light metallic engineering material. However, the use of these alloys is limited due to their surface properties under extreme loads and aggressive environments. Surface treatments can be applied to these alloys to increase their usage areas and improve their weak surface properties. In this study, the micro-arc oxidation method was applied to improve the surface properties of LA91 alloy. The corrosion and adhesion behaviour of the coated samples were investigated. The lowest corrosion current density in the coatings was obtained under Experiment 3. Experiment 3 has the highest Lc2 value due to the coating thickness and the denser and smaller diameter pores of the functional intermediate layer.

  İncele
• MakaleYalnız künye2023/r/gumushane/16770
  Wear Behavior of Dental Restorative Materials

  Sen, Sadri; Zamanlou, Hamid; Karabudak, Filiz; Süküroglu, Ebru Emine

  Gradual wear of opposing teeth is a normal phenomenon in human dentition. There is a need for quality dental restorative materials to repair or replace natural teeth to ensure a higher quality of life through dental health. One of the main physiological mechanism that exists in dental materials during normal muscle function is called abrasion. There are two types of that in teeth which are common; Two-body and three-body. If the teeth are contacted directly, it is referred to as two-body abrasion. However, when there is abrasive slurry-like food between the teeth, this abrasive is called to be three-body abrasive. Several types of materials are available in current dentistry for teeth restoration and replacement, and new materials are being promoted every year. Dental specialists need to understand the wear mechanisms of these new types of dental restorative materials, alone or in combination with either enamel or other dental restorative material. The present study evaluates the abrasive resistance of three restorative materials groups: direct composites, indirect composites, and ceramics. To define the resistance of the wear, the authors then perform a micro-wear test on chosen materials. The results show that the wear mechanism is abrasive due to its low hardness compared to zirconia ball. The wear path in the nanohybrid (Grandio (R), 87s% w/w (71s% volume) inorganic nanohybrid filler, BisGMA, UDMA, TEGDMA) sample was smooth and without particles. In this study wear FEM analysis calculated for all models and the answers compared with experimental data.

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