Sürdürülebilir Kalkınma Amaçları
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- MakaleAçık Erişim2025Investigation of Tensile and Fatigue Behavior of Cr/CrN/TiCrN/TiCrCN Multilayer Films Coated on AA6063 and AZ91 Alloys by Closed-Field Unbalanced Magnetron Sputtering Process
Yeşildal, Ruhi; Sezer, Sadberk; Karabudak, Filiz
Despite the widespread use of Mg and Al alloys among light metals in the automobile and aviation industries, they have low tensile and fatigue strength. Therefore, in the present work, AZ91 Mg and AA6063 Al alloys were coated with a multilayer transition metal nitride film (Cr/CrN/TiCrN/TiCrCN) to increase fatigue and tensile strength. Films with Cr/CrN/TiCrN/TiCrCN microstructure architecture were synthesized on the surfaces of AZ91 Mg and AA6063 Al alloys using the CFUBMS (closed-field unbalanced magnetron sputtering) system, one of the PVD (physical vapor deposition) techniques. Films’ structural properties were analyzed by XRD, SEM, and EDAX, whereas mechanical properties were investigated using tensile and rotary bending fatigue testing machines. According to the SEM examination, the Cr, CrN, TiCrN, and TiCrCN multilayer nitride films on the two alloys have a columnar and dense microstructure. The XRD analysis detected Cr (211), CrN (111) and (200), TiN (111), (200) and (222), and TiCN (200) and (311) diffraction peaks. The Cr/CrN/TiCrN/TiCrCN multilayer coating increased the fatigue limit value of AZ91 by 11.22% from 70.26 MPa to 78.15 MPa. The fatigue limit value of AA6063 decreased by 9.79% from 79.71 MPa to 71.9 MPa. After coating, the tensile strength value of AZ91 increased from 137.89 MPa to 139.65 MPa, while the tensile strength of AA6063 decreased from 129.35 MPa to 118.16 MPa.
- MakaleAçık Erişim2024Fatigue and tensile behaviour of Ti+TiN+Ti+TiVN multilayer nitride films coated on AZ91 magnesium alloy by closed field unbalanced magnetron sputtering
Alibeyoğlu, Fatih; Karabudak, Filiz; Yeşildal, Ruhi; Balcı, Arif; Efeoğlu, İhsan; Ateş, Onur Kazım
Despite their extensive use in the automotive and aerospace industries, Mg and Mg alloys, which are light metals, exhibit low fatigue and tensile strength. In this study, transition metal-nitride (TMN) multilayer coatings (Ti+TiN+Ti+TiVN) were coated twice on AZ91 Mg alloy using a Confined Field Unbalanced Magnetron Sputtering (CFUBMS) system to increase fatigue and tensile strength. The structural properties of the films were analyzed by using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometry (EDS) methods, and the mechanical properties were analyzed by rotating bending fatigue and tensile testing machines. Ti+TiN+Ti+TiVN multilayer nitride surface coatings on AZ91 Mg alloys showed a dense and columnar microstructure and according to XRD results (111) was the preferred orientation with the dominant peak. The fatigue limit value of the AZ91 base material was fixed at 60.46 MPa, while it increased to 68.48 MPa after being coated with multilayer nitride. Along with the multilayer nitride coating, the tensile strength increased from 169.98 MPa to 175.43 MPa. As a result, the multilayer hard nitride coating with low surface roughness, which fills the defects, notches, and voids on the surface of the AZ91 base material, increased the fatigue and tensile strength in parallel. Based on the outcomes of the research, the literature has been enriched with an innovative approach through the enhancement of fatigue and tensile strengths by applying a CFUBMS coating to lightweight metals and alloys, such as AZ91, especially in the transportation industry where lightness and dynamic load resistance are essential.
- MakaleYalnız künye2023The Effect of Surface Roughness on Fatigue Life in AZ31 Magnesium Alloy
Karabudak, Filiz; Şüküroğlu, Ebru Emine; Şüküroğlu, Süleyman; Yeşildal, Ruhi
Magnesium alloys have excellent properties such as high specific strength, rigidity, good damping, electromagnetic shielding, castability, and machinability. However, corrosion, creep, and fatigue resistance are generally the properties that need to be improved. In this study, a hybrid coating was formed on AZ31 magnesium alloy with different surface roughness at different frequencies. In the hybrid coating, an oxide coating was first grown on the surface by the micro-arc oxidation method, and then, the epoxy coating was grown on this oxide coating by the dipping method. The characterization of the coatings was performed by XRD, SEM, and EDS analysis. Furthermore, the relationship between fatigue life and surface roughness was also discussed in this study. The fatigue life and strength of the coated samples were determined as a result of the tests performed on the fatigue device. It was concluded that the fatigue life and strength of hybrid coatings were much better compared to uncoated and single-layer coated samples.
- MakaleYalnız künye2018Differential scanning calorimetry (DSC) and Ni+2 release analysis of NiTi-shape-memory dental alloys coated by micro-arc oxidation (MAO) method
Yeşildal, Ruhi; Karabudak, Filiz; Şüküroğlu, Ebru Emine; Şüküroğlu, Süleyman; Zamanlou, Hamid; Bayındır, Funda; Şen, Sadri; Totik, Yaşar
This study aims to prevent the release of Ni+2 and increase the biocompatibility of NiTi-shape-memory dental alloys with the micro-arc oxidation (MAO) coating by preserving the shape-memory feature in the oral environment. The TiO2-ceramic coating and Ag-doped TiO2 coating have been grown on shape-memory, co-atoms’ dental NiTi alloys with the MAO method. Biocompatibility properties of the coating were determined by in-vitro tests. In-vitro tests have been made as retention tests in a simulated body fluid (SBF). Whether the grown surface coating impacts the shape-memory properties of the base material or not has been determined by differential scanning calorimetry (DSC) analysis. It was observed as a result of retention tests that bone-like apatite form occurred on the surface of TiO2-coated NiTi and Ag-doped TiO2-coated NiTi coating. It was determined as a result of retention tests in SBF that the Ni+2 release rate from the base material was below the limit of detection in coated samples. As a result of DSC analysis, it was not observed any significant changes in transformation temperature with the MAO coating. It was concluded that the thin-film coatings formed by MAO technique prevent the release of Ni in the oral environment and increase the biocompatibility by preserving shape memory properties of NiTi dental alloys.
- MakaleYalnız künye2017An Investigation of Corrosion Resistance and Antibacterial Sensitivity Properties of Nano-Ag-Doped TiO 2 Coating and TiO 2 Coating Grown on NiTi Alloy with the Micro-Arc Oxidation Process
Karabudak, Filiz; Yeşildal, Ruhi; Şüküroğlu, Ebru Emine; Şüküroğlu, Süleyman; Zamanlou, Hamid; Dikbaş, Neslihan; Bayındır, Funda; Şen, Sadri; Totik, Yaşar
In this study, TiO 2 coatings were grown with nano-Ag doped and micro-arc oxidation technique on NiTi shape memory alloy. The antibacterial sensitivity and corrosion resistance characteristics of both coatings were investigated. The microstructure and composition analyses of the coatings were performed with scanning electron microscope, energy dispersive X-ray spectrometry, and X-Ray diffraction (XRD). The XRD results showed that there were only TiO 2 crystal phases (anatase and rutile) on the coating. The results showed that a clean and dense oxide layer was grown on the surface successfully. The surface of nano-Ag-doped TiO 2-coated samples appear to be smoother than the surface of the coatings without Ag. The corrosion tests of the coated and uncoated samples were carried out in three different environments (simulated body fluid, synthetic saliva, and cola) at 37 ∘ which is human body temperature. The corrosion tests showed that the corrosion resistance of TiO 2-coated and nano-Ag-doped TiO 2-coated samples was much higher than the corrosion resistance of the NiTi substrate. Seven different bacteria including (S. aureus, L. monocytogenes, Bacillus subtilis, Salmonella enteritidis, Yersinia enterocolitica, and E. coli, P.aeruginosa) which have the human pathogen feature were used in the antibacterial susceptibility tests. The process was conducted based on the disk diffusion method to test the susceptibility of bacterial strains on the selected coated and uncoated samples, and antimicrobial activity was evaluated in the nano-Ag-doped TiO 2-coated material; P.aeruginosa, Y. enterocolitica, and E. coli (zone diameter of 8–14 mm) were found to be moderately susceptible; S. aureus, L. monocytogenes, B. subtilis, and S. enteritidis (zone diameters of 8–14 mm) were found to be resistant. The antimicrobial activity of the coating material NiTi was found to be sensitive for all antibacterial tests. According to the TiO 2-coated material results, S. aureus, P.aeruginosa, L. monocytogenes, E. coli were found to be moderately sensitive and Y. enterocolitica, S. enteritidis, and B. subtilis were found to be resistant.