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- 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 Erişim2017Scopus SJRQ3The Effect of Porosity and Cu Rate on Microstructure and Mechanical Properties of Co Alternative Powder Metallurgy Compound
Çelik, Ertugrul; Aslan, Ali Kemal
Cu-Ni-MX1480 powder compound were prepared at six different alloy ratios and cold pressed with a pressure of 300 MPa. Then 12 samples were obtained by hot pressing at 700 degrees C with 20 MPa pressure and at 800 degrees C with 30 MPa pressure for 4 minutes in a vacuum atmosphere hot pressing machine. Porosity ratios of samples were calculated by the different between theoretical density and measured density of samples. Effect of porosity on microstructure and mechanical properties were investigated by performing SEM, XRD, hardness measurements and TRS tests. It was observed that as a result of increased hot pressing parameters and increased Cu ratio, porosity ratio was decreased and better mechanical properties achieved.
AtıfWoS15OpenAlex14İncele - MakaleYalnız künye2017Scopus SJRQ1Passive flow control in the near wake of a circular cylinder using attached permeable and inclined short plates
Ozkan, Gokturk M.; Firat, Erhan; Akilli, Huseyin
The main objective of this study is to assess the effectiveness of attached permeable plates in suppressing nominally two-dimensional vortex shedding from a fixed cylinder. The permeable plate along the entire span of the cylinder was made of a chrome-nickel screen and was attached normal to the cylinder surface. The main parameters of the study are porosity of the permeable plate, β, and the plate angle of the cylinder-plate arrangement, θ, with respect to the freestream. Experiments were performed using Particle Image Velocimetry (PIV) and Flow Visualization Techniques. Additionally, drag force measurements were carried out in a wind tunnel to analyze the effects of permeable plates on drag coefficient of the circular cylinder. The results revealed that the use of a permeable plate successfully suppresses the vortex shedding downstream of the circular cylinder by reducing the velocity fluctuations in the wake, elongating the vortex formation region further downstream and attenuating the vortex shedding frequency. The porosity values of β=0.4 and 0.5 with plate angles in the range of 35°≤θ≤90° were found to be effective on suppressing the vortex shedding. Furthermore, both the drag coefficients of the cylinder-plate arrangement and the <TKE>maxwere reduced almost for all porosity ratios for θ<30°.
AtıfScopus63WoS55OpenAlex59İncele - MakaleAçık Erişim2011Scopus SJRQ1Geometric network simulation of high porosity foods
Gueven, A.; Hicsasmaz, Z.
Solid foods are formed of a network of air cells distributed within a solid matrix. Size of air cells and how they are interconnected influence moisture sorption, thermal conductivity, aroma retention and texture of cellular foods. Available geometric pore structure models widely used in petroleum reservoir engineering, soil science, and catalysis are for low porosity (<= 0.4) materials. However, food materials generally have higher porosities (0.5-0.9). Microstructure of cookie (porosity = 0.54) and bread (porosity = 0.90) samples were simulated using the one-dimensional (1-D) corrugated pore model. Model parameters were: Unit cell dimensions; number of capillary segments, number of diameter sub-ranges, geometric placement of capillary segments in the unit cell; capillary segment length, and the seed number in random number generation. Accurate simulation of porosity depended on number of corrugated pores, and thus the number of diameter sub-ranges in the unit cell. For the cookie sample, a cubic unit cell that was able to accommodate more than a single capillary segment in a unit square and 3 diameter sub-ranges gave realistic results. Simulation of the bread crumb required a similar cubic unit cell arrangement with 12 diameter sub-ranges. (C) 2011 Elsevier Inc. All rights reserved.
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