Browsing by Author "Hacaloglu, Tugce"
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Article Citation Count: 8Development of hard, anti-reflective coating for mid wave infrared region(Elsevier, 2021) Kaftanoğlu, Bilgin; Hacaloglu, Tugce; Kaftanoglu, Bilgin; Manufacturing EngineeringIn the 3-5 mu m Mid Wave Infrared (MWIR) thermal imaging region, the number of alternative transparent optical substrate materials are quite limited. Silicon (Si) and germanium (Ge) are among the common optical materials used in the MWIR region. However, these materials and the thin film coatings on them, suffer from low hardness and brittleness hence need to be protected against scratches and hard flying particles like sand, dust, etc.. In industry, a single layer amorphous Diamond Like Carbon (DLC) coating is used to protect the outer layer while transmitting MWIR energy. This paper suggests single layer Boron Nitride (BN) and Boron Carbide (B4C) coatings as alternatives to commercial DLC coating, providing the necessary protection and transmission efficiency with anti-reflective properties. The proposed boron-contained coatings also have an advantage of greater temperature resistance over DLC. Finally, a two-layer anti-reflective coating containing Boron Carbide layer as an outer protective coating is demonstrated.Article Citation Count: 7Experimental investigation of friction in deep drawing(Springer London Ltd, 2017) Kalkan, Hakan; Kaftanoğlu, Bilgin; Kaftanoglu, Bilgin; Manufacturing EngineeringInvestigation of friction is carried out in the radial drawing region between the die and blank holder and also in the stretching zone over the punch in deep drawing. Two methods are developed to calculate the coefficient of friction in each zone using the experimentally determined data such as punch force diagrams and strain distributions obtained by an optical scanning system. The current methods differ from the existing techniques which are obtained in simulative tests. The proposed methods can be applied in room temperature and at elevated temperatures. Comparisons of friction coefficients are made with those obtained by other techniques.Article Citation Count: 3Histomorphometric and biomechanical evaluation of the osseointegration around micro- and nano-level boron-nitride coated titanium dental implants(Elsevier, 2022) Kaftanoğlu, Bilgin; Cakal, Gaye Ozgur; Gokmenoglu, Ceren; Ozmeric, Ahmet; Oduncuoglu, Bahar Fusun; Hacaloglu, Tugce; Kaftanoglu, Bilgin; Manufacturing EngineeringIntroduction: Titanium dental implants has been coated with different materials such as polymers and biomi-metic agents, bone morphogenetic protein, calcium phosphate to enhance surface properties of the titanium implants for osseointegration. The aim of this study was to evaluate the bone tissue healing around Boron Nitride-coated (BN-coated) titanium implants histomorphometrically and biomechanically and also observe the effect of different coating thicknesses on osseointegration. Materials and methods: BN was coated on dental titanium implants with two different coating thicknesses by using RF magnetron sputtering system. Totally fifty-four implants were inserted into the tibias' of 12 New Zealand rabbits bilaterally under general anesthesia. All animals were sacrificed after 4-weeks. Bone-implant contact (BIC) and new bone area/total area ratios (BATA) were calculated. Also, the removal torque (RT) test was performed. Results: The highest new bone area in the medullary cavity was around the nano-BN-coated surface with 15.70%. In micro-BN-coated surface and control group, this ratio was determined as 10.48% and 8.23%, respectively. The BIC ratios in upper-side of implants and cortical-associated BIC ratios in lower-side were found significantly higher in control and micro-BN-coated group than nano-BN-coated group (p > 0.05). Sim-ilar BIC values were observed between control and micro-BN-coated groups (p > 0.05). BATA values did not show statistically significant differences between all three groups (p > 0.05). The RT values measured in all groups were found comparable and no statistically significant differences were found (p > 0.05). Conclusion: No inflammatory reaction developed around any implant. Relatively more new bone formation around nano-BN-coated titanium implants indicates the promising osseoinductive effect of BN coating. BN-coated implants showed similar biomechanical and histomorphometrical outcomes to that of the conven-tional titanium implants through a 4-week evaluation period. (c) 2022 Elsevier Masson SAS. All rights reserved.Letter Citation Count: 0Theoretical modelling of magnetron sputtering of boron nitride coating(Springer Heidelberg, 2023) Kaftanoğlu, Bilgin; Kaftanoglu, Bilgin; Hacaloglu, Tugce; Aydogan, Asude; Manufacturing EngineeringThe fundamentals of the magnetron sputtering (MS) technique are simple. However, the complex interplay of various physical and chemical sub-processes lies in its simplicity. The direct simulation Monte Carlo (DSMC) method is used to model the MS of the Boron Nitride (BN) coating. The Lorentz force, which is created by an electric field, magnetic field and particle collision, is utilised to model the BN coating. Three distinct bias voltages are used to generate three different BN-coating models under the same conditions. The modelling of BN coatings reveals that the deposition rate decreases as the substrate voltage increases.