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Article Ultrasonic Vibration-Assisted Machining of Invar 36 Alloy Manufactured by Wire Arc Additive Manufacturing(Elsevier, 2025) Namlu, Ramazan Hakk i; Kucukoztasa, Korcan; Kalkan, Hakan; Kaftanoglu, BilginInvar 36, known for its low coefficient of thermal expansion, is widely used in applications like composite moulds, electronics, and optics. Although Wire Arc Additive Manufacturing (WAAM) offers high deposition rates and cost-effectiveness for Invar 36, it creates rough surface textures requiring machining as post-processing. In order to overcome Invar 36's machinability challenges, Ultrasonic Vibration-Assisted Machining (UVAM) was applied for the first time on WAAM-fabricated Invar 36. The results showed that UVAM outperformed conventional machining in terms of cutting force, surface roughness and topography, subsurface microhardness and tool wear with improvements observed in both building and deposition directions. (c) 2025 CIRP. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.Article Citation - WoS: 62Citation - Scopus: 67A Mechanistic Approach To Investigate Drilling of Ud-Cfrp Laminates With Pcd Drills(Elsevier, 2014) Karpat, Y.; Bahtiyar, O.; Deger, B.; Kaftanoglu, BilginCarbon fiber reinforced plastics (CFRPs) possess desirable material properties that satisfy the aerospace industry's high strength to weight ratio objective. Therefore, CFRPs are commonly used in structural parts, either alone or together with aluminum and titanium alloys. Drilling of CFRPs has been studied extensively in the literature in recent years, with special emphasis on process parameters and delamination. This study identifies mechanical properties of uni-directional CFRPs through drilling tests. Drilling of uni-directional CFRP plates with and without pilot holes has been performed, and cutting and edge force coefficients are identified. A polycrystalline diamond (PCD) drill was used in tests since this type of drill is commonly used in practice. Finally, validation tests on multi directional CFRP laminates have been performed and good results have been obtained. (C) 2014 CIRP.Article Citation - WoS: 7Citation - Scopus: 9Histomorphometric and Biomechanical Evaluation of the Osseointegration Around Micro- and Nano-Level Boron-Nitride Coated Titanium Dental Implants(Elsevier, 2022) Ozmeric, Nurdan; Cakal, Gaye Ozgur; Gokmenoglu, Ceren; Ozmeric, Ahmet; Oduncuoglu, Bahar Fusun; Hacaloglu, Tugce; Kaftanoglu, BilginIntroduction: 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.Article Citation - WoS: 8Citation - Scopus: 9Development of Hard, Anti-Reflective Coating for Mid Wave Infrared Region(Elsevier, 2021) Ozhan, Alp Eren Sinan; Hacaloglu, Tugce; Kaftanoglu, BilginIn 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.
