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    Effects of Graphite Incorporation and Annealing on the Structural, Tribological, and Functional Properties of Electroless Ni-B Coatings
    (Springer, 2026) Bulbul, Ferhat; Kara, Adem; Bulbul, Leman Elif; Gunes, Kubra
    This study explores the synergistic effects of graphite nanoparticles (0.1 wt.%) and thermal annealing (100-600 degrees C) on electroless Ni-B coatings for AISI 4140 steel. Graphite-enabled multifunctional performance-crystallization control, friction reduction, and antibacterial activity-are unlike conventional Ni-B systems. XRD showed amorphous-to-crystalline (Ni3B/Ni2B) transformation, with graphite acting as a nucleation agent below 300 degrees C before degrading at 600 degrees C. The 300 degrees C-annealed composite achieved optimal properties: 0.2 friction coefficient (75% lower than uncoated steel), 60% higher wear resistance, and hardness of 777 HV (+ 3.6% over as-deposited), attributed to graphite lubrication and nanocrystalline Ni3B formation. Antibacterial tests revealed a 3.4-mm inhibition zone against E. coli, though efficacy declined at higher temperatures due to graphite oxidation. All composites maintained superhydrophilicity (contact angle approximate to 0 degrees) without mechanical compromise. By correlating annealing temperature with microstructure, this work provides a design framework for Ni-B/graphite coatings combining low friction (mu = 0.2), high hardness (785 HV), and antibacterial functionality-addressing critical needs for wear-resistant, hygienic surfaces in biomedical and industrial applications.
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    Hidrotermal Yöntem ile WS2 Sentezi ve Karakterizasyonu
    (Bayburt University, 2020) Kara, Adem; Ertugrul, Mehmet
    Özet Kritik bir öneme sahip olan hidrotermal yöntem kullanılarak sentezlenen Geçiş Metali Dikalkojenitlere (TMDs) bağlı olarak enerji depolama aygıtları, fotovoltaikler, elektro katalizler, elektronik aygıtlar, sensör ve biyomedikal uygulamalarından dolayı, İki boyutlu (2D) tabakalı bileşenlerin araştırılmasını uzun süredir ilgi çekmektedir. Bu yüzden, WS2 (Tungsten disülfit) herhangi bir Sürfaktant kullanmadan tek basamakta hidrotermal yöntem ile nano flower yapısında sentezlendi. WS2 sentezinde Sıcaklık ve NaWO4.2H2O/CH3CSNH2 Stokiyometrik oranın etkisine araştırıldı. Bu sebepten, uygun şartlar belirlendi. Sentezlenen örneğin morfolojisi ve kristal yapı karakteristikleri (XRD, SEM ve EDAX) de bu çalışmada karakterize edildi.
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    Investigation of the Effects of Low-Temperature Thermal Treatment Applied to Graphite in Spent Lithium-Ion Anode Recycling
    (Springer, 2025) Kara, Adem; Temur, Hakan
    As the use of lithium-ion batteries (LIB) increases rapidly, recovery of graphite, the main component of the anode, from spent batteries has become important from environmental and economic perspectives. In this study, an acid leaching step followed by thermal treatment under partial atmosphere at a relatively low calcination temperature was investigated to recover graphite from spent lithium-ion batteries. The molecular and chemical structures of the recovered graphite in all spent anode samples were investigated using FTIR, ICP-MS, XRD, SEM-EDX and TEM-EDX. It was observed that organic impurities and volatile components were largely removed after acid leaching and thermal treatment at 750 degrees C. In addition, it was observed that graphite layers were rearranged and the distance between the layers decreased under the effect of thermal treatment. Partial atmosphere calcination at 750 degrees C can be considered as a feasible method for graphite recovery, offering energy efficiency and scalability. However, in an efficient calcination, it is necessary to maintain controlled oxygen levels to prevent excessive graphite loss and to perform preliminary acid leaching to reduce metal impurities. In order to best recycle graphite in waste lithium-ion anode recovery, a balance must be achieved between temperature, energy efficiency and material recovery. Considering this balance, a calcination temperature of 750 degrees C appears to be preferable for recycling.
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    Multifunctional electroless nickel boron composite coatings incorporated by magnesium diboride ceramic particles
    (Wiley, 2024) Bulbul, Ferhat; Kara, Adem
    In this study, the role of MgB2 in composite coatings is pivotal. Electroless Ni-B plating, a current-free chemical reduction process, deposits nickel-boron coatings. Other than MgB2, reinforcements like SiC, B4C, and so forth are used with Ni-B coatings for improved properties. The research focuses on Ni-B/MgB2 coatings on AISI 4140 steel using electroless deposition and annealing at different temperatures. Initially, the coating appears dense and amorphous, transforming into worm-like structures through crystallization with MgB2. Higher annealing temperatures lead to brush-like, feathery, and oyster mushroom structures, forming crystalline nickel boron compounds and oxide phases due to synergy. Interestingly, the newly introduced phases disrupt friction patterns nonlinearly, which is linked to MgB2's ceramic nature and reinforcement quantity. Conversely, incorporating MgB2 and annealing-induced intermetallic phases notably enhances hardness (up to 6) and improves hydrophilicity and antibacterial traits in the coating.
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    Physical, chemical and thermal characterization of bacterial nanocellulose produced using sugar beet molasses by Komagataeibacter sp. SB2569
    (Springer, 2026) Kara, Adem; Bayram, Sinan
    Bacterial nanocellulose (BNC) is a biopolymer synthesized by bacteria utilizing various carbon sources. The biocompatible and biodegradable nature of BNC offers considerable advantages for its application in fields such as medicine, biomedical engineering, cosmetics, food, nanocomposites, and organoelectronics. Nevertheless, the high production costs necessitate the development of more cost-effective and efficient BNC production methodologies. This study aimed to produce BNC utilizing cost-effective sugar beet molasses. To achieve this, bacteria isolated from various vinegar samples were assessed, revealing that the BNC production potential of these isolates ranged from 2.09 to 3.21 g L-1. The 16S rDNA gene of the strain with the highest BNC yield was amplified and sequenced, and it was subsequently deposited in the GenBank database as Komagataeibacter sp. SB2569, with the accession number PV231799.1. XRD analysis revealed characteristic diffraction peaks at 14.8 degrees, 16.5 degrees, 22.6 degrees, and 34.5 degrees, confirming the cellulose 1 beta crystalline structure and high crystallinity of the synthesized BNC. FTIR analysis exhibited characteristic absorption bandsthat, confirming the presence of beta-1,4-glycosidic linkages and the cellulose I structure of BNC. TGA analysis showed an initial weight loss of similar to 5% between 0-100 degrees C, a major degradation of similar to 75% occurring at 220-350 degrees C with a maximum decomposition rate at 343 degrees C, and a residual mass of approximately 10-20% remaining above 600 degrees C. The findings indicate that the Komagataeibacter sp. SB2569 strain holds significant potential for BNC production using low-cost carbon sources.