Yazar "Degirmenci, Unal" seçeneğine göre listele

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    Determination of mechanical and tribological properties of vacuum sintered hybrid reinforced Al-4Cu composites
    (Sage Publications Ltd, 2024) Usca, Usame Ali; Sap, Serhat; Uzun, Mahir; Degirmenci, Unal
    This study aims to modernize commonly preferred hybrid aluminum composites in the automotive and defense industries. For this purpose, Al-4Cu/B4C-SiC hybrid composites were manufactured using the hot pressing method and their microstructure, mechanical, and tribological properties were investigated. SEM/EDS analyses of the samples were conducted to examine morphological characteristics. Hardness, relative density, and three-point bending tests were performed on the produced samples. Additionally, wear tests were conducted under dry sliding conditions and different loads (5-10-15 N) to investigate tribological properties. The addition of hybrid reinforcements resulted in high hardness (88.54 HB) and relative density (98.83%) values. The highest bending stress (556.9 MPa) was observed in sample AC-4 (Al-4Cu/2B4C-2SiC). The lowest mass loss (1.1 x 10-3 g) was encountered in sample AC-6 (Al-4Cu/6B4C-6SiC), where all reinforcements were present together. Plastic deformation, oxidation, and residual wear mechanisms were identified on the worn surfaces of the samples. Consequently, the addition of hybrid reinforcements to Al-4Cu composites shows promising potential in enhancing the mechanical and tribological performance of the composites.
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    Enhancing machinability of cold work tool steels through soluble SiO2-based nanofluids in milling operations
    (Elsevier, 2026) Gulseren, Caner; Yar, Adem; Usca, Usame Ali; Sap, Serhat; Degirmenci, Unal; Okbaz, Abdulkerim
    In this study, the effects of innovative and environmentally friendly cooling-lubrication techniques on the machinability properties of CPOH cold-work tool steel were comprehensively investigated. The main objective of the research was to determine the contribution of nanofluid-based cutting fluids to machining performance and to propose new solutions that can serve as alternatives to traditional methods for sustainable manufacturing practices. Experimental studies were conducted on a CNC milling machine using an Al-TiN coated carbide milling cutter. Two different cutting speeds (100 and 130 m/min), two different feed rates (0.08 and 0.1 mm/rev), and a constant depth of cut (0.7 mm) were applied in the experiments. The nanofluids used in the study were prepared by adding certain proportions of SiO2 nanoparticles to the synthetic cutting oil used as the base. To compare the effects of different nanoparticle ratios on machining performance, nanofluids were evaluated at 0.1 wt% and 0.2 wt% ratios. Key performance criteria such as surface roughness (Ra), cutting temperature (Tc), tool wear (Vb), and power consumption were analyzed to evaluate machinability. The findings indicate that the use of nanofluids significantly improves machining performance. In particular, the 0.2 wt% SiO2added nanofluid resulted in lower surface roughness and cutting temperature values, resulting in less tool wear, while also minimizing power consumption. It was determined that nanofluids with SiO2 nanoparticles offer significant advantages in terms of thermal control, tool life, and surface quality in the milling of cold-work tool steels, and represent a strong alternative to conventional cutting fluids in terms of energy efficiency and environmental sustainability. These findings significantly contribute to the development of sustainable manufacturing technologies.
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    Evaluation of Machinability and Energy Consumption of CK45 Steel Using Synthetic-Based Nanofluid and Minimum Quantity Lubrication Cutting Fluid
    (Mdpi, 2025) Sap, Emine; Usca, Usame Ali; Degirmenci, Unal; Sap, Serhat; Uzun, Mahir
    CK45 steel has various industrial uses due to its durability, wear resistance and strength. It is generally used in machinery, automotive industry, hydraulic cylinders, bearings, gears and similar applications. It is important to investigate the machinability properties of CK45 steel, which is frequently used in the manufacturing industry, in different cooling/lubrication environments. This study focused on the effects of a synthetic-based nanofluid cooling strategy and different cutting parameters during the milling of CK45 steel. Additionally, Taguchi analysis was performed to reduce the number of experiments and costs. Sustainable cooling/lubrication techniques were used during milling. A three-axis computer-controlled machine was used for the milling process. According to the findings, flank wear, surface roughness, and energy consumption were reduced by machining in the nanofluid environment. It was observed that Cu nanoparticles added into the nanofluid increased the machinability properties. Furthermore, statistical analysis was employed to ascertain the predominant control variables influencing the response parameters. Machinability efficiency can be increased by using nanoparticulate fluids as a coolant during milling. In addition, costs can be reduced by identifying the most effective factors in the experiment through statistical analysis.
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    Tribological behaviors and mechanical properties of novel Al-5Cu hybrid composites under dry sliding conditions
    (Sage Publications Ltd, 2024) Sap, Serhat; Degirmenci, Unal; Usca, Usame Ali; Uzun, Mahir
    This study aims to develop aluminum composites, which are widely used in the automotive and aerospace industries. For this purpose, novel Al-5Cu/Al2O3-SiC hybrid composites were produced, and their mechanical and tribological performances were investigated. Hardness, density, and three-point bending analyses of hybrid composites were performed. In addition, wear and friction analyses were carried out under dry sliding conditions and applying different loads (5-10-15 N). In addition, the morphological properties of the produced hybrid composites were determined by microstructural analysis (SEM/EDS). High density, hardness, and strength values were obtained in hybrid composites produced using powder metallurgy and hot pressing methods. As a result of the wear test, it was determined that the hybrid reinforcements showed positive effects on the wear resistance. The lowest specific wear rate (SWR) value was 2.09 x 10-6 mm3/N.m. It was determined that the SWR values of the hybrid composites decreased with the increase of the applied load. In addition, plastic deformation and adhesion wear were observed as a result of SEM/EDS analyses taken from the worn surfaces.