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Öğe Advances in PEKK Thermoplastic Composites: Reinforcing With MWCNTs and GNPs for Enhanced Performance(Wiley, 2025) Ferik, Erdem; Yilmaz, Sukran Guney; Birak, Selahattin Berat; Demirel, Merve Ozkutlu; Oz, Yahya; Kaboglu, CihanPolyetherketoneketone (PEKK) is a highly regarded material in polymer science due to its outstanding thermal stability, mechanical strength, and chemical resistance. Despite substantial research on PEKK composites reinforced with CNTs and GNPs, two primary challenges remain: inconsistent glass transition temperature behavior at varying filler contents, leading to unpredictable shifts in both thermal and mechanical performance, and the absence of direct comparisons under uniform processing conditions that would allow quantitative evaluation of each filler's effect. In this work, PEKK/MWCNT and PEKK/GNP nanocomposites were produced via the same hot-press molding protocol and systematically evaluated for thermal and mechanical performance, electrical conductivity (using S-value analysis) and microstructural morphology. A range of mechanical tests, including tensile, Charpy impact, and hardness tests, were conducted alongside physical analyses such as differential scanning calorimetry (DSC), thermogravimetric analysis, dynamic mechanical analysis (DMA), thermal conductivity, electrical conductivity, and scanning electron microscopy (SEM). The results demonstrated that both MWCNTs and GNPs significantly enhanced PEKK's properties. The incorporation of MWCNTs raised the glass transition temperature (T-g) to 169 degrees C and the crystallization temperature (T-c) to 327 degrees C, whereas GNPs increased the decomposition temperature (T-d) to 572 degrees C. Adding 1 wt.% of either nano-additive notably improved tensile and flexural strength, while an optimal concentration of 0.1 wt.% was determined for Charpy impact performance. Additionally, higher concentrations resulted in exceptional electrical and thermal conductivity.Öğe Comprehensive Optimization of Selective Laser Melting Process Parameters for Microstructure, Density, Hardness, and Tribological Performance of Pure Copper(Int Inst Science Sintering (I I S S), 2024) Ozkan, Burcu Asli; Dilsiz, Yusuf; Kucukelyas, Burak; Sever, Ahmet; Bademlioglu, Ali Husnu; Kaboglu, Cihan; Uzunsoy, DenizThis study is concerned with the optimisation of the processing parameters for the selective laser melting (SLM) of pure copper. The influence of these parameters on the microstructure, density and mechanical properties of copper samples produced by SLM is investigated in detail. Taguchi analysis is used to assess the importance of key building parameters including layer thickness, laser spot size and hatch distance on density. In addition, ANOVA is used to describe the contribution of each parameter to the density. The results reveal that layer thickness is the most effective parameter on density with an impact rate of 88.86%. Contrary to this situation, it appears that the effect of laser spot size and hatch distance on the density is quite limited, with an impact rate of 2.57% and 0.10%, respectively. Optimum results, including a relative density of 95.4% and a hardness of 63 HV, are achieved under specific parameters: a layer thickness of 0.03 mm, a hatch distance of 110 mm and a laser spot size of 70 mu m. This study provides a valuable insight into SLM processing of pure copper and offers practical recommendations for optimising the parameters used.Öğe Determination of Production Parameters of CuCrZr Alloy by Selective Laser Melting Process(2025) Özkan, Burcu Aslı; Dilsiz, Yusuf; Ozates, Cem; Sevinç, Enes Furkan; Kaykılarlı, Cantekin; Kaboglu, Cihan; Uzunsoy, DenizCuCrZr alloy is a widely preferred material in the space, defense, and electronics industries with its high thermal and electrical conductivity properties. There are limited publications on the investigation of the tribological properties of CuCrZr alloys produced via the selective laser melting (SLM) method. In this study, it was aimed to optimize the process parameters and examine the effect of process parameters on density, hardness, microstructure, and tribological properties of domestically produced CuCrZr powder to be produced by the SLM method, which allows the production of complex structured parts. The optimum process parameters of the CuCrZr alloy were determined as laser power of 435 W, scanning speed of 350 mm/s, layer thickness of 0.02 mm, laser diameter of 0.1 mm, hatch distance of 0.1 mm, and energy density of 621.42 J/mm3. The relative density, hardness, COF, and wear values of the samples produced with the optimized SLM process parameters were obtained as 99% and 96 HV, 0.5520 ±0.1648, and 1.17x 10-4 (mm3/N.m), respectively.Öğe Effect of curvature and stacking sequence on flexural strength in glass fiber reinforced composites(Walter De Gruyter Gmbh, 2023) Kaboglu, Cihan; Eken, Taha Yasin; Guney, SukranMost of the structures in vehicles used in the automotive, aviation, and marine industries are exposed to different loads. It is seen that these structures are more exposed to flexural stress. Structures can sustain dangerous damage over time under the effects of flexural loads. The resistance of curved glass fiber reinforced polymer composites to flexural force is very important. In this study, the diameters of curved composites of 760 mm, 380 mm, and 304mm are studied. Also, fiber stacking sequences were determined as [0/0/-45/+45/90/90](S) and [90/90/-45/+45/0/0](S) and compared. All specimens were produced by vacuum infusion method. Three-point flexural tests were performed according to the ASTM D7264 standard at 1mm.min(-1) punch speed. Among all composites, 760mm diameter and Type 2 stacking were found to have the highest flexural strength. Hence, it was observed that the flexural strength decreased with the increase in curvature, and Type 2 fiber layer sequencing is more durable than Type 1 sequencing. This is because the 90 degrees fiber direction in the substrate has a damping effect on the applied force.Öğe Effect of graphene nanoplatelet and multi-walled carbon nanotube additives on polyphenylene sulfide nanocomposites(Sage Publications Ltd, 2025) Guney Yilmaz, Sukran; Ferik, Erdem; Berat Birak, Selahattin; Ozkutlu Demirel, Merve; Kaboglu, Cihan; Oz, YahyaThe performance of current materials remains inadequate in the face of advancing technology and challenging working conditions. Due to the advantages and versatility, they offer, composite materials are utilized in numerous industries. Polyphenylene sulfide (PPS) has attracted significant interest in the aerospace industry due to its lightweight, high strength, high-temperature resistance, availability, and mechanical and physical properties. In this study, PPS was reinforced with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) to enhance its mechanical properties. Composite materials were produced by mixing PPS matrix material with nanofillers at different weight ratios and then subjected to compression molding. The specified tests were applied to the produced composite materials. When the thermal conductivity properties are examined, it is observed that there is a 490% increase when 10 wt% GNP is added, and a 45% increase when 10 wt% MWCNT is added. When 10 wt% of MWCNT is added to pure PPS, it has been observed that electrical conductivity at mid-frequency measurements increases by 222 % making it a conductive material. Uniform nanofiller distribution is crucial for optimal impact and mechanical performance. Agglomeration reduces properties such as tensile strength, hardness, and impact resistance.Öğe High-performance thermoplastic nanocomposites for aerospace applications: A review of synthesis, production, and analysis(Sage Publications Ltd, 2026) Yilmaz, Sukran Guney; Ferik, Erdem; Birak, Selahattin Berat; Demirel, Merve Ozkutlu; Oz, Yahya; Kaboglu, CihanThermoset polymers are cured under natural or synthetic created conditions and retain their solid form when exposed to heat. Unlike thermosets, thermoplastics melt when exposed to heat after production. Thermoplastics are preferred as raw materials because they can be easily shaped after production, have a high shelf life and are recyclable. In this regard, the prominence of high-performance engineering polymers in recent years has led to the preference of alternative polymers to thermosets. High-performance engineering thermoplastics include thermoplastics such as polyphenylene-sulfide (PPS), polyether-ether-ketone (PEEK), polyether-ketone-ketone (PEKK), polyphenylene-ether, polysulfone,polyoxadiazole, polyimide, polyether-amide, polyether-amide-imide, polynaphthalene, and polyamide-imide. These polymers exhibit application potential in aerospace, defense, automotive, marine, energy, and medical sectors. In challenging conditions such as high pressure, temperature, and corrosive environments, they possess high service temperatures, enhanced mechanical and physical properties, preferable chemical resistance as well as out-of-autoclave and rapid processing properties. In this review article, nanomaterial production methods (bottom-up and top-bottom) are mentioned. In the following sections, PPS, PEEK, and PEKK thermoplastics are explained, and carbon- and boron-based nano additives used in constructing nanocomposites are investigated. In the last section, PPS, PEKK, and PEEK polymer nanocomposites are investigated.Öğe Performance Optimization of Auxetic Structures on Energy Absorption of Cylindrical Sandwich Using Taguchi and ANOVA Methods(2023) Kaya, Onur; Bademlioglu, Ali Husnu; Kaboglu, CihanHigh engineering requirements of shock absorbers have increased interest in auxetic materials, which have higher specific energy absorption performance compared to conventional solid absorbers. Last decade, many optimization studies were conducted to improve the energy absorption performance of auxetic tubular structures. Most studies focused on adding inner and outer shells to thin-walled auxetic tubular absorbers with different types of lattice structures to enhance energy absorption of the cylindrical sandwiches. There are limited studies on thicker-walled auxetic tubes and their related shell thicknesses to optimize performance. In this study, the thickness of the thicker-walled auxetic core thickness (1.2 mm, 1.6 mm, 2 mm), shell thickness (16 mm, 20 mm, 24 mm), and auxetic lattice structure (Re-Entrant Circular, SiliComb, and ArrowHead) were optimized to improve the specific energy absorption of cylindrical sandwiches. The Taguchi method was used to determine the optimum parameters for cylindrical sandwiches. In addition, the effect ratio of the parameters on the specific energy absorption was investigated using the ANOVA method. The energy absorption properties of the cylindrical sandwiches were determined using the drop-weight test. The highest specific energy absorption was obtained using a shell thickness of 1.2 mm and a core thickness of 16 mm using an SiliComb lattice. It was determined that the lattice geometry was the most effective parameter on the specific energy absorption of cylindrical sandwiches, with an effect rate of 61.62%.Öğe RTM Yönteminde Jelkot ve Laminasyon Planının Nihai Ürünün Mekanik Özelliklerine Etkisi(2023) Topbasoglu, Mustafa Can; Kaboglu, Cihan; Keleş, MustafaBu çalışmada, Reçine Transfer Kalıplama (RTM) yöntemiyle üretilmiş cam fiber takviyeli kompozit plakalarda elyaf ağırlığının ve jelkotun mekanik özelliklere etkisi incelenmiştir. Üç farklı laminasyon planı ve bu planların jelkotlu halleri kullanılmıştır. Numunelerin incelenmesi için çekme testi, üç nokta eğme testi ve Barcol sertlik testleri yapılmıştır. Laminasyon planlarında 300 g/m2, 450 g/m2, 600 g/m2 olmak üzere 3 farklı ağırlıkta elyaf kullanılmıştır. Ayrıca laminasyon arasında 180 g/m2 ve 250 g/m2 polipropilen köpük malzeme kullanılmıştır. Her laminasyon için bir jelkotlu, bir jelkotsuz plaka üretilmiştir. Üretim sonunda kalınlıkları 2.5 – 3.2 mm arasında değişen 6 plaka üretilmiştir. Üç nokta eğme ve çekme testi için 10’ar numune kesilmiştir, Barcol sertlik testi plaka üzerinde 5 noktadan alınmıştır. Testler sonucunda elyaf ağırlığının artmasıyla mukavemet değerlerinin arttığı, uzama değerlerinin azaldığı gözlemlenmiştir. Her laminasyonun jelkotlu hallerinde %5 - 15 aralığında mekanik özellik düşüşü gözlemlenmiştir.Öğe Surface characteristics of plasma electrolytic oxidation coatings on Cp-Ti and hot-dip aluminised Cp-Ti(Taylor & Francis Ltd, 2022) Celtik, Cansu; Yurekturk, Yakup; Gecu, Ridvan; Kaboglu, Cihan; Muhaffel, FaizPlasma electrolytic oxidation (PEO) coatings on commercial pure titanium (Cp-Ti) and hot-dip aluminised Cp-Ti surfaces were prepared in an alkaline electrolyte. The morphological, structural, wear, and corrosion characteristics of the coatings were studied by using SEM, EDS, XRD, electrochemical polarisation, and dry sliding wear tests. The experimental results showed that the main compositions of the PEO coating on Cp-Ti are TiO2 and Al2TiO5 phases, while the PEO coating on hot-dip aluminised (HDA'ed) Cp-Ti mainly consists of the Al2O3 phase. The single PEO coating exhibited more porosity with small diameter micro-pores compared to the PEO coating on the HDA'ed sample. Electrochemical polarisation tests revealed that the PEO coating on the HDA'ed sample exhibited approximately 4.6 times more polarisation resistance than the single PEO coating and 10 times that of the bare Cp-Ti sample. According to the wear test results, the wear resistance of the bare Cp-Ti was doubled by hot-dip aluminising (HDA) and PEO treatments, while the single PEO treatment resulted in better resistance against dry sliding wear.Öğe Tailored mechanical and thermal properties of polyphenylene sulphide (PPS) reinforced with nano-materials(Sage Publications Inc, 2025) Yilmaz, Sukran Guney; Demirel, Merve Ozkutlu; Oz, Yahya; Kaboglu, CihanVarious approaches have been proposed to enhance the thermal conductivity of polymers, primarily by incorporating high thermal conductivity nano-additives into the polymer matrix. In this study, graphene nano-platelet (GNP) and titanium diboride (TiB2) were used as nano-additives while polyphenylene sulphide (PPS) was used as polymer matrix. Materials were dry-mixed in predetermined weight ratios and produced using compression molding. Tensile as well as hardness testing, thermal conductivity measurements and scanning electron microscopy analyses were conducted on the produced composite materials. Results show that an improvement in thermal conductivity values was observed. When 0.1 wt% TiB2 is added, there is a 21% increase in the thermal conductivity compared to pure PPS, whereas the addition of 0.1 wt% GNP results in a 15% increase. Regarding mechanical properties, an increase of 11% in the tensile strength was observed with the addition of 0.1 wt% GNP.Öğe The effect carbon nanotube on three-point bending behavior of fiber reinforced composite(Natl Inst Science Communication-Niscair, 2022) Kaboglu, Cihan; Ferik, ErdemThe aim of this research article has been to show the effect of Carbon Nanotube (CNT) additive on the performance of composite plate materials with fiber reinforced polymer matrix produced by vacuum infusion method under bending test. In this study, multiple layered composite plates have produced by glass, carbon, and aramid fiber reinforcements with 0.5% CNT addition by mass. In addition, a hybrid composite plate containing glass, carbon and aramid (Kevlar) fiber has produced with CNT addition by using the same production parameters. Three point bending test has performed on the composite plates under 1 mm/min bending with ASTM D7264 standard. As a result, CNT addition has increased the flexural performance but has decreased the elongation of glass and carbon fiber reinforced systems. In aramid reinforced system, both flexural strength and elongation has increased. However, in the hybrid fiber reinforced system, different fiber types have damaged at different elongation distances within the structure under different loads, and gradually more than one failure have observed. When the CNT has added to the hybrid system, the elongation increased but the flexural strength has decreased.
