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Öğe Corrosion behavior of dual phase 600 and 800 steels in 3.5wt.% NaCl environment(Taylor & Francis Ltd, 2020) Gerengi, Husnu; Sen, Nuri; Uygur, Ilyas; Kaya, ErtugrulDual phase (DP) steels have a great deal of importance in the automotive industry. These steels are used to fabricate structural parts of vehicles with the goal of passenger safety. In this study, the corrosion properties of DP 600 and 800 steel in 3.5wt.% NaCl environment were evaluated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss methods. Although the samples were quite similar to each other in their composition, it was observed that the very small differences changed the corrosion resistance property. For this reason, the calculated charge transfer resistance (R-ct) of the DP-800 in the 3.5wt.% NaCl environment was 51% greater than that of the DP-600 sample. This finding was confirmed by using weight loss, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and optical profilometer (OP) analysis.Öğe Cure cycle optimization of infrared cured composites using Taguchi method(Wiley, 2023) Alpay, Yakup O.; Uygur, Ilyas; Kilincel, Mert; Samtas, GurcanKnowing that cure cycle has a significant effect on the mechanical properties of the composite materials, determining the effects of cure cycle parameters - such as heating rate, maximum temperature, and dwell time, has gain importance. This study addresses the optimum cure cycle of an infrared cured carbon fiber pre-preg material. An infrared oven equipped with 1 kW halogen infrared heating unit and vacuum system was used. Different cure cycles determined by means of Taguchi experiment design approach and a cure cycle was found maximizing the tensile strength of the material. Results showed that infrared curing is a strong alternative to the autoclave despite its shortcomings regarding the product geometry. The optimized cure cycle showed 23% increase in the tensile strength comparing the tested cure cycle which is resulted with the minimum tensile strength. Besides, comparing the specimens cured with the optimum cure cycle, the infrared cured specimens showed slightly higher tensile strength than the autoclave cured counterparts. According to Taguchi optimization, optimum values for maximum tensile strength were found as 10 degrees C/min, 130 degrees C for heating rate and 60 min for plateau time. According to the analysis of variance, the most effective parameter affecting the tensile strength was the heating rate.Öğe Energy consumption, mechanical and metallographic properties of cryogenically treated tool steels(De Gruyter Poland Sp Z O O, 2023) Savas, Ahmet Fevzi; Oktem, Hasan; Ozturk, Burak; Uygur, Ilyas; Kucuk, OzkanThis article examines energy consumption, microstructure, mechanical properties, and the change in the wear amount during the machining of GGG-42 cast iron material with two types of guide cutting tool produced by powder metallurgy and casting method The tap. tool samples used as cutting tool material were first subjected to the traditional hardening process and then to two different cryogenic treatments (24-16 h) at -90?. The internal structures of the guide samples obtained from conventional heat treatment and cryogenic treatment were examined with an optical microscope and Scanning Electron Microscope. The hardness changes were checked with Vickers measurement method. The wear amount forming after the threading process was measured with CLEMEX program in a light microscope. In addition, by measuring the current amount drawn during the machining of the cast iron with guide cutter tools, instantaneous power consumption during cutting and power consumption during chip removal were calculated. The application of heat treatment and cryogenic process increased the hardness of the guides. Moreover, the power consumption during the chip removal was also seen to increase. This can be commented that cutting tools produced with powder metallurgy perform better than the cutting tools produced via casting and 30% energy saving.Öğe Friction-wear performance in environmentally friendly brake composites: A comparison of two different test methods(Wiley, 2021) Akincioglu, Gulsah; Uygur, Ilyas; Akincioglu, Sitki; Oktem, HasanIn this study, an eco-friendly brake composite sample (EFP) was produced with 3.5% hazelnut shell dust as a natural additive material. Friction tests were performed on the manufactured pad sample and on a commercial pad (CP) using both a Chase-type test machine and a specially designed device. A different approach is presented with the evaluation of the two different test device results. The experimental results were compared using the Taguchi method and it was concluded that the braking performance of the sample with hazelnut shell dust was in accordance with international standards. As a result of the study; the nominal friction coefficient value was found to be 0.505 mu. The shearing force of the EFP and CP samples was measured at 607.3 and 850.5 N, respectively. The friction coefficient values obtained from the EFP and CP samples were in accordance with the SAE J-661 standard and are in the F letter class.Öğe The hybrid approach of genetic algorithm and particle swarm optimization on reduced weld line defect in plastic injection molding(Sage Publications Ltd, 2024) Oktem, Hasan; Uygur, Ilyas; Sari, Ece Simooglu; Shinde, DineshWeld lines are a serious defect observed in plastic injection molded parts, impacting both their cosmetic appearance and mechanical properties. Controlling the conditions of plastic injection is crucial to mitigate these weld lines. This study introduces a novel approach to identify polypropylene injection molding (PIM) conditions aimed at reducing weld lines in polypropylene parts. The PIM conditions considered in this study include melt temperature, injection pressure, packing pressure, packing time, and cooling time. An orthogonal array Taguchi L27 design was employed for the experimental setup, producing 27 polypropylene parts with varying combinations of process conditions. The width of weld lines generated on the parts' surfaces was measured using an optimum microscope for all trials. Parametric analysis was conducted using response surface plots and contour plots to estimate the process conditions yielding minimum weld lines. Analysis of variance and regression analysis were employed to interpret the experimental data, with the resulting regression equation used to predict weld lines for a set of PIM process conditions. Finally, two efficient optimization algorithms, genetic algorithm (GA), and particle swarm optimization (PSO), were implemented using MATLAB programming to estimate the optimum process conditions for minimizing weld lines. The GA and PSO predicted weld line widths of 6.12302 mu m and 6.123 mu m, respectively, representing an 18.51% improvement in results. These findings demonstrate that the novel approach presented in this study can be effectively and reliably applied to address plastic product defects in the industry.Öğe Novel bionanocomposites of chitosan-based blend containing LaB6: Thermal, dielectric, and biological properties(Wiley, 2023) Erol, Ibrahim; Hazman, Omer; Aksu, Mecit; Uygur, IlyasIn the presented study, a strategy that will offer alternative usage areas by strengthening the physicochemical properties of the green polymer chitosan (CS) is aimed. For this purpose, a compatible blend of CS (CS-PFPAMA) with poly 2-(4-fluorophenyl)-2-oxoethyl-2-methylprop-2-enoate (PFPAMA), a methacrylate-based synthetic polymer, was prepared by hydrothermal method. Miscibility and compatibility of the CS-PFPAMA blend were confirmed by the single glass transition temperature (T-g) determined by differential scanning calorimetry (DSC). Then, lanthanum hexaboride (LaB6) nanoparticles (NPs) prepared by the chemical method were successfully added to the CS-PFPAMA blend at different weight ratios by hydrothermal method. Morphological characterizations of CS-PFPAMA blend and produced nanocomposites were performed with Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy, and atomic force microscopy, and thermal characterizations were made with thermogravimetric analysis and DSC. The thermal stability and T-g values of the obtained CS-PFPAMA blend and nanocomposites were lower than the values of the CS. However, LaB6 NPs increased the dielectric properties of the CS-PFPAMA blend. Thus, the potential use of the produced nanocomposites in electronic devices may be in question. According to the results of antibiogram tests performed by the disk diffusion method, it was determined that nanocomposites showed a serious resistance against Escherichia coli and Staphylococcus aureus pathogens. In addition, both antioxidant and oxidant properties of nanocomposites showed values close to the reference material used. The determined biological properties indicate that the CS-based nanocomposites can be used as biomaterials.Öğe A novel study of hybrid brake pad composites: new formulation, tribological behaviour and characterisation of microstructure(Taylor & Francis Ltd, 2021) Oktem, Hasan; Akincioglu, Sitki; Uygur, Ilyas; Akincioglu, GulsahIn the production of brake pad composites, a well-designed new composition formulation plays a key role in improving performance. The purpose of this study; was to investigate the effectiveness of a specifically developed formulation under brake-test conditions. The composition of the brake lining consists of 18 powder materials. As the friction adjuster, Petro-coke powder was used instead of Cashew, which is cheaper and more readily available. The wear tests were carried out in a special design test device simulated close to the real environment. The results obtained have been compared with commercial brake pads. The friction coefficient values decrease with increasing disc temperatures. Brake tests showed that as a friction modifier, petro-coke provided a more effective stabilizer for the friction coefficient and improved the specific wear rate. Also the study can be utilized effectively in determining the friction coefficient and the specific wear rate of designed brake composites.Öğe Sodium nitrite as a corrosion inhibitor of copper in simulated cooling water(Nature Research, 2021) Rizvi, Marziya; Gerengi, Husnu; Kaya, Savas; Uygur, Ilyas; Yildiz, Mesut; Sarioglu, Ibrahim; El Ibrahimi, BrahimThe corrosion inhibition behavior of sodium nitrite (NaNO2) towards pure copper (99.95%) in simulated cooling water (SCW) was investigated by means of electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS). NaNO2 interferes with metal dissolution and reduce the corrosion rate through the formation or maintenance of inhibitive film on the metal surface. Surface morphologies illustrated that the surface homogeneity increased on adding sodium nitrite. Sodium nitrite's adsorption on copper surface followed the modified form of Langmuir, Freundlich and Frumkin isotherms. Physiosorption mode was involved in the corrosion protection. Electrochemical results revealed an corrosion resistance of copper increases on increasing the inhibitor concentration. The DEIS results indicated that copper corrosion mechanism could be hindered by 50% even after interval of 24 h by optimum concentration of sodium nitrite. The maximum inhibition was achieved with 2000 ppm of NaNO2. With this concentration, inhibition efficiency of up to 61.8% was achievable.Öğe Synthesis of novel PVA-PFPAMA nanocomposites by the hydrothermal method: Evaluation of thermal, antimicrobial, and anticarcinogenic properties(Elsevier Science Sa, 2023) Erol, Ibrahim; Hazman, Omer; Ozkan, Mehmet; Uygur, Ilyas; Khamidov, Gofur; Gerengi, HusnuIn this study, a mixture of poly 2-(4-fluorophenyl)-2-oxoethyl-2-methylprop-2-enoate (PFPAMA) and PVA was first prepared and characterized using the hydrothermal method. Copper (II) oxide nanoparticles (CuO NPs) prepared by solution plasma process (SPP) were hydrothermally incorporated into the PVA-PFPAMA blend at 3 %, 5 %, and 7 %. FTIR spectroscopy was used to identify the functional groups of the obtained materials. Morphological and structural analysis of the materials was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The glass transition temperatures (Tg) of the materials were investigated by differential scanning calorimetry (DSC), and their thermal stability by thermogravimetric analysis (TGA). All materials showed excellent antimicrobial effects against E. coli, S. aureus, and C. albicans strains. It was also found that the anticarcinogenic activity increased with the proportion of CuO NPs in the nanocomposites. The results showed that the thermal and biological properties of the nanocomposites were positively affected after the inclusion of CuO NPs in the PVA-PFPAMA blend. The synergistic effects of PFPAMA and CuO NPs improved the overall performance of the materials.Öğe Tribological and mechanical exploration of polymer-based hemp and colemanite composite as a friction material(Iop Publishing Ltd, 2024) Karakas, Hamdi; Oktem, Hasan; Uygur, IlyasNatural and organic-based composite materials are widely used in many industrial applications due to their low cost, easy recyclability, economic feasibility, and ready availability. In this study, a polymer-based composite friction material consisting of Hemp-Colemanite composition (HCFCo) has been developed for the automotive sector to exhibit lower cost, environmentally friendly characteristics, and suitable friction-wear behaviors. For this purpose, three different ratios (%4, %8 and %12) of HCFCo composites were produced using a coating technique called impregnation process with a specially designed device. During the production stage, homogeneity of the composites was ensured, and then the final shape was given by the hot pressing method. Local based natural materilas frequently used for as anon-asbestos friction materails. For this reason, hemp and colomanited based composites were tested. Properties such as hardness, density, water and oil absorption, friction coefficient, and specific wear of HCFCo samples were examined. In addition, the microstructures of HCFCo composites were investigated to determine the bonding form between hemp fiber and colemanite. The results obtained revealed that the friction coefficient values decreased with an increase in temperature, while no significant change was observed in hardness and density values. Throughout the entire testing process, the friction coefficients varied between 0.14 and 0.29 on average. It was concluded that the developed fiber-reinforced composite can be reliably used in industrial applications and can contribute significantly to innovations in the literature.Öğe Wear response of non-asbestos brake pad composites reinforced with walnut shell dust(Springer, 2020) Akincioglu, Gulsah; Akincioglu, Sitki; Oktem, Hasan; Uygur, IlyasWith automobile numbers continuing to increase, competition among manufacturers of brake pads is also increasing along with the search for additives to serve as alternatives to the materials presently being used. In addition to the cost of the additives used, another important consideration in choosing materials is that they should be safe for the environment and human health. This study investigated the effect on braking performance of brake pads produced using walnut shell powder as a natural additive material. Two different types of brake pad samples were produced using 3.5 (2A) and 7% (2B) walnut shell dust in the contents. A commercial Clio brake tip was used as the reference (CO). The produced brake pads were subjected to thermal conductivity, friction wear, density, hardness and water and oil absorption tests and microstructure analysis. A Chase type device was used for wear friction tests, and the results were obtained according to SAE-J661(Brake Lining Quality Test Procedure) standards. The experimental data were compared with those of the commercial brake pads, and the performances of the natural additive brake pads were evaluated. The addition of walnut shell was shown to be compatible within the composition and exhibited a positive effect on the friction coefficient.
