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Öğe The Effect of Sintering Temperature and Time on Microstructure, Hardness and Wear Behaviors of Al 99.9/GNP Composites(Int Inst Science Sintering (I I S S), 2023) Pul, Muharrem; Erdem, Ümit; Pehlivanlı, Zühtü OnurIn this study, it was aimed to investigate the microstructure, hardness and wear behavior of graphene nanoplate (GNP) reinforced composites with Al 99.9 matrix produced by powder metallurgy. Different temperatures and times were applied in the sintering process. The hardness values of the composites increased as the sintering temperature and time increased. The hardness values decreased with the increase of GNP reinforcement ratio. The wear losses decreased depending on the increase in sintering temperature and time. With the increase in the GNP reinforcement ratio, reductions in wear losses were recorded. It has been concluded that the GNP reinforcement element in the composite structure reduces the friction coefficient and wear losses by having some lubricating effect. It was observed that the neck and bonding formation between Al 99.9 matrix grains improved with increasing sintering temperature and time. It was concluded that with the development of intergranular bonds, the porosity in the composite structure decreased and the mechanical properties increased.Öğe The effect of cutting depth and cutting tool geometry on surface roughness and tool wear behavior in the machining of Al 6061 alloy(Gazi Univ, Fac Engineering Architecture, 2022) Pul, Muharrem; Özerkan, Hacı BekirPurpose: Al 6061 alloy is used in many different areas in the manufacturing sector. However, in the majority of machinability studies in the literature, it was revealed that shear forces were examined, and surface roughness was investigated in a few studies. In addition, in most of these studies examining surface roughness, it is seen that constant cutting depth and uniform cutting tool are used. In this experimental study on machinability, it was aimed to investigate the effect of cutting depth and cutting tools with different geometrical properties on the roughness of the machined surface in the turning of Al 6061 aluminum alloy. Aluminum and its alloys constitute the metal group with the most usage area in the industry after steel. Theory and Methods: utting tools with cutting depths of 0.4 -0.8 -1.6 -2.4 mm and ISO codes, SNMA 120408 KR, KNUX 160405 R11, TNMG 160404, DCGT 11T308 ALU were used in the turning experiments. The experiments were carried out on a conventional lathe with a constant feed rate of 0.2 mm/rev and two different cutting speeds of 125 m/min and 250 m/min. Results: As a result of the experiments, each cutting tool exhibited different surface roughness values and the lowest roughness values were obtained with the SNMA 120408 KR coded cutting tool. As the depth of cut values decreased, the roughness of the surfaces decreased in general. However, in the SNMA 120408 KR coded tool, the opposite behavior was observed and the highest roughness value was obtained at 0.4 mm depth of cut. In the change of cutting speed, different surface roughness values were obtained according to the type of cutting tool. In the change of cutting speed, different surface roughness values were obtained according to the type of cutting tool. However, the expected decrease in roughness values did not occur with increasing cutting speed. DCGT coded tool used in aluminum processing could not outperform the other cutting tools in terms of surface roughness. Conclusion: When evaluated in terms of price and performance, it has been evaluated that the SNMA 120408 KR coded tools are more suitable and optimum solution than the other selected tools.Öğe The Effect of Cutting Tool Wear Behaviors on Feed Rates in Turning of Metal Matrix Composites(Gazi Univ, 2014) Pul, Muharrem; Şeker, UlviComposite materials, one of them is metal matrix composites (MMCs), is a group of engineering materials who seapplication fields expandrapidly. In this study, to make an interpretation on machinability of MMCs materials, MMC smaterials reinforced Al matrix and MgO which were produced in 5%, 10% and 15% reinforcement-volumeratios (R-V) were subjected to machining tests by carbide (C) and coated carbide (CC) cutting tools. Machining tests were conducted with 300 m/dak cutting speed, at three different feed rates (0.075, 0.15 and 0.225 mm/dev) and fixed depth of cut (1 mm). After the machining tests, wear characteristics were examined by the help of scanning electron microscope (SEM) views of cutting tools and the findings were discussed. In the evaluation of SEM views of cutting tools, the built up edge(BUE) was observed at the head of all cutting tools. As not being within the tool life bound, it is deduced that with the increase in feed rate, a trace of flank wear mechanism on C cutting tools were detected. Generally it is deduced that while CC tools reveal better performance, with regard to tool costs, C tools could be used to operate this kind of MMC smaterials.Öğe The effect of carbon nanotube amount in machining of ZA-27 matrix carbon nanotube reinforced nano composite(Univ Fed Rio De Janeiro, Lab Hidrogenio, 2022) Pul, MuharremIn recent years, the usage area of nano material reinforced composites has been increasing gradually. Accordingly, machining of metal matrix and nano material reinforced composite materials becomes important. In this study, the effect of carbon nanotube (CNT) on the machining of CNT-reinforced ZA-27 (zinc-aluminum) nano composite was investigated. For this purpose, 0.5%, 1.0%, 1.5%, 3.0% CNT-reinforced ZA-27 based composites were produced by powder metallurgy method. Firstly, SEM images of composites were taken. Then, hardness measurements were made and pore amounts were determined. At the last stage, the machinability tests of nano composites have been carried out. Machinability tests were carried out by turning method to determine the cutting forces and surface roughness amounts. The tests were carried out with cemented carbide cutting tools under dry cutting conditions. Cutting speeds of 75, 125, 175, 225 m/min, feed values of 0.05, 0.10, 0.20 mm/rev and constant cutting depth of 1.0 mm were chosen as test parameters. The data obtained as a result of the tests were interpreted together with microstructure, porosity and hardness values. Hardness values decreased and the pore amounts increased with the increase in the CNT-reinforcement ratio within the composite structure.Cutting forces and the surface roughness amounts increased with the increase in feed value. Cutting forces and surface roughness amounts decreased together with increase in cutting speed. CNT-reinforcement material in the composite structure caused a decrease in cutting forces. However, surface roughness values showed an increase with the increase of CNT-reinforcement ratio. It has been determined that CNT-reinforcement material facilitates machining by lubricating effect in dry machining conditions. Built-up edge (BUE) was observed on all cutting tool bits used in machining tests. BUE amounts increased in itself with the increase in CNT ratios and feed rates.Öğe Synthesis of biocompatible Ti-6Al-4V composite reinforced with ZrO2 and bioceramic produced by powder metallurgy: Morphological, structural, and biocompatibility analysis(Wiley, 2024) Pul, Muharrem; Erdem, Ümit; Bozer, Büşra Moran; Şimşek, Tuncay; Yılmazel, Rüstem; Erten, Mustafa YasinIn this experimental study, the initial phase involved preparing composite structures with various mix ratios using the Ti-6Al-4V alloy, widely used in clinical applications, in conjunction with ZrO2 and hydroxyapatite (HA) synthesized via the precipitation method, employing powder metallurgy techniques. Subsequently, the microstructures of the resultant hybrid composite materials were imaged, and x-ray diffraction (XRD) phase analyses were conducted. In the final phase of the experimental work, tests were performed to determine the biocompatibility properties of the hybrid composites. For this purpose, cytotoxicity and genotoxicity assays were carried out. The tests and examinations revealed that structures compatible both morphologically and elementally were obtained with no phase transformations that could disrupt the structure. The incorporation of ZrO2 into the Ti-6Al-4V alloy was observed to enhance cell viability values. The value of 98.25 +/- 0.42 obtained by adding 20% ZrO2 gave the highest cell viability result. The addition of HA into the hybrid structures further increased the cell viability values by approximately 10%. All viability values for both HA-added and HA-free groups were obtained above the 70% viability level defined in the standard. According to the genotoxicity test results, the highest cytokinesis-block proliferation index values were obtained as 1.666 and 0.620 in structures containing 20% ZrO2 and 10% ZrO2 + 10% HA, respectively. Remarkably, all fabricated composite and hybrid composite materials surpassed established biocompatibility standards and exhibited nontoxic and nongenotoxic properties. This comprehensive study contributes vital insights for future biomechanical and other in vitro and in vivo experiments, as it meticulously addresses fundamental characterization parameters crucial for medical device development.Öğe Analysis of the Effect of Boron Carbide Amount on Mechanical, Thermal, and Electrical Properties of Copper Based Boron Carbide Added Composites(Springer, 2024) Pul, MuharremCopper is used widely due to its high conductivity and good machinability. But there are some limitations in its use due to its low mechanical resistance. In this experimental study, copper-based and boron carbide added composite materials were produced by synthesizing pure copper and boron carbide by powder metallurgy method. The effects of boron carbide additives on the microstructure, phase structure, hardness, compressive strength, abrasion resistance, thermal and electrical conductivity behavior of the copper composite were investigated. It has been observed that with the increase of boron carbide ratio in the composite structure, porous regions are formed in the microstructure, the hardness value and wear resistance increase, but the compressive strength decreases. Compared to pure copper, it was determined that the thermal conductivity coefficient of the boron carbide added composite materials decreased significantly and the specific heat capacity increased. With the addition of boron carbide, the electrical resistance of pure copper increased and its electrical conductivity decreased. However, although the conductivity decreased with the addition of boron carbide, it was still found to have higher electrical conductivity than most metals. The new generation B4C added Cu-based composite material obtained from the study can be preferred in engineering applications where the use of existing copper materials is limited and subject to higher thermal and mechanical stress. It has been evaluated that this new generation copper-based composite material can be used in engineering applications that require higher mechanical and thermal resistance and acceptable electrical conductivity.Öğe A novel approach for enhancing the mechanical behavior of additively manufactured metal matrix composite structures: Preliminary investigation(Sage Publications Ltd, 2024) Yalcin, Hasan; Abdelmoula, Mohamed; Kaya, Duran; Kucukturk, Gokhan; Pul, MuharremAdditive Manufacturing is a promising technique for expanding the boundaries of Metal Matrix Composites. In this study, Powder Bed Fusion (PBF) technique, employing Electron Beam as the heat source, was used to print Ti6Al4V metal matrix in different geometric shapes with a new approach for MMC fabrication. Yttria Stabilized Zirconia (YSZ) powder was then incorporated into these pattern shapes, compacted, and sintered to bind the powder particles together. The findings showed that successful sintering was achieved, resulting in the formation of a flexible interface region, with the circular design achieving the best interface region among all pattern designs. Regarding the mechanical performance evaluation of the developed Metal Matrix Composites, it was found that the mechanical strength was significantly increased with the hexagonal and circular patterns achieving the best results. Future research should pay more attention to further design development for the metal matrix model to achieve outstanding performance and create a new field for Metal Matrix Composites using the developed method.Öğe Effect of sintering temperature on pore ratio and mechanical properties of composite structure in nano graphene reinforced ZA27 based composites(SPRINGER, 2020) Pul, MuharremNano graphene platelet (Gr) reinforced nano composites with a zinc-aluminum alloy (ZA27) matrix were produced by powder metallurgy at four different mass ratios (0.5wt%, 1.0wt%, 2.0wt% and 4.0wt%) and three different sintering temperatures (425, 450, and 475 degrees C). In order to investigate the effect of sintering temperatures and nano graphene reinforcement materials on the composite structure, the microstructures of the composite samples were investigated and their densities were determined with a scanning electron microscope. Hardness, transverse rupture, and abrasion wear tests were performed to determine the mechanical properties. According to the test results, the porosity increased and the mechanical strength of the nano composites decreased as the amount of nano graphene reinforcement in ZA27 increased. However, when the composites produced in different reinforcement ratios were evaluated, the increase in sintering temperature increased the mechanical structure by positively affecting the composite structure.Öğe Investigation of the tool wear, surface roughness, and chip formation in the machining of ZrO2-reinforced aluminum composites(SPRINGER HEIDELBERG, 2020) Pul, MuharremThe aim of this study is to reveal how ZrO2(zirconia) contributes to the machinability of aluminum 1050. In the first stage of this study, composite materials were produced by the vortex method by adding different amounts of ZrO2(5%, 10%, 20%, and 30%) into commercial aluminum of 99.5% purity. Then, microstructure images of composite materials were taken under the scanning electron microscope (SEM), and the hardness of these composite materials was measured. In the last stage, the machinability tests of the composite materials were performed on the lathe under dry machining conditions at 125, 175, and 225 m/min cutting speeds and 0.03-0.06 and 0.12 mm/rev feed rates, with 1.5 mm constant depth of cut. Uncoated cementite carbide cutting tool inserts were used in machining tests. SEM images of the cutting tool inserts were taken, and the roughness values of the machined surfaces were measured. Chip samples were taken and investigated. It was observed that all the cutting tools had a Built-Up Edge (BUE) formation. Surface roughness and BUE formation increased as the feed rates were increased and decreased with increasing cutting speed. The roughness values decreased slightly and then increased again depending on the ZrO(2)ratio. As the feed rates increased, a transition from ribbon chip type to the helical and saw-toothed forms was observed. It was also observed that the chip formation changed depending on the amount of ZrO(2)in the composite structure.Öğe Investigation of Mechanical Properties of B4C / SiC Additive Aluminum Based Composites and Modeling of Their Ballistic Performances(Gazi Univ, 2020) Pul, Muharrem; Baydaroglu, VolkanIn this study, 7075 grade aluminum-based composites reinforced with SiC (silicon carbide) and B4C (boron carbide) were produced with powder metallurgy at 40%, 20% and 10% reinforcement ratios. The mechanical properties of the composite samples produced in the first stage experiments were investigated. For this purpose, density, hardness, cross fracture and abrasive wear tests were performed. The results of the experiments were evaluated together with the microstructure and the microscope images of the composite samples. In the second stage of the study, the composite samples were modeled and their ballistic performance was examined by the finite element method. In ballistic analysis, 10% reinforced composites could not perform, while ballistic performance was obtained in increasing reinforcement ratios. When the production, hardness, wear and ballistic analyzes of the samples were evaluated together, it was seen that the reinforcement rate of 40% was high in such composites and not suitable for mechanical properties, 20% of the reinforcement ratio was both productibility and ballistic optimum result.Öğe Effect of sintering on mechanical property of SiC/B4C reinforced aluminum(Iop Publishing Ltd, 2019) Pul, MuharremIn this study, SiC (silicon carbide) and B4C (boron carbide) added Al 7075 based composites were prepared at 40%, 20% and 10% reinforcement ratios. Using powder metallurgy, composite sample with 9 different structures were produced at 700 MPa pressing pressure, at 550 degrees C in 90, 120, 150 min applying three different sintering times. According to Archimedes principle, theoretical densities of composite samples were calculated. Then, the hardness measurements and transverse rupture tests were conducted. Lastly, wear tests were conducted using the Pin on Disc Method. Images of composite samples were taken at optical microscope and Scanning Electron Microscope (SEM), and the microstructures were examined. It was determined that increase in SiC and B4C reinforcement ratios decreased the fracture resistance. However, when every reinforcement ratio was evaluated separately, it was observed that increase in sintering time affected the fracture resistance positively. Increase in sintering time also increased the density values, and the hardening values and wear resistance decreased. Increase in reinforcement ratios and sintering time affected the composite wear behavior negatively. Increase in reinforcement ratio in composite structure decreased the density; however, hardening values increased. In conclusion, in such type of composites, reinforcement ratios in definite proportions (similar to 20%) affect mechanical features positively, and excess in that ratio affect mechanical features negatively. Especially 40% reinforcement ratio was high for such type of composites and was not suitable for mechanical features.Öğe Investigation of cutting tool wear behaviors in machining of silicon carbide and magnesium oxide reinforced aluminum 2024 matrix composites(Iop Publishing Ltd, 2019) Pul, MuharremIn this study, first Silicon Carbide (SiC) and Magnesium Oxide (MgO) powders of <= 105 micron particle size were mixed in equal amounts. Then, the powder mixture was reinforced by using vortex method in liquid Al2024 aluminum alloy in three different ratios (3%, 6% and 12%) to produce composites. Finally, on composite samples, machinability tests were carried out with a uniform cutting tool at constant cutting depth (1 mm) and dry cutting conditions. Three different cutting speeds (100, 150, 200 m min(-1)) and three different feed values (0.03; 0.06; 0.12 mm/rev) were used in the machining experiments. Machinability tests were performed on a Computer Numerically Controlled (CNC) lathe. Wear behavior of cutting tools were examined by using SEM microscope images. In all of the cutting tools, built-up edge (BUE) was observed while small amount of flank wear occurred. It was concluded that the selected cutting tool and cutting parameters maybe suitable for the machining of such composite materials.Öğe Effect of B4C Reinforcement Ratio and Sintering Temperature on the Mechanical Behavior in Al-B4C Composites(Int Inst Science Sintering (I I S S), 2018) Pul, MuharremIn this study, powders of Al 1070 and B4C were prepared by volume in three different reinforcement ratios 4 % B4C, 8 % B4C and 16 % B4C compacted under the pressure of 500 MPa with cold pressing method then sintered under the temperatures of 500, 550 and 600 degrees C. Then the hardness was measured and wear test was performed using pin-on-disk method. In the results of tests, the compression pressure of 500 MPa was not sufficient for composite structure to achieve the required density. The highest hardness values were achieved at sintering temperature of 550 degrees C and in 8 % B4C reinforced composite. The highest wear rate was measured in 4% B4C reinforced composite specimen sintered at 600 degrees C. It is determined that a sintering temperature above 550 degrees C had adverse effects on the mechanical properties.Öğe An Investigation on the Microstructure and Wear Properties of TiB2 Reinforced AA2014 Aluminium Alloy Produced by Vacuum Infiltration(Walter De Gruyter Gmbh, 2015) Araz, Sule Ocak; Çalın, Recep; Pul, Muharrem; Bican, Osman; Okur, OnurIn this study, microstructural, mechanical and wear properties of TiB2 reinforced Al 2014-based composites produced by vacuum infiltration were investigated under different production temperatures. It was observed that the microstructures of the composites consisted of Al matrix and TiB2 particles. TiB2 particles exhibit various shapes such as cubic, triangle and spherical. It was observed that the hardness and porosity of the composites increased with increasing TiB2 content. It was also observed that the production temperature has an important effect on the porosity and hardness of the produced composites. The highest wear resistance was obtained from Al 2014-8% TiB2 composite among the materials tested. It was observed that the production temperature and hardness are effective parameters on wear of produced composites. Evaluation of microstructural and mechanical test results suggest that it would be beneficial to keep the production temperature around 800 degrees C and Al 2014-8% TiB2 composite can be recommended for engineering applications where the hardness and wear resistance are considered to be significant factors.Öğe The Effect of Reinforcement Volume Ratio on Porosity and Thermal Conductivity in Al-Mgo Composites(Univ Fed Sao Carlos, Dept Engenharia Materials, 2012) Çalın, Recep; Pul, Muharrem; Pehlivanli, Zuhtu OnurIn this study, the effects of reinforcement volume ratios (RVR) on composite structure and thermal conductivity were examined in Al-MgO reinforced metal matrix composites (MMCs) of 5%, 10% and 15% RVR produced by melt stirring. In the production of composites, EN AW 1050A aluminum alloy was used as the matrix material and MgO powders with particle size of -105 mu m were used as the reinforcement material. For every composite specimen was produced at 500 rev/min stirring speed, at 750 degrees C liquid matrix temperature and 4 minutes stirring time. Composite samples were cooled under normal atmosphere. Then, microstructures of the samples were determined and evaluated by using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis. In general, it was observed that the reinforcement exhibited a homogeneous distribution. Furthermore, it was determined that the increase in the RVR increased porosity. From the Scanning Electron Microscope images, a thermal Ansys model was generated to determine effective thermal conductivity. Effective thermal conductivity of Al-MgO composites increased with the decrease in reinforcement volume ratio.Öğe Artificial neural network analysis of heat pumps using refrigerant mixtures(Pergamon-Elsevier Science Ltd, 2004) Arcaklioglu, E; Erisen, A; Yilmaz, RIn this study, we have investigated the performance of a vapor compression heat pump with different ratios of R12/R22 refrigerant mixtures using artificial neural networks (ANN). Experimental studies were completed to obtain training and test data. Mixing ratio, evaporator inlet temperature and condenser pressure were used as input layer, while the outputs are coefficient of performance (COP) and rational efficiency (RE). The back propagation learning algorithm with three different variants and logistic sigmoid transfer function were used in the network. It is shown that the R-2 values are about 0.9999 and the RMS errors are smaller than 0.006. With these results, we believe that the ANN can be used for prediction of COP and RE as an accurate method in a heat pump. (C) 2003 Elsevier Ltd. All rights reserved.
