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Corrosion Behaviour of 17-4 PH Stainless Steels Produced by Adding Different Amounts of Alloying Element and Aged at Different Times
(Maik Nauka/Interperiodica/Springer, 2023) Kocak, Salih cagatay; Simsek, Dogan; Simsek, Ijlal; Ozyurek, Dursun
In this study the corrosion behaviour of 17-4 PH (precipitation hardening) stainless steel alloys, produced by adding Ta different amounts with the method of powder metallurgy, and aged at different times was investigated. Four different amounts tantalum (0.15, 0.30, 0.45 and 0.60% weight) was added to the alloy. The prepared powders were produced green compacts at circle minus 10 x 6 mm dimensions (800 MPa) after mixing with turbule for 2 hours. Green compacts produced were sintered for 1 h at 1300 degrees C under a vacuum of 10-6 mbar. The sintered samples were aged 1, 4 and 8 hours at 480 degrees C after being in solution at 1050 degrees C. Polarization measurements were performed in a corrosion cell, using three different electrode technique. In the corrosion tests, 0.1 M H2SO4 was used as the electrolyte medium. As a result of the studies, the alloy the hardness and densities were increased with increasing Ta amount. Similarly, the hardness and densities of produced samples were with increasing aging time. The corrosion tests revealed that increasing the amount of Ta added to the alloy increased the alloy's resistance to corrosion. The alloy's corrosion resistance decreased as aging time increased. The active corrosion mechanism was seen to be pitting corrosion in all alloys.
THE DETERMINATION OF OPTIMUM INJECTION PRESSURE IN AN ENGINE FUELLED WITH SOYBEAN BIODIESEL/DIESEL BLEND
(Vinca Inst Nuclear Sci, 2014) Celik, M. Bahattin; Simsek, Dogan
In this study, the optimum blend rate and injection pressure in a four-stroke, single cylinder, direct injection diesel engine using soybean methyl ester were investigated experimentally. The tests were conducted at two stages. Firstly, the engine was tested with diesel fuel, B25 (25% biodiesel + 75% diesel fuel), B50, B75, and B100 fuels at full load and at a constant speed. According to the test results, it was determined that the most suitable fuel was B25 in terms of performance and emission. Secondly, the engine was tested at different loads with diesel fuel at original injection pressure and with B25 at different injection pressures (160, 180, 200, 220, and 240 bar) for comparison. It was determined from tests performed with B25 that the most suitable injection pressure in terms of performance and emissions was 220 bar. The specific fuel consumption and power values of the B25 were found to be nearly the same as those of diesel fuel at 220 bar injection pressure. In addition, HC, CO, and smoke emissions were reduced by about 33%, 9%, and 20%, respectively. On the other hand, NO emission increased by about 12%.
Dry Sliding Wear Behaviors of Iron Addition to Nickel-Aluminum Bronze Produced by Mechanical Alloying
(Springer India, 2020) Simsek, Dogan; Colak, Niyazi Y.; Simsek, Ijlal; Ozyurek, Dursun
In this study, different amounts of iron are added to nickel-aluminum bronze produced by mechanical alloying and its effects on microstructure, hardness, and wear behaviors are investigated. Four different amounts of Fe (3.5, 4, 4.5, and 5 wt%) was added to Cu10Al5Ni alloy and mechanically alloyed for 60 min. After cold pressing (600 MPa), the alloy powders were sintered at 800 degrees C and cooled in furnace to room temperature. The samples were characterized with scanning electron microscope (SEM + EDS), X-ray diffraction and hardness and density measurements. Wear tests were performed using a block-on-ring wear testing device with 0.2 m/s sliding velocity, four different sliding distances (400-1600 m) and three different loads (10 N, 20 N, and 30 N). As a result of the studies, it was found that the hardness value increased, and the density decreased with increasing Fe amount. Cu10Al5Ni containing 5% Fe was measured with the highest hardness value (55.74 HV) and the lowest density value (7.72 g/cm(3)). Also, Fe- and Ni-rich kappa intermetallic compounds were formed in the microstructure of the alloy. The wear tests showed that the alloy containing 5% Fe had the lowest weight loss and wear rate as well.
Effect of Alloying Time and Heat Treatment on Microstructure and Tribological Properties of Mechanical Alloyed Cu-Al-Ni Shape Memory Alloy
(Springer, 2023) Yavuzer, Bekir; Bicakci, Unal; Simsek, Dogan; Ozyurek, Dursun
In this study, the effects of milling time and heat treatment on microstructure and wear behavior of Cu-Al-Ni shape memory alloys produced by the mechanical alloying method were investigated. Cu-Al-Ni shape memory alloys were produced by mechanical alloying in four different durations (2.5, 5, 7.5 and 10 h) in a planetary-type mill. The produced Cu-Al-Ni shape memory alloys were characterized by microstructure (SEM + EDS), x-ray diffraction, thermal analysis (TG/DTA-DSC), and hardness, density, and dust size measurements. In the wear tests, three different loads (10, 20, and 30 N), five different sliding distances (400, 800, 1200, 1600, and 2000 m) and a sliding speed of 1 ms-1 were used. As a result of the studies, it was observed that the powder size decreased with the increase in MA time. It was observed that the density of heat-treated shape memory alloys decreased compared only to sintered alloys. According to the wear test, the lowest wear rate was obtained in Cu-Al-Ni shape memory alloys exposed to mechanical alloying for 7.5 h, with the highest hardness value. In addition, it was observed that the wear rates decreased in heat-treated Cu-Al-Ni shape memory alloys as the sliding distance increased.
Effect of Ti Content on Microstructure and Wear Performance of TZM Alloys Produced by Mechanical Alloying Method
(Korean Inst Metals Materials, 2021) Sirali, Haktan; Simsek, Dogan; Ozyurek, Dursun
In this study, changes in microstructure, hardness and wear performance of titanium-zirconium-molybdenum (TZM) alloys produced by mechanical alloying method with the addition of different amounts of titanium (Ti) were investigated. Mechanically alloyed powders were sintered at 1300 degrees C for 4 h under 10(-6) mbar vacuum environment. The produced alloys were characterized by scanning electron microscope (SEM + EDS), X-ray diffraction, grain size distribution, hardness and density measurements. In the wear tests, three different loads and five different sliding distances were used. Results showed that the produced TZM alloys were porous, and the pores in the alloys containing 0.40% and 0.45% Ti were generally located on the grain boundaries. In alloys containing 0.50% Ti, inside the grain the pore sizes increase, while in the alloy containing 0.55% Ti, the pore sizes in grain boundary decrease. Grain size distribution results show that as the Ti content increased, the amount of grain size over 6 mu m decreased and smaller than 6 mu m increased. Hardness and density results show that while the hardness of TZM alloys produced increases depending on Ti content, their density decreases. The highest hardness was obtained in the TZM alloy containing 0.55% Ti, while the lowest density was obtained in the same alloy. Wear test results show that the lowest weight loss was obtained in TZM alloy containing the highest amount of Ti (0.55%) under all loads. Graphic
Effect of TiC Content on Wear Performance of A356 Matrix Composites at Different Temperatures
(Springer, 2022) Simsek, Dogan; Ozyurek, Dursun; Salman, Serdar
With the developing technology, aluminum matrix composites (AMCs) are widely used in many system parts in the automotive industry. One of the most important parts is the friction materials used in the brake system operating at varying temperatures. This study examined the wear performance of aluminum matrix composites produced by adding different amounts of TiC to the A356 matrix at different temperatures. TiC in 4 different amounts (3, 6, 9, and 12 wt.%) and 2% graphite as a solid lubricant were added to the A356 alloy. The powders prepared in mentioned proportions were mechanically alloyed for 240 min using a planetary mill. The AMCs were sintered for 60 min at 550 degrees C in a 10(-6) mbar vacuum environment. Afterward, the AMCs prepared through standard metallographic processes (sanding with 200-100 mesh sandpaper and polishing with 1 mu m diamond solution) were characterized by scanning electron microscopy (SEM + EDS), X-ray diffraction spectroscopy (XRD), as well as hardness and density measurements. Wear tests were carried out by adding a temperature module in accordance with the ASTM-G99 standard. The study results showed a homogeneous distribution of TiC particles in the structure. Measurements showed that the hardness and density of the composites improved as the amount of reinforcement phase in the matrix increased. The highest hardness (821 HV) and the highest density (2.803 g/cm(2)) values were established for the AMC with 12% of TiC. The wear tests demonstrated that the weight loss was lower with the increasing reinforcement phase in the matrix. As the test temperature increased, the weight loss of the composites became higher. At all temperatures, the lowest weight loss was recorded for the AMC with the added 12% TiC. The coefficient of friction also increased with the higher temperature.
Effects of Different Solid Solution Temperatures on Microstructure and Mechanical Properties of the AA7075 Alloy After T6 Heat Treatment
(Walter De Gruyter Gmbh, 2019) Tekeli, Suleyman; Simsek, Ijlal; Simsek, Dogan; Ozyurek, Dursun
In this study, the effect of solid solution temperature on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment was investigated. Following solid solution at five different temperatures for 2 hours, the AA7075 alloy was quenched and then artificially aged at 120 degrees C for 24 hours. Hardness measurements, microstructure examinations (SEM+EDS, XRD) and tensile tests were carried out for the alloys. The results showed that the increased solid solution temperature led to formation of precipitates in the microstructures and thus caused higher hardness and tensile strength.
Investigation of the Effect of Zirconium Amount on Grain Size and Wear Performance in TZM Alloys Produced by Mechanical Alloying Method
(Springer India, 2022) Sirali, Haktan; Simsek, Dogan; Ozyurek, Dursun
In this study, the relation between grain size, hardness and wear performance of Titanium-Zirconium-Molybdenum (TZM) alloys with different amounts (0.06, 0.07, 0.08 and 0.09 wt%) of Zr added by the mechanical alloying method was investigated. As a result of the studies, it was observed that the number of pores in the structure increased with the increase in the amount of Zr, while there was a decrease in the grain size. In the hardness and density results, it was observed that while the hardness values increased with increasing Zr amount, there was a decrease in the density values. As a result of the wear tests, the lowest weight loss at 10-30 N loads was obtained in the TZM alloy with the highest Zr added (0.09% Zr). The lowest friction coefficient in the friction coefficient results was obtained in TZM alloy with 0.09% Zr added.
Investigation of Wear Behaviors of SiO2 Reinforced Aluminium Composites Produced by Pressureless Infiltration Method
(Gazi Univ, 2019) Simsek, Ijlal; Yildirim, Musa; Ozyurek, Dursun; Simsek, Dogan
In this study, the wear behaviors of SiO2 reinforced AA7075 matrix composites produced by pressureless infiltration method were investigated in the scope of the work, 10%, 20%, 30%, and 40% SiO2 were added into AA7075 Al alloy and produced by infiltration method. Produced samples' density values were measured by Archiment method, hardness values were measured in micro hardness device under 2 N load. Wear tests were performed using 1 ms(-1) sliding speed at five difference sliding distance under 15 N load by pin-on-disc type apparatus. As a result of the study, the density values were decreased by increasing SiO2 amount and hardness values were increased by increasing SiO2 amount. In addition the weight loss and friction coefficient were decreased depending on increasing of SiO2 amount.
Investigation of Wear Performance of Different Amount SiC Reinforcements A356 Matrix Composite Materials Produced by Semi-Solid Process Method
(Gazi Univ, 2020) Simsek, Ijlal; Simsek, Dogan; Ozyurek, Dursun
In this study, the wear performance of A356 matrix composite materials produced by different amount SiC reinforcement semisolid moulding method was investigated. In the A356 matrix, was added four different amounts (5%, 10, 15 and 20) SiC. Composite powders mixed without ball (30 minutes) in the vibrating type mill were cold pressed (800 MPa) and green compacts were produced. The produced green compacts, in 550 degrees C mold temperature and in 600 degrees C furnace temperature, 100 MPa pressing force was pressed for 1 minute. Produced samples were characterized with microstructure, hardness and sphericity ratio. The wear tests were performed using a pin on-disk type wear testing device with 0.2 ms(-1) sliding speed, under two different loads (30 and 60 N) and at four different sliding distances (500 m, 1000, 1500 and 2000). As a result of the studies, the hardness increases with increasing amount of SiC in the composite material, while the sphericity rates decrease. As a result of the wear tests, while the highest weight loss, 5% SiC was obtained, the lowest weight loss was obtained in 20% SiC additional composite materials.
Optimizing of Wear Performance on Elevated Temperature of ZrO2 Reinforced AMCs Using Weighted Superposition Attraction Algorithm
(Natl Inst Science Communication-Niscair, 2022) Simsek, Dogan; Ozyurek, Dursun; Ileri, Erol; Akpinar, Sener; Karaoglan, Deniz
In the current study, the zirconium oxide (ZrO2) reinforced Aluminium Matrix Composites (AMCs) was designed as a brake lining and produced by mechanical alloying (MA) method. Wear tests of AMCs were performed according to ASTM G-99 at different sliding distance, operating temperatures and load in the range of 53 to 94 m, 20 to 340 degrees C and 10 to 30 N respectively. Optimum wear performance parameters were determined using the Weighted Superposition Attraction (WSA) algorithm. Firstly, to formulize the problem as an optimization problem through the guidance of the regression modelling, an experimental design has been constructed, and the wear tests have been done at different reinforced rates, operating temperature and loads. Secondly, WSA algorithm has been adapted to tackle the formulated optimization problem. According to the results of WSA algorithm, the optimum rate of zirkonium oxide (ZrO2), load and operating temperature was determined as 12%, 206.33 degrees C and 21.20 N respectively while keeping the friction coefficient between 0.15-0.24.
Optimizing tribological performance in elevated temperature of TiC reinforced A356 matrix composites designed as automotive friction materials using dragonfly algorithm
(Sage Publications Ltd, 2023) Simsek, Dogan; Ozyurek, Dursun; Ileri, Erol; Karaoglan, Aslan Deniz
The objective of this study designed in three steps is to evaluate the optimization of tribological performance in the elevated temperature of TiC reinforced A356 matrix composites, produced by mechanical alloying (MA), using the dragonfly algorithm (DA). In the first step, an experimental design is created to formulate the problem as an optimization problem with the help of regression modeling, and wear tests by adding a temperature module according to ASTM G99-05 standards are performed at various reinforced rates, operating temperatures, and loads. In the second step, regression models are fitted to the experimental results. In the third step, the dragonfly algorithm (DA) - one of the recent nature inspired metaheuristic optimization algorithms - has been adapted to optimize the formulated problem. The results of DA indicate that the optimum factor levels for the reinforced rate, operating temperature, and load are determined as 7%, 10 degrees C, and 20 N respectively to optimize the responses, namely weight loss, wear rate, and friction coefficient.
Wear behaviors at different temperatures of ZrO2 reinforced A356 matrix composites produced by mechanical alloying method
(Emerald Group Publishing Ltd, 2022) Simsek, Dogan; Ozyurek, Dursun; Salman, Serdar
Purpose The purpose of this study, the tribological behaviors at different temperatures of aluminium matrix composites (AMCs) with different amounts of ZrO2 added were investigated. Design/methodology/approach Aluminium graphite (A356/2 wt% graphite (solid lubricant)) composite powders prepared by adding four different amounts (3 wt%, 6 wt%, 9 wt% and 12 wt%) of Zirconia (ZrO2) to the matrix were mechanically alloyed for 4 h. Wear tests were conducted at five different temperatures (20 degrees C, 100 degrees C, 180 degrees C, 260 degrees C and 340 degrees C) and for three different sliding distances (53 m, 72 m and 94 m) on the pin-on-disc type wear tester. Findings Results of the study showed that the highest hardness and density value were measured for 12% ZrO2 added AMC material. Wear test results showed that weight loss increases with increasing temperature; weight loss decreases at all temperatures with the increasing amount of reinforcement in the matrix. Originality/value In this paper, the tribological properties of aluminium matrix composites produced by the mechanical alloying method by adding different amounts of ZrO2 were determined by simulating the tribological properties at different loads and temperatures.
The Wear Performance at High Temperatures of ZrO2-Reinforced Aluminum Matrix Composites Produced by Mechanochemical Reaction Method
(Asme, 2020) Simsek, Dogan; Ozyurek, Dursun
In this study, high-temperature wear performance of A356+Gr-ZrO2 aluminum matrix composites (AMCs) produced by the mechanochemical reaction method was investigated. After the aluminum composite powders were cold-pressed (750 MPa), the green compacts were sintered under 10(-6) mbar vacuum for an hour at 550 degrees C. Sintered AMCs have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), hardness and density measurements. Wear tests were conducted in two different loads (10 N and 30 N), five different temperatures, and three different sliding distances in the standard pin-on-disc type wear tester. Result showed that ZrO2 added to the matrix tends to cluster in grain boundaries. AMCs hardness and densities increased with the increasing amount of reinforcement, and the highest hardness and density value was obtained with 12% ZrO2-added AMCs. Weight loss increased with increasing load and temperature and decreased with increasing amount of reinforcement in the matrix at all loads and temperatures.

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