Browsing by Author "Çavdar U."
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Item Sintering with induction(European Powder Metallurgy Association (EPMA), 2008) Çavdar U.; Atik E.In this study; iron powder metals were sintered via induction heating process. Sintering process has been achieved with an induction generator that has 10 kW power supply and 20-30 kHz frequency. ASC10029 grade Iron powder was mixed with zinc stearat with a ratio of %0.8 of iron mass by weight. Several duration in the range of 5-10 minutes was studied during induction sintering. Transverse rupture strength, hardness and micro structural investigations were done. Obtained mechanical properties and microstructures were compared with traditionally sintered samples. At the end of the induction sintering process for a period of 5 minutes, the maximum stress values that were gotten from classically ovensintered samples for a period of 30 minutes are reached.Item Induction sintering of Fe-2Cu PM compacts(European Powder Metallurgy Association (EPMA), 2009) Çavdar U.; Atik E.Fe powders mixed with 2% Cu by weight were compacted with 600 MPa to form 3-point bending samples having dimensions of 10×10×55 mm. Compacted powders were sintered by using medium-low frequency (30 kHz, 12kW) induction energy in conveyor system. Sintering process was completed in several sintering durations from 400 to 1300 seconds at 1120°C under atmospheric environment (open air). Micro structural and mechanical properties of sintered samples were investigated. Maximum stress for 3-point bending was achieved at 1000 seconds of sintering duration at 1120 °C. The mechanical properties of induction sintered samples were compared with conventionally sintered samples at 1120 °C for 30 minutes of sintering duration under argon atmosphere. The maximum stress values for induction sintered sample were nearly similar to conventionally sintered samples.Item Thermal analyses for induction sintering of powder metal compacts up to sintering temperature(Palladin Institute of Biochemistry of the NASU, 2014) Çavdar U.; Atik E.; Akgül M.B.; Karaca H.Induction sintering is developed as an alternative method to conventional sintering in order to sinter iron-based powder metal (PM) compacts. In this study, the 12 kW power and 30 kHz frequency induction-sintering machine is used for 3 wt.% copper-mixed iron. The effects of different shapes and sizes of the induction coil, and temperature differences on the PM compacts up to sintering temperature are investigated; these parameters are determined both theoretically and experimentally during induction sintering. Iron-based PM compacts are sintered at 1120°C. Induction sintering of iron-based PM compacts are simulated using a program to examine the effects of magnetic flux and temperature distribution in the sample over time. The results are compared with the experimental studies.Item Effect of the copper amount in iron-based powder-metal compacts(Institute of Metals Technology, 2014) Çavdar U.; Ünlü B.S.; Atỳk E.In this study, iron-based powder-metal (PM) compacts were sintered using a medium-frequency induction-heating system. The effects of copper amounts on mechanical properties were investigated. Iron-based powders were mixed with mass fractions w = 1 % to 6 % copper (Cu) and 0.8 % zinc stearate in a V-type mixer. During the sintering process, PM compacts were sintered at a frequency of 30-50 kHz (medium frequency), at 12 kW and 1120 °C for 400 s in an atmospheric environment. Mechanical properties, microstructural properties, densities and microhardness values were investigated for the sintered material. The highest mechanical properties were obtained for the iron-based PM compacts including 3 % Cu.Item Properties of boronized, carbonitrided and steamed iron-based compacts(2014) Çavdar U.; Atik E.In this study, powder metal (P/M) compacts were prepared by mixing iron powder with 0-1 wt.-% Al, 2-3 wt.-% Cu and 0.2-0.8 wt.-% graphite. The 16 different P/M compacts compositions were prepared with 0.8 wt.-% zinc stearate as lubricant. The compacts' dimensions were 10 × 10 × 55 mm. All compacts were pressed at 600 MPa and sintered at 1120 °C for 30 minutes using a conventional sintering furnace and then boronizing, steaming and carbonitriding heat treatments were applied. The results of all the compacts in regard of the effects of corrosion endurance, density, and HV microhardness results were compared. © Carl Hanser Verlag GmbH & Co. KG.Item Mechanical properties of hot forged ANS11050 steel(Carl Hanser Verlag, 2014) Çavdar U.In this study, two different heating methods have been used for the hot forging process of ANSI 1050 steel. Some specimens were heated by induction generator at 250 kW, 3.2 kHz up to a temperature of 1250 °C ± 5 °C in 5 minutes under ambient conditions via a continuous conveyor belt system. Other steel specimens were heated continuously in a conventional furnace up to a temperature of 1230 °C ± 40 °C at ambient conditions in 30 minutes. All specimens were subjected to Charpy, three-point bending, fracture strain, and hardness tests (surface and cross-section measurements). Almost all mechanical test results were better for the specimens heated by the induction generator and also appeared as more stable than those for the specimens heated by conventional furnace which varying some showed results. Grain growing was found in the microstructure of the conventional heated specimens. Induction heated specimens were heated more homogenously than the conventional heated specimens which is the reason for more stable results. © Carl Hanser Verlag, München Materials Testing.Item Effects of surface finishing on the mechanical properties of induction welded iron based sintered compacts(Carl Hanser Verlag, 2014) Çavdar U.; Yalamac E.; Gülsahin I.In this study, iron based sintered parts were welded by high frequency induction welding. The effects of surface roughness on the mechanical properties of induction welded samples were investigated. Polished and unpolished samples were welded and mechanically tested by three point bending test. The hardness of the samples increased from the base material towards the weld metal. The weld metal, heat affected zone and the base material of the samples were investigated by light microscopy. In contrast to the polished samples, corrosion attack was registered in the welded region of unpolished samples. According to the results, the welding duration affects the mechanical properties. However, the surface finishing process was the dominant factor for the bending strength of the welded samples. © Carl Hanser Verlag GmbH & Co. KG.Item Mechanical properties and hardness results of the medium frequency induction sintered iron based powder metal bushings(International Institute for the Science of Sintering (IISS), 2014) Çavdar U.; Atik E.; Ataç A.In this study; iron based powder metal (PM) bushing compacts were sintered via medium frequency induction heating system. Iron based powders were mixed with 2 wt.% copper (Cu), 0.3 wt.% carbon (C) and 1 wt.% zinc stearat (Zn-st) via V-Type mixer. PM compacts were sintered by 2 different sintering processes. One of them was conventional sintering method other was medium frequency induction sintering method. In conventional sintering process, PM bushing compacts were sintered under inert environmental at 11200C for 30 minutes. In medium frequency induction sintering process, PM bushing compacts were sintered between 30-50 kHz frequency (Medium frequency) at 2 kW, 11200C for 1 or 3 minutes under atmospheric environmental. Mechanical properties, densities and micro hardness’ were investigated for all sintered processes. SEM and micro structural images were taken from polished broken surface of the sintered PM bushing compacts. 3 minutes induction sintered compacts were reached the compressive strength, microhardness and density values of the conventional sintered PM bushing compact. © 2014,International Institute for the Science of Sintering (IISS). All rights reserved.Item Ultra High Frequency Induction Welding of Powder Metal compacts(Centro Nacional de Investigaciones Metalurgicas, 2014) Çavdar U.; Gülşahin I.The application of the iron based Powder Metal (PM) compacts in Ultra High Frequency Induction Welding (UHFIW) were reviewed. These PM compacts are used to produce cogs. This study investigates the methods of joining PM materials enforceability with UHFIW in the industry application. Maximum stress and maximum strain of welded PM compacts were determined by three point bending and strength tests. Microhardness and microstructure of induction welded compacts were determined. Copyright: © 2014 CSIC.Item Effects of coil design on induction welding of sintered iron based compacts(Carl Hanser Verlag, 2014) Çavdar U.; Kusoglu I.M.Sintered iron based compacts were welded by applying a high frequency induction process. The cross-sections of the compacts were square in shape so two different coil shapes, cylindrical and square, were studied with respect to the effect of magnetic flux. The effect of welding duration on the macrostructural changes and mechanical properties of the induction welded compacts were investigated for welding durations of 3, 5 and 10 minutes. © Carl Hanser Verlag GmbH & Co. KG.Item Mechanical properties of heat treated iron based compacts(Elsevier Ltd, 2015) Çavdar U.; Ünlü B.S.; Pinar A.M.; Atik E.In this study, powder metal (PM) compacts were prepared by mixing iron powder with 1-6. wt.% ratio of Cu and 0.2-0.8. wt.% ratio of graphite. The 20 different PM compacts compositions were prepared with a 0.8. wt.% ratio of zinc striate as the lubricant. The dimension of compacts were 10. ×. 10. ×. 55. mm. All the compacts were pressed at 600. MPa and, sintered at 1120. °C for 30. min using a conventional sintering furnace and then boronizing, steaming and carbo-nitriding heat treatments were applied. The results of all compacts for the bending test, microstructure images and HV microhardness results were compared. As a result of the experiments, it was concluded that, the highest bending strength was obtained at carbo-nitrided samples, the highest surface hardness was measured at boronized samples and all these heat treatments increase the densities of iron based samples. © 2014 Elsevier Ltd.Item Comparative energy consumption analyses of an ultra high frequency induction heating system for material processing applications(Centro Nacional de Investigaciones Metalurgicas, 2015) Taštan M.; Gökozan H.; Taškin S.; Çavdar U.This study compares an energy consumption results of the TI-6Al-4V based material processing under the 900 kHz induction heating for different cases. By this means, total power consumption and energy consumptions per sample and amount have been analyzed. Experiments have been conducted with 900 kHz, 2.8 kW ultra-high frequency induction system. Two cases are considered in the study. In the first case, TI-6Al-4V samples have been heated up to 900 °C with classical heating method, which is used in industrial applications, and then they have been cooled down by water. Afterwards, the samples have been heated up to 600 °C, 650 °C and 700 °C respectively and stress relieving process has been applied through natural cooling. During these processes, energy consumptions for each defined process have been measured. In the second case, unlike the first study, can be used five different samples have been heated up to the various temperatures between 600 °C and 1120 °C and energy consumptions have been measured for these processes. Thereby, the effect of temperature increase on each sample on energy cost has been analyzed. It has been seen that as a result of heating the titanium bulk materials, which have been used in the experiment, with ultra high frequency induction, temperature increase also increases the energy consumption. But it has been revealed that the increase rate in the energy consumption is more than the increase rate of the temperature. Copyright: © 2015 CSIC.Item Effect of Ekabor 2 powder on the mechanical properties of pure iron powder metal compacts(Centro Nacional de Investigaciones Metalurgicas, 2016) Altintaş A.; Sarigün Y.; Çavdar U.Ekabor 2 powder of different weights, used by V type powder mixture was mixed with pure iron powder. Specimens were created by dry pressing into die followed by cold isostatic press at a pressure of 100 bar for purpose of resizing. The conventional sintering process at 900 °C and 950 °C was carried out for 4 h using conventional furnaces. Specimens were gradually cooled by air. The sintered pellets were examined in terms of density, wear abrasion, surface roughness and hardness at 900 °C and 950 °C. Microstructure of pellets was observed with optic microscope. The results show that the hardness gradually increased with additions of 0 wt. % to 10 wt. % of Ekabor 2 however, after 10 wt. %, this hardness tended to decrease. Copyright: © 2016 CSIC.Item A study of soil tillage tools from boronized sintered iron(Springer New York LLC, 2017) Yazici A.; Çavdar U.Acomparative analysis of the properties of boronized sintered iron and quenched steels 30MnB5, 28MnCrB5 used for making soil tillage tools is performed. The microstructure, phase composition, hardness and strength characteristics of the materials are studied. The composition of the boride phase formed in the sintered iron after boronizing is determined by an x-ray method. The losses to abrasive wear are evaluated with the help of a device containing a special bin with a sample of abrasive soil. © 2017 Springer Science + Business Media New York.Item In-situ compaction and sintering of Al2O3-B4C composites by using a High-Frequency Induction System(Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, 2018) Çavdar U.; Altintaş A.; Karaca B.Alumina powders containing varying ratios of B4C were mixed in a V-type mixer for 30 min with 35 cycle/min to obtain a homogeneous mixture. Six different chemical compositions were prepared and sintered at 1600°C for 20 min using an Ultra-High-Frequency Induction Heated System. The samples were cooled by air. The density, surface roughness, hardness and microstructure of samples were investigated. The results showed that when the amount of B4C increased, the values of hardness increased and the values of surface roughness decreased. © 2018 Institute of Materials and Machine Mechanics, Slovak Academy of Sciences. All rights reserved.Item The mechanical and tribological characteristic of Aluminium-Titanium dioxide composites(CSIC Consejo Superior de Investigaciones Cientificas, 2018) Gezici L.U.; Gül B.; Çavdar U.The purpose of this work was to investigate the mechanical and tribological effects of Titanium dioxide (TiO2) reinforcement in Aluminium (Al). Aluminium composites consist of 99.8% pure aluminium reinforced with five different partions of TiO2. Aluminium powders were mixed with TiO2 by ball milling for 30 minutes in a planetary mixer. The powder mixture was compacted by the cold pressing technique at 250 MPa. Two different methods used for sintering. The green compact was sintered at 600 °C for 300 seconds in open atmosphere with an Ulta-High Frequency Induction System (UHFIS) and with furnace at 600 °C for 1800 seconds. The mechanical and microstructural properties of examples were compared for different amount of reinforcement. We have observed a maximum hardness for 5 wt.% TiO2 reinforced composites. © 2018 CSIC.Item The Effect of Sintering on the Microstructure, Hardness, and Tribological Behavior of Aluminum–Graphene Nanoplatelet Powder Composites(Springer New York LLC, 2018) Çavdar U.; Akkurt O.In this study, aluminum and graphene nanoplatelet (GNP) powders were mixed in different ratios and sintered by the conventional method. The powder mixtures were stirred for 2 h at a speed of 35 rpm in a V-type mixer to obtain a homogeneous dispersion. The nanocomposite powder mixtures were pressed by the CIP (Cold Isostatic Pressing) method at a pressure of 400 MPa. Sintering was carried out at 620°C for 1 h under argon gas. The density, surface roughness, weight loss, and Vickers hardness of the nanocomposites were evaluated. SEM, EDX, and XRD analyses were performed and the obtained results were examined. The effect of the graphene addition to aluminum was evaluated, and the optimum contribution of 0.8 wt.% GNP has been determined. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Item In-situ compaction and sintering of Al2O3-B4C composites by using a High-Frequency Induction System(Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, 2018) Çavdar U.; Altintaş A.; Karaca B.Alumina powders containing varying ratios of B4C were mixed in a V-type mixer for 30 min with 35 cycle/min to obtain a homogeneous mixture. Six different chemical compositions were prepared and sintered at 1600◦C for 20 min using an Ultra-High-Frequency Induction Heated System. The samples were cooled by air. The density, surface roughness, hardness and microstructure of samples were investigated. The results showed that when the amount of B4C increased, the values of hardness increased and the values of surface roughness decreased. © 2018 Institute of Materials and Machine Mechanics, Slovak Academy of Sciences. All rights reserved.Item Analysis of artificial aging with induction and energy costs of 6082 Al and 7075 Al materials(CSIC Consejo Superior de Investigaciones Cientificas, 2019) Taştan M.; Gökozan H.; Çavdar P.S.; Soy G.; Çavdar U.In the study, 6082 Al and 7075 Al samples were subjected to a solution taking place at 580 °C for 1 min using ultrahigh frequency induction heating system (UHFIHS) and water was supplied at the end of the process. Artificially aging was then carried out at 190 °C for 2, 4, 6 and 8 min. In both applications, heating was carried out using an induction system with a frequency of 900 kHz and a power of 2.8 kW. For these aluminum series and shapes, induction heating and heat treatment costs in different shapes are calculated. In addition, the hardness values obtained from artificially aged 6082 Al and 7075 Al samples at 190 °C for 10 h were compared with conventional methods after 5 h at 540 °C for 5 h. As a result, the hardness values of 6082 Al samples, which were obtained in 10 h by conventional methods, were obtained by artificial aging for only 8 min using induction system. © 2019 CSIC.Item The Effect of Graphene Nanoplatelets on the Wear Properties of High-Frequency Induction Sintered Alumina Nanocomposites(Springer New York LLC, 2019) Altintaş A.; Çavdar U.; Kuşoğlu I.M.Alumina nanoparticles mixed with up to 1wt% graphene nanoplatelets (GNPs) were mixed by high-speed ball milling for 2 h at 350 rpm and sintered in a graphite die at 1650 °C for 20 min in an ultra-high-frequency induction heated system (UHFIHS) under uniaxial load in a vacuum chamber. The effect of different GNPs ratios on the microstructure, hardness and wear rate of alumina nanocomposites was examined. The results showed that the mechanical properties of Al 2 O 3 –GNPs nanocomposites gradually improved with GNP additions of 0.1 wt% to 0.6 wt%. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.