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Öğe Effect of plasma nitration process at various temperatures on wear behavior of aisi 4340 steel(Gazi Univ, 2018) Basak, Hudayim; Duzcukoglu, Hayrettin; Senyurt, Muhammet AliIn this study, AISI 4340 (34CrNiMo6) tempered steel was applied to the plasma nitration process at different temperatures and at different periods in order to increase the wear resistance of the outer surface without decreasing the hardness of the core under 40-44 HRC, and to prevent the component from distortion during heat treatment. The sufficient core strength and tensile stress of some mechanical elements such as mold, drill, U-Drill are required not to fall below a certain value. There were five different temperatures (450, 475, 500, 530 and 550 degrees C) and two different time values (18 and 32 hours) used with these temperatures utilized in the study. The study tried to identify the optimum nitriding temperature and time for the limit values determined by considering the wear value after nitriding. The wear characteristics of the samples in dry conditions were also investigated. It was observed that the ideal target values (core 40-44 HRC) in the nitrided components were reached at 450 degrees C in 32 hours.Öğe Enhancement of Wear and Friction Characteristics of Epoxy Resin by Multiwalled Carbon Nanotube and Boron Nitride Nanoparticles(TAYLOR & FRANCIS INC, 2015) Duzcukoglu, Hayrettin; Ekinci, Serafettin; Sahin, Omer Sinan; Avci, Ahmet; Ekrem, Mursel; Unaldi, MahmutEpoxy resins are widely used in engineering applications. However, their low thermal stability limits their usage at high sliding velocities and loads. The mechanical properties and thermal stability of a machine element subjected to friction and wear are very important. In this study, friction and tribology behaviors of multiwalled carbon nanotubes (MWCNTs) and boron nitride (BN)-modified epoxy resin have been investigated. Epoxy resin modified by three different nanoparticle configurations, 0.3% MWCNT, 0.5% BN, and 0.5% MWCNT/0.3% BN, was investigated. The tribological characteristics of nanoparticle-modified epoxy resin were compared with properties of neat resin. The friction and tribological behavior of modified epoxy resin were tested using a ball-on-disc test stand at 1.2 and 1.5 ms(-1) sliding velocities under 10 N applied load. The tests were done under dry condition and 1,800 m distance. The friction coefficient, wear loss, and temperature increase during testing were recorded and compared with that obtained for neat epoxy. It is observed that nanoparticle modification resulted in enhanced wear resistance and a reduction in friction coefficient and working temperatures.Öğe Examining the Abrasion Behaviour of PA 66 Gears in Different Cycles(HINDAWI PUBLISHING CORPORATION, 2014) Yakut, Rifat; Duzcukoglu, HayrettinGears made of plastic-based materials are anticorrosive, resistant to magnetic environments, and light and have pulse decay, low noise, and self-lubrication properties, and therefore their usage areas are widening every single day. In this experiment, the working conditions of 30% fibreglass PA 66 (PA 66 GFR 30) plastic material with PA 66 (PA 66 GFR 30) plastic material and AISI 8620 couple gear are observed. Usage of PA 66 GFR 30 material as gear material at 56.75 Nm constant load and 750 rpm, 1000 rpm, and 1500 rpm was analysed. The load capacity damage formation of the material was also analysed. The tooth surface temperature, corrosion depth of the tooth profile, tooth damage, and the tooth surface were examined with an scanning electron microscopy (SEM) and the corrosive behaviour of gears was analysed.Öğe Friction and Wear Performance of Epoxy Resin Reinforced With Boron Nitride Nanoplatelets(ASME, 2018) Ekrem, Mursel; Duzcukoglu, Hayrettin; Senyurt, Muhammet Ali; Sahin, Omer Sinan; Avci, AhmetIn this study, the effects of addition of boron nitride nanoplatelets (BNNPs) upon friction and wear behavior of epoxy resin have been investigated by using pin-on-disk test. It has been reported in the literature that certain amounts of BNNP addition can be useful for enhancement of mechanical properties. Therefore, it is very important to obtain the effect of such addition upon friction and wear performance of epoxy resin. BNNPs have been incorporated at 0.3-0.5-0.7-1 wt %. It is shown that BNNP addition results in decrease in friction coefficient and wear. It is also shown that the best results are obtained with 0.5% nanoplatelet addition. It is also observed that heat conduction of epoxy resin is enhanced by the nanoplatelet addition.Öğe Investigation of Wear Performance of Canola Oil Containing Boric Acid under Boundary Friction Condition(TAYLOR & FRANCIS INC, 2011) Duzcukoglu, Hayrettin; Sahin, Omer SinanThe aim of this study is to investigate the tribological behaviors of pure canola oil and 5% boric acid-added canola oil after unexpected oil drainage. Tests were performed under 0.6 m/s sliding velocity and 80 N contact force using a pin-on-disc test stand. Tests were started with full lubrication and continued for 800 m. After that the oil was drained from the oil tank and the system was run for 10,000 m without lubrication. The variation of friction coefficient, contact temperature, and wear was compared for pure and boric acid-added oil. It was observed that boric acid-added oil can continue lubricating even after oil was drained from the tank.Öğe PA 66 spur gear durability improvement with tooth width modification(ELSEVIER SCI LTD, 2009) Duzcukoglu, HayrettinUnder heavy loading and large numbers of revolutions, the most commonly encountered gear damage is the thermal damage that is caused by an accumulation of heat on the surface of the tooth. The maximum Hertzian surface stress occurs at the single tooth pair contact region. The aim of this study was to delay the formation of thermal damage in the region of single tooth meshing by decreasing the Hertzian surface pressure by increasing the tooth width. The F/b (N/mm) tooth load was decreased in the single tooth pair contact region. Experiments show that the appearance of thermal damage is delayed for the width-modified gear teeth in comparison with unmodified gear teeth. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Pitting Formation in Concave-Convex Gears Manufactured from AISI 8620 Steel(AMER SOC TESTING MATERIALS, 2018) Uzun, Mahir; Munis, Mehmet Mehdi; Duzcukoglu, HayrettinIn this study, the pitting formation of the tooth flank of concave-convex involute gears was investigated. The gears were manufactured from AISI 8620 steel with computer numerical control (CNC) machining and subjected to a cementation hardening process because they could not be produced using traditional methods. The results of the experimental studies with these gears were compared to those obtained with spur gears. As a result of this comparison, and because the pitch line of spur gears is less than the pitch line of concave-convex gears with exactly the same dimensions, the maximum Hertz stress formed in the pitch point of concave-convex gears is found to be less than that formed in the pitch point of spur gears. Therefore, the formation of pitting in concave-convex gears is quite delayed.Öğe Relation between wear and tooth width modification in spur gears(ELSEVIER SCIENCE SA, 2007) Imrek, Huseyin; Duzcukoglu, HayrettinIn this experimental study, width modification of a spur gear was investigated to fix instantaneous pressure changes along single meshing area on the gear profile. In this gear, variable pressure distribution caused by the single and double teeth meshing and the radius of curvature along the active gear profile was approximately kept constant by maintaining a constant ratio of applied load to the tooth width (F/b) on every point. Hence, Hertz pressure distribution along the gear profile was approximately equally achieved. Other factors affecting wear were kept constant during the experiment. The specimen used was made from AISI 4140 steel. Finally, the amount of wear in the teeth profiles between the modified and unmodified gears was compared. And wear depth of modified gear along the meshing area was almost uniform. (c) 2006 Elsevier B.V. All rights reserved.Öğe Study on development of polyamide gears for improvement of load-carrying capacity(ELSEVIER SCI LTD, 2009) Duzcukoglu, HayrettinIn polyamide based gears, thermal damage of the gear tooth surfaces occurs during gear meshing due to accumulated heat in the tooth body. In the experimental study reported in this paper, polyamide gear teeth have been modified in order to distribute the generated heat on the tooth surface by means of drilled cooling holes at different locations on the gear tooth body. The main aims of this paper were to study the effect of cooling holes on the accumulated heat on the tooth surface and on the measured wear. It was shown that the drilled cooling holes on the tooth body decreased the tooth surface temperature and led to an increase in the load carry capacity and improved wear resistance. Geometrically modified gears have showed an improved service life and a decreased surface temperature. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Wear behaviors of Polytetrafluoroethylene and glass fiber reinforced Polyamide 66 journal bearings(ELSEVIER SCI LTD, 2014) Demirci, Mehmet Turan; Duzcukoglu, HayrettinIn this study, the effect of sliding velocity, bearing pressure and temperature on friction and wear of PA66 (Polyamide 66), PA66 + 18% PTFE (Polyamide 66 + 18% Polytetrafluoroethylene) and PA66 + 20% GFR + 25% PTFE (Polyamide 66 + 20% glass fiber + 25% Polytetrafluoroethylene) journal bearings were examined at ambient conditions. The results of experiments are presented in graphics which proves that friction coefficients, contact temperatures and wear rates are affected by forming film, increasing temperature, pressure and velocities depending on GFR and PTFE mechanical properties. There are many factors and their widely fluctuation characters on the polymer friction and wear behaviors. The best wear behavior was seen at the PA66 + 20% GFR + 25% PTFE journal bearing. (C) 2014 Elsevier Ltd. All rights reserved.
