Browsing by Author "Atik E."

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    Experimental microhardness for AA 1030, Cu, CuSn7, CuZn30 and 6114 alloys and a correlation with the Hall-Petch relation
    (Elsevier Science Ltd, 1999) Meriç C.; Atik E.; Engez T.
    In this experimental study, the strip-formed specimens made from aluminum alloy 1030, pure Cu, CuSn7, CuZn30, and low-carbon steel 6114 were cold worked to different ratios. To determine the microhardness values of the materials, microhardness tests were applied. The grain sizes of the materials were determined by the Heyn method, using a metal microscope. The hardness of materials, H, is dependent on the grain diameter, d, in a way similar to the yield stress in the Hall-Petch relation H = HO + KHd- 1/2 , where HO and KH are constants. The microhardness of the materials was found, with reasonable accuracy, to vary with grain size according to the Hall-Petch equation.
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    Boronizing of iron based P/M materials; [Demir esasli T/M malzemelerin borlanmasi]
    (2002) Atik E.; Meriç C.; Yavuz N.
    Iron based machine parts produced by powder metallurgy become widespread in industry. Since these parts are produced from low carbon iron powders, they are used generally in sintered form without a heat treatment. The boronizing method which is already used for hardening of metalsurfaces can be applied to sintered iron based machine parts subjected to friction. With boronizing, which produced hard, low friction coefficient, high wear resistant surfaces under appropriate tribological conditions, resistance to corrosive environment can also be achieved.
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    The effects of conventional heat treatment and boronizing on abrasive wear and corrosion of SAE 1010, SAE 1040, D2 and 304 steels
    (2003) Atik E.; Yunker U.; Meriç C.
    The effects of conventional heat treatment and boronizing on SAE 1010 and SAE 1040 structural steels, D2 tool steel, and 304 stainless steel were investigated. During this investigation, layer thicknesses, corrosion and wear strength were examined by applying carburisation, nitriding, transformation hardening and boronizing to the specimens. Abrasive wear tests were carried out in a wear cup model device. Sand of 1 mm diameter was used and the test duration was 40 hours with a velocity 0.157 m/s. Corrosion tests were undertaken in a 10% H2SO4 solution at a temperature of 56°C. Through metallographic analyses, hard layer thicknesses and Vickers hardness values were determined for each hardening treatment. © 2002 Published by Elsevier Science Ltd.
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    The effect of precipitation-hardening conditions on wear behaviours at 2024 aluminium wrought alloy
    (2003) Kaçar H.U.; Atik E.; Meriç C.
    In this study, wear behaviours of 2024 aluminium wrought alloy were investigated in different tribological conditions based on its ageing conditions. For this purpose, the alloy aged in five different temperatures and periods (at room temperature for 1 week, at 120°C for 24h, at 150°C for 18h, at 160°C for 16h, at 200°C for 2h) was worn in pin-on disc model wear test apparatus using different abrasive grit size (5, 11, 18 and 30μm SiC papers). Furthermore, the effects of different sliding speeds (0.078, 0.156, 0.208 and 0.338ms-1) and loads (6.45, 9, 9.3 and 11N) on wear resistance were also examined. It was measured amounts of mass loss and examined worn surfaces. The mass loss of the specimens increased with load and the abrasive grit size. © 2003 Published by Elsevier B.V.
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    Determination of friction coefficient at journal bearings by experimental and by means of artificial neural networks method
    (Association for Scientific Research, 2004) Ünlü B.S.; Durmuş H.; Meriç C.; Atik E.
    Knowing friction coefficient is important for determination of wear loss conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. In this study, friction coefficient at CuSn10 Bronze radial bearings has been determined by a new approach as experimental and artificial neural networks method. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities.
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    Effect of aging on abrasive wear of deformable aluminum alloy AA6351
    (2004) Meriç C.; Atik E.; Kaçar H.
    Special features of abrasive wear of deformable aluminum alloy AA6351 are studied as a function of aging conditions and modes of friction tests. After aging in different modes the specimens are tested for wear in a special installation by the method of "brad against disk" with the use of abrasives with different grain sizes. The effects of different speeds of sliding and loads on the wear resistance and surface roughness are studied. © 2004 Plenum Publishing Corporation.
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    Determination of hardness of AA 2004 aluminium alloy under ageing conditions by means of artificial neural networks method
    (2004) Atik E.; Meric C.; Karlik B.
    As known, 2XXX and 7XXX Aluminium wrought alloys can have high strength values by means of precipitation hardening heat treatment. Determination of the precipitation hardening conditions, which can give the most suitable strength values of an alloy, requires numerous tests. But the results of this process which require long time and high cost can be obtained in a shorter time and at a lower cost with less data by means of Artificial Neural Networks method. Since this method is used, less number of experiments and therefore less data are needed. Then other values are found by means of Artificial Neural Networks (ANN) method. This paper, presents the feed forward ANN to determine hardness of alloy for different temperatures. For this purpose, a classic Back-Propagation Algorithm was used that is structure as 1:2:4.
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    Determination of friction coefficient in journal bearings
    (Elsevier Ltd, 2007) Ünlü B.S.; Atik E.
    Knowing friction coefficient is important for the determination of wear loss conditions at journal bearings. Tribological events that influence wear and its variations effect experimental results. In this study, friction coefficient as example at bronze radial bearings has been determined by a new approach. In experiments, friction effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities. © 2005.
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    Effect of loading capacity (pressure-velocity) to tribological properties of CuSn10 bearings
    (Elsevier Ltd, 2007) Ünlü B.S.; Atik E.; Meriç C.
    Bronze is widely used as a journal bearing material for copper-based alloys. These alloys ensure that journal bearings possess the expected properties. These materials that possess tribological properties give good results at journal bearings. In this study, friction and wear properties of journal bearings manufactured by CuSn10 bronze and the effect of p.v. (pressure-velocity) parameter have been examined and compared. SAE 1050 steel shaft has been used as counter abrader. Experiments have been carried out for p.v. values of 0.0125, 0.025 and 0.05 (N/mm s) and for every half an hour totalling to 2.5 h by using radial journal bearing wear test rig. As a result, depending on p.v. values, high friction coefficient and weight loss have been obtained under dry condition more than those obtained under lubricated condition. © 2006 Elsevier Ltd. All rights reserved.
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    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.
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    Study on lubricant quality and its effect on engine component performance
    (2008) Beşergil B.; Sabih Özer M.; Eskici M.; Atik E.
    Purpose- This paper aims to determine the usage time of the test lubricant N0, prepared from base oils of Aliaga Plant, Izmir, in gasoline and diesel-engines, and the investigations of high-temperature oxidation, engine-protective properties, and property changes of the lubricant in performance time.Design/methodology/approach- Physical and chemical properties of the lubricating oil were initially established, and the oil was then subjected to Petter W-1 gasoline and Petter AV-1 diesel test engines. Dismantling of the engine parts was followed by the examination of pistons, piston rings and bearings, and analysis of the lubricant was also undertaken. The engine performance test results and the quality control of the lubricating oil assessments were evaluated according to the International Engine Lubricant Specifications.Findings- The lubricating oil, under sluggish experimental conditions, appears to meet a 40-hour test in gasoline engines and a 120-hour test in diesel engines with the specifications. This means that under usual working conditions the lubricants keep the engine protective properties in 7,000 km distance for gasoline run-vehicles, and in 5,000 km distance for diesel run-vehicles, after which change of the oil is required.Originality/value- The paper provides information of value to those involved with lubrication and engine performance. © 2008, Emerald Group Publishing Limited
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    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.
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    Tribological properties of journal bearings manufactured from particle reinforced Al composites
    (2009) Ünlü B.S.; Atik E.
    In this study, journal bearings were manufactured from composite structures by casting method reinforcing 3% (Al2O3 and SiC) and (3% Al2O3 + 3% SiC) into pure Al. Tribological properties of these bearings were investigated by wear experiments at lubricated conditions under 20 N load and 1500 rpm on the radial journal bearing wear test rig. Effects of these composites on wear properties were investigated. Consequently, tribological properties of these particle reinforced composite bearings have significantly improved. In addition, particle reinforced Al composites were used to produce journal bearing. © 2008 Elsevier Ltd. All rights reserved.
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    Tribological properties of polymer-based journal bearings
    (Elsevier Ltd, 2009) Ünlü B.S.; Atik E.; Köksal S.
    Polymer-based materials are widely used due to their good corrosion resistance, self lubrication, and wear resistance properties at low speeds and but are not suitable for lubrication in journal bearings. High performance engineering polymers ensure desired properties for journal bearings and give good tribological results. In this study, tribological behaviors of polymer-based PE, PA, POM, PTFE, and Bakelite bearings have been investigated and evaluated. As a result, the highest wear resistance has occurred in PA and POM bearings. © 2008.
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    Tribological behaviors of polymer based journal bearings manufactured from particle reinforced bakelite composites
    (2009) Ünlü B.S.; Atik E.; Yilmaz S.S.
    Polymer based materials are widely used do to their good corrosion resistance, self lubrication, and wear resistance properties at low speeds, but are not suitable for lubrication in journal bearings. High performance engineering polymers offer desired properties for journal bearings and give good tribological results. In this study, tribological behaviors of polymer based composite bearings manufactured from particle reinforced bakelite have been investigated and evaluated. Reinforcement significantly improved wear resistance of bronze-bakelite composite bearings. © 2009.
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    Investigation of tribological properties of boronised pure Cu journal bearings
    (2010) Ünlü B.S.; Atik E.
    Cu based materials are widely used as journal bearings. These materials have a good tribological performance in journal bearings. Pure copper is not generally used due to its low mechanical and wear properties. It is generally used as alloys. In this study, tribological properties of copper bearings manufactured from pure copper were investigated by boronising at 950°C. The SAE 1050 steel shaft was used as counter abrader. Experiments were carried out at 20 N load and 1500 rev min-1 speed every 30 min for 2•5 h using radial journal bearing wear test rig. As a result, boronising increased wear resistance. © 2010 Institute of Materials, Minerals and Mining.
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    Tribological behaviors of polymer-based particle-reinforced PTFE composite bearings
    (2010) Ünlü B.S.; Uzkut M.; Atik E.
    In this study, tribological behaviors of polymer-based particle-reinforced PTFE bearings have been investigated and evaluated. Tribological properties of these particle-reinforced PTFE composite bearings have improved two- or three-fold. © 2010 SAGE Publications.
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    Investigation of tribological properties of boronized Fe-based SAE 1020 and TS-DDK 40 journal bearings at high loads
    (2010) Ünlü B.S.; Atik E.
    In practice, ferrous based materials are not used because they show similar properties to shaft material and are known to cause adhesive wear in journal bearings. With boronizing process, adhesive wear can significantly be decreased. In this study, boronizing has been applied to some ferrous based (SAE 1020, TS-DDK 40) journal bearings. Wear experiments were done on SAE 1050 steel shaft as counter abrader with 100 N loads, and 1500 rpm for 5 h by using a radial journal bearing test rig. Boronizing treatment increased wear resistance of SAE 1020, TS-DDK 40 about 10-25, and 5-7 times respectively. © 2009 Elsevier Ltd. All rights reserved.
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    Evaluation of effect of alloy elements in copper based CuSn10 and CuZn30 bearings on tribological and mechanical properties
    (2010) Ünlü B.S.; Atik E.
    Brass and especially bronze in copper based alloys are widely used as journal bearing material. Pure copper materials are not used as journal bearing material due to their low mechanical and hardness properties. These materials having acceptable tribological and mechanical performance give satisfactory results in journal bearings. In this study, tribological and mechanical properties of journal bearings manufactured from copper based CuSn10 bronze and CuZn30 brass were investigated. Moreover, the effect of alloy elements of Cu, Sn and Zn on tribological and mechanical properties of journal bearings was evaluated. SAE 1050 steel shaft (journal) was used as counter abrader. Wear experiments were carried out at 20 N loads, 1500 rpm for 2.5 h by using radial journal bearing wear test rig. © 2009 Elsevier B.V. All rights reserved.