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Öğe The effect of Al2O3 on the friction performance of automotive brake friction materials(Elsevier Sci Ltd, 2007) Boz, Mustafa; Kurt, AdemThis study consists of two stages. In the first stage, bronze-based break linings were produced and friction-wear properties of them were investigated. In the second stage, 0.5%, 1%, 2% and 4% alumina (Al2O3) powders were added to the bronze-based powders and Al2O3 reinforced bronze-based break linings were produced. Friction-wear properties of the Al2O3 reinforced samples were asto investigated and compared to those of plain bronze-based ones. For this purpose, friction coefficient and wear behaviour of the samples were tested on the grey cast iron disc. The hardness and density of the samples were also determined. Microstructures of the samples before and after the sintering and the worn surfaces of the wear specimens were examined using a scanning electron microscope (SEM). The sample compacted at 350MPa and sintered at 820 degrees C exhibited the optimum friction-wear behaviour, With increase in friction surface temperature, a reduction in the friction coefficient of the samples was observed. The lowest reduction in the friction coefficient with increasing temperature was for the 2% and 4% Al2O3 reinforced samples. The SEM images of the sample indicated that increase in Al2O3 content resulted in adhesive wear. With increase in Al2O3 content, a reduction in mass loss of the samples was also observed. Overall, the samples reinforced with 2% and 4% Al2O3 exhibited the best results. (c) 2006 Elsevier Ltd. All rights reserved.Öğe The effect of process parameters on copper powder particle size and shape produced by electrolysis method(Techno-Press, 2013) Boz, Mustafa; Hasheminiasari, MasoodIn this study, an electrolyzing device for the production of metal powders was designed and fabricated. The production of copper powders was performed using a variety of current densities, anode-cathode distances and power removal times. The effect of these parameters on powder particle size and shape was determined. Particle size was measured using a laser diffraction unit while the powder shape was determined by SEM. Experimental results show that an increase in current density leads to a decrease in powder particle size. In addition particle shape changed from globular dendritic to acicular dendritic with increasing the current density. Distance between the cathode and anode also showed a similar influence on powder particle size and shape. An increase in time of powder removal led to an increase in powder particle size, as the shape changed from acicular dendritic to globular dendritic.Öğe The Effect of Time of Powder Removal on Powder Particle Size and Shape Copper Powder Produced by Electrolysis Method(Trans Tech Publications Ltd, 2011) Kurt, Adem; Boz, MustafaIn this study, electrolyze unit, which is used for the production of metal powders, was designed and produced. The production of powder was carried out by using different parameter times of powder removal (5, 10, 20, 30 and 40 min.). The effect of time of powder removal on powder particle size and shape was examined. Laser particle measurement machine and SEM were also used to measure particle size and particle shape respectively. Experimental results indicated that an increase in time of powder removal caused an increase in powder particle size and its shape changed from acicular dentritic to globular dentritic.Öğe Fracture surface investigations of api pipes welded with parameters determined by taguchi method(2018) Asıkuzun, Elif; Çetinkaya, Cemil; Boz, Mustafa; Ada, HakanIn this study, SEM images of the samples taken from welded nick break tests of API 5L X65 pipe joints,whose welding parameters were determined by Taguchi method, were examined. As a result of theinvestigations, the elongations and orientations exhibited by the grains showed that ductile and brittlefractures were observed in the welded joints. As it was observed from equiaxed, honeycomb like imagesthat the fractures exhibited a ductile behavior. Brittle fractures that occurred due to cleavage breaks in someregions were detected. An apparent effect of welding direction was observed in fracture behavior. It wasdetected from the SEM images that a ductile fracture structure had occurred in all joints that were performedfrom bottom to top, while it was observed in the joints performed from top to bottom that generally cleavageplanes had developed along with fibrous structures in places, therefore brittle fractures had occurred.Öğe Gaz atomizasyon yöntemi ile az31 mg tozu üretiminde gaz basıncının etkisinin araştırılması(2019) Akkas, Mehmet; Akra, Kamal Mohamed Em; Çetin, Tayfun; Boz, MustafaBu çalışmada, gaz atomizasyonu yöntemi ile üretilen AZ31 Mg alaşımı tozunun şekli ve boyutu üzerine gaz basıncınınetkisi deneysel olarak araştırılmıştır. Deneyler 790 °C sabit sıcaklıkta, 2 mm nozul çapında ve 4 farklı gaz basıncı (5, 15,25 ve 35 bar) uygulanarak yapılmıştır. Ergiyiğin atomize işlemi argon gazı ile yapılmıştır. Üretilen AZ31 Mg tozununşeklini belirleyebilmek için taramalı elektron mikroskobu (SEM), üretilen tozların iç-yapılarında oluşan fazları ve bufazların % oranlarını belirleyebilmek için XRD ve XRF analizi, toz boyut analizi için ise lazer ölçüm cihazıkullanılmıştır. Üretilen AZ31 Mg alaşım tozlarının genel görünümlerinin ligament, çubuksu, damlamsı, flake (pul) veküresel şeklinde olduğu, gaz basıncının artmasına bağlı olarak tozların şeklinin çoğunlukla flake ve küresel’e doğrudeğiştiği görülmüştür. Elde edilen en ince tozun 790 °C sıcaklıkta, 2 mm nozul çapında 35 bar gaz basıncında oluştuğuve tozların genelinin damlamsı ve küresel şekilli olduğu tespit edilmiştir.Öğe Gaz atomizasyonu yöntemi ile al 12 si tozu üretimi ve karakterizasyonu(2018) Çetin, Tayfun; Boz, MustafaBu çalışmada, gaz atomizasyonu yöntemi ile üretilen Al 12 Si alaşım tozunun şekli ve boyutu üzerine sabitsıcaklıkta, farklı nozul çaplarında ve farklı gaz basınçlarında deneysel çalışmalar yapılmıştır. DeneylerKarabük Üniversitesi Teknoloji Fakültesi İmalat Mühendisliği Laboratuvarında bulunan Gaz AtomizasyonÜnitesi’nde yapılmıştır. Deneyler 770 °C sabit sıcaklık, 2 ve 4 mm nozul çaplarında ve 6 farklı gaz basıncı (5-10-15-20-30-35 bar) uygulanarak yapılmıştır. Ergiyiği atomize etmek için argon gazı kullanılmıştır. ÜretilenAl 12 Si tozlarının boyut ve şeklini belirleyebilmek için taramalı elektron mikroskobu (SEM) görüntüleri ve Elekanalizi yöntemiyle toz boyut analizleri yapılmıştır. Yapılan analizler sonucunda, nozul çapının küçülmesi vegaz basıncının artmasıyla toz boyutunun küçüldüğü ve toz şeklinde genelinde ligament, damlamsı, çubuksu vekarmaşık şekilli olduğu tespit edilmiştir. Elde edilen en ince tozların 2 mm nozul çapında 35 bar gaz basıncıile olduğu gözlemlenmiştir.Öğe INVESTIGATION OF GAS PRESSURE EFFECT ON POWDER CHARACTERIZATION OF AZ31 ALLOY PRODUCED BY GAS ATOMIZATION METHOD(Yildiz Technical Univ, 2019) Akkas, Mehmet; Em Kara, Kamal Mohamed; Cetin, Tayfun; Boz, MustafaIn this study, the effect of gas pressure on the shape and size of the AZ31 alloy powder produced by using the gas atomization method was investigated experimentally. Experiments were carried out at 840 degrees C constant temperature, in 2 mm constant nozzle diameter and by applying 4 different gas pressures (5, 15, 25 and 35 bar). Argon gas was used to atomize the melt. Scanning electron microscope (SEM) to determine the shape of produced AZ31 powders, XRD and XRF analysis to determine the phases forming in the internal structures of the produced powders and the percentages of these phases and a laser measuring device for powder size analysis were used. The general appearances of AZ31 alloy powders produced had general appearances of complex, ligament, acicular, droplet, flake and spherical shape, but depending on the increase in gas pressure, the shape of the powders is seen to change mostly towards droplet and spherical.Öğe Investigation of hardness and microstructure properties of non alloyed and hardox steel combined with submerged arc welding method(Gazi Univ, Fac Engineering Architecture, 2018) Erden, Mehmet Akif; Gunduz, Suleyman; Caligulu, Ugur; Boz, MustafaIn this work, low carbon steel and hardox steel joined by using submerged arc welding under three different conditions. Same welding parameters (325 A, 30-32 V) were used during welding. Welded joints were characterised in terms of hardness test, macro and microstructures. The results indicated that hardox welded joints showed the highest hardness. In addition, as a result of macro and microstructure study, heat affected zone (HAZ) of structural steels were observed much larger.Öğe Investigation of the compressibility and sinterabilty of AZ91 powder production and particle production by gas atomisation method(Keai Publishing Ltd, 2019) Akkas, Mehmet; Boz, MustafaThis study intends to determine the pressability and sinterability of AZ91 powder production by gas atomisation method and that of the produced powder for partial production. Therefore, first, a gas atomisation unit has been designed and manufactured in the laboratories of the Karabuk University, Department of Manufacturing Engineering. Atomised powder production has been achieved at a temperature of 795 degrees C, with nozzle diameters of 2 and 4 mm and four different gas pressures (5, 15, 25, 35 bars). Argon gas has been used for atomisation and as a protective gas atmosphere. Scanning electron microscope (SEM) is used to determine the shape of the produced AZ91 powder, and a laser particle size analyzer is used to analyze the powder size. Additionally, a microhardness (HV0.025) measurement has been conducted to determine the hardness of the produced powders. To achieve a homogeneous distribution, the produced powders are mixed in a three-dimensional moving turbulator for 30 min. Mixed powders have been pressed at 300, 400, 500 and 600MPa and have been sintered at 500 degrees C, 550 degrees C and 600 degrees C. Additionally, the density values have been determined before and after sintering of the materials. SEM images have been obtained from the fractured surfaces of the samples before and after sintering. XRD and EDX analyses have been performed to determine the chemical composition. Further, microhardness (HV0.5) is obtained from the pressure surfaces of the samples to determine the effects of the pressing pressure and the sintering temperature on the hardness. As a result of the experimental studies, it has been observed that the powder size decreases with the increase in gas pressure and that the powder shape generally changes from ligament and complex shape to droplet and spherical shape. From the XRD, XRF and EDX results, it has been determined that the structure comprises an alpha phase (Mg main matrix) and Mg17Al12 interphase, which is beta phase, and very small amounts of MgO have been observed. The hardness of the produced powders increased based on the increase in gas pressure. The densities of the samples increased with both increasing pressing pressure and sintering temperature. It has been observed from the fractured surface SEM images that the number of pores formed in the samples decrease with an increase in the pressing pressure. It has been determined that the post-sintering structure exhibits a typical dendritic structure. In addition to the alpha-Mg matrix phase, beta (Mg17Al12) intermetallic and alpha + beta eutectic were formed in the structure. The microhardness values of the samples decreased depending on the sintering temperature; the highest hardness value was measured as 64,02 HV0.5 at a pressing pressure of 300 MPa and a sintering temperature of 500 degrees C, whereas the lowest hardness value was measured as 54,86 HV0.5 at a pressing pressure of 600 MPa and a sintering temperature of 600 degrees C. (C) 2019 Published by Elsevier B.V. on behalf of Chongqing University.Öğe 'Investigation of the effect of gas pressure on powder characterization of AM60 magnesium alloy powder produced by gas atomization method(Gazi Univ, Fac Engineering Architecture, 2020) Cetin, Tayfun; Akkas, Mehmet; Boz, MustafaIn this study, the effect of gas pressure on the shape and size of AM60 magnesium alloy powder produced by the gas atomization method has been experimentally investigated. The experiments were carried out at a constant temperature of 820 degrees C with a 2 mm nozzle diameter and 4 different gas pressures (5, 15, 25, 35 bar). Argon gas was used to atomize the melt. In order to determine the shape of the AM60 powder produced, scanning electron microscope (SEM), XRD, XRF and SEM-EDX analysis were used to determine the phases formed in the internal structures of the powders and the% ratios of these phases, and laser measuring device was used for the powder size analysis. Hardness tests were performed to determine the mechanical properties of the powders produced. The general appearance of the AM60 alloy powders produced was ligament, acicular, droplet, flake and spherical in shape, but due to the increase of gas pressure, the shape of the powders changed mostly towards flake and spherical. It was determined that the finest powder was formed at 820 degrees C, 35 bar gas pressure at 2 mm nozzle diameter and the powder was generally complex.Öğe Soğuk deforme edilmiş aisi-304 paslanmaz çeliğin direnç kaynak kabiliyeti(2008) Kaçar, Ramazan; Gündüz, Süleyman; Kahraman, Nizamettin; Boz, Mustafa; Demir, Bilge-Öğe Tozaltı kaynak yöntemi ile birleştirilen alaşımsız ve hardoks çeliklerin mikroyapı ve sertlik özelliklerinin araştırılması(2018) Erden, Mehmet Akif; Gündüz, Süleyman; Çalıgülü, Ugur; Boz, MustafaBu çalışmada, tozaltı kaynak yöntemi ile birleştirilen genel amaçlı yapı çeliği ve hardoks hituf çelikmalzemeler kullanılarak üç farklı kaynaklı bağlantı yapılmıştır. Bütün kaynaklı bağlantılarda aynı kaynakparametreleri (325 A, 30-32 V) kullanılmıştır. Birleştirilen parçalara sertlik testi uygulanmıştır. Birleştirme bölgesinde meydana gelen makro ve mikroyapı değişimi tespit edilmiştir. Sonuçlarda hardoks hituf çelikmalzeme kullanılarak yapılan kaynaklı bağlantıların daha yüksek sertlik gösterdiği tespit edilmiştir. Ayrıcayapılan makro ve mikroyapı çalışmaları sonucunda ITAB bölgesinin genel amaçlı yapı çeliğinde daha genişolduğu görülmüştür
