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Öğe A Comparative Study on the Effect of CNT or Alumina Nanoparticles on the Tensile Properties of Epoxy Nanocomposites(SPRINGER HEIDELBERG, 2019) Yazman, Sakir; Samanci, AhmetIn this paper, the mechanical properties of the carbon nanotube (CNT) or alumina (Al2O3) nanoparticles (NPs)-modified epoxy composites were investigated experimentally. Composite dog-bone tensile specimens were prepared and tested according to ASTM D638-14 standards with CNT or Al2O3 nanoparticle contents of neat, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2.0% of the total resin weight. In order to compare the effect of nanoparticle type and content on the mechanical properties, tensile stress-strain curves were drawn for each parameter. Also, the ultimate tensile strength (UTS), Young's modulus and toughness values were obtained and compared. Considerable improvements of the mechanical properties were observed by adding NPs. The results indicated that the UTS, Young's modulus, and toughness values reached a maximum with an increment of 27.6, 18.7 and 187.9%, respectively, at Al2O3 nanoparticle content of 1.0wt%, according to neat epoxy. Due to lower cost and good mechanical properties of the Al2O3 nanoparticle-modified composites, the Al2O3 nanoparticle can be used as a reinforced particle for epoxy composites. On the other hand, it was observed that the CNTs were not as effective as Al2O3 nanoparticles.Öğe THE EFFECT OF BUILD UP EDGE FORMATION ON THE MACHINING CHARACTERISTICS IN AUSTEMPERED FERRITIC DUCTILE IRON(AMER SOC MECHANICAL ENGINEERS, 2013) Yazman, Sakir; Akdemir, Ahmet; Uyaner, Mesut; Bakircioglu, BariIn this study, chip formation mechanism during the machining of austempered ferritic DI and the effect of the emerging chip morphology on such machining properties as surface roughness and cutting forces has been scrutinized. After austenitizing at 900 degrees C for 90 min, DI specimens were austempered in a salt bath at 380 degrees C for 90 min. Chip roots were produced by using a quick stop device during the machining of austempered specimens in different cutting speeds. The metallographies of these specimens were performed and chip morphologies were examined. The fact that the cutting speed increased led to a decrease in built-up edge formation. Depending on this fact, it was detected that the change in built-up edge thickness substantially affected the surface roughness and cutting forces. It was also detected that during the machining, with the effect of cutting forces and stress, spheroidal graphites were broken off in the chip and lost their sphericity and so that the chip became fragile and unstable and grafites here displayed a lubricant feature.Öğe THE EFFECT OF Si MORPHOLOGY ON MACHINABILITY OF AL-Si ALLOYS(PAMUKKALE UNIV, 2015) Uludag, Muhammet; Yazman, Sakir; Bakircioglu, Baris; Dispinar, DeryaMany of the cast parts require some sort of machining like milling, drilling to be used as a finished product. In order to improve the wear properties of Al alloys, Si is added. The solubility of Si in Al is quite low and it has a crystallite type structure. It behaves as particulate metal matrix composite which makes it an attractive element. Thus, the wear and machinability properties of these type of alloys depend on the morphology of Si in the matrix. In this work, Sr was added to alter the morphology of Si in Al-7Si and Al-12Si. Cylindrical shaped samples were cast and machinability characteristics of Sr addition was studied. The relationship between microstructure and machinability was evaluated.Öğe The Effects of Cutting Speed and Depth of Cut on Machinability Characteristics of Austempered Ductile Iron(ASME-AMER SOC MECHANICAL ENG, 2012) Akdemir, Ahmet; Yazman, Sakir; Saglam, Haci; Uyaner, MesutDuctile iron can acquire enhanced thermal and mechanical properties from austempering heat treatment. The present study aims to identify the function of different cutting parameters affecting machinability and to quantify its effects. Turning was performed to test machinability according to the ISO3685-1993 (E) standard. After austenitizing at 900 degrees C for 90 min, austempered ductile iron (ADI) specimens were quenched in a salt bath at 380 degrees C for 90 min. The cutting force signals along three directions were measured in real time, whereas flank wear and surface roughness were measured offline. For the cutting parameters, the cutting speed and depth of cut were varied, but the feed rate was kept constant. In the flank wear tests, machining length was corresponded to tool life. In addition, in order to find out the effect of cutting parameters on surface roughness (R-a), tangential force (F-t), and flank wear (VB) during turning, response surface methodology (RSM) was utilized by using experimental data. The effect of the depth of cut on the surface roughness was negligible but considerable in the cutting forces. The increased cutting speed produced a positive effect on surface roughness. It is found that the cutting speed was the dominant factor on the surface roughness, tangential force, and flank wear. [DOI:10.1115/1.4005805]