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    Effect of matrix temperature and powder size on the infiltration height of SiO2 -reinforced Al 7075 matrix composites produced by vacuum infiltration
    (Adcotec Ltd, 2011) Calin, Recep; Pul, Muharrem; Citak, Ramazan; Seker, Ulvi
    In this study, Al-MgO metal matrix composites (MMC) were produced with 5 %, 10 % and 15 % reinforcement-volume (R-V) ratios by the melt stirring method. In the production of composites 99.5 % pure Al was used as the matrix and MgO powders with the particle size of -105 mu m were used as the reinforcement. For every R-V ratio; stirring was made at 500 rev/min at 750 degrees C liquid matrix temperature for 4 minutes and the samples were cooled under norrnal atmosphere. Then hardness and fracture strengths of the samples were determined and their microstructures were evaluated by using Scanning Electron Microscope (SEM). In general, it was observed that the reinforcement exhibited a homogeneous distribution in horizontal direction. But there is a slight inhomogeneity in vertical direction. It was determined that the increase in the R-V ratio increased the porosity and also the hardness. As for the fracture strength, the highest strength was obtained with the 5 % MgO reinforced sample.
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    Öğe
    Effect of Reinforcement Ratio on Infiltration Behavior in Vacuum Infiltration of MgO-Al Composites With Lower Reinforcement
    (Gazi Univ, 2009) Pul, Muharrem; Calin, Recep; Citak, Ramazan; Seker, Ulvi
    In this study, MgO powders, with particle size 149 mu m were filled in steel tubes with 5 %, 10 %, 15 % volume fraction of reinforcement and liquid matrix alloy was vacuum infiltrated into MgO compact under same vacuum condition 550 mmHg, same time 5 min and at different temperatures and volume fraction of reinforcement. Infiltration distance was measured and microstructure and fracture behavior of composite was investigated. It has been found that infiltration distance and fracture strength were decreased with increasing volume fraction of reinforcement. Increasing matrix temperature also facilitates infiltration.
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    Investigation of machinability in Al-MgO composites produced by melt-stirring
    (Walter De Gruyter Gmbh, 2013) Pul, Muharrem; Uzun, Gultekin; Çalın, Recep; Seker, Ulvi
    In this study, Al-MgO reinforced metal matrix composites of 5%, 10% and 15% reinforcement-volume ratios were produced by melt-stirring and subjected to machining tests by carbide and coated carbide cutting tools. Machining tests were conducted with 150, 200, 250 and 300 m/min cutting speeds, 0.075, 0.15 and 0.225 mm/rpm feed rates and 1 mm depth of cut. Piezoelectric quartz crystal type dynamometer was used to measure cutting forces. As a result of the tests, it was observed that the increase in cutting speed first led to an increase and then a decrease in main cutting force values (Fc), and the increase in feed rate was accompanied with increased main cutting forces. The most consistent results in terms of Fc values were displayed by 10% MgO reinforced composites. While no abrasion occurred on the surfaces of cutting tools, build up edge formation was observed in the machining tests.
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    An investigation of surface quality of turning in al matrix mgo reinforced composite material
    (Gazi Univ, Fac Engineering Architecture, 2011) Pul, Muharrem; Çalın, Recep; Citak, Ramazan; Seker, Ulvi
    In this study; Al/MgO composites having 5 %, 10 %, 15 % volume fraction of reinforcement are produced by vacuum infiltration method and microstructure of composites are determined. Produced materials of metal matrix composite (MMC) machined with uncoated cemented carbide (WC), cubic boron nitrite (CBN) and coated cubic boron nitrite (CBN-C) cutting tools. The average surface roughness values (Ra) are determined by measuring surface roughnesses of composite samples. Ra values showed tendency to decrease by increasing cutting rate but it has proportionality with raising feed rates. The maximum roughness value is obtained at the cutting speed of 150 rev/min. It was observed that the most raugh sample is 15 % MgO reinforced sample. In terms of surface roughness 15 % MgO reinforced material is determined as the worst machinable sample. The best surface quality is obtained with WC cutting tool while machining 5 % and 10 % MgO reinforced samples and the best results are obtained 15 % MgO reinforced samples with CBN-C tools at high feed rates.
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    The Effect of Cutting Tool Wear Behaviors on Feed Rates in Turning of Metal Matrix Composites
    (Gazi Univ, 2014) Pul, Muharrem; Seker, Ulvi
    Composite materials, one of them is metal matrix composites (MMCs), is a group of engineering materials who seapplication fields expandrapidly. In this study, to make an interpretation on machinability of MMCs materials, MMC smaterials reinforced Al matrix and MgO which were produced in 5%, 10% and 15% reinforcement-volumeratios (R-V) were subjected to machining tests by carbide (C) and coated carbide (CC) cutting tools. Machining tests were conducted with 300 m/dak cutting speed, at three different feed rates (0.075, 0.15 and 0.225 mm/dev) and fixed depth of cut (1 mm). After the machining tests, wear characteristics were examined by the help of scanning electron microscope (SEM) views of cutting tools and the findings were discussed. In the evaluation of SEM views of cutting tools, the built up edge(BUE) was observed at the head of all cutting tools. As not being within the tool life bound, it is deduced that with the increase in feed rate, a trace of flank wear mechanism on C cutting tools were detected. Generally it is deduced that while CC tools reveal better performance, with regard to tool costs, C tools could be used to operate this kind of MMC smaterials.