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Öğe EFFECT OF Al2O3 AMOUNT ON MICROSTRUCTURE AND WEAR PROPERTIES OF Al-Al2O3 METAL MATRIX COMPOSITES PREPARED USING MECHANICAL ALLOYING METHOD(Springer, 2010) Ozyurek, D.; Tekeli, S.; Gural, A.; Meyveci, A.; Guru, M.This paper reports the outcome of an investigation into the effect of Al2O3 content on the microstructure and wear properties of Al-Al2O3 metal matrix composites. The Al-Al2O3 composites are prepared by a mechanical alloying method using Al2O3 powders up to 20 vol.% as reinforcement. Alloying is performed in a vibration mill using a ball-to-powder ratio 10: 1 and a milling time varying from 30 to 100 min at a rate of 710 Hz. The prepared compositions are cold pressed at 630 MPa with a single action and sintered at 560 degrees C for 30 min under Ar gas atmosphere. The experimental results show that the reinforcing phase Al2O3 is homogeneously dispersed in the Al matrix and the interface between Al matrix and Al2O3 is well formed. Wear tests are carried out under dry sliding conditions using a pin-on-disk testing machine at three different loads of 10, 25, and 50 N and at a sliding speed of 2.08 m/sec. Total sliding distances are selected as 400, 800, 1200, and 1600 m. It is seen that the wear rate decreases with increasing Al2O3 content and sliding distance at a sliding speed of 2.08 m/sec.Öğe The Effect of Milling Time on Microstructure and Wear Behaviours of AISI 304 Stainless Steel Produced by Powder Metallurgy(Polish Acad Sciences Inst Physics, 2019) Yavuzer, B.; Ozyurek, D.; Guru, M.In this study, the effect of milling time on wear behavior of the AISI 304 stainless steel produced by the mechanical alloying method was investigated. In the study element powders were prepared and mechanically milled at five different milling times (30, 60, 90, 120, and 150 min) in a mechanical alloying device. The milled powders were pre-shaped and sintered at 1300 degrees C for 1 h and cooled to room temperature in the furnace. Produced samples microstructure and XRD examination were carried out. Wear tests were performed using a pin-on-disc type wear testing device. In this study, the hardness values were found to have increased by increasing milling time. The maximum hardness values were measured for the 150 min milled samples. The lowest weight losses were measured with 150 min milled samples. The wear test results were compatible with hardness results.Öğe Effect of Sintering Time on Hardness and Wear Behaviours of Carbon Nanotubes Reinforced Aluminium Matrix Composites(Polish Acad Sciences Inst Physics, 2017) Yildirim, M.; Ozyurek, D.; Guru, M.In this study, the effects of sintering time on hardness and wear behaviour were investigated of carbon nanotubes reinforced aluminium matrix composites. 1% multi wall carbon nanotubes (90% purity with 9.5 nm in diameter, 1.5 mu m in length) and gas atomized 7075 Al alloy powders were mechanical milled for 120 min in a planetary ball mill. Mechanical milled aluminium composite powders were cold pressed under 520 MPa. Pre-shaped samples were sintered in atmosphere controlled furnace at 580 degrees C for three different sintering times (1, 2, and 3 h). As a result of study, it was observed that the hardness values of composites were decreased with increasing sintering time and the weight loss was decreased. It was determined from worn surface SEM images that adhesive wear mechanisms were dominant.Öğe Investigation of Mechanical Properties of AA7075 Alloys Aged by Various Heat Treatments(Maik Nauka/Interperiodica/Springer, 2020) Sunar, T.; Tuncay, T.; Ozyurek, D.; Guru, M.In this study, annealing (O), artificial aging (T6), retro-regression aging (RRA) and high temperature pre-precipitation (HTPP) heat treatments were applied to AA7075 aluminium alloys. The effects of these treatments on the mechanical properties of AA7075 alloy were investigated. The microstructures of the samples were examined by Optical Microscope (OM), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) analysis. Then, X-ray diffraction analysis (XRD) was conducted to identify intermetallics formed in the microstructure of the samples. Tensile and hardness tests were carried out to investigate the mechanical properties. Results showed that secondary phase particles such as Al2Cu, Al2CuMg and MgZn2 are formed in the microstructures. In terms of the mechanical properties, T6 applied samples showed the best results. The HTPP applied alloy which presented optimum ductility behaviour among the other heat-treated samples. Dimples and some cleavage surfaces were observed on the fracture surfaces of the samples. Therefore, it is concluded that a ductile/semi-ductile fracture occurred on the samples.Öğe Investigation of Mechanical Properties of AA7075 Alloys Aged by Various Heat Treatments (vol 121, pg 1440, 2020)(Maik Nauka/Interperiodica/Springer, 2021) Sunar, T.; Tuncay, T.; Ozyurek, D.; Guru, M.[No abstract available]Öğe Obtainment of Copper(II) Fluoroborate by High-Energy Impacted Ball-Milling(Polish Acad Sciences Inst Physics, 2019) Aydin, D. Y.; Guru, M.; Ipek, D.; Ozyurek, D.In this study, copper(II) fluoroborate, one of the special boron products, was synthesized by high energy impacted ball milling method and characterization studies were carried out by means of FTIR and BF4- ion selective electrode. Copper fluoride and elemental boron were used as reactants in the study. Mechanochemical method by means of ball milling was carried out, in a three-dimensional spex-type ball mill in an argon atmosphere. Specimens were prepared at different mole ratios and mechanically milled in a ball mill for a fixed time to determine the optimum mole ratio and the reaction period was optimized in the next step. As a result of the experiments, the most efficient reaction was obtained when reactant mole ratio (n(B)/n(CuF2)) of 0.85:1 and reaction period of 1500 minutes. Copper(II) fluoroborate was produced with a yield of 84.5% under the optimum conditions.
