Browsing by Author "Esen, C"

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    Effect of Gr Contents on Wear Properties of Al2024/MgO/Al2O3/Gr Hybrid Composites
    Ovali, I; Esen, C; Albayrak, S; Karakoç, H
    In the present study, hybrid metal matrix composites, Al2024/10Al2O3, Al2024/10Al2O3/3MgO, Al2024/10Al2O3/6MgO, Al2024/10Al2O3/3MgO/1.5 Gr, Al2024/10Al2O3/3MgO/3Gr, and reinforcement samples (AA 2024) produced with powder metallurgy process. AA 2024 and reinforcement powders were determined mixture rations and separately mixed during 30 minutes in a three-dimensional Turbula mixer. The mixed compositions were pressed at 300 MPa and sintered at 550 degrees C during 1 h. After that, three materials were extruded at the same temperature. Experimental results show that hybrid metal matrix composites (HMMCs) a better wear resistance than the reinforcement samples because of higher hardness. Gr behave as a lubricant during wear process. The wear resistance of HMMCs can be optimized with controlling of the reinforcement content and type.
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    Mechanical Properties of Al2024/Al2O3/MgO/Graphite composites via hydro-thermal hot pressing route
    Ovali, I; Esen, C; Albayrak, S; Karakoç, H; Kumar, MS; Yang, CH
    Currently, the research community is focused on hybrid composites with two different reinforcements. However, it's difficult to attain both mechanical strength and wear resistance simultaneously. So, the prime novelty of this research work is to enhance both the mechanical strength and wear performance of the composites by adding three reinforcement particles effectively through the hydro-thermal hot pressing technique. In this research, Al2024 alloy was reinforced with Al2O3-MgO-Gr particles in five different reinforcement combinations. With the help of a 3D mixer, the reinforcements were mixed in determined ratios for 30 min. The mixed powders were cold pressed under 50 MPa pressure, and then hot pressed at 550 degrees C under 200 MPa pressure. The fabricated hybrid composite materials were evaluated for their density and porosity. Further, hardness, transverse rupture strength and wear performance were investigated. The predominant wear mechanism was examined by wear mechanism maps under various sliding and normal conditions. The outcome shows that the inclusion of excess (>3%) nano MgO and (>1.5%) Gr particles decrease the density of the composite materials by forming micro -pores. The optimum reinforcement combination of 10% Al2O3, 3% of MgO and 1.5% of Gr particles shows improved cross-fracture strength of 132.6 MPa, minimum volume loss of 0.55 mm3 and decreased frictional coefficient of 0.18. Further, the smoothness in the worn-out surface SEM images of the composites substantiates the enhanced wear performance.