Browsing by Author "Okay F."

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Investigation of machinability properties of aluminium matrix hybrid composites
(2021-08-01) Okay F.; Islak S.; Turgut Y.
In this study, machinability properties of aluminium matrix boron carbide (B4C) and carbon nanofiber (CNF) reinforced hybrid composite material produced by powder metallurgy in drilling were investigated. In the study, the samples produced with hot pressing technique having 6 different volume rates were used. The drilling operations were performed using drills with 3 point angles (90°–118°–135°) at 30–45-67.5 m/min cutting speed and 0.1–0.15–0.225 mm/rev feed rate. As a result of the experiments, the thrust force, moment, and surface roughness were measured and the delamination factor forming at hole exits was calculated. In addition, the effect of reinforcement rate on the machinability was also investigated. In all drill types, it was determined that as the feed rate increased, the thrust force increased and as the reinforcement rate increased, moment values also increased. Surface roughness values increased with the increased feed rate but decreased as the cutting speed increased. As the drill point angle increased, the surface roughness value decreased but the hole exit damage increased.
Microstructure and Mechanical Properties of Aluminium Matrix Boron Carbide and Carbon Nanofiber Reinforced Hybrid Composites
(2022-05-03) Okay F.; Islak S.
In this study, aluminium matrix boron carbide (B4 C) and carbon nanofiber (CNF) reinforced hybrid composite was produced by powder metallurgy method and their microstructure and mechanical properties were investigated. The samples were produced at 6 percentage volume ratios using hot pressing technique. Microstructure examination, hardness measurement, transverse rupture test, and wear tests were carried out in order to determine the mechanical properties of the samples. Also three-point bending test was performed to determine their transverse rupture strength (TRS). Wear tests were carried out based on the ball on disc method. The microstructure examination revealed that the reinforcing elements were relatively homogeneously distributed in the aluminium matrix. In addition, the fracture was brittle due to the notch effect and agglomeration occurred with increasing amount of CNF. As the CNF amount of the samples increased, their hardness values increased but their TRS values decreased. Results of the wear test indicate that the increased amount of CNF increased the wear resistance. The friction coefficient values of the samples varied between 0.535 and 0.646. When the hardness was examined together with TRS and wear test results, the most suitable sample was determined to be Al-7%B4 C-1%CNF.