Yazar "Abdulhamid, Farouk" seçeneğine göre listele

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    Öğe
    Annealing effect on green synthesized cerium oxide nanoparticles
    (Altınbaş Üniversitesi / Lisansüstü Eğitim Enstitüsü, 2021) Abdulhamid, Farouk; Kaygusuz, Hakan
    Annealing is a process that often results in aggregation of the crystallite particles and therefore an increase in crystallite size is often observed. In this study, the behavior of biopolymer-assisted synthesized cerium oxide nanoparticles under the influence of annealing is investigated. Cerium (III) alginate hydrogels were thermally decomposed at 450 °C to synthesize cerium oxide nanoparticles, which is reported in literature as a green method and results in surface functionality of the nanoparticles. The particles were annealed at two different temperatures (600 and 800 °C) for 2, 4 and 8 hours. X-ray diffraction was used to characterize the powder samples for observing the average crystallite sizes, which were calculated using Scherrer’s equation. Additionally, the grain size distribution of the nanoparticles is also studied by a semi-numerical method based on diffraction patterns. Results indicate that the annealing increases the sample size 2 to 4 times, which can be useful for designing the average crystallite size in advanced studies such as optics and drug delivery.
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    Öğe
    Heat-assisted machining of superalloys: A review
    (Springer Nature, 2021) Bijanzid, Armin; Munir, Talha; Abdulhamid, Farouk
    Superalloys are vastly used in the aerospace industry due to their alluring properties such as maintaining their strength at high-temperature applications. Nevertheless, manufacturing these raw materials to the desired geometrical shapes is one of the main challenges of the subtractive manufacturing industry and they are categorized as hard-to-machine materials. Several approaches such as high-speed machining (HSM), cryogenic cooling, minimum quantity lubrication (MQL), and heat-assisted machining (HAM) are introduced to tackle this matter. HAM is a technique that introduces external heat sources to the workpiece (pre-heating or real-time heating methods) to increase the ductility of the superalloy and therefore reduce the yield and shear strength of the workpiece. By this means, the machining parameters demonstrate an improvement compared to conventional machining. This review article focuses on the research approaches conducted to evaluate the efect of the various heat source applications (gas fame, induction, laser, and plasma) on the material properties and the machinability of the superalloys. Additionally, the heating methodology and heat assistance impact on cutting parameters (forces, tool life, surface integrity, and chip morphology) are outlined. Finally, a comparison of the heat source efciency and the economics of the various heat applications is performed.