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    Challenges in introducing ceramic fiber and other hybrid reinforcements in friction materials
    (Springer, 2025) Oktem, Hasan; Konada, Naresh Kumar; Uygur, Ilyas; Karakas, Hamdi
    In this study, an attempt was made to develop a high strength thermal resistant friction material using ceramic fiber as the main fiber and varying the wollastonite content. In addition to the ceramic fiber, 19 various ingredients were considered as fibers, frictional additives and fillers for improving the performance of the composite. The main challenge is to develop a friction material capable of withstanding dynamic loads and severe temperatures encountered during braking. Three friction materials (CERA-I, CERA-II, and CERA-III) were fabricated using a hot press method. After fabrication, the samples were evaluated for physical and mechanical properties. The actual performance was predicted using a friction test rig equipment. The tests were carried at pressures of 30 MPa and 15 MPa under a speed of 600 rpm. The materials were characterized using Scanning electron microscope (SEM), EDXA, porosity and thermo-gravimetric analysis (TGA) for determination of distribution of ingredients and chemicals present in the composite. The results revealed that, inclusion of ceramic fiber with other ingredients possess superior properties in terms of mechanical, physical and wear properties. Out of these three samples, CERA-III friction material exhibited better performance compared to the remaining samples.
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    Tribological and mechanical exploration of polymer-based hemp and colemanite composite as a friction material
    (Iop Publishing Ltd, 2024) Karakas, Hamdi; Oktem, Hasan; Uygur, Ilyas
    Natural and organic-based composite materials are widely used in many industrial applications due to their low cost, easy recyclability, economic feasibility, and ready availability. In this study, a polymer-based composite friction material consisting of Hemp-Colemanite composition (HCFCo) has been developed for the automotive sector to exhibit lower cost, environmentally friendly characteristics, and suitable friction-wear behaviors. For this purpose, three different ratios (%4, %8 and %12) of HCFCo composites were produced using a coating technique called impregnation process with a specially designed device. During the production stage, homogeneity of the composites was ensured, and then the final shape was given by the hot pressing method. Local based natural materilas frequently used for as anon-asbestos friction materails. For this reason, hemp and colomanited based composites were tested. Properties such as hardness, density, water and oil absorption, friction coefficient, and specific wear of HCFCo samples were examined. In addition, the microstructures of HCFCo composites were investigated to determine the bonding form between hemp fiber and colemanite. The results obtained revealed that the friction coefficient values decreased with an increase in temperature, while no significant change was observed in hardness and density values. Throughout the entire testing process, the friction coefficients varied between 0.14 and 0.29 on average. It was concluded that the developed fiber-reinforced composite can be reliably used in industrial applications and can contribute significantly to innovations in the literature.