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    Powder metallurgical fabrication of graphene reinforced near-eutectic Al-Si matrix composites: Microstructural, mechanical and electrochemical characterization
    (Elsevier - Division Reed Elsevier India Pvt Ltd, 2022) Akcamli, Nazli; Senyurt, Berk; Gokce, Hasan; Agaogullari, Duygu
    Al-10 wt% Si matrix composites reinforced with a few-layered graphene (FLG) were fabricated via a powder metallurgical route. FLG in varying amounts (0.25, 0.5, 1, 2, and 5 wt%) was incorporated into the Al10Si matrix via mechanical alloying (MA) for different durations in a high-energy ball mill. The mechanically alloyed (MAed) powders were consolidated by uniaxial pressing and pressureless sintering processes. The as-blended (non-MAed) and MAed powders and bulk composites were investigated comparatively in terms of microstructural, thermal, mechanical, tribological and corrosion properties. The MAed powders demonstrated refined and semi-equiaxed particle morphology with reduced crystallite size values. Additionally, the FLG/Al10Si composites exhibited advanced microstructural and mechanical properties by the contribution of MA and reinforcing particles compared to those of the as-blended and unreinforced matrix. The highest hardness and lowest wear rate values were obtained for the 4 h-MAed Al10Si-2FLG (138 HV and 6.485x10-4 mm(3)/N.m) and Al10Si-5FLG (178 HV and 7.456x10-4 mm(3)/N.m) composites. Moreover, the compressive strength of the Al-10Si matrix improved approximately by 50 and 20% via 0.5 and 2 wt% FLG addition, respectively. Also, lower corrosion resistance properties were observed for the FLG reinforced composites compared to the Al10Si matrix. (c) 2021 Karabuk University. Publishing services by Elsevier B.V.
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    Processing and characterization of graphene nano-platelet (GNP) reinforced aluminum matrix composites
    (Carl Hanser Verlag, 2016) Akçamlı, Nazlı; Gokce, Hasan; Uzunsoy, Deniz
    Aluminum matrix composites containing graphene nanoplatelets (GNPs) as reinforcement additive were fabricated by a two-step process consisting of mechanical alloying and pressureless sintering. The effects of graphene nano-platelets amounts and mechanical alloying duration on the microstructural and mechanical properties of aluminum were investigated. The characterization studies were performed by X-ray diffractometry, Raman spectroscopy, scanning electron microscopy/energy dispersive spectrometry, particle size analysis, differential scanning calorimetry, Archimedes' density and microhardness test method. The microhardness of composites increased gradually by the addition of 0.5 and 1 wt.-% GNP, whereas an adverse effect was observed by the increment of the GNP amount to 2 wt.-%.
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    Thermomechanical properties of aluminium titanate (Al2TiO5)-reinforced forsterite (Mg2SiO4) ceramic composites
    (Elsevier Sci Ltd, 2018) Küçük, İsrafil; Boyraz, Tahsin; Gokce, Hasan; Ovecoglu, Mustafa Lutfi
    Aluminium titanate (Al2TiO5)-reinforced forsterite (Mg2SiO4) ceramics were prepared by the powder metallurgy route including sintering the Al2TiO5-reinforced Mg2SiO4 green compacts at 1600 degrees C. Sivas talc (3MgO center dot 4SiO(2)center dot H2O) was used as a precursor for the Mg2SiO4 ceramics due to its excellent mechanical properties like thermal shock and abrasion resistance. In order to investigate thermal shock resistance behaviour, the as prepared samples were quenched in water and assessed. Investigations were carried out to study the effect of Al2TiO5 addition on microstructural, physical, thermal and mechanical properties of Al2TO5-reinforced Mg2SiO4 ceramic composites. The thermal and mechanical properties were examined before and after thermal shock tests. The results showed that the best thermal expansion coefficient (0.76 x 10(-6) (K-1)) and thermal shock resistance (6.82 GPa) of the Al2TiO5-reinforced forsterite (Mg2SiO4) ceramic composites were obtained after thermal shock test, which were better than those of the other concentrations of the Al2TiO5-reinforced forsterite (Mg2SiO4) ceramic composites. These findings suggest that 20 wt% Al2TiO5-reinforced forsterite (Mg2SiO4) ceramic composites possess good thermomechanical properties and thus might be suitable for potential applications such as filter material, pharmaceuticals, cosmetic manufacturing, optical, and chemical devices.