Functional Materials and Metallurgy

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Authors: Mehmet Safa Bodur, Mustafa Bakkal, Karl Englund
Abstract: In this study, the hybridization effect on the mechanical properties of the natural fiber reinforced composites was investigated. For this purpose, glass fibers in different ratios of 2.5, 5 and 10 wt% were added in the polymer composites with cotton fibers at the ratios of 12.5 and 25 wt%. In order to have better interfacial bonding and increase the effectiveness of glass fiber on the mechanical properties, maleic anhydride coupling agent was added in the hybrid composite structures. At the end of the study, the best ratios of maleic anhydride, cotton and glass fiber for this kind composites were explored with respect to the economical and mechanical concerns. This study suggests that hybridization can be considered as most promising way to improve the mechanical properties for this novel composite materials.
Authors: P. Subramanya Reddy, R. Kesavan, B. Vijaya Ramnath
Abstract: The investigation of mechanical properties of silicon carbide (SiC) powders reinforced with aluminum alloy composites are recorded in this paper. SiC powders of approximately 35µm size were added in an aluminum alloy matrix to manufacture the samples of ratios 1, 2, 3 and 4 by weight % using the stir casting technique. The specimens were fabricated and several tests were conducted to evaluate the mechanical properties such as tensile strength, hardness and impact strength and then the values are compared with the base alloy. It has been observed from the results that the hardness, impact energy and tensile strength increases with the increase in % of SiC particles until 2% and drops on further increase in the SiC particles.
Authors: Sıddıka Mertdinç, Emre Tekoğlu, Hasan Gökçe, Duygu Ağaoğulları, M. Lütfi Öveçoğlu
Abstract: In this study, the effect of mechanical alloying (MA) on the microstructural, mechanical and physical properties of vanadium boride particulate reinforced Al-7 wt. % Si matrix composites were investigated. VB-VB2-V3B4 containing vanadium boride hybrid powders were mechanochemically synthesized for 5 h from the V2O5-B2O3-Mg powder blends and leached with hydrochloric acid (HCl) for purification. Laboratory-synthesized VB-VB2-V3B4 powders were incorporated into the Al-7wt. % Si matrix powders with the amount of 2 wt.% via MA for 4h in a SpexTM Mixer/Mill using hardened steel vial/balls with a ball-to-powder weight ratio of 7/1. After the MA process, phase analysis (X-ray diffraction), particle size analysis (laser particle size measurement), surface area analysis (Brunauer-Emmett-Teller measurement) and microstructural characterization (scanning electron microscope (SEM) micrograph) and thermal analysis (differential scanning calorimetry (DSC)) of the non-milled/milled Al-7 wt.% Si-2wt.% (VB-VB2-V3B4) powders were conducted. As-blended and MA’d powders were compacted at a uniaxial hydraulic press to obtain cylindrical compacts with a diameter of 12 mm under a pressure of 400 MPa. Green bodies were sintered at 570°C for 2 h under Ar gas flowing conditions. Microstructural characterizations of the sintered samples were carried out using XRD and optical microscope (OM). Physical and mechanical properties of the composites were investigated in terms of density (Archimedes method), Vickers microhardness and wear rate. The microhardness and wear rate of the 4h of MA’d and sintered sample respectively increased to 0.865±0.256 GPa and 0.0036 mm3/N.m as compared with those of as-blended and sintered sample.

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