Person: YUMUŞAK, GÖRKEM
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YUMUŞAK
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GÖRKEM
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Publication Metadata only Optimization of Sintering Parameters and Post Sintering Characterisation in Mullite-Zircon Ceramics(2023-05-25) YUMUŞAK, GÖRKEM; ARTIR, RECEP; Bal E., Yumuşak G., Artır R.In this study, with the help of the known effect of Fe2O3, which is a sintering aid additive for sintering, it is possible to synthesize products at temperatures much lower than 1500°C, which is the known sintering temperature in the phase diagram of the mullite-zircon system. In addition to the phase and microstructure analysis of the produced products as a result of the addition of sintering aid additive (Fe2O3) and reaction sintering process, mechanical characterizations were performed. The sintering aid additive (Fe2O3) was mixed into the Mullite-Zircon structure by adding 1 wt.%, 2 wt.% and 3 wt.%. 1% by weight of PAN was used as the binder. This mixture was formed into pellets before sintering under the selected pressing force of 2500 psi. These pellets were sintered at 1500°C, 1450°C, and 1400°C sintering temperatures, respectively, with a sintering time of 5 hours for each temperature. As a result of these processes, the effect of sintering temperature and the effect of the amount of sintering aid additives were examined by using characterization methods. It was aimed to determine the optimum parameters for this material, considering the important properties of ceramics such as porosity, hardness, density, and microstructure of the product to be produced with these additives and parameters. X-Ray Diffraction analyses were performed, and the phases formed as a result of the reaction were determined. Microstructure analyses were made for sintering temperatures of 1500°C, 1450°C, and 1400°C using an optical microscope. The optimum sintering temperature for the parameters used in this study and the amount by weight of the sintering aid additive to be used were selected considering variable factors in this study, and it was aimed to find the product with the best properties and the lowest cost.Publication Metadata only Gd and Tb doping effects on the physical properties of Nd2Sn2O7(ELSEVIER SCI LTD, 2018) YUMUŞAK, GÖRKEM; Saleh, Adli A.; Hamamera, Hanan Z.; Khanfar, Hazem K.; Qasrawi, A. F.; Yumusak, G.In the current study, we report the light doping effects of the gadolinium and the terbium on the structural, morphological, optical and electrical properties of Nd2Sn2O7 pyrochlore ceramics. The pyrochlore which is prepared by the conventional solid state reaction technique is analyzed by means of scanning electron microscopy, energy dispersive X-ray analyzer, X-ray diffraction, ultraviolet- visible light spectrophotometry and temperature dependent current -voltage characteristics techniques. It is found that even though the doping content of both metals is low (2%), they significantly alter the physical properties of the pyrochlore. Particularly, it is observed that, these two doping agents increases the lattice parameter and strain and reduces the crystallite size and dislocation density. Optically, the effect of Gd doping on shrinking the energy band gap value of the Nd(2)Sn(2)O(7 )pyrochlore ceramic is more pronounced than that of Tb. On the other hand, the electrical investigations have shown that while the Gd make the pyrochlore exhibit p-type conductivity through forming shallow acceptor levels, the Tb forces n-type conductivity by forming deep donor levels below the conduction band edge. Such acceptor and donor impurity levels increases the electrical conductivity of the Nd(2)Sn(2)O(7 )pyrochlore ceramics by 390 and 58 times, respectively.Publication Metadata only Fabrication and characterization of anodic films on 304 stainless steel(2022-11-19) SARIOĞLU, CEVAT; YUMUŞAK, GÖRKEM; Ağırlar N., Bağcı N. C., Arkalı E., SARIOĞLU C., YUMUŞAK G.