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Article Citation - WoS: 8Effect of Austenitizing Temperatures on the Microstructure and Mechanical Properties of Aisi 9254 Steel(Walter de Gruyter Gmbh, 2021) Murathan, Omer Faruk; Davut, Kemal; Kilicli, VolkanIn this study, the effect of austenitizing temperatures and low-temperature isothermal heat treatment (below martensite start temperature) on the microstructure and mechanical properties of AISI 9254 high silicon spring steel has been investigated. Experimental studies show that ultra-fine carbide-free bainite, tempered martensite and carbon enriched retained austenite could be observed in isothermally heat-treated samples where the as-received sample consisted of fine pearlite. A high tensile strength of similar to 2060 MPa, a total elongation of similar to 8 %, and absorbed energy of 105 J were achieved in a commercial high-Si steel by austempering below the Ms temperature. A good combination of strength and ductility has been obtained in prolonged austempering below the martensite start temperature (225 degrees C) from an austenitizing temperature of 870 degrees C.Review Citation - WoS: 21Citation - Scopus: 35Principles of Reverse Electrodialysis and Development of Integrated-Based System for Power Generation and Water Treatment: a Review(Walter de Gruyter Gmbh, 2022) Othman, Nur Hidayati; Kabay, Nalan; Guler, EnverReverse electrodialysis (RED) is among the evolving membrane-based processes available for energy harvesting by mixing water with different salinities. The chemical potential difference causes the movement of cations and anions in opposite directions that can then be transformed into the electrical current at the electrodes by redox reactions. Although several works have shown the possibilities of achieving high power densities through the RED system, the transformation to the industrial-scale stacks remains a challenge particularly in understanding the correlation between ion-exchange membranes (IEMs) and the operating conditions. This work provides an overview of the RED system including its development and modifications of IEM utilized in the RED system. The effects of modified membranes particularly on the psychochemical properties of the membranes and the effects of numerous operating variables are discussed. The prospects of combining the RED system with other technologies such as reverse osmosis, electrodialysis, membrane distillation, heat engine, microbial fuel cell), and flow battery have been summarized based on open-loop and closed-loop configurations. This review attempts to explain the development and prospect of RED technology for salinity gradient power production and further elucidate the integrated RED system as a promising way to harvest energy while reducing the impact of liquid waste disposal on the environment.Article Citation - WoS: 1Citation - Scopus: 1Impact Behavior of Sandwich Composites With S2-glass/Epoxy and PVC Foam Under Low Velocity Loading(Walter de Gruyter Gmbh, 2025) Karakuzu, Ramazan; Sarioglu, Rifat; Kandas, HalisThe purpose of this research is to examine the absorbed energy, resistance to impact load of sandwich composite, and power exercised by impactor, experimentally. Therefore, low velocity impact tests were performed at three different energy levels for two distinct noses on sandwich composite with a PVC core and varying amounts of S2-glass layers. The vacuum-assisted resin infusion method (VARIM) was used to manufacture sandwich composites. S2-glass fabric with an areal density of 190 gm-2 and polyvinyl chloride (PVC) core material with a thickness of 10 mm were utilized. For every face sheet material, three distinct layer numbers of S2-glass fabrics were used. It is seen that composites exposed to flat impactors absorb considerably more energy than hemispherical ones.Article Citation - WoS: 21Silent Enhancement of Sers Signa Without Increasing Hot Spot Intensities(Walter de Gruyter Gmbh, 2018) Postaci, Selen; Yildiz, Bilge Can; Bek, Alpan; Tasgin, Mehmet EmrePlasmonic nanostructures enhance nonlinear response, such as surface enhanced Raman scattering (SERS), by localizing the incident field into hot spots. The localized hot spot field can be enhanced even further when linear Fano resonances take place in a double resonance scheme. However, hot spot enhancement is limited with the modification of the vibrational modes, the breakdown of the molecule, and the tunneling regime. Here, we present a method which can circumvent these limitations. Our analytical model and solutions of 3D Maxwell equations show that: enhancement due to the localized field can be multiplied by a factor of 10(2)-10(3). Moreover, this can be performed without increasing the hot spot intensity which also avoids the modification of the Raman modes. Unlike linear Fano resonances, here, we create a path interference in the nonlinear response. We demonstrate on a single equation that enhancement takes place due to cancellation of the contributing terms in the denominator of the SERS response. Our method can be implemented on an atomic force microscope tip, decorated (or "contaminated") with appropriate quantum emitters.Article Citation - WoS: 3Citation - Scopus: 3Nondestructive Microstructural Characterization of Austempered Ductile Iron(Walter de Gruyter Gmbh, 2023) Tuzun, Mert Yagiz; Yalcin, Mustafa Alp; Davut, Kemal; Kilicli, VolkanAustempered ductile iron (ADI) has been preferred in a wide range of applications due its unique combination of high strength, good ductility, wear resistance and fracture toughness together with lower cost and lower density compared to steels. Magnetic Barkhausen noise (MBN) measurement offers a better alternative to traditional characterization techniques by being fast and non-destructive. A simple linear regression using only one single independent variable cannot correlate the MBN with the microstructure of ADI, since its microstructure is multi component. Multiple linear regression analysis (MLRA) was used to build a model that uses the characteristic features of microstructural constituents as input parameters to predict the MBN. For that purpose, Cu-Ni-Mo alloyed ductile iron samples austempered between 325 and 400 degrees C and for 45-180 min duration were used. The results show that MBN is most sensitive to the size and shape of acicular ferrite and retained austenite. Moreover, MBN is almost insensitive to the size, morphology and volume fraction of graphite particles. This indicates that retained austenite pins the domain walls more effectively than the graphite particles. Considering the results MLRA, MBN technique can be used to characterize the ausferritic microstructure of ADI.
