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- MakaleYalnız künye2026Scopus SJRQ2Oxide Dispersion, Microstructure, and Functional Evolution in La2O3 Modified Cu-Al-Mn-Fe Shape Memory Alloys
Karaduman, Oktay; Doğan, Fatih; Dehghanpour, Heydar; Yüzüak, Gizem Durak; Yüzüak, Ercüment; Canbay, Canan Aksu
Cu-Al-Mn-Fe high-temperature shape memory alloys containing 0-1.0 wt.% La2O3 were fabricated by vacuum arc remelting to investigate oxide-dispersion effects on microstructure, martensitic transformation, wear, and corrosion behavior. XRD and SEM analyses revealed that low La2O3 additions (0.2-0.4 wt.%) promoted β1′ martensite refinement and enhanced crystallinity, while higher contents induced structural heterogeneity. The alloy with 0.4 wt.% La2O3 exhibited the highest transformation enthalpy (7.49 J g−1), reduced friction coefficient (~0.55), and the narrowest wear scar (~501 µm). Electrochemical tests in 3.5 wt.% NaCl showed a fivefold decrease in corrosion current density and increased charge-transfer resistance (2512 Ω cm2) for the same composition. Excessive La2O3 led to performance degradation due to particle agglomeration and interfacial defects. The results demonstrated that controlled La2O3 addition enabled microstructural refinement and multifunctional performance enhancement in Cu-based shape memory alloys.
- MakaleAçık Erişim2024Scopus SJRQ4Experimental Study on Engineering Properties of Recycled Olivine Aggregate Filled CF Reinforced Electrically Conductive Mortars
Dehghanpour, Heydar; Doğan, Fatih; Subaşı, Serkan; Maraşlı, Muhammed
Electrically conductive concretes produced for different purposes were introduced years ago and since then, intensive scientific research has been going on. Studies in the literature have generally been carried out on conventional concretes with electrical conductivity for floor applications. The current study investigates carbon fiber reinforced mortars filled with fine olivine aggregate. Fine aggregate filled mortars are generally produced for building facade applications. Within the scope of the study, the mechanical, electrical, dynamic and microstructural properties of cementitious mortars containing 0.5%, 0.75% and 1.0% carbon fiber and 100% recycled olivine aggregate were investigated. The purpose of performing dynamic resonance tests was to investigate the effect of carbon fiber on damping ratio. 28-Day compressive, flexural, dynamic resonance, ultrasonic pulse velocity (UPV), Leeb hardness and dry density tests of conductive mortar samples obtained from four different mixtures were performed. In addition, 2, 14, 28, 90 and 180 days electrical conductivity tests were carried out to determine their resistivity in different time intervals. The purpose of performing dynamic resonance tests was to investigate the effect of carbon fiber on damping ratio. While a significant positive effect of CF on electrical conductivity and damping ratio was observed, a negligible decrease in mechanical results was observed. Calcium silicate hydrate (C-S-H) structure formed by hydration using olivine filler in the cement mixture confirmed the binding formations.
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İncele - MakaleAçık Erişim2023Experimental investigation of engineering properties of silica sand filled mortars containing high doses of SWCNT
Subaşı, Serkan; Dehghanpour, Heydar; Maraşlı, Muhammed; Doğan, Fatih
Recently, great efforts have been made by researchers on the mixture of electrically conductive concretes that have been developed for different purposes. In this study, an experimental research was carried out on electrically conductive mortar mixtures especially for shell elements produced for building facade cladding. Six different mixtures were produced, including the non-conductive reference mixture. Single-walled carbon nanotube (SWCNT) was used as nano-sized conductive additive material. SWCNT was added at 0.2% and 0.3% of cement weight. SF was added to the same mixtures as another group at the rate of 4% by total weight. 2, 14, 28, 90 and 180 days electrical resistivities of the obtained conductive mortar samples were measured. As a non-destructive method, dynamic resonance testing was performed and the 28-day damping rates of the samples were determined. Ultrasonic pulse velocity (UPV) and Leeb hardness tests were performed, respectively, by using other non-destructive testing methods to obtain information about the internal structure voids and surface hardness of the samples. SWCNT, which causes low machinability and therefore internal structure voids, caused a decrease in compressive strength and flexural strength, as well as a significant increase in electrical conductivity.
AtıfOpenAlex1İncele - MakaleAçık Erişim2022Characterization of carbon fiber reinforced conductive mortars filled with recycled ferrochrome slag aggregates
Doğan, Fatih; Dehghanpour, Heydar; Subaşi, Serkan; Maraşli, Muhammed
Recently, it has been known that carbon fiber, a conductive fiber, is used in different mixture designs and the development of electrically conductive cementitious materials. Howev-er, the evaluation of ferrochrome slag as a recycled aggregate in the mixture of these special concretes has still not been investigated. In this study, electrically conductive mortars were produced using 100% recycled ferrochrome slag aggregate with a particle size of less than 1 mm as filling material and using carbon fiber in 4 different ratios, 0%, 0.5%, 0.75%, and 1%. To investigate the electrical conductivity properties, the resistivity values of the samples were measured at five different times within 2–180 days. In addition, 28-day compressive strength, flexural strength, dynamic resonance, ultrasonic pulse velocity, Leeb hardness, scanning elec-tron microscope, and X-Ray Diffraction tests were performed on all samples. The results were compared with the literature, proving that ferrochrome slag could be used as a reasonable aggregate in conductive mortars. The age effect was minimal in CF-added mixtures. With the addition of 1% CF, the resistivity values decreased approximately 40 times compared to the ref-erence. Moreover, SEM analyses of the CF-0.75 sample showed that the CFs adhered to form a conductive network between the components in the ferrochrome-filled compact structure.
AtıfScopus10TR Dizin5İncele - MakaleAçık Erişim2022Effects of single-walled carbon nanotubes and steel fiber on recycled ferrochrome filled electrical conductive mortars
Dehghanpour, Heydar; Doğan, Fatih; Subaşi, Serkan; Maraşli, Muhammed
The production of electrically conductive concrete was introduced years ago among construction materials, generally for anti-icing. The present study investigates the electrical, mechani-cal, dynamic, and microstructural properties of recycled ferrochrome filled cementitious mortars containing single-walled carbon nanotubes (SWCNTs) and steel fiber. Within the scope of the study, a total of 5 different mixtures were obtained. 7, 14, and 28-day non-destructive and 28-day compressive and bending tests of cementitious conductive mortars obtained from five different mixtures were performed. The two-point uniaxial method was used to determine the electrical conductivity properties of the samples. The damping ratio of the samples was obtained by performing dynamic resonance tests. Ultrasound pulse velocity (UPV) and Leeb hardness tests were performed as other non-destructive testing methods. Microstructure analysis at the interfaces of conductive concrete samples was characterized by scanning elec-tron microscopy (SEM), EDS (Energy-Dispersive X-ray Spectroscopy), and X-ray diffraction (XRD). The results showed a logical agreement when comparing their mechanical, physical, and dynamic properties. When SWCNT is used with steel fiber, the conductive mortar samples exhibited good conductivity, while their compressive and bending strengths turned below.
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