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    Dry-sliding wear behavior of AISI 4140 barrel steel at elevated temperatures
    (Carl Hanser Verlag, 2020) Kocyigit, Fatih; Yildiz, Fethullah; Gok, M. Sabri; Cay, Vedat Veli
    In this study dry sliding wear behavior of AISI 4140 steel at given elevated temperatures was examined. The experiments were performed on a heat-modulated ball-on-disc wear device under 3, 5, 7 and 10 N loads at room temperature, 100, 200, 300 and 450 degrees C. 3D optical microscopy was performed for determining the volume loss of the worn samples. SEM (scanning electron microscopy) was used to determine the morphology of the worn surfaces of the samples while Raman spectrometry was used for determining oxide types occurring as a result of wear. Experimental applications showed that volume loses slightly increased as a function of indenter load elevation. The experiments performed at 300 degrees C, the volume loss ratios were found to be lower compared to all other samples. The highest volume loss was obtained in the experiments performed at 450 degrees C. Volume loss decreased in all samples under 10 N load. A tribological layer formed on the surface of samples subjected to a dry-sliding process. In the experiments performed at 100 degrees C and 200 degrees C, the delamination type was the dominant wear mechanism at all loads.
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    The Effect of Natural Resin on Thermo-physical Properties of Expanded Vermiculite-Cement Composites
    (Springer/Plenum Publishers, 2020) Kocyigit, Fatih; Cay, Vedat Veli
    This study focuses on production of lightweight concrete that presents thermal insulation property. Lightweight concretes were produced using resin-added cement and expanded vermiculite. The rates of expanded vermiculite were determined as 20%, 40%, 60%, and 80% of the total volume in the mixture. The amount of tragacanth resin in the mixture was detected as 0%, 0.5% and 1% of the total weight of cement and expanded vermiculite. Thermal, mechanical and microstructure properties of the samples produced were determined. Porosity ratio increased by 15.01% to 55.22%, 0.5% and 1% in samples without resin and by 18.97% to 57.88% and 19.64% to 60.73% in resin-added samples, respectively. As the resin increased, density, thermal conductivity, compressive strength decreased and porosity, abrasion loss and water absorption rates increased. Similarly, when expanded vermiculite rate of the samples without resin in the mixture was increased from 20% to 80%, density, thermal conductivity, and compressive strength decreased at the rates of 14.13% to 21.29%, 14.32% to 24.36%, and 31.37% to 39.82%, respectively, compared to 0.5% resin samples and the rates of 12.34% to 13.05%, 12.37% to 19.59%, and 17.65% to 35.29% compared to 0.1% resin samples. Also, the water absorption rates of the samples were found to be lower than 30%, which is the critical value. It was shown that expanded vermiculite and tragacanth resin-added lightweight concrete samples would provide a good performance in non-load bearing places in the buildings, in the partitions instead of bricks, in the ceiling and floor covering, and as plaster and gypsum.
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    Effect of the sintering temperature on the coating of duplex stainless steel with Ni3Al
    (Carl Hanser Verlag, 2018) Cay, Vedat Veli; Kati, Nida; Ozan, Sermin; Cetin, Tayfun
    In this study, duplex stainless steel was coated with Ni3Al powder via self-propagating high-temperature synthesis (SHS) and the effect of the sintering temperature on the coating characteristics was investigated. An SEM electron microscope with EDX (energy dispersive X-ray spectroscopy) was used to examine the microstructure of samples that were coated according to the SHS method and likewise to detect the element content of the phases in the structure. Microhardness tests were conducted on the samples to determine the mechanical properties of the coated material. As a result of these studies, it was found that duplex stainless steel can be reliably coated with an Ni3Al intermetallic compound. The increase in sintering temperature within the given range significantly decreased the size of the disconnected area which completely disappeared.
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    Neutron Radiation Tests about FeCr Slag and Natural Zeolite Loaded Brick Samples
    (Hindawi Ltd, 2014) Cay, Vedat Veli; Sutcu, Mucahit; Gencel, Osman; Korkut, Turgay
    Neutron shielding performances of new brick samples are investigated. Brick samples including 10, 20, and 30 percentages of ferrochromium slag (FeCr waste) and natural zeolite are prepared and mechanical properties are obtained. Total macroscopic cross sections are calculated by using results of 4.5MeV neutron transmission experiments. As a result, neutron shielding capacity of brick samples increases with increasing FeCr slag and natural zeolite percentages. This information could be useful in the area of neutron shielding.
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    Properties and Corrosion Resistance of AISI H13 Hot-Work Tool Steel with Borided B4C Powders
    (Korean Inst Metals Materials, 2020) Gunen, Ali; Karahan, Ismail Hakki; Karakas, Mustafa Serdar; Kurt, Bulent; Kanca, Yusuf; Cay, Vedat Veli; Yildiz, Murat
    In this study, the surface of AISI H13 steel was borided with powder blends of B4C and NaBF(4)using the powder-pack method at 800, 900 and 1000 degrees C for 2, 4 and 6 h. The structural and mechanical characteristics of the boride layers formed on the surface were characterized using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, 2D surface profilometry, microhardness and electrochemical corrosion (3.5 wt% NaCl) tests. The boride layer exhibited a single phase structure (Fe2B) in samples coated at 800 degrees C and a dual-phase structure (FeB + Fe2B) at higher boriding temperatures (900 and 1000 degrees C). The boride layers were compact and crack-free in all boriding conditions. Depending on boriding parameters, the thickness, hardness and average surface roughness (R-a) of the coatings were found to range between 5.81 and 102.46 mu m, 1635-1915 HV and 0.315-0.650 mu m, respectively. The borided AISI H13 steel displayed up to 33.5 times and 2.4 times higher corrosion resistance than untreated AISI H13 steel and martensitic AISI 431 steel, respectively. This suggests potential use of borided AISI H13 steel in the steam turbines and marine applications as an alternative to the more costly martensitic and duplex stainless steel grades. The corrosion resistance depended on the phase structure (single- or dual-layer), density, thickness and surface roughness of the boride coatings. Graphic
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    Properties of bricks with waste ferrochromium slag and zeolite
    (Elsevier Sci Ltd, 2013) Gencel, Osman; Sutcu, Mucahit; Erdogmus, Ertugrul; Koc, Vandettin; Cay, Vedat Veli; Gok, Mustafa Sabri
    Effect of ferrochromium slag, zeolite and combinations on physical, mechanical, thermal conductivity and microstructure properties of bricks was investigated. They were substituted to brick raw material. Semi-dry mixtures were compressed with 20 MPa. Samples were fired at rate of 5 degrees C/min until 900 degrees C for 2 h. Characterization of fired bricks, density, porosity, water absorption, weight loss, compressive and bending strength, thermal conductivity properties and microstructural and phase analysis of bricks were determined. Mechanical strengths of bricks were higher than 7 MPa. Thermal conductivity of samples decreases 42.3%. Results showed that bricks with zeolite and slag could be used as construction material. (C) 2013 Elsevier Ltd. All rights reserved.
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    Radiographic inspection of AISI 420 steel friction welds
    (Carl Hanser Verlag, 2018) Kati, Nida; Cay, Vedat Veli; Ozan, Sermin; Caligulu, Ugur; Turkmen, Mustafa
    In this study, X-ray radiographic tests of AISI 420 steel welded by friction welding were studied. During the welding process, three different rotations, 700, 1000 and 1300, were employed while the other parameters such as friction pressure, friction time, upsetting-pressure and upsetting-duration were unchanged. After the completion of welding process, the welded joints were subjected to radiographic tests by X-raydiffraction. The result of the radiographic tests indicates that by increasing rotation speed the amount of flash and joining properties/performance increases in all samples. The best properties of the AISI 420 martensitic stainless steel joints were observed in samples welded at a rotation speed of 1300 (rpm). It has been determined that in harmony with the definition of welding defects and respective radiographic images, lack of fusion is the most common welding defect.
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    Recycling of metallurgical wastes in ceramics: A sustainable approach
    (Elsevier Sci Ltd, 2022) Er, Yusuf; Sutcu, Mucahit; Gencel, Osman; Totic, Ermedin; Erdogmus, Ertugrul; Cay, Vedat Veli; Munir, Muhammad Junaid
    This pioneering study focuses on the production, testing, and comparative assessment of iron-rich metallurgical wastes, including copper slag (CS), rolling mill scale (RMS), and ferrous-metal grinding dust (FGD), incorporated fired clay bricks. For this purpose, the fired clay bricks incorporating CS, FGD, and RMS are prepared considering three different dosages of wastes (i.e., 10 %, 20 %, and 30 % of the weight of clay) and fired at two different temperatures (i.e., 900 degrees C and 1000 degrees C). Various tests were performed to examine different physical, mechanical, durability, and leaching characteristics of bricks. Results show increased porosity and loss-on-ignition of brick samples with increased CS dosage. However, decreased apparent porosity and loss-on-ignition of brick samples are observed with the increased dosages of RMS and FGD. All the brick samples incorporating metallurgical wastes satisfy the compressive strength and water absorption requirements as per ASTM C62 and other building standards. Scanning electron microscopy shows homogeneous and dense microstructures for brick samples incorporating 30 % RMS and FGD dosages. For all the brick samples fired at 1000 degrees C, amounts of heavy metals in the leachates are detected well below the Environmental Protection Agency specified limits. Based on the results, recycling of CS, RMS, and FGD in brick manufacturing is an attractive solution to avoid environmental issues related to landfilling of hazardous wastes and achieve efficient waste management.