Browsing by Subject "Particle morphologies"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Factors influencing the crushing strength of some Aegean sands(Springer Verlag, 2012) Erzin Y.; Patel A.; Singh D.N.; Tiga M.G.; Yılmaz I.; Srinivas K.Engineering properties of sands mainly depend on the integrity of the particles, which in turn has a strong bearing on their crushing strength. Seven different Aegean sands were tested for mineralogy, particle shape, size and specific gravity and the influence of aspect ratio, particle composition, particle shape and size on the crushing strength was examined. As the Aegean sands have a small range of sphericity and roundness, crushing strength tests were also performed on five Anatolian sands. A multiple regression analysis was carried out and an equation proposed to determine the crushing strength value of the Aegean sands. The computed values were found to be in good agreement with those obtained from the experimental investigations. It is concluded that the equation is sufficiently accurate to be a useful, time- and cost-effective way of obtaining crushing strength estimations at the preliminary stage of site investigations. © 2012 Springer-Verlag.Item Investigations into factors influencing the CBR values of some Aegean sands(Sharif University of Technology, 2016) Erzin Y.; Türköz D.; Tuskan Y.; Yilmaz I.The California Bearing Ratio (CBR) value of the soils is very important for geotechnical engineering and earth structures. A CBR value is affected by the soil type and different soil properties. With this in view, in this paper, an attempt has been made for investigating the factors that affect the CBR values of some Aegean sands collected from nine different locations in Manisa (Turkey). The sand samples were tested for mineralogy, particle shape and size, and specific gravity. The CBR tests were then performed on these samples at different dry densities to examine the influence of dry density, relative density, water content, and particle shape and size on the CBR value. Multiple Regression Analysis (MRA) was performed to predict the CBR value of the sands by using the experimental results. Moreover, several performance indices, such as coefficient of correlation and variance account for mean absolute error and root mean square error, were calculated to check the prediction capacity of the proposed MR equation. The obtained indices make it clear that the equation derived from the samples used in this study applies well, with an acceptable accuracy, to the CBR estimation at the preliminary stage of site investigations. © 2016 Sharif University of Technology. All rights reserved.Item Structural and optical properties of SrAl2O4: Eu2+/Dy3+ phosphors synthesized by flame spray pyrolysis technique(Elsevier B.V., 2019) Gültekin S.; Yıldırım S.; Yılmaz O.; Keskin İ.Ç.; Katı M.İ.; Çelik E.In this study Sr0.985Al2O4:0.005Eu2+/0.01Dy3+ luminescent materials with long afterglow and high intensity were synthesized by flame spray pyrolysis (FSP) method for the first time. Precursor solution was divided into two separate part. One of the parts was used FSP process, the other one was dried to simulate sol-gel process. Thermal properties and organic content of FSP derived particles and dried gel were compared using DTA-TG and FTIR devices. FSP derived particles were sintered in argon medium at 1200 oC. Phase and elemental analysis of the final phosphors were carried out by X-Ray Diffraction (XRD) and X-Ray Photo electron Spectroscopy (XPS) measurements. Scanning electron microscopy (SEM) images were obtained to observe particle morphology. Optical properties of phosphor were determined by Photoluminescence (PL), thermoluminescence (TL) and radioluminescence (RL) measurements. The emission spectra of Sr0.985Al2O4:0.005Eu2+/0.01Dy3+ were composed by a green band at 525 nm at room temperature when it was excited by 350 nm light, assigned to anomalous luminescence originated by Eu2+ and Dy3+ in the host lattice. There were estimated peaks at around 90, 130, 170 and 200 oC under the main glow curve in the sample irradiated by X-ray and He-Ne laser (λexc = 632 nm). RL spectrum of Sr0.985Al2O4:0.005Eu2+/0.01Dy3+ powders have four distinct emission peaks at around 527 nm, 576 nm, 667 nm, 753;nm and a comparatively weak emission band at about 846 nm. © 2018 Elsevier B.V.Item Characterization of Tantalum–Titanium Powders with Universal Powder Bed (UPB) System for Electron Beam Melting Process(Pleiades Publishing, 2020) Ahu Celebi; Gulizia S.; Doblin C.; Fraser D.; Prentice L.Electron beam melting (EBM) is a powder bed fusion additive manufacturing (AM) technique that produces three-dimensional (3D) parts by fusing metallic powders with a high-energy electron beam. Powder has been major issue for the properties of the final parts. Hence, establishing the effect of powder properties on the final product properties is important for producing parts of quality. In this study, Ta–60Ti, Ta–50Ti, Ta–40Ti was a blend of tantalum and titanium powders. The blend of powder was characterized in terms of the particle size distribution (PSD), bulk and tap density, flowability in Hall Funnel flowmeter and particle morphology. In addition, a universal powder bed (UPB) system was used to characterize the powder behavior raking because the UPB system allows a quick assessment of the powder spreading behavior in AM processes. Surface roughness’s of the powder after raking with universal powder bed (UPB) system, the microstructural heterogeneity, defect distributions were investigated. © 2020, Allerton Press, Inc.