Drastic microstructural modification of Bi2Ca2Co2Oy ceramics by Na doping and laser texturing

Bi2Ca2-xNaxCo2Oy materials with x = 0 = x = 0.125, have been prepared either by sintering through the classical ceramic method, or textured using the laser floating zone technique. XRD results have shown that Bi2Ca2Co2Oy phase is the major one, independently of the Na content, in both kind of samples. SEM studies have shown a drastic microstructural modification between sintered and laser-textured materials. Na-doping increases density and grain sizes in sintered materials, while it enhances grain alignment in laser-grown materials. Moreover, it decreases secondary phase content in all cases. Electrical resistivity is also drastically reduced through texturing, when compared to the sintered samples, and Na-doping further decreases it. The lowest values determined in the laser-textured samples (26 mO cm at 650 °C) are around 40% lower than the best in sintered materials. On the other hand, S has been only slightly affected for Na-doping or processing method for all samples. Consequently, the highest power factor at 650 °C (0.18 mW/K2 m) has been obtained in laser-grown 0.075Na-doped samples, which is around 20 and 70% higher than the measured in undoped laser-textured samples, and sintered ones, respectively. Se han preparado materiales de composición Bi2Ca2-xNaxCo2Oy, con x = 0 ≤ x ≤ 0,125, por el método de estado sólido, además de texturarlos mediante la técnica de zona flotante inducida por láser. Los resultados de XRD han mostrado que la fase Bi2Ca2Co2Oy aparece como la mayoriraria, independientemente del contenido de Na, en ambos tipos de muestras. Los estudios SEM han encontrado una drástica modificación microestructural entre materiales sinterizados y texturados. El dopado con Na aumenta la densidad y el tamaño de grano en materiales sinterizados, mientras que mejora la orientación de los granos en materiales texturados. Además, disminuye el contenido de fases secundarias en todos los casos. La resistividad eléctrica disminuye drásticamente con el texturado, en comparación con las muestras sinterizadas, mientras que el dopado con Na la disminuye aún más. Los valores más bajos determinados en muestras texturadas (26 mΩ cm a 650 °C) son alrededor del 40% menor que los mejores datos publicados en materiales sinterizados. Por otro lado, S solo se ha visto afectado levemente, tanto por el dopado como por el método de procesado. En consecuencia, el máximo factor de potencia a 650 °C (0,18 mW/K2 m) se ha obtenido en muestras dopadas con 0,075 Na y texturadas, que es alrededor de un 20 a un 70% superior al medido en muestras texturadas sin dopar y sinterizadas, respectivamente

Peat and lignite leaching process with tetralin in autoclave to produce oil

Instead of directly burning a lignite having low calorific value and peat, the Elbistan lignite (L) and the Adiyaman peat (P) were mixed and leached in an autoclave to obtain an oil to not only provide the demand for energy but also protect the environment. The effects of the peat ratio in the mixture on the properties of co-liquefaction products (oil, char, asphaltene, and preasphaltene) and oil yield were investigated in details. The products were characterized by XRD, FTIR, and elemental analysis. In addition, the composition of the oil was identified by GC/MS, showing that the peat ratio did not affect the chemical composition of the oil due to the high lignin content and the nearly same elemental compositions. On the other hand, the oil yield for a co-liquefaction process was found as 34.3% to be higher than the average value of oil yields obtained from the individual feeds (24.3% for lignite and 28% for peat), showing the synergistic effects between the lignite and peat. The obtained oil was paraffinic-low waxy oil with 5138.62 kcal/kg of calorific value and 0.94 g/cm3 density. Finally, it was suggested that the production of a more valuable product using the peat and the lignite having low calorific value will not only contribute more to the country's economy in future but also be better for the environment, instead of directly burning them

Effect of Microwave Radiation on Coal Flotation

Most low-rank coals are high in moisture and acid functional groups, therefore showing poor floatability. Drying, which removes the water molecules trapped in the pores and adsorbed at the surface of coal, decreases the hydrophilic character and improves the floatability. Microwave heating, whose simplest application is drying, was applied at 0.9 kW power level for 60 sec exposure time in the experiments to decrease the moisture content of coal in order to enhance the hydrophobicity. The flotation tests of microwave-treated coal by using heptanol and octanol lead to a higher flotation yield and ash removal than original coal

Sedimentology, petrography and diagenesis of Eocene-Oligocene evaporites: the Tuzhisar Formation, SW Sivas Basin, Turkey

The study area is situated in the southwestern part of the Sivas Basin. Sediments of the Ortakoy Formation (Middle-Upper Eocene) of flysch facies were deposited in a shallow marine environment and consist of interstratified sandstone, shale and calcareous mudstone. The Karaziyaret basaltic dikes cut the Ortakoy Formation. The Ortakoy Formation is comformably overlain by the evaporite-dominated Tuzhisar Formation. Gradual transitions between these two stratigraphic units crop out between Yenikoy and Yenituzhisar villages

New lightweight colemanite-added perlite brick and comparison of its physicomechanical properties with other commercial lightweight materials

Lightweight bricks can be produced by mixing the expanded perlite, CMC, coal dust and water. However, it may not achieve some of the physicomechanical properties. Therefore, colemanite is chosen in the present study to obtain lightweight bricks with high strength, heat and sound insulating and neutron shielding properties in the field of construction. The bricks were prepared by using different amount of colemanite (0-20% by weight) at different temperatures (200-400 °C). Optimum physicomechanical property of the brick was obtained after the heat treatment at 400°C when 10% colemanite was added into the brick. Its physicomechanical properties (compressive strength, point loading index, unit weight, ultrasonic transit speed, water adsorption, porosity, heat and sound conductivity and sound insulation and neutron shielding effectiveness) were compared with the commercial lightweight construction bricks (normal brick, sandwich brick, gas concrete and pumice block). Our results indicated that brick studied in this article had better physical properties than the other construction bricks. © 2014 Elsevier Ltd. All rights reserved.BOREN-2008-B0201This work is supported by National Boron Research Institute (BOREN) via project number BOREN-2008-B0201

Exergetic Comparison of Various Flow Patterns in PEMFCs

In this study, 6 different novel flow channels of the "proton exchange membrane" (PEM) type fuel cells were designed and modeled, while evaluations were conducted on three-dimensional channels of various designs using COMSOL Multiphysics simulation software. Proposed fuel cell designs and flow channel geometries were compared to existing exergetically-efficient fuel cell designs in terms of total exergy efficiency in a 3D manner as a novel tool for fuel cell investigations. Exergy efficiency analyses were conducted on the membrane surfaces of the proposed designs in addition to the anode and cathode side exergy analyses, and exergetic efficiencies of the alternatives. It is found that Design 6 is the best flow channel design with relatively high values and homogeny in exergy efficiency. The multi-inlet/outlet style while sustaining the reaction long enough for the reactant depletion leads to high-efficiency levels as seen from the results with average efficiency of 24%

A Study on Characterization and Use of Flotation to Separate Unburned Carbon in Bottom Ash from Cayirhan Power Plant

WOS: 000285349700009In this study, bottom ash from the Tuncbilek power plant has been characterized by X-ray fluorescence, X-ray diffraction, and infrared analysis. The bottom ash sample is potentially of class C type and has unburned carbon. The unburned carbon was separated from the bottom ash in a laboratory flotation cell. In the flotation experiment, sodium silicate (as a potential dispersant and depressant), butanol (promoter), kerosene oil (collector), and pine oil (frother) were used and the optimization of these flotation reagents were done through statistical modeling using a full two-level factorial design in order to evaluate the main and interaction effects of variables in flotation of unburned carbon; the evaluation of the results was done by Yates' notation. Test results showed that a product with 45.41% combustible grade at 40.0% recovery and 94.86% ash rejection was obtained at 1.98 g/kg sodium silicate, 1.38 g/kg promoter, 4.95 g/kg collector, and 2.41 g/kg frother.Nigde University [FEB2008/14]This work has been supported by Nigde University, Scientific Research Projects Directorate (BAP), Project FEB2008/14. The authors would like to thank Nigde University

Thermoluminescence study of Mn doped lithium tetraborate powder and pellet samples synthesized by solution combustion synthesis

In this paper, the thermoluminescence (TL) dosimetric characteristics under beta-ray, x-ray and gamma-ray excitations of powder and pellet Mn-doped lithium tetraborates (LTB) which were produced by solution combustion synthesis technique were investigated, and the results were compared with that of TLD-100 chips. The chemical composition and morphologies of the obtained LTB and Mn-doped LTB (LTB:Mn) were confirmed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) with EDX. LTB:Mn was studied using luminescence spectroscopy. In addition, the effects of sintering and annealing temperatures and times on the thermoluminescence (TL) properties of LTB:Mn were investigated. The glow curves of powder samples as well as pellet samples exposed to different beta doses exhibited a low temperature peak at about 100 °C followed by an intense principal high temperature peak at about 260 °C. The kinetic parameters (E, b, s) associated with the prominent glow peaks were estimated using Tm-Tstop, initial rise (IR) and computerized glow curve deconvolution (CGCD) methods. The TL response of integral TL output increased linearly with increasing the dose in the range of 0.1-10 Gy and was followed by a superlinearity up to 100 Gy both for powder and pellet samples using beta-rays. Powder and pellet LTB:Mn were irradiated to a known dose by a linear accelerator with 6 and 18 MV photon beams, 6-15 MeV electron beams and a traceable 137Cs beam to investigate energy response. Further, TL sensitivity, fading properties and recycling effects related with beta exposure of LTB:Mn phosphor were evaluated and its relative energy response was also compared with that of TLD-100 chips. The comparison of the results showed that the obtained phosphors have good TL dose response with adequate sensitivity and linearity for the measurement of medical doses. © 2016 Elsevier B.V. All rights reserved.North Atlantic Treaty Organization: SfP984649 FEF2014YL3, FUA-2015-4300 Firat University Scientific Research Projects Management Unit British Association for Psychopharmacology: 2015/54This research is sponsored by NATO ?s Emerging Security Challenges Division in the framework of the Science for Peace and Security Programme (Belgium) under the Project number SfP984649 and the Cukurova University Rectorate through the Projects FUA-2015-4300 and FEF2014YL3 . We gratefully acknowledge NATO, Belgium and Cukurova University for their financial support. We would like to thank Baskent University Hospital, Radiation Oncology Department for their permission in performing the x-ray photon irradiations and the Transfusion Center for gamma ray irradiations, and acknowledge Assoc. Prof. Dr. Aysen Yilmaz for the XRD results. We appreciate Prof. S. Ubizskii, Dr. Y. Zhydachevskii and Dr. A. Luchechko a lot analyzing spectroscopic measurements. The authors also thanks to Inonu University Scientific Research Projects Directorate (BAP) that also partially funded the project (Project number: 2015/54 )