Download or read book Production of Cerium Oxide Microspheres by an Internal Gelation Sol gel Process written by Jeffrey John Wegener and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The experiments performed for this research were completed to produce solid cerium oxide microspheres by an internal gelation sol-gel process. The motivation for this work was to develop a process that would enable the fabrication of a storage or transmutation form for the plutonium and transuranics (TRU) from the Uranium Extraction Plus (UREX) used fuel reprocessing process. This process is being investigated by the Department of Energy (DOE) and the Advanced Fuel Cycles Initiative (AFCI) through the Nuclear Energy Research Initiative. The internal gelation production of cerium oxide involves the combination of hexamethylenetetramine (HMTA), urea, and cerium nitrate solutions at ~100°C. Microspheres were produced by injection of a broth solution into a flowing stream of hot silicone oil. The captured microspheres were aged, washed, and then underwent Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and XRay Diffraction (XRD) analysis. The process variables examined in this study include the concentrations of HMTA, urea and cerium nitrate, the process temperature, the postgelation aging time, and the product washing conditions. Over a series of 70 experiments, it was determined that a broth solution containing a mixture of 1.45 M cerium nitrate and 1.65 M HMTA and urea (1:1 ratio) solutions produced the best cerium oxide microspheres. The spheres were aged for 30 to 60 minutes and then washed in hexane to remove the silicone oil and a subsequent series of ammonium hydroxide washes to remove unreacted product and to fully gel the microspheres. Through DSC analysis it was determined that excess wash or unreacted product may be removed by an exothermic reaction at approximately 200°C. The XRD analysis of unheated spheres showed the presence of cerium oxide with additional cerium-bearing organics. Following heating, the microspheres were completely converted to cerium oxide.
Download or read book Processing and Characterization of Sol Gel Cerium Oxide Microspheres written by and published by . This book was released on 2016 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of interest to space exploration and power generation, Radioisotope Thermoelectric Generators (RTGs) can provide long-term power to remote electronic systems without the need for refueling or replacement. Plutonium-238 (Pu-238) remains one of the more promising materials for thermoelectric power generation due to its high power density, long half-life, and low gamma emissions. Traditional methods for processing Pu-238 include ball milling irregular precipitated powders before pressing and sintering into a dense pellet. The resulting submicron particulates of Pu-238 quickly accumulate and contaminate glove boxes. An alternative and dust-free method for Pu-238 processing is internal gelation via sol-gel techniques. Sol-gel methodology creates monodisperse and uniform microspheres that can be packed and pressed into a pellet. For this study cerium oxide microspheres were produced as a surrogate to Pu-238. The similar electronic orbitals between cerium and plutonium make cerium an ideal choice for non-radioactive work. Before the microspheres can be sintered and pressed they must be washed to remove the processing oil and any unreacted substituents. An investigation was performed on the washing step to find an appropriate wash solution that reduced waste and flammable risk. Cerium oxide microspheres were processed, washed, and characterized to determine the effectiveness of the new wash solution.
Download or read book Fabrication of Cerium Oxide and Uranium Oxide Microspheres for Space Nuclear Power Applications written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cerium oxide and uranium oxide microspheres are being produced via an internal gelation sol-gel method to investigate alternative fabrication routes for space nuclear fuels. Depleted uranium and non-radioactive cerium are being utilized as surrogates for plutonium-238 (Pu-238) used in radioisotope thermoelectric generators and for enriched uranium required by nuclear thermal rockets. While current methods used to produce Pu-238 fuels at Los Alamos National Laboratory (LANL) involve the generation of fine powders that pose a respiratory hazard and have a propensity to contaminate glove boxes, the sol-gel route allows for the generation of oxide microsphere fuels through an aqueous route. The sol-gel method does not generate fine powders and may require fewer processing steps than the LANL method with less operator handling. High-quality cerium dioxide microspheres have been fabricated in the desired size range and equipment is being prepared to establish a uranium dioxide microsphere production capability.
Download or read book High Performance Ceramics X written by Wei Pan and published by Trans Tech Publications Ltd. This book was released on 2018-08-31 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the papers presented at the Tenth International Conference on High-Performance Ceramics (CICC-10), which was held from November 4 to 7, 2017, in Nanchang, China. The Collection covers most aspects in the field of high-performance ceramics (advanced ceramics), including processing, microstructures, and properties of structural and functional ceramics. Especially, the papers gave an overview of the most recent development in high-performance ceramics in China.
Download or read book Sol Gel Process Development and Microsphere Preparation written by and published by . This book was released on 1966 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Academic Studies in Science and Mathematics Sciences written by Sema Isisag Ucuncu and published by Livre de Lyon. This book was released on 2020-12-15 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Academic Studies in Science and Mathematics Sciences
Download or read book Preparation Coating Evaluation and Irradiation Testing of Sol Gel Oxide Microspheres written by and published by . This book was released on 1966 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Methodology for Determining Optimum Process Parameters for Production of Hydrous Metal Oxides by Internal Gelation written by J. L. Collins and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this report is to describe a simple but very useful experimental methodology that was used to determine optimum process parameters for preparing several hydrous metal-oxide gel spheres by the internal gelation process. The method is inexpensive and very effective in collection of key gel-forming data that are needed to prepare the hydrous metal-oxide microspheres of the best quality for a number of elements.
Download or read book A sol gel process for the production of ceramic microspheres of thorium dioxide from low viscosity sols written by C. W. Turner and published by . This book was released on 1986 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preparation of Glass Microspheres by Sol gel Process written by Jack Yuan-Chieh Ding and published by . This book was released on 1988 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1973 with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preparation of Lanthanide Oxide Microspheres by Sol gel Methods written by C.J. Hardy and published by . This book was released on 1967 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation on Preparation of ThO2 Microspheres by Internal Gelation Method 11 Modified H process written by and published by . This book was released on 1975 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fabrication and Characterization of Hollow Silica Aerogel Spheres Using Sol gel Processing in the Dual Nozzle Generation System Final Report written by and published by . This book was released on 1993 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: A system was designed for fabricating uniform, hollow silica aerogel spheres of controlled size, thickness, and porosity that may be required for manufacture of cryogenic ICF Targets. The method was a combination of a droplet generation method and sol-gel processing. The parameters controlling the properties of the resulting silica aerogel spheres were the detailed chemical makeup of the reactant solution and the gelation medium, and the dimensions and relative positions of the nozzles used for the droplet generation. A detailed study designed to understand and control the kinetics of the sol-gel processing that was responsible for the hollow silica-aerogel sphere formation is reported. Specifically, the optimum rheology and stoichiometry of the reactant solution, the make-up of the gelation/levitation gas mixture, and the characteristics of the resulting silica-aerogel spheres, such as size, thickness, porosity, pore size, and density, were investigated. Supercritical drying was performed for the elimination of residual solvents without shrinkage and cracking of hollow spheres. To monitor the hydrolysis and polymerization reactions Fourier Transform Infrared Spectroscopy, and Nuclear Magnetic Resonance were used. Thermogravimetric Analysis and Differential Thermal Analysis were used, along with the measurement of weight loss and linear shrinkage, to study the response of the aerogel spheres under heat treatment. Nitrogen adsorption-desorption isotherms were obtained to get such information as average pore size, pore size distribution, and specific surface area for the characterization of the internal structure of silica aerogel spheres. Hollow silica aerogel spheres with a low density and a high specific surface area were obtained from a reactant solution of 134-composition by using a gas levitation gelation method.
Download or read book Sol gel Synthesis of Mesoporous Silica Migrospheres for Use in Liquid Chromatography written by Donal Anthony Keane and published by . This book was released on 2007 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Monodisperse mesoporous SiO2 microspheres have been synthesized by combining two sol-gel processes : the Stöber, Fink, Bohn (SFB) method for the synthesis of monodisperse SiO2 microspheres and the surfactant templating approach for the synthesis of mesoporous molecular sieves. These spheres fall into two categories : monodisperse precipitates and surfactant templated silica, the backgrounds of which are described in the introduction. The particle and pore size have been tailored to meet specifications for Ultra Performance Liquid Chromatography (UPLC). Chapter 2 shows how the particle size is controlled : by relating experimental conditions (reactant concentration, temperature, agitation and batch size) to final particle size in a systematic manner. Important processing issues such as reproducibility and particle aggregation are investigated. Chapter 3 shows how the pore size is controlled : by postsynthesis hydrothermal treatments in 1) water-amine emulsion and 2) in aqueous NaOH/HF. Treatment effect on particle size is established. Chapter 4 describes preliminary experiments for the preparation of hierarchically porous SiO2 and SiO2-CeO2 composite thin films by spin coating from colloidal sphere suspensions. Further investigations on a SiO2-CeO2 powder composite are also reported. In Chapter 5 the significant conclusions are briefly outlined. Finally, in appendix A external chromatographic evaluation of the tailored silica spheres is described.
Download or read book Encyclopedia of Materials written by K. H. J. Buschow and published by . This book was released on 2001 with total page 1024 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accompanyind CR-ROM conrtains The Encyclopedia of Materials Science and Technology on a web access disc.
Download or read book Key Engineering Materials written by and published by . This book was released on 1987 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
