Chemical Interaction Between Uranium Oxide and Zircaloy-4 in the Temperature Range Between 900 and 1500°C

2009 ◽  
pp. 537-537-24 ◽  
Author(s):  
P Hofmann ◽  
C Politis
Keyword(s):  
Uranium Oxide ◽  
Chemical Interaction ◽  
Temperature Range

Silicon Carbide and Uranium Oxide Based Composite Fuel Preparation Using Polymer Infiltration and Pyrolysis

2006 ◽  
Author(s):  
Abhishek K. Singh ◽  
Suraj C. Zunjarrao ◽  
Raman P. Singh
Keyword(s):  
Silicon Carbide ◽  
Uranium Oxide ◽  
Chemical Interaction ◽  
Processing Technique ◽  
Spherical Particles ◽  
Ceramic Yield ◽  
Processing Scheme ◽  
Carbide Matrix ◽  
Silicon Carbide Matrix ◽  
Polymer Infiltration

Ceramic composite pellets consisting of uranium oxide, U3O8, particles in a silicon carbide matrix are fabricated using a novel processing technique based on polymer infiltration and pyrolysis (PIP). In this process, spherical particles of depleted uranium oxide, in the form of U3O8, are dispersed in liquid allylhydridopolycarbosilane (AHPCS), and subjected to pyrolysis up to 900°C under a continuous flow of ultra high purity (UHP) argon. Pyrolysis of AHPCS produces near-stoichiometric amorphous SiC at 900°C. Multiple polymer infiltration and pyrolysis (PIP) cycles are required to minimize open porosity and densify the silicon carbide matrix, in order to enhance the mechanical strength of the material. Structural characterization is carried out after first pyrolysis to investigate chemical interaction between U3O8 and SiC. The physical and mechanical properties are also quantified, and it is shown that this processing scheme promotes uniform distribution of uranium fuel source along with a high ceramic yield of the parent matrix. Furthermore, the processing technique involves lower energy requirements than conventional sintering processes currently in practice.

Chemical Interaction of Phosphates MII2P4O12 with Melted MICl or MINO3 (MI – Li, Na, K; MII – Mg, Co, Ni, Zn)

2015 ◽  
Vol 230 ◽  
pp. 297-302 ◽  
Author(s):  
Oksana V. Livitska ◽  
Nataliya Yu. Strutynska ◽  
Igor V. Zatovsky ◽  
Nikolay S. Slobodyanik
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ftir Spectroscopy ◽  
Powder Diffraction ◽  
Diffuse Reflectance ◽  
Chemical Interaction ◽  
Crystalline Phases ◽  
X Ray ◽  
Temperature Range ◽  
Scanning Electron

The interaction in the systemsMII2P4O12-MICl (MINO3) (MI– Li, Na, K;MII– Mg, Co, Ni, Zn) was investigated in temperature range 1073-673 K. The conditions of formation phosphates: Li3PO4,MIMIIPO4(MI– Na, K), Na4MII3(PO4)2P2O7, Na9Co3(PO4)5have been established. Obtained crystalline phases have been investigated using X-ray powder diffraction, Diffuse reflectance, Raman and FTIR spectroscopy and scanning electron microscopy methods.

scholarly journals Diffusion and chemical interaction of hydroxyl generated from photodissociation of water vapor in the temperature range in 294 K–891 K in helium flow

AIP Advances ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 115315
Author(s):  
Jun Shao ◽  
GuoHua Li ◽  
JingFeng Ye ◽  
ZhenRong Zhang ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Chemical Interaction ◽  
Helium Flow ◽  
Temperature Range

scholarly journals Physico-chemical interaction patterns of oxidized polyvinyl alcohol fraction with 4- and 5-aminosalicylic acids

2019 ◽  
Vol 58 (4) ◽  
pp. 77-84
Author(s):  
Galia G. Kutlugildina ◽  
◽  
Zalia F. Ramazanova ◽  
Yury S. Zimin ◽  
◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Aqueous Solutions ◽  
Stability Constants ◽  
Chemical Interaction ◽  
Average Molecular Weight ◽  
Complex Compounds ◽  
Interaction Patterns ◽  
Aminosalicylic Acid ◽  
Temperature Range ◽  
Aminosalicylic Acids

The interaction of the oxidized fraction of polyvinyl alcohol (OF of PVA) with 4- and 5-aminosalicylic acids (4- and 5-ASA) in aqueous solutions was examined by ultraviolet spectroscopy. OF of PVA is obtained by oxidation of polyvinyl alcohol in an aqueous medium affected by hydrogen peroxide (363 K, [PVA] = 3.5% wt., [H2O2] = 1 mol/l, toxid. = 45 min), further separated from the solution by acetone addition. The average molecular weight of the oxidized fraction of PVA, calculated from the experimentally found value of the characteristic viscosity using the Mark-Kun-Houwink equation, amounted to 4.5 kDa. It was found that the addition of the original (non-oxidized) polyvinyl alcohol to aqueous solutions of 4- and 5-ASA does not change their UV spectra. At the same time, the introduction of an oxidized fraction of polyvinyl alcohol into aqueous solutions of aminosalicylic acids leads to spectral changes, indicating intermolecular interactions and complexation. By the method of molar ratios, it was shown that in dilute aqueous solutions OF of PVA forms complex 1 : 1 compounds with 4-ASA and 5-ASA, i.e., one molecule of 4- or 5-aminosalicylic acid accounts for one carboxyl group of the oxidized PVA fraction. Using this method, in the 291-316 K temperature range, the stability constants (K) of the resulting complex compounds were calculated. The results analised demonstrated that the oxidized fraction of polyvinyl alcohol forms strong enough complexes with 4- and 5-aminosalicylic acids: the K values in the temperature range under study vary within (1-7)∙104 l/mol. It was found out that with increasing temperature, the values of stability constants of complex compounds decrease. The study of the temperature dependence of K made it possible to determine the standard values of the changes in the Gibbs energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) of complexing. Negative values of thermodynamic parameters indicate a spontaneous process of formation of complexes, their exothermicity and the resulting constraints of the movements of molecules.

scholarly journals INTERACTION OF TITANIUM DIOXIDE WITH EUTECTIC MELT NaCl - CaCl2

2020 ◽  
Vol 86 (11) ◽  
pp. 24-33
Author(s):  
Anatoliy Omel’chuk ◽  
Olexandr Ivanenko ◽  
Yuliia Pohorenko ◽  
Tamara Pavlenko ◽  
Igor Skryptun
Keyword(s):  
Titanium Dioxide ◽  
Chemical Interaction ◽  
Calcium Titanate ◽  
Solid Residue ◽  
Exchange Reactions ◽  
Temperature Range ◽  
Salt Phase ◽  
Increasing Temperature ◽  
Titanium Compounds ◽  
Eutectic Melt

The results of studies of the interaction of titanium dioxide with the eutectic melt of (0.48) NaCl–(0.52) CaCl2 (mol.) in the temperature range of 823–1073 K are shown. It is established that the interaction of titanium dioxide with the melt of sodium chlorides and calcium is accompanied by the formation in the salt phase of titanium compounds soluble in 1.0% solution of hydrochloric acid, and in the solid residue is recorded calcium titanate, and the number of products formed in both phases substantially. At temperatures above 923 K is formed calcium titanate, the relative amount of which increases with increasing temperature by reducing the equilibrium content of titanium compounds in the salt phase. At temperatures below 923 K, calcium titanate was not detected in the interaction products, and the content of titanium compounds in the salt phase was higher than at higher temperatures. The absence of calcium titanate in the solid residue after prolonged isothermal contact of TiO2 with the NaCl-CaCl2 melt in the temperature range 823–923 K may be due to the fact that at such temperatures, the dissolution of titanium dioxide occurs by physical mechanism or by a mixed physicochemical mechanism. The results of the calculations by the Schroe­der-Le Chatelier equation support this. In the specified temperature range, the concentration of titanium compounds increases with tempe­rature.  Starting   from 923 K the nature of the interaction between titanium dioxide and the melt changes. Apparently at such temperatures (923–1073 K), the contribution of the chemical interaction between the components accompanied by the formation of calcium metatanate and volatile titanium compounds is dominant. The quantitative content of the phase, which in composition in the solid residue is identified as CaTiO3, increases, and the number of titanium compounds in the salt phase (based on TiO2) decreases. The change of isobaric isothermal potential (∆G) in the temperature range of 300–1300 K of the exchange reactions between sodium chloride and calcium and titanium oxide is positive, so self-directed course is unlikely. The lowest Gibbs free energy values correspond to the reaction of the interaction of calcium chloride with titanium dioxide to form titanate or calcium oxide and tetrachloride or titanium oxochloride.

scholarly journals JUSTIFICATION OF THE SEARCH FOR THE COMPOSITION AND TECHNOLOGY OF PRODUCTION OF HEAT INSULATING MATERIAL OF HIGHER STRENGTH

2021 ◽  
pp. 87-100
Author(s):  
A.G. Nevynsky ◽  
◽  
S.Yu. Kel’ina ◽  
V.A. Chvyr ◽  
◽  
...  
Keyword(s):  
Phase Composition ◽  
Wide Temperature Range ◽  
Liquid Glass ◽  
Chemical Interaction ◽  
Environmental Safety ◽  
Optical Methods ◽  
Technological Parameters ◽  
Insulating Material ◽  
X Ray ◽  
Temperature Range

Abstract. The growth of requirements for the quality and performance of materials used for the construction of ship premises indicates the need to create new types of heat-insulating and structural and finishing products that can provide the stability of operational properties in a wide temperature range, high aesthetics and environmental safety. One of the means of providing these requirements is the use of non-flammable and non-toxic heat-insulating materials of increased strength during a fire. The processes of interaction between the components, the structure and phase composition of the obtained materials studied using complex X-ray phase, IR spectroscopic, and electron-optical methods of analysis. The main estimated quality indicators of the manufactured samples were taken: material density, thermal conductivity, ultimate strength in static bending, water absorption, also flammability and fire resistance, which determined in accordance with the current state standard and international ISO standards. The determination of the basic recipe composition of the raw mixture and the influence of technological parameters on the strength characteristics of the composite material was carried out using the method of mathematical planning of the experiment. The results obtained made it possible to fairly accurately outline the boundaries of variation of the composition of the vermiculite-silicate presscomposition and the main technological parameters. The results of the studies carried out correlate with the indicators of the physical, mechanical and technical properties of the varieties of the modified material, which makes it possible to purposefully search for the optimal composition and technological modes of manufacturing heat-insulating material for shipbuilding purposes. Using the methods of X-ray structural and electron-optical analysis, infrared spectroscopy, it has been established that as a result of heat treatment of the vermiculate-silicate presscomposition, complex physicochemical processes occur. It was found that in the system vermiculate–liquid glass –hardener, the chemical interaction of Al2O3 of vermiculate with liquid glass occurs with the formation of aluminosilicates. Additional crystallization at the vermiculite-water glass interface causes the formation of an intermediate layer of products, which prevents the occurrence of tension. The main regularities of directed synthesis in the system vermiculate–binder–hardener of neoplasms characterized by high strength and thermal stability in a wide temperature range have been studied. The optimal ratios of the main recipe components (vermiculate–binder–hardener), also a certain influence of water repellents, modifiers and reinforcing components on the processes of interaction between components, phase composition and structure of the composite have been determined.

Interaction of UO2 and Zircaloy During the Chernobyl Accident

1996 ◽  
Vol 465 ◽  
Author(s):  
S. V. Ushakov ◽  
B. E. Burakov ◽  
S. I. Shabalev ◽  
E. B. Anderson
Keyword(s):  
Chernobyl Accident ◽  
Uranium Oxide ◽  
Chemical Interaction ◽  
Liquid Immiscibility ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
The West ◽  
X Ray ◽  
The Core ◽  
Different Types

ABSTRACTA summary of the results collected during the studies of the products of a chemical interaction between uranium oxide fuel and Zircaloy cladding in the Chernobyl accident is presented in this paper. The reaction products are mainly Zr-U-containing phases with different U/Zr ratio and are described on the basis of electron microprobe and X-ray diffraction (XRD) analyses. The Zr-U-bearing phases were discovered among the inclusions in different types of Chernobyl fuel-containing masses (”lava”) inside the destroyed 4th Unit and in hot particles collected up to 12 km from the 4th Unit along the West Plume. A correlation of data on the chemical composition and phase interrelations obtained in investigated samples with a phase diagram of Zr(O) - UO2 shows, that a temperature >1900 °C was reached in a part of the core before the explosion. The detection of hot particle with segregated morphology points out that liquid immiscibility existed between U-rich and Zr-rich melts. This and other observations indicate that the core temperature locally was above 2400–2600°C.

Defects in ion implanted silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 386-387
Author(s):  
J.A. Lambert ◽  
P.S. Dobson
Keyword(s):  
Defect Structure ◽  
Dislocation Loops ◽  
Frank Loop ◽  
Burgers Vector ◽  
Temperature Range ◽  
Perfect Dislocation ◽  
Contrast Analysis ◽  
Image Position ◽  
Ion Implanted

The defect structure of ion-implanted silicon, which has been annealed in the temperature range 800°C-1100°C, consists of extrinsic Frank faulted loops and perfect dislocation loops, together with‘rod like’ defects elongated along <110> directions. Various structures have been suggested for the elongated defects and it was argued that an extrinsically faulted Frank loop could undergo partial shear to yield an intrinsically faulted defect having a Burgers vector of 1/6 <411>.This defect has been observed in boron implanted silicon (1015 B+ cm-2 40KeV) and a detailed contrast analysis has confirmed the proposed structure.

Domain coarsening by grain boundary migration in ordered Ni4Mo

1986 ◽  
Vol 44 ◽  
pp. 560-561
Author(s):  
K. Vasudevan ◽  
H. P. Kao ◽  
C. R. Brooks ◽  
E. E. Stansbury
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Short Range ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Rapid Cooling ◽  
Temperature Range ◽  
Fee Structure ◽  
Domain Coarsening ◽  
Boundary Reaction

The Ni4Mo alloy has a short-range ordered fee structure (α) above 868°C, but transforms below this temperature to an ordered bet structure (β) by rearrangement of atoms on the fee lattice. The disordered α, retained by rapid cooling, can be ordered by appropriate aging below 868°C. Initially, very fine β domains in six different but crystallographically related variants form and grow in size on further aging. However, in the temperature range 600-775°C, a coarsening reaction begins at the former α grain boundaries and the alloy also coarsens by this mechanism. The purpose of this paper is to report on TEM observations showing the characteristics of this grain boundary reaction.

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