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1.
V. A. Sokolov T. Ya. Malysheva M. D. Gasparyan 《Refractories and Industrial Ceramics》2008,49(2):146-148
Details are given of the synthesis and testing of flux-cast refractory materials in the alumina-rich region of the Al2O3-MgO-B2O3 system; XRD and petrography indicate that the main structure-forming phases are corundum and magnesian spinel. In subordinate
amounts there are the boroaluminate 9Al2O3·2B2O3 and the previously unknown compound 4Al2O3·MgO·2B2O3, whose composition has been established by microprobe analysis. Corrosion tests showed that three-component systems containing
magnesium and boron oxides at levels of 5–10% do not increase the corrosion resistance of refractories in molten sodium-calcium-silicate
glass and electrovacuum borosilicate glass.
__________
Translated from Novye Ogneupory, No. 3, pp. 161–163, March, 2008. 相似文献
2.
Structure and crystalline behavior of the ternary system ZnO-B2O3-P2O5 glasses were investigated by means of X-ray diffraction (XRD) and infrared Raman spectra. The research showed that number
of the planar [BO3] units increases with the increase of B2O3 content. When the B2O3 content is above ≥10 mol %, the relative content of planar [BO3] units increases rapidly and causes weakening of the glass structure and decrease in the chemical stability. In the crystallized
glasses the predominant crystal phase Zn2P2O7 decreases with the increase of B2O3 content, while the crystal phase BPO4 increases with it, which cause the declining of chemical stability and the decrease of thermal coefficients of expansion. 相似文献
3.
Physical (density, viscosity) and thermophysical (heat capacity, thermal conductivity) properties of a melt of the eutectic
composition (wt %) 84NaPO3 · 8Na2B4O7 · 8LiF have been investigated. It has been demonstrated that this eutectic mixture is a promising material for the use as
a high-temperature heat-transfer agent. 相似文献
4.
The effect of the relative volume of the conducting phase on the electroconductivity of phase-separated glasses in the ternary system Na2O–B2O3–SiO2, whose compositions are on the same glass transition isotherm at 550°C, is investigated. It is demonstrated that the electroconductivity of phase-separated sodium borosilicate glasses does not depend on the relative volume of the conducting phase (within the limits from 0.3 to 0.9) under the condition that its composition invariable. 相似文献
5.
The crystallization of strontium borate glasses containing 16.7–43.0 mol % SrO is investigated. New crystalline compounds of the hypothetical compositions 2SrO · 3B2O3 (metastable) and SrO · 5B2O3 (stable below 750°C), as well as the metastable diborate modification β-SrO · 2B2O3, are revealed, and their X-ray powder diffraction data are obtained. It is demonstrated that, with a deficit of strontium oxide, the 4SrO · 7B2O3 compound forms solid solutions. Strontium triborate SrO · 3B2O3, which was previously prepared only through the dehydration of crystal hydrates, is produced using crystallization of glasses. The thermal stability of this compound is studied. The influence of the dispersity on the stability of different crystalline phases is discussed. Variants of the phase diagram for the SrO · B2O3-B2O3 system in the case of monolithic and dispersed samples are proposed from analyzing the experimental results and the data available in the literature. 相似文献
6.
I. A. Zvereva A. M. Sankovich A. B. Missyul’ V. L. Ugolkov 《Glass Physics and Chemistry》2010,36(2):209-216
The processes of phase formation in the Nd2O3-TiO2-Na2CO3 system have been investigated in the temperature range 500–1100°C. The mechanism of the high-temperature solid-phase reaction
of formation of the complex oxide Na2Nd2Ti3O10 has been studied. It has been established that the Na2Nd2Ti3O10 compound is formed from the intermediate product Na0.5Nd0.5TiO3 with a perovskite structure in the temperature range 830–890°C and from the NaNdTiO4 oxide with a perovskite-like layered structure in the temperature range 960–1100°C. 相似文献
7.
Yu. K. Startsev A. A. Pronkin I. A. Sokolov I. V. Murin 《Glass Physics and Chemistry》2011,37(3):263-282
The glasses, in which oxygen was partially replaced with sulfur, have been synthesized in the Na2O-P2O5-Na2S system. The chemical and chromatographic analyses of the glasses synthesized have been performed. The temperature-concentration
dependences of electrical conductivity of the glasses have been studied over a wide temperature range; the glass transition
temperatures and the nature of charge carriers have been determined. The IR spectra and Raman spectra have been recorded at
room temperature; the density and microhardness of the glasses and ultrasound velocity have been measured. A comparison of
the electrical conductivities of the investigated glasses with those of the earlier studied glasses in the Na2O-P2O5 system has shown their fair coincidence. The introduction of sodium sulfide into the Na2O-P2O5 system is accompanied by an approximately threefold increase in electrical conductivity, although the concentrations of charge
carriers (sodium ions) in the glasses amount to ∼17 and ∼26 mmol/cm3, respectively. The rise in electrical conductivity has been assumed to be caused by the increase in the degree of dissociation
of polar structural chemical units including sulfide ions and by the higher mobility of sodium ions in the oxygen-free matrix. 相似文献
8.
The temperature-concentration dependence of the electrical conductivity of glasses in the Na2SO4-NaPO3 and Na2O-P2O5 systems has been investigated. Based on the obtained experimental data (IR spectra, density, microhardness, sound velocity,
and paper chromatography), it has been demonstrated that SO42− ions form terminal groups through the incorporation into polyphosphate fragments of the structure of glasses in the Na2SO4-NaPO3 system. An increase in the electrical conductivity of glasses in this system by a factor of ∼1000 (as compared to NaPO3) at 25°C and a decrease in the activation energy for electrical conduction from 1.40 to 1.10 eV have been interpreted from
the viewpoint of the decrease in the dissociation energy E
d of polar sulfate phosphate structural chemical fragments formed in the glass bulk upon introduction into sodium metaphosphate
Na2SO4. This leads to an increase in the number of dissociated sodium ions, which are charge carriers, and to a decrease in the
energy (E
a) of their activation shift in the sublattice formed by sulfate phosphate fragments of the structure. 相似文献
9.
SrAl2O4: (Eu2+, Dy3+) phosphor was prepared by solid state reaction. B2O5 as a flux was added in SrAl2O4:(Eu
2+, Dy3+) in order to accelerate a solid state reaction. In this paper, the effects of B2O3 on the crystal structure and the phosphorescent properties of the material have been evaluated. The synthesized phosphor
exhibited a broad band emission spectrum peaking at 520 nm, and the spectrum peak showed little effect by the B2O3 contents. The maximum afterglow intensity of the SrAl2O4: (Eu2+, Dy3+) phosphor was obtained at the B2O3 content of 5%. Adding the B2O3 caused uniform distortion to the crystal structure of the phosphor and resulted in reducing the lengths of a and c axes and
Β angle of the SrAl2O4 crystal. The uniform distortion was accompanied with crystal defects which can trap the holes generated by the excitation
of Eu2+ ions. The afterglow characteristic of the SrAl2O4: (Eu2+, Dy3+) phosphor was thus enhanced. 相似文献
10.
The Sb2O3 doping lead-free glass in Bi2O3-B2O3-BaO ternary system were prepared in the composition of several different subsystem, and the glass powder was produced through
the process of water quenching. Glass transition temperatures (T
g
), glass soften temperatures(T
s
), the volume resistivity (ρ) in the temperature range of 80–200°C, and linear thermal coefficients of expansion in the temperatures
range of 25–300°C (α25–300) were measured for subsystems along with the different ratio of Bi2O3, B2O3 and BaO. For these subsystems, T
g
ranged from 458 to 481°C, and T
s
ranged from 490 to 512°C, both decreasing with the increasing of Bi2O3/B2O3 ratio, and increasing with the increasing of BaO/B2O3 ratio. The measured α25–300 ranged from 65.3 to 76.3 × 10−7 K−1, with values increasing with increasing Bi2O3/B2O3 and BaO/B2O3 ratio. The volume resistivity remains at a high standards, which may caused by it’s non-alkali composition, and it fluctuated
from 1013 to 1011 Ω cm with the temperature varied from 80–200°C. The structure of Bi2O3-B2O3-BaO ternary leadfree glass system was mearsured by FT-IR. The IR studies indicate that these glasses are made up of [BiO6], [BO3], and [BO4] basic structural units, and it appears that Ba2+ acts as a glass-modifier in this ternary system, but the Bi3+ has entered the glass network when it is in relative high content so as to change the α25–300, T
s
and T
g
. 相似文献
11.
V. V. Golubkov N. G. Tyurnina Z. G. Tyurnina V. L. Stolyarova 《Glass Physics and Chemistry》2009,35(5):455-462
The structure of single-phase glasses in the SrO-B2O3-SiO2 system has been studied by the small-and large-angle X-ray scattering technique. The glasses containing 35, 40, and 45 mol
% SrO upon equimolar replacement of B2O3 by SiO2 have been investigated. It has been demonstrated that the glasses do not contain chemical inhomogeneity regions. The inhomogeneity
of the glasses is determined only by thermal density fluctuations. The isothermal compressibility varies insignificantly upon
replacement of B2O3 by SiO2 and decreases with an increase in the SrO content. The glass structure is consistent with the model of ideal associated solutions. 相似文献
12.
N. G. Tyurnina O. L. Belousova A. I. Domanskii L. A. Doronina V. L. Ugolkov 《Glass Physics and Chemistry》2010,36(3):294-303
The glass formation region in the SrO-B2O3-SiO2 system has been refined. The order of formation of crystalline phases in the system has been investigated at SrO contents
of 50–75 mol %. It has been demonstrated that, at low temperatures, the 2SrO · SiO2 and 3SrO · B2O3 phases crystallize first irrespective of the composition. The congruent melting temperature of the 3SrO · B2O3 · SiO2 compound is determined to be 1180 ± 10°C. The triangulation previously performed for the SrO-B2O3-SiO2 system in the concentration range 50–75 mol % SrO has been confirmed. 相似文献
13.
I. A. Sokolov I. V. Murin Yu. K. Startsev M. Yu. Zubkova A. A. Pronkin 《Glass Physics and Chemistry》2010,36(1):21-26
The glass formation region in the Na2Se-P2Se5 system and the temperature-concentration dependences of the electrical conductivity of glasses have been investigated over
a wide range of temperatures. The densities and glass transition temperatures T
g
of glasses have been determined. A comparison of the electrical conductivity of glasses in the Na2Se-P2Se5 and Na2O-P2O5 systems has demonstrated that the conductivity of selenium-containing glasses (at 25°C) is approximately three orders of
magnitude higher than the electrical conductivity of oxide glasses. The assumption has been made that an increase in the electrical
conductivity of glasses with selenium is caused by the increase in the degree of dissociation of Na+[Se−PSe3/2] polar structural chemical units and the higher mobility of sodium ions in the oxygen-free matrix. 相似文献
14.
A composition of NASICON (Na3Zr2Si2PO12) was synthesized by the solid-state reaction method using a new compound Na2HPO42H2O. The X-ray diffraction patterns of all samples exhibit monoclinic Na3Zr2Si2PO12 as a major phase with a very small amount of monoclinic-ZrO2. The maximum relative density (97 %) and maximum conductivity is obtained in the samples sintered at 1200 °C (N3) which is slightly higher than β-Al2O3. The activation energy is ~ 0.20 eV for the N3 sample which is lower than for β-Al2O3. The dilatometeric study and Arrhenius plots confirmed a phase transition of NASICON from monoclinic to rhombohedral. The micro-structural study of the samples done by scanning electron microscopy (SEM) indicated a significant influence of the processing conditions on the microstructures. Raman spectroscopy demonstrated that the sample N3 exhibits minor structural changes compared to other samples. 相似文献
15.
The specific conductivity and tracer of diffusion of sodium and barium ions have been determined and the values of the transport numbers and correlation factor for diffusion have been calculated in two melts of the Na2O–BaO–Ga2O3–SiO2 system. 相似文献
16.
A new version of the STRUCTON-1.2 computer program (2009) has been presented. The program combines the algorithm for calculating
real distributions of Q
n
structons in binary silicate melts (with allowance made for their disproportionation) and the statistical simulation of molecular-mass
distributions of polymerized ions at different temperatures. This model has been used to perform test calculations for two
melts in the Na2O-SiO2 system (Na6Si2O7, Na6Si3O9). The results of the calculations have made it possible to trace variations in the set and concentrations of chain and ring
silicon-oxygen complexes with a decrease in the temperature in the order: stochastic molecular-mass → distribution molecular-mass
distribution at T = 2000 K → molecular-mass distribution at the liquidus temperature. The main result of these calculations is that the dominant
species of silicon-oxygen anions at the liquidus temperatures (in contrast to the stochastic distributions) exactly correspond
to the stoichiometry of the initial melts: the Si2O76− chain anions and (Si
n
O3n
)3n− ring complexes are dominant in the Na6Si2O7 and Na6Si3O9 melts, respectively. It has been established that, with a decrease in the temperature, the average size of polymer complexes
varies weakly in the Na6Si2O7 melt but increases by a factor of approximately 1.5 in the metasilicate system. 相似文献
17.
Nanoporous silica membrane without any pinholes and cracks was synthesized by organic templating method. The tetrapropylammoniumbromide
(TPABr)-templating silica sols were coated on tubular alumina composite support ( γ-Al2O3/ α-Al2O3 composite) by dip coating and then heat-treated at 550 °C. By using the prepared TPABr templating silica/alumina composite
membrane, adsorption and membrane transport experiments were performed on the CO2/N2, CO2/H2 and CH4/H2 systems. Adsorption and permeation by using single gas and binary mixtures were measured in order to examine the transport
mechanism in the membrane. In the single gas systems, adsorption characteristics on the α-Al2O3 support and nanoporous unsupport (TPABr templating SiO2/ γ-Al2O3 composite layer without α-Al2O3 support) were investigated at 20–40 °C conditions and 0.0–1.0 atm pressure range. The experimental adsorption equilibrium
was well fitted with Langmuir or/and Langmuir-Freundlich isotherm models. The α-Al2O3 support had a little adsorption capacity compared to the unsupport which had relatively larger adsorption capacity for CO2 and CH4. While the adsorption rates in the unsupport showed in the order of H2> CO2> N2> CH4 at low pressure range, the permeate flux in the membrane was in the order of H2≫N2> CH4> CO2. Separation properties of the unsupport could be confirmed by the separation experiments of adsorbable/non-adsorbable mixed
gases, such as CO2/H2 and CH4/H2 systems. Although light and non-adsorbable molecules, such as H2, showed the highest permeation in the single gas permeate experiments, heavier and strongly adsorbable molecules, such as
CO2 and CH4, showed a higher separation factor (CO2/H2=5-7, CH4/H2=4-9). These results might be caused by the surface diffusion or/and blocking effects of adsorbed molecules in the unsupport.
And these results could be explained by surface diffusion.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
18.
I. A. Zvereva O. I. Silyukov A. V. Markelov A. B. Missyul’ M. V. Chislov I. A. Rodionov D. -Sh. Li 《Glass Physics and Chemistry》2008,34(6):749-755
The processes of phase formation in the Na2CO3-TiO2 and Na2CO3-TiO2-Nd2O3 systems are investigated in the temperature range 600–900°C. The high-temperature solid-phase reactions underlying the process of formation of complex oxide NaNdTiO4 are studied. It is established that the synthesis of the NaNdTiO4 compound occurs through the reaction of the intermediate product Na8Ti5O14 with neodymium oxide in the temperature range 720–780°C. The optimum method is proposed for synthesizing NaNdTiO4, which makes it possible to reduce the temperature of the synthesis, to avoid the formation of impurities, and to obtain the product in a finely dispersed state. 相似文献
19.
N. A. Sennova R. S. Bubnova S. K. Filatov I. G. Polyakova 《Glass Physics and Chemistry》2007,33(3):217-225
The thermal expansion of two layered sodium borates is investigated using high-temperature X-ray powder diffraction. It is established that both compounds are characterized by strong anisotropy of thermal expansion due to the hinge mechanism. Special (singular) points are revealed in the temperature dependences of the angular lattice parameters for the α-Na2B4O7 compound. The temperature of manifestation of these singularities corresponds to the glass transition temperature of the melt of the same chemical composition. The assumption is made that the angular lattice parameters (angles between atomic rows) in compounds with a considerable degree of ionic bonding are more sensitive to variations in temperature as compared to the linear lattice parameters (interatomic distances). It is experimentally in situ demonstrated with high-temperature X-ray diffraction that the β-NaB3O5 borate is peritectically melted at a temperature of 725 ± 10°C with the formation of the α-Na2B8O13 octaborate. 相似文献
20.
In this study, 10B2O3/polyimide (PI) hybrid materials were synthesized with the aim to improve their thermal stability and neutron shielding properties.
3,3′-Diaminodiphenyl sulfone (DADPS) reacted with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) in N-methyl-2-pyrrolidone (NMP) and mixed with amine functionalized 10B2O3 to prepare a series of poly (amic acid), meanwhile, corresponding PIs were obtained via the thermal imidization procedures.
The morphologies and structures of the prepared hybrid materials were characterized by scanning electron microscopy (SEM)
and Fourier transform infrared spectroscopy (FT-IR). The thermooxidative and flame retardancy properties of the PI films were
examined by thermogravimetric analysis (TGA) and limiting oxygen ındex (LOI). The experimental results showed that as the
amount of functionalized 10B2O3 was increased, flame retardant properties of the hybrid films were increased. Hybrid materials were also irradiated with
thermal neutrons. The neutron shielding properties increasing depends on the amount and the distribution of the 10B isotope. 相似文献