Addition Of Na2O Research Articles

Effect of Li2O and Na2O Addition on Structure and Properties of Glass System (B2O3-ZnO)

Effect of Li2O and Na2O Addition on Structure and Properties of Glass System (B2O3-ZnO)

Effects of Na<sub>2</sub>O and B<sub>2</sub>O<sub>3</sub> Addition on Viscosity and Electrical Conductivity of CaO–Al<sub>2</sub>O<sub>3</sub>–MgO–SiO<sub>2</sub> System

Effects of Na<sub>2</sub>O and B<sub>2</sub>O<sub>3</sub> Addition on Viscosity and Electrical Conductivity of CaO–Al<sub>2</sub>O<sub>3</sub>–MgO–SiO<sub>2</sub> System

Effect of Na2O and B2O3 Addition on Nonlinear Electrical Properties of WO3-Based Capacitor–Varistors

WO3-based varistors with added Na2O and B2O3 were synthesized by the solid-state reaction. The undoped and B2O3-doped WO3 ceramics exhibited weak nonlinear I–V characteristics. The nonlinear I–V characteristics of the ceramics increased slightly after the addition of Na2O and more significantly after the addition of Na2O and B2O3. The nonlinearity coefficients α of the WO3, Na0.005WO3, and Na0.005WO3–5 wt % B2O3 ceramics were 1.86, 2.03, and 5.22, respectively. The breakdown voltages of the WO3, Na0.005WO3, and Na0.005WO3–5 wt % B2O3 ceramics were 1.56, 6.05, and 12.42 V/cm, respectively. The dielectric constant and the dielectric loss of the Na0.005WO3–5 wt % B2O3 ceramic were ~50–150 and less than 0.3, respectively, for frequencies ranging from 1 to 1000 kHz.

Effect of Na2O and Rb2O on Inclusion Removal in C96V Saw Wire Steels Using Low-Basicity LF (Ladle Furnace) Refining Slags

Inclusion removal and modification of C96V saw wire steel using Na2O- and Rb2O- containing novel low-basicity LF (ladle furnace) Refining Slags have been researched. The results indicated that the addition of Na2O deteriorates inclusion removal; by contrast, the addition of Rb2O seems to significantly enhance inclusion removal. In detail, Rb2O can improve the cleanliness in the as-quenched C96V saw wire steel melts compared to preexisting synthetic LF refining slag compositions: (i) The average inclusion diameter experienced a remarkable decrease after reaction between the liquid steel and the synthetic LF refining slag; (ii) In addition, the number of inclusions also suffered from a dramatic decrease, with the reaction time increasing from 900 to 2700 s (15 to 45 min); (iii) Furthermore, both of the MnO-SiO2-Al2O3 and CaO-SiO2-Al2O3 inclusion system mainly concentrated in the low melting zone when the composition of Rb2O in synthetic refining slag was ≥5.0 wt%. This is mainly because Na2O significantly reduces the viscosity of refining slag, while Rb2O increases it. Then, there are two remarkable influences causing the increase of viscosity of refining slag with the addition of Rb2O: the inclusions can be sufficiently entrained within the slag once absorbed due to the significant increase in the viscosity; and the slag entrapment during refining process weakened dramatically.

Molecular dynamics simulations of P2O5-Fe2O3-FeO-Na2O glasses

Phosphate glasses due to their properties can be used in many fields like medicine, optics, electronics, environmental protection etc. Unfortunately, pure phosphate glasses have low chemical durability what limits their application. The addition of iron to the glass improves the durability considerably. Glass with composition 60P2O5-40Fe2O3 have one of the highest chemical resistance. The glass properties are strongly related to the structure of the glass network which can be tested experimentally and also by application of computer simulations.In the paper classical molecular dynamics simulations were used to study the influence of the gradual addition of Na2O on the structure of 55P2O5-30Fe2O3-15FeO glass. Increasing sodium content in the glass causes depolymerization of the glass network and increasing number of non-bridging oxygens in [PO4] tetrahedra. The number of chemical durable P-O-Fe bridges decreases and they are replaced by P-O-Na. This leads to separation of iron cations from [PO4] units and formation of iron oxides clusters. The network of the glass with over 30 mol% of Na2O consists mainly of separated [PO4] tetrahedra and short pyrophosphate chains of [P2O7]4−. The glass structural properties due to sodium content increase are discussed.

Rheological Transitions of the Solid-Bearing Slag During Cooling Process

The viscosity of basic oxygen furnace slag modified by the addition of Al2O3, SiO2, and Na2O was measured via a rotational-type rheometer. The experiment was performed under both continuous cooling condition (5 °C/min) at a constant rotational speed (30 rpm) and isothermal condition at various rotational speeds (between 2 and 120 rpm). The present work suggests that during cooling from liquid to solid, the slag successively undergoes Newtonian regime, shear thinning (time depedent) and thixotropy with a time-dependent apparent yield stress. The corresponding slag microstructure is (1) a fully liquid or partially liquid slag with negligible crystal–crystal interaction in the Newtonian regime, (2) a liquid slag with crystal aggregates/clusters in the shear thinning regime and (3) a skeletal solid network in the regime of thixotropy with a certain level of apparent yield stress.

Effect of high Na2O addition on distribution of phosphorus in low-basicity converter slag

In order to improve the dephosphorization efficiency of low-basicity converter slag and decrease the consumption of solid CaO, the effect of high Na2O addition (0–15 mass%) on the distribution of P2O5 between solid solution and matrix phase was investigated. The thermodynamic properties of slag samples were calculated by FactSage 7.0 software. Then, the dissolution behavior of phosphorus element from slag was studied. The results show that the mass fraction of 2CaO·SiO2–2CaO·Na2O·P2O5 solid solution increases when the Na2O content is increased in slag. However, the amount of formed solid solution changes little when the Na2O addition is more than 10 mass%. Moreover, the content of Na2O in solid solution would reach saturation when adding 15 mass% Na2O into the slag. With the increase in Na2O content in slag, the distribution ratio of P2O5 between solid solution and matrix phase increases. The values are evidently higher than the results reported in the literature. Meanwhile, the activity of P2O5 in matrix phase and the activity coefficient of P2O5 in solid solution are decreased with increasing the Na2O content in slag. Furthermore, the dissolution ratio of phosphorus in citric acid solution could be improved by adding Na2O into slag, but the increment of dissolution ratio would decrease when the Na2O content exceeds 10 mass% in slag.

Structural and Dielectric Studies on Na2O-PbO-SiO2 Glasses

Structural studies on x Na2O.(50-x)PbO.50SiO2 glasses have been carried out by different spectroscopic techniques. FTIR, EDX, NMR and dielectric spectroscopies are applied to follow the change in glass structure in terms of bridging oxygen (BO), non-bridging oxygen (NBO), and cluster species upon adding of Na2O at expense of PbO. NBOs are formed in the silicate network upon Na2O addition, since Na2O plays the role of glass modifier. Changes in relative area of Q2 (obtained from IR analysis) and NMR chemical shift of silicon nuclei with increasing Na2O are indicative for formation of the less shielded silicate units. While in sodium rich silicate glasses, the structural role of Na2O is changed due to changing Na coordination. FTIR analysis could be used to elucidate the changes related to changing the role of Na2O. The data obtained are correlated with that obtained from EDX spectroscopy. Moreover, the role of Na2O on the process of cluster formation when it substitutes PbO is determined. NBOs only are formed in the silicate network upon Na2O addition up to 30 mol%. On the other hand, in sodium rich silicate glasses an additional type of oxygen (free oxygen O2−) is present. The free oxygen is required for sodium to form aggregated cluster, specially at high concentration of Na2O (50 mol%). An increase in Na2O concentration in Na2O-rich silicate network results in increasing Na coordination instead of breaking more silicon–oxygen bonds. Scanning electron micrographs (SEM) and EDS spectroscopy in correlation with FTIR results confirm the presence of Na cluster species. The effect of clusters formation on AC conductivity was discussed according to jump relaxation model. Some parameters related to AC conductivity are found to be affected by the presence of cluster species in the glass network.

Effects of Na2O/BaO ratio on the structure and the physical properties of low-temperature glass-ceramic vitrified bonds

Effects of Na2O/BaO ratio on the structure and the physical properties of Li2O-Al2O-B2O3-SiO2 low-temperature glass-ceramic vitrified bonds had been systematically studied. Structure and properties of as-quenched samples were analyzed by DSC, FTIR, and Raman. According to the results of (X3)2/X2 derived from deconvolution results of Raman, the degree of polymerization (DOP) of glass structure decreased with increasing Na2O/BaO. In addition, LiAlSi2O6 and LiAlSi3O8 were the major crystalline phases in the vitrified bonds sintered at 730 °C for 2 h. Meanwhile, Li2SiO3 and BaAl2Si2O8 were determined as the minor crystalline phases by XRD. The results showed that the addition of Na2O promoted the coefficient of thermal expansion (CTE) of vitrified bonds sintered at 730 °C for 2 h. Bending strength tests and SEM indicated that the optimum content of dispersed plate-like BaAl2Si2O8 crystals inlaid in A2 (Na2O/BaO = 0.33) vitrified bonds contributed to showing the highest mechanical strength among the five samples. Moreover, SEM and EDS proved the wettability between A2 vitrified bonds and cBN grains were effective.

Влияние добавок Na2O и TiO2 на свойства биоактивных тонкопленочных материалов на основе системы SiO2–P2O5–СаO

Влияние добавок Na2O и TiO2 на свойства биоактивных тонкопленочных материалов на основе системы SiO2–P2O5–СаO

Distribution of P2O5 and Na2O Between Solid Solution and Liquid Phase in the CaO-SiO2-Fe2O3-P2O5-Na2O Slag System with High P2O5 Content

The phosphorus content in hot metal will increase in future, because iron ores are steadily deteriorating in quality. Na2O addition to slag is considered an effective method for increasing the efficiency of dephosphorization. In addition, Na2O modification also facilitates phosphorus recovery from dephosphorization slag with high P2O5 content by selective leaching. Therefore, it is necessary to investigate the distribution ratios of P2O5 and Na2O between solid solution and liquid phase in the CaO-SiO2-Fe2O3-P2O5-Na2O slag system. A linear relationship was found between the distribution ratio of P2O5 and the Na2O content in slag, and was independent of P2O5 content. When the Na2O content was high, the Na2O content in the solid solution approached saturation and a new 2CaO·SiO2-2CaO·Na2O·P2O5 solid solution formed. The addition of Na2O decreased the P2O5 content in solid solution, while it increased the mass fraction of solid solution in slag. The distribution ratio of P2O5 increased with increase in the Fe2O3 content and basicity of slag. An increase in P2O5 content in slag results in an increase in the activity coefficient of P2O5 both in the liquid phase and in the solid solution.

Effect of increasing concentration of Na2O on structural, elastic and optical properties of (90 − x)GeO2–xNa2O–10PbO glass system in the germanate anomaly region

Ternary germanate glasses (90 − x)GeO2–xNa2O–10PbO (x = 10–30 mol%) have been prepared by the melt-quenching method. Density, ρ increased with Na2O content up to maxima at 20 mol% while molar volume, Va showed an opposite trend to the density, with a minima at 20 mol% of Na2O content indicating the presence of the germanate anomaly. Ultrasonic velocity measurements showed both longitudinal, vl and shear, vs velocities increased up to 20 mol% before decreasing with further addition of Na2O. Independent longitudinal, L and shear, G moduli along with Young’s modulus, Y, mean sound velocity, vm, Debye temperature, θD, and hardness, H recorded maximum values at 20 mol% of Na2O content which were suggested to be related to the germanate anomaly. Structural modification occurring due to conversion of six-membered GeO4 rings to three-membered rings of GeO4 changed bond density and compactness of the glass systems and caused the increase in rigidity and stiffness of the glasses. Beyond 20 mol% of Na2O, the decrease in the elastic moduli was due to depolymerization of the glass network. Meanwhile, optical energy gap, Eopt exhibited a minima at 20 mol% whereas Urbach energy, EU and refractive index, n showed a maxima at the same concentration, thereby indicating variation in polarizability due to changes in concentration of bridging and non-bridging oxygen.

Photoluminescence of sodium germanosilicate glass synthesized by melting mixture of SiO2, GeO2, and Na2CO3

Glasses with the composition (SiO2)50(GeO2)50-x(Na2O)x (x=0, 20–40) were synthesized at 1600°C by melting in air, and their photoluminescence properties were investigated. Furthermore, the formation of non-bridging oxygens (NBOs) and oxygen vacancies in the (SiO2)50(GeO2)50-x(Na2O)x glasses was examined using X-ray photoelectron spectroscopy. In contrast to the violet-blue emission of the (SiO2)50(GeO2)50 glass, the (SiO2)50(GeO2)20(Na2O)30 glass exhibits a quasi-white emission under ultraviolet light. The internal quantum efficiency of the (SiO2)50(GeO2)20(Na2O)30 glass at an excitation wavelength of 250nm was 37%. It was confirmed that the number of NBOs increases with the addition of Na2O in (SiO2)50(GeO2)50 glass.

Distribution Ratios of Phosphorus Between CaO-FeO-SiO2-Al2O3/Na2O/TiO2 Slags and Carbon-Saturated Iron

In order to effectively enhance the efficiency of dephosphorization, the distribution ratios of phosphorus between CaO-FeO-SiO2-Al2O3/Na2O/TiO2 slags and carbon-saturated iron ( $$ L_{\text{P}}^{\text{Fe-C}} $$ ) were examined through laboratory experiments in this study, along with the effects of different influencing factors such as the temperature and concentrations of the various slag components. Thermodynamic simulations showed that, with the addition of Na2O and Al2O3, the liquid areas of the CaO-FeO-SiO2 slag are enlarged significantly, with Al2O3 and Na2O acting as fluxes when added to the slag in the appropriate concentrations. The experimental data suggested that $$ L_{\text{P}}^{\text{Fe-C}} $$ increases with an increase in the binary basicity of the slag, with the basicity having a greater effect than the temperature and FeO content; $$ L_{\text{P}}^{\text{Fe-C}} $$ increases with an increase in the Na2O content and decrease in the Al2O3 content. In contrast to the case for the dephosphorization of molten steel, for the hot-metal dephosphorization process investigated in this study, the FeO content of the slag had a smaller effect on $$ L_{\text{P}}^{\text{Fe-C}} $$ than did the other factors such as the temperature and slag basicity. Based on the experimental data, by using regression analysis, $$ \log L_{\text{P}}^{\text{Fe-C}} $$ could be expressed as a function of the temperature and the slag component concentrations as follows: $$ \begin{aligned} \log L_{\text{P}}^{\text{Fe-C}} & = 0.059({\text{pct}}\;{\text{CaO}}) + 1.583\log ({\text{TFe}}) - 0.052\left( {{\text{pct}}\;{\text{SiO}}_{2} } \right) - 0.014\left( {{\text{pct}}\;{\text{Al}}_{2} {\text{O}}_{3} } \right) \\ \, & \quad + 0.142\left( {{\text{pct}}\;{\text{Na}}_{2} {\text{O}}} \right) - 0.003\left( {{\text{pct}}\;{\text{TiO}}_{2} } \right) + 0.049\left( {{\text{pct}}\;{\text{P}}_{2} {\text{O}}_{5} } \right) + \frac{13{,}527}{T} - 9.87. \\ \end{aligned} $$

Electronic structures and physical properties of Na2O doped silicate glass

Ab initio molecular dynamics has been applied to construct seven sodium silicate glass models with Na2O concentration ranging from 0 to 50 mol. %. The structures of the simulated (Na2O)x(SiO2)1-x glasses are critically analyzed and validated by comparing with available experimental data. Because the initial seed model is based on a near-perfect continuous random network model for amorphous SiO2 with periodic boundaries, the structures of these silicate glasses are highly reliable. The electronic structure, interatomic bonding, and the mechanical and optical properties of seven models are calculated using the first-principles density functional method. In particular, a single quantum mechanical metric, the total bond order density (TBOD), is used to characterize the internal cohesion of sodium silicate glass. This is a significant step beyond the traditional analysis of glasses based purely on the geometric parameters. The TBOD value is found to decrease with increasing Na content, indicating the destruction of silica network connectivity. The calculated mass density and refractive index increase with x are in good agreement with experiment. The elastic coefficients and bulk mechanical properties exhibit a nonlinear variation in the series and depend greatly on the internal bonding and cohesion of the glass. The calculated Poisson's ratio indicates that the glass becomes more ductile with the addition of Na2O. Our results indicate that sodium silicate glass tends to be unstable for x greater than 0.4 due to the total destruction of the SiO2 network.

Nucleation inhibition despite lower glass viscosities? - Effect of the B2O3, Na2O and K2O addition on the crystallization behavior of lithium disilicate glasses

Abstract Stoichiometric lithium disilicate glasses were doped with up to 2 mol% B 2 O 3 , Na 2 O or K 2 O and the crystallization kinetics were determined as a function of the temperature using in situ hot-stage microscopy. The additives lead to a decrease of the glass viscosities in the studied temperature range with the exception of the boron-containing samples which show slightly higher viscosities in the nucleation range. While in the boron-containing samples, lithium disilicate solid solutions precipitate during thermal treatment, in the other samples a mixture of lithium disilicate, lithium metasilicate and cristobalite was detected. The steady-state nucleation rates decrease by up to one order of magnitude and especially in the case of the additive B 2 O 3 , the induction times for nucleation are remarkably longer. While the additives B 2 O 3 and K 2 O lead to a decrease of the crystal growth velocities, in case of Na 2 O, the contrary effect can be noticed. Possible reasons for the observed effects are discussed.

Effect of Na2O Addition on Phosphorus Dissolution from Steelmaking Slag with High P2O5 Content

Slag with high P2O5 content generated during the use of high-P iron ores is an important potential source of phosphate. Because the P-rich 2CaO·SiO2–3CaO·P2O5 solid solution in the slag was preferentially dissolved compared with other phases in aqueous solutions, selective leaching of P from slag with high P2O5 content was applied to recover soluble P in this study. To improve dissolution of the P-rich solid solution, the effects of Na2O addition on slag dissolution were investigated under different leaching conditions. The results show that a new 2CaO·SiO2–2CaO·Na2O·P2O5 solid solution was formed in the slag after Na2O was added, resulting in a higher dissolution ratio of P. However, at pH 7, further increase in Na2O content did not promote P dissolution because of phosphate precipitation. At pH 5, a better P dissolution was obtained and its dissolution ratio increased with an increase in Na2O content, indicating that Na2O addition promoted the dissolution of the solid solution from slag. In the citric acid solution, more than 90% of the solid solution was dissolved and the dissolution of the matrix phase was suppressed dramatically by Na2O addition, leading to a low dissolution ratio of Fe. An excellent selective leaching of P from slag was achieved.

Effect of Na<sub>2</sub>O and K<sub>2</sub>O on the Solubility and Chemical Properties of P<sub>2</sub>O<sub>5</sub>-CaO-Na<sub>2</sub>O-K<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub> Glass

The effect addition of Na2O on the solubility properties of phosphate glass of the composition, 45P2O5-18CaO-xNa2O-(34-x)K2O-6Al2O3, where x = 0,5,10,15 and 20 wt. %. has been studied. Glass transition temperature (Tg) of glass samples, weight loss and pH of the immersion solution were measured. The Tg value of the phosphate glass also decreased with the incorporation of Na2O up to 10 wt. % and increased with the incorporation of 15 and 20 wt. %. These results indicates that the solubility and Tg value of phosphate glass were highly influence by the glass composition. The substitution of Na2O to the phosphate glass system with the present of K2O has decrease the solubility of phosphate glass. The released of phosphate and calcium ion seem to decrease with the increasing of Na2O content in the glass composition.

Influences of Na2O and K2O Additions on Electrical Conductivity of CaO-MgO-Al2O3-SiO2 Melts

The present study investigated the influences of Na2O and K2O additions on electrical conductivity of blast furnace type CaO-MgO-Al2O3-SiO2 melts by the four-electrode method. Both the single addition of Na2O or K2O and the double additions of Na2O and K2O were studied. It was found that electrical conductivity monotonously increased as the amount of Na2O addition was gradually increased, whereas, when K2O was added, there was a continuous decrease of electrical conductivity. With melts containing both Na2O and K2O, electrical conductivity first decreased but then increased when Na2O was gradually substituted for K2O while keeping the molar fractions of other components constant. In other words, the mixed-alkali effect took place in CaO-Mg-Al2O3-SiO2-ΣR2O melts.

Stability of Fluorine-Free CaO-SiO2-Al2O3-B2O3-Na2O Mold Fluxes

B2O3 and Na2O are key components of fluorine-free mold fluxes for continuous casting, but both are highly volatile, which affects the flux stability. This paper investigated the evaporation of the SiO2-CaO-Al2O3-B2O3-Na2O fluxes (Na2O: 6 to 10 wt pct, CaO/SiO2 ratio: 0.8 to 1.3) in the temperatures ranging from 1573 K to 1673 K (1300 °C to 1400 °C) using thermogravimetric analysis. The weight loss as a result of the flux evaporation increased with the increasing temperature for all fluxes. The rate of evaporation was found to be very small for the Na2O-free flux but significantly increased with the addition of Na2O. The high evaporation rate of fluxes in the presence of B2O3 and Na2O was attributed to the formation of highly volatile NaBO2. Changing the ratio of CaO/SiO2, however, did not affect the rate of evaporation. Kinetic analysis of the evaporation processes demonstrated that external mass transfer contributed to the rate of evaporation.