Effect Of P2O5 Research Articles

Effect of P2O5 on the viscous flow and crystallisation behaviour of slag in the double slag converter steelmaking process

In the current study, the effect of P2O5 on the viscous flow and crystallisation behaviour of slag in the double slag converter steelmaking process was investigated in laboratory. The results indicated that with the increase of P2O5 content, the softening temperature, hemispherical temperature and flowing temperature of steelmaking slag showed a decreasing trend, however, the viscosity increased. The FactSage thermodynamic software was used to predict the types and contents of crystallisation phases in the crystallisation process of steelmaking slag. It showed that with the increase of P2O5 content, the precipitation content of Ca5P2SiO12 increased, while the precipitation content of melilite decreased. The composition and microstructure of crystallisation phases were analysed using X-ray diffraction and scanning electron microscopy. The phase composition did not change with the increase of P2O5 content, but the diffraction peak intensity of each crystallisation phase was different. Besides, the precipitation of phosphorus-enriched phase was enhanced with the increase of P2O5 content.

Extraction of Vanadium from CaO–SiO2–MgO–Al2O3 Slags Based on Vaporization of Vanadium Pentoxide

Vanadium is an important micro‐alloying element for various steel grades. Consequently, it is also present in the slags used in the production of those grades. During steelmaking, the vanadium vaporization from the slag is not desirable, as it increases vanadium consumption and at the same time releases toxic vapors of its higher oxides. However, the recovery of vanadium from the slag after the processing is worthwhile. In oxidic form as vanadium pentoxide (V2O5), vanadium can be extracted from the slag. In this research, the vaporization behavior of vanadium from CaO–SiO2–MgO–Al2O3 industrial slag is investigated at 1873 K. The effect of different process parameters, e.g., the pressure in the furnace chamber, the duration of the oxygen treatment of the slag, and the oxygen flow rate, is considered. The effect of P2O5 and Fe2O3 addition on the extraction of vanadium is studied. It is possible to induce formation of V2O5 gas bubbles in the slag due to the oxidation of vanadium. Thus, vanadium respectively V2O5 is extracted from the slag.

Investigation of the effect of P2O5 and CaF2 on the crystallization behavior of La2O3-bearing calcium–silicate–aluminum slags using the single hot thermocouple technique

The effects of P2O5 and CaF2 components of rare earth (RE)-bearing slags on their crystallization behavior were investigated using single hot-thermocouple technique (SHTT). The time temperature transformation (TTT) diagram exhibited single-nose curves within the examined slag composition range, in agreement with the individual CaLa4(SiO4)3O-type phase detected by an isothermal crystallization experiment in a furnace. Additionally, an increase in the P2O5 content shortened the incubation time and increased the nucleation rate of the columnar CaLa4(SiO4)3O-type phase in the 1350–1150 °C temperature range, while an increase in the CaF2 content had the opposite effects on the incubation time and nucleation rate. The sizes of the CaLa4(SiO4)3O-type phases in the slags with CaF2 were larger than those in the slags with P2O5, as verified by both in situ SHTT images and the crystallization experiment. The continuous cooling transformation (CCT) diagram suggested that an increase in the P2O5 content increased the initial crystallization temperature, whereas an increase in the CaF2 content decreased it. An analysis of the isothermal crystallization kinetics revealed that the columnar CaLa4(SiO4)3O-type phase exhibited phase diffusion-controlled growth. An increase in the P2O5 content tended to decrease the crystallization activation energy, while an increase in the CaF2 content increased the activation energy.

Effect of P2O5 on the structure and phase separation of sodium borosilicate glasses

Effect of P2O5 on the structure and phase separation of sodium borosilicate glasses

Selective precipitation and non-isothermal crystallization kinetics of britholite from low grade REE-bearing slag

In order to improve the recovery rate of rare earth, the effect of P2O5 and cooling rate on the selective precipitation of CaO–SiO2–TiO2–P2O5–Nb2O5–CeO2–CaF2 slag system was explored using X-ray powder diffraction, a scanning electron microscope, an electron probe micro-analyzer and a confocal laser scanning microscope. The apatite (Ca2.02Ce7.98Si6.00O26.00) is tiny and difficult to be separated from the slag without P2O5. When the addition of P2O5 is 6 wt%–10 wt%, the cerium and phosphorus are found to be enriched in britholite (Ca5–xCex[(SiO4)x(PO4)3–x]F) phase while x is negatively correlated with P2O5 content in the slag. The influence of P2O5 and cooling rate on the non-isothermal crystallization kinetics was also investigated. For the cooling rate between 5 and 40 °C/min, continuous cooling transformation diagram of britholite was constructed when the P2O5 content is between 6 wt%–10 wt%. The modified Avrami model was applied to determine the crystallization mode of slag with 10 wt% P2O5. It is shown that the crystallization mode is diffusion-controlled with constant nucleation rate and one-dimensional growth. In consideration of quantity and volume of crystals, the reasonable cooling rate is between 10 and 30 °C/min.

Optical transmittance and energy storage properties of potassium sodium niobate glass-ceramics

In this work, 0.8(K2O-Na2O-2Nb2O5)−0.2((1-x)B2O3-xP2O5) (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) glass-ceramics have been fabricated. The effects of P2O5 on the microstructure and properties of the glass-ceramics were comprehensively studied. The addition of P2O5 promotes the transition of the glass network structure from a negatively charged [B∅4]- tetrahedron to an electrically neutral [BP∅4] tetrahedron. With the increase of P2O5 content, the formation of K2B4O7 is inhibited, with major phase of Na0.9K0.1NbO3 and minor phase of K2B4O7. It is found that the band gap width of the glass-ceramics increases from 3.34 eV to 3.52 eV firstly and then decreases to 3.43 eV. The grain size of the glass-ceramics decreases from 150 nm to 50 nm. High optical transmittance (63%), large discharge energy density (4.58 J/cm3) and large energy storage efficiency (98%) have been simultaneously obtained for K2O-Na2O-Nb2O5-B2O3-P2O5 glass-ceramics, which are potential for the applications of the transparent pulse capacitors.

Effect of P2O5 and Na2O on the Solubility of Molybdenum and Structural Features in Borosilicate Glass.

In this paper, the effect of doping phosphorus in a borosilicate glass matrix to improve the solubility of Mo was investigated by X-ray diffraction (XRD), Raman, and solid-state nuclear magnetic resonance (NMR) spectroscopy, and the effectiveness of Na content on P species inhibiting the growth of the crystallization of Mo was assessed. The results indicate that phosphate-doped borosilicate glass can host 4 mol% of Mo, and that such a borosilicate glass matrix could only accommodate 1 mol% of Mo without phosphate doping. The effectiveness of phosphorus may be correlated with the Na content in borosilicate glass, and a high Na content borosilicate glass matrix requires more P doping to accommodate Mo. In addition, incorporating large amounts of P can compromise the aqueous durability of the glass matrix.

Formation and crystal growth of needle-like rutile in glass- ceramics

Glass-ceramic, which has negligible dielectric loss, high mechanical strength, excellent drop resistance, low CTE, and low density for lightweight design, is the best option for the back cover of mobile devices in the 5 G era. Herein, the effect of P2O5 on the phase separation and crystallization of MgO–Al2O3–SiO2-TiO2 glass-ceramics is studied. The incorporation of P2O5 in the glass structure leads to phase separation, in which the P and Mg-enriched phase was formed in the glass matrix, and promotes the increase of Tg. With the increase of P2O5 content, the precipitated crystals change significantly. First, the silicate crystals (Mg2SiO4) disappear, whereas the phosphate crystals (LiMgPO4) emerge when 2 mol% P2O5 is introduced. Second, titanate crystal (MgTi2O5) can not be observed when 4 mol% P2O5 is introduced. The Ti5O9 crystals appear simultaneously with LiMgPO4 crystals and transform to rutile TiO2 crystals at high temperature. Interestingly, the needle-like rutile TiO2 crystals, which is 300 nm long and 20 nm wide, have been found in a glass with 4 mol% P2O5. The large L/D ratio of needle-like crystals increases the hardness significantly from 6.08 GPa to 7.14 GPa. Similar to other fiber reinforced composites, this needle-like crystals provide a new strategy to improve the mechanical properties of glass ceramics.

Effect of P2O5, CaF2 and Basicity on the Viscosity and Structure of La2O3-Bearing Calcium–Silicate–Aluminum Slag System

Effect of P2O5, CaF2 and Basicity on the Viscosity and Structure of La2O3-Bearing Calcium–Silicate–Aluminum Slag System

Effect of P2O5 and Al2O3 on crystallization, structure, microstructure and properties of Li2O–MgO–Al2O3–SiO2–TiO2–ZrO2 glass ceramics

The structure, microstructure, thermal and mechanical properties of glasses and glass-ceramics in the LMAS (Li2O, MgO, Al2O3, SiO2) system and the effect of P2O5 and Al2O3 additives have been studied. The transition temperatures of both glasses and glass-ceramics increase with the P2O5 and Al2O3 concentration, but at high temperatures the melt viscosity decreases. The main crystalline phases formed are lithium aluminium silicate, enstatite and β-spodumene, being the growth of β-spodumene favoured by fluorine ions, P2O5 and the heat treatment temperature as well. Raman and FT-IR spectroscopies have shown the formation a silica-rich glass phase which acts as a matrix of the crystallites containing Al2O3 and P2O5 in its composition. The shape and aspect ratio of the crystallites depend on the Al2O3 concentration. For low Al2O3 concentration a variety of tubular, granular and plate-like crystals appear, while for high Al2O3 concentration the main shape of the crystals is spherical or globular. Hv, E and CTE properties are related to the crystalline phases formed during the crystallization treatment, and their variations are in accordance with the increase of the crystal aspect ratio. The CTE values of the GCs decrease as the P2O5 content increases up to 3%, while for the Al2O3 concentration of 16% the minimum CTE value is obtained. Hv and E values of the GCs are higher than those corresponding to their respective parent glasses. According to these values, these glasses and glass-ceramics are not appropriate for machining.

Effect of compositional changes on the structural properties of borophosphate glasses: ATR-FTIR and Raman spectroscopy

In the present work, two sets of glass compositions: (79.5-x) B2O3 + x P2O5 + 10 Na2O + 10 PbO + 0.5AgO and 54.5 B2O3 + (25-x) P2O5 + (10+x) Na2O + 10 PbO + 0.5AgO (x = 0, 5, 10, 15, 20, 25 mol%), were prepared and investigated by means of their density, molar volume, UV-Vis optical absorption, IR absorption and Raman spectroscopic methods. Both density and molar volume properties with x mol% of P2O5 and Na2O in glasses were discussed. The effects of P2O5, B2O3 and Na2O in the optical energy gap (Eopt) are also presented and discussed. In Raman analysis, an increase of P2O5 resulted in a clear conversion of B Ø3 to B Ø4 units with four non-bridging oxygens bonded to phosphate groups (POB linkages, pyro- and ortho-phosphates) identified in all the spectra. With increasing Na2O, the metaphosphate network gets extensively depolymerized, resulting in the conversion of Q1 to Q° structural units. In IR absorption analysis, the addition of P2O5 at the expense of B2O3 resulted in the decrease of BO bonds with enhancements of P-O- and P=O bonds in PO2- groups. An increase of Na2O at the expense of P2O5, evinced a tendency of B Ø4 tetrahedra/BØ3 trigonal to create diborate/pyroborate groups to accommodate excess amount of Na cations into the BO network.

Influence of P2O5 and SiO2 Addition on the Phase, Microstructure, and Electrical Properties of KNbO3

In this contribution, the effect of P2O5 and SiO2 addition on the phase, microstructure, and electrical properties of KNbO3 was studied. Sample powders with the general formula (1-x)KNbO3.xP2O5 (x = 0.03, 0.05) and (1-x)KNbO3.xSiO2 (x = 0.1) were prepared via mixed-oxide route. The thermal behavior of the mixed-milled powder was investigated by TG/DTA which revealed an overall weight loss of 33.4 wt % in the temperature range of 30 < T < 1200 C and crystallization exotherm occurring at about 795 C. The present results indicated that P2O5 acted as a sintering aid and lowered the sintering temperature by about 30 C and promoted densification of KNbO3. Sample compositions at various stages of processing were characterized using X-ray diffraction. Samples sintered at T < 1020 C revealed mainly KNbO3 together with a couple of low-intensity K3NbO4 peaks as a secondary phase. The SEM images of (1-x)KNbO3.xSiO2 (x = 0.1) samples showed a slight increase in the average grain size from 3.76 um to 3.86 um with an increase in sintering temperature from 1000 C to 1020 C. Strong variations in dielectric constant and loss tangent were observed due to P2O5 and SiO2 addition as well as frequency of the applied AC signals.

Growth-front hopping via stress-induced nucleation illustrated for the crystallization of Ba1-xSrxZn2Si2O7 from a glass in the BaO-SrO-ZnO-SiO2 system

The effect of P2O5 and Ce2O3 on the crystallization behavior of a BaO-SrO-ZnO-SiO2 glass was investigated using thermal analyses, X-ray diffraction, scanning electron microscopy including electron backscatter diffraction as well as laser scanning microscopy. Heat treatments lead to the precipitation of Ba1-xSrxZn2Si2O7, Zn2SiO4, and CeO2 at the surface. While Zn2SiO4 crystals form 1 µm deep immersions in the surface, CeO2 crystals originate from near-surface areas. The star-shaped CeO2 crystals show mostly three different orientations, among which the <001>- or <111>-orientation perpendicular to the surface are clearly preferred. In the bulk, many (Ba, Sr)5(PO4)3Cl crystals are observed acting as nucleation sites for Ba1-xSrxZn2Si2O7. This nucleation process is clearly facilitated by the occurring stresses. Moreover, an epitaxial growth of Ba1-xSrxZn2Si2O7 on (Ba, Sr)5(PO4)3Cl is indicated. If the surface-crystallized layer consisting of Ba1-xSrxZn2Si2O7 crystals approaches the (Ba, Sr)5(PO4)3Cl crystals in the bulk, nucleation is induced and the thus provoked growth in the same growth direction as the (Ba, Sr)5(PO4)3Cl crystal leads to a shift of the growth front towards the sample volume and hence growth-front hopping occurs.

Effect of P2O5 on Crystallization Behavior and Chemical Resistance of Dental Glasses in the Li2O-SiO2-ZrO2 System

Effect of P2O5 on Crystallization Behavior and Chemical Resistance of Dental Glasses in the Li2O-SiO2-ZrO2 System

On the search for nucleation agents in BaO-SrO-ZnO-SiO2 glasses: The influence of P2O5

Glasses in the system BaO-SrO-ZnO-SiO2 from which a phase with the composition Ba1-xSrxZn2Si2O7 can be precipitated possess a strong tendency towards surface crystallization and due to the high anisotropy of the coefficient of thermal expansion of this crystal phase, the obtained glass ceramics often show microcracking. The present article deals with the effect of P2O5 on the crystallization behavior of BaO-SrO-ZnO-SiO2 glasses. The phase formation and the microstructure of the glass ceramics are studied using thermal analyses, X-ray diffraction, optical microscopy, as well as scanning electron microscopy. While the stoichiometric glass melt spontaneously crystallizes upon cooling, the P2O5 addition leads to a stabilization of the glass enabling the preparation of a glass without any crystals. The appearance of stresses and microcracks during crystallization can be assigned to certain crystallographic directions using electron backscatter diffraction. Moreover, it is possible to achieve volume crystallization in this otherwise solely surface crystallizing glass system.

Effect of P2O5 on mechanical properties of porous natural hydroxyapatite derived from cortical bovine bones sintered at 1,050°C

In the current study, the effect of P2O5 on the mechanical properties of porous natural hydroxyapatite (NHA) derived from cortical bovine bones sintered at 1,050°C is assessed. Hydroxyapatite (HA: Ca10(PO4)6(OH)2) was synthesized using several methods and manufactured from natural materials such as coral or bone after removal of the organic matter by heating (noted NHA). The in vitro and in vivo studies showed that the natural apatite was well tolerated and has better osteoconductive properties than synthetic HA. Consequently, the NHA was manufactured from cortical bovine bone in all our studies. Nevertheless, its poor mechanical properties are one of the most serious obstacles for wider applications. So, P2O5 was added into NHA in order to enhance its initially poor mechanical strength. A careful combination between the main parameters controlling NHA elaboration such as milling techniques, compacting pressure, sintering temperature, and holding time may lead to an interesting NHA-based bioceramics. In this way, a vibratory multidirectional milling system using bimodal distribution of highly resistant ceramics has been used for obtaining submicron-sized NHA powders. To enhance the densification and lower the sintering temperature of porous NHA, different percentages of P2O5 (0.5–5.0 wt%) were added into NHA powders. The porosity ratio ranged between 36 and 41%. Using this modified milling system, the best Vickers micro-hardness and the three-point bending strength values of powders sintered at 1,050°C were 1 GPa and about 46 MPa, respectively. The latter value is significantly higher than that reported by other researchers (35 MPa) using the sol–gel method.

Effect of P2O5 on optical parameters of (25−x) CaO–xP2O5–B2O3–SiO2–ZnO sol–gel glasses: a theoretical assessment

The present investigation is an attempt to address the effect of P2O5 on the optical properties, cross link density (nc) as well as theoretical parameters like Poisson’s ratio and bulk modulus for (25−x)%CaO−x%P2O5–60%SiO2–5%B2O3–10%ZnO (x = 5, 10, 15, 20) novel sol–gel glasses. The optical basicity, oxide polarisability, direct/indirect band gaps and theoretical elastic constants have been calculated for all the glasses. In addition to this, the cross-link density, average force stretching constant and number of network bonds per unit volume (nb) have been calculated. The values of optical basicity and polarisabilty have allowed the same trend for all these glasses. The cross-link density decreases when the P2O5 content increases from 5 to 20 %.

Effect of P2O5 and FetO on the Viscosity and Slag Structure in Steelmaking Slags

The present paper investigates the influence of P2O5 and FetO on the viscosity and structure of steelmaking slags. An understanding of the viscous behavior and structure of FetO-bearing smelting slags is essential to control the dephosphorization in steelmaking process and to efficiently recycle the phosphorus from steelmaking slags. It is found that the viscosity of CaO-SiO2-Al2O3-MgO-FetO-P2O5 slags slightly increases with increasing P2O5 content, while the viscosity decreases with increasing FetO content. The degree of the polymerization of quenched slags, determined from Raman spectra, is found to increase with increasing P2O5 content and decrease with increasing FetO content. It is also noted that the peaks of Raman spectra between 800 and 1200 cm−1 were nearly absent at the FetO content of 22.46 wt pct; whereas according to 29Si MAS-NMR and FTIR analysis, it is clearly seen that the [SiO4]-tetrahedra-related peaks existed even for the same slag. This may confirm that small quantities of extra-framework iron species can absorb the Raman scattering and damp the Raman signal intensity and the presence of FetO in the slag does not necessarily eliminate [SiO4]-tetrahedra.

Influence of P2O5 and Al2O3 content on the structure of erbium-doped borosilicate glasses and on their physical, thermal, optical and luminescence properties

The effect of P2O5 and/or Al2O3 addition in Er-doped borosilicate glasses on the physical, thermal, optical, and luminescence properties is investigated. The changes in these glass properties are related to the glass structure modifications induced by the addition of P2O5 and/or Al2O3, which were probed by FTIR, 11B MAS NMR and X-ray photoelectron spectroscopies. Variations of the polymerization degree of the silicate tetrahedra and modifications in the [3]B/[4]B ratio are explained by a charge compensation mechanism due to the formation of AlO4, PO4 groups and the formation of AlOP linkages in the glass network. From the absorption and luminescence properties of the Er3+ ions at 980nm and 1530nm, declustering is suspected for the highest P2O5 concentrations while for the highest Al2O3 concentrations no declustering is observed.

The effect of titanium and phosphorus on ferric/ferrous ratio in silicate melts: an experimental study

The effect of TiO2 and P2O5 on the ferric/ferrous ratio in silicate melts was investigated in model silicate melts at air conditions in the temperature range 1,400–1,550 °C at 1-atm total pressure. The base composition of the anorthite–diopside eutectic composition was modified with 10 wt % Fe2O3 and variable amounts of TiO2 (up to 30 wt %) or P2O5 (up to 20 wt %). Some compositions also contained higher SiO2 concentrations to compare the role of SiO2, TiO2, and P2O5 on the Fe3+/Fe2+ ratio. The ferric/ferrous ratio in experimental glasses was analyzed using a wet chemical technique with colorimetric detection of ferrous iron. It is shown that at constant temperature, an increase in SiO2, TiO2, and P2O5 content results in a decrease in the ferric/ferrous ratio. The effects of TiO2 and SiO2 on the Fe3+/Fe2+ ratio was found to be almost identical. In contrast, adding P2O5 was found to decrease ferric/ferrous ratio much more effectively than adding silica. The results were compared with the predictions from the published empirical equations forecasting Fe3+/Fe2+ ratio. It was demonstrated that the effects of TiO2 are minor but that the effects of P2O5 should be included in models to better describe ferric/ferrous ratio in phosphorus-bearing silicate melts. Based on our observations, the determination of the prevailing fO2 in magmas from the Fe3+/Fe2+ ratio in natural glasses using empirical equations published so far is discussed critically.