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1.
Er-doped 12CaO·7Al2O3 (C12A7:Er) powders were prepared using the sol-gel method followed by annealing inorganic precursors. X-ray diffraction (XRD), Raman and absorption spectra revealed that Er ions existed and substituted Ca2 lattice site in C12A7. The photoluminescence of C12A7:Er at room temperature was observed in the visible and infrared region using 488 nm (2.54 eV) Ar line as excitation source, respectively. The sharp and intense green emission bands with multi-peaks around 520 nm and 550 nm correspond to the transitions from the excited states 2H11/2 and 4S3/2 to the ground state 4I15/2, respectively. Furthermore, red emission band around 650 nm was also observed. It was attributed to the electronic transition from excited states 4F9/2 to the ground state 4I15/2 inside 4f-shell of Er3 ions. The intensive infrared emission at 1.54μm was attributed to the transition from the first excited states of 4I13/2 to the ground state (4I15/2). The temperature dependent photoluminescence of infrared emission showed that the integrated intensity reached a maximum value at near room temperature. The forbidden transitions of intra-4f shell electrons in free Er3 ions were allowed in C12A7 owing to lack of the inversion symmetry in the Er3 position in C12A7 crystal field. Our results suggested that C12A7:Er was a candidate for applications in Er-doped laser materials, and full color display. 相似文献
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铁矿石中SiO2 CaO MgO及Al2O3的系统分析 总被引:1,自引:0,他引:1
以无水碳酸钠、四硼酸钠为熔剂,在装有石墨粉的瓷坩埚内进行快速熔融试样,熔块以盐酸浸取,溶解盐类,对铁矿石、球团矿、烧结矿中二氧化硅、氧化钙、氧化镁、三氧化二铝进行系统分析。与国家标准方法相比,本法具有操作简便,准确性好,速度快,成本低,测定范围宽等特点。 相似文献
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The CaO · SiO2-CaO · Al2O3 · 2SiO2-CaO · TiO2 · SiO2 system is analyzed. Thermodynamic analysis of monovariant and invariant solidification shows that, for invariant equilibrium and for solidification along the boundary curve between the solidification fields of anorthite and sphene, peritectic processes are observed. The invariant-state parameters of the system are determined: t = 1513 K; a CaO = 0.0407; $a_{SiO_2 } = 0.5268$ ; $a_{Al_2 O_3 } = 0.00003$ , $a_{TiO_2 } = 0.005$ ). A corrected phase diagram is presented. 相似文献
4.
The influence of SiC particle on viscosity of CaO–MgO–Al2O3–SiO2 melts was investigated by the rotating-cylinder method. It was found that temperature dependence of viscosity could be described by the Arrhenius law for systems with or without SiC particle addition. The activation energies of liquid–solid mixtures were mainly determined by liquid phase. Temperature had little influence on the relative viscosity (defined as the viscosity ratio of solid–liquid mixture to pure liquid). Viscosity and relative viscosity increased as decreasing rotation speed and increasing volume fraction of SiC solid particle. For the same volume fraction of SiC particle, relative viscosity was affected by the liquid slag compositions. The relative viscosity was smaller when composition of liquid slag had a larger CaO/SiO2 ratio or MgO/Al2O3 ratio. Meanwhile, it was found that the smaller SiC particle will lead to a larger relative viscosity. 相似文献
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《钢铁冶炼》2013,40(7):486-492
AbstractThe viscosity of CaO–5MgO–Al2O3–SiO2 slag with low silica was measured by rotating cylinder method up to 1823 K. Slag compositions were chosen based on five different levels of SiO2 content between 0 and 11·80%. The MgO content was 5·0%. The mass ratio of CaO/Al2O3 was varied from 0·66 to 1·95. It was shown that viscosity decreased with increasing temperature and decreased with increasing the mass ratio of CaO/Al2O3, following by an increase with further increasing the mass ratio of CaO/Al2O3. The viscosity decreased with the NBO/T ratio increasing, and the trend that flow activation energy changes with the NBO/T ratio of slag was the same as the trend that viscosity changes with the NBO/T ratio. Based on the experimental data as the boundary of the homogenous phase region, the mass triangle model was used to calculate the viscosity of low silica region. 相似文献
6.
《钢铁冶炼》2013,40(7):553-560
AbstractMagnesium oxide (MgO) based refractories are widely used in secondary refining processes, and their dissolution into refining slag is the primary cause of their shortened lifespan. The dissolution rate was investigated for sintered MgO and commercial MgO–C and MgO–Cr2O3 refractories in a synthesised 50CaO–45Al2O3–5SiO2 liquid (mass-%) slag. The change in slag composition was measured after a refractory sample was placed into the molten slag that was stirred by flowing argon gas at 1773?K. The dissolution rate of the sintered MgO was above those of the MgO–C and MgO–Cr2O3 refractories under the same gas flowrate, although the dissolution rate of all samples increased as the gas flowrate was increased from 25 to 75?mL·min??1. The slag containing 5?mass-% FeO considerably promoted the dissolution of the MgO–C refractory because of the oxidation of carbon by FeO. The dissolution of all the refractories was greatly affected by penetration of the liquid slag, with the mass transfer of MgO in the penetrating slag at lower gas flowrates likely being the rate controlling step. At high gas flowrates, Ar bubbles covered the surface and blocked the contact between the liquid slag and the solid phase, reducing the dissolution rate. 相似文献
7.
摘要:为了深入了解非均相脱磷剂中固体CaO在3CaO·P2O5-2CaO·SiO2(C2S-C3P)饱和熔渣中的溶解及反应机理,采用静态浸入法和旋转圆柱法研究固体CaO在C2S-C3P饱和CaO-SiO2-FetO-P2O5(10%)渣中的溶解行为,运用FESEM/BSED EDS对固体CaO和熔渣界面进行了观察,分析了固体CaO与C2S-C3P饱和熔渣间的反应机理。结果表明,加强对熔池的搅拌,能够加快固体CaO在熔渣中的侵蚀速度和溶解速度;发现了固体CaO在饱和熔渣中的溶解数量受熔渣中FeO通过边界层向固体内部渗透深度的影响,FeO渗透深度越深,溶解越多;固体CaO先与熔渣中的硅和磷反应生成磷含量低的C2S-C3P固溶体,待一段时间后,最终生成磷含量高的Ca5(PO4)2SiO4。 相似文献
8.
《钢铁冶炼》2013,40(10):732-737
AbstractDissolution of Al2O3 into molten CaO–Al2O3–CaF2, a base system of mould flux for continuous casting of high Al steel, has been investigated by employing a rotating cylinder method. The dissolution rate of an alumina rod into molten CaO–Al2O3–CaF2 flux increased with increase in rotating speed and temperature. The apparent activation energy for mass transport of flux C was calculated to be 255·6 kJ mol?1. The rate controlling step during the dissolution process of the alumina rod into molten CaO–Al2O3–CaF2 flux was found to be the diffusion of the solute in the flux boundary layer. The dissolution rate of alumina into molten CaO–Al2O3–CaF2 flux increased with increasing CaO/Al2O3, and it may be caused by the increase in thermodynamic driving force and the decrease in the viscosity of the flux. When the Al2O3 rod was immersed into molten flux, an intermediate compound of CaO.2Al2O3 formed firstly and then dissolved into molten flux. 相似文献
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CaO—SiO2—Al2O3熔渣脱氮的理论探讨 总被引:3,自引:0,他引:3
本文借助于一些试验数据和有关的热力学数据,对CaO-SiO_2-Al_2O_3熔渣脱氮进行理论探讨。结果表明,熔渣脱氮的适宜热力学条件为合适的熔渣组成,钢中较低的a_o和适当低的温度,适宜的熔渣组成为%CaO=35-45,%SiO_2=50-60,%Al_2O_3=0-10。 相似文献
12.
The crystallization and structure of non-conventional lime-silica-based mold fluxes after undergoing slag-steel interaction in casting high-AI transformation induced plasticity(TRIP)steel were studied.The results showed that the crystallization temperatures of the mold fluxes decreased with decreasing the SiO2/Al2O3 ratio,and CaO/MnO2 ratio had an opposite effect on the crystallization temperatures.The crystalline phases precipitated in the mold flux were Ca4Si2O7F2 and NaAlSiO4.Decreasing SiO2/Al2O3 ratio and increasing CaO/MnO2 ratio in the mold fluxes have no influence on the types of crystalline phases.The dominant crystalline phase precipitated in each mold flux was Ca4Si2O7F2 with dendritic morphology,except for part of that with globular morphology in the mold flux without MnO2 addition.NaAlSiO4 crystals are distributed in the space among Ca4Si2O7F2 crystals.The size of Ca4Si2O7F2 crystals in the slag with higher S1O2/AI2O3 ratio is smaller,which is attributed to the polymerization degree of the mold flux with increasing SiO2/Al2O3 ratio.[SiO4]-tetrahedral,[AlO4]-tetrahedral and T-O-T bending(T denotes Si or Al)depolymerized gradually with decreasing SiO2/Al2O3 ratio,and an opposite trend was observed for the case with increasing CaO/MnO2 ratio.The polymerization degree of the mold fluxes decreased,which would result in the decrease in the viscosity of the mold fluxes. 相似文献
13.
Russian Journal of Non-Ferrous Metals - The effect of K2O on phase relation and viscosity of the CaO–SiO2–25 wt % “FeO”–12 wt % ZnO–3 wt % Al2O3 slags... 相似文献
14.
Considering the significance of CaO–Al2O3–RE2O3 (RE?=?rare earth) phase diagrams, the Redlich–Kister expression was employed to evaluate the binary phase diagrams of CaO–Al2O3, La2O3–Al2O3 and CaO–La2O3 systems in the present work. Also, the activities of CaO and Al2O3 in the CaO–Al2O3 binary system were calculated. The phase diagram of the CaO–Al2O3–La2O3 ternary system was first assessed by Kohler extrapolation method. The accuracy of calculated phase diagrams was validated by comparing with existing experimental points and the calculation results from the literature. The obtained diagrams will lay a foundation for Al-killed steelmaking process, metallurgical flux and other fields’ industrial application. 相似文献
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Hyuk Kim Hiroyuki Matsuura Fumitaka Tsukihashi Wanlin Wang Dong Joon Min Il Sohn 《Metallurgical and Materials Transactions B》2013,44(1):5-12
The effect of Al2O3 and CaO/SiO2 on the viscosity of the CaO-SiO2-10 mass pct MgO-Al2O3 slags was studied at fully liquid temperatures of 1773 K (1500 °C) and below. At fixed CaO/SiO2 between 0.8 and 1.3, higher Al2O3 content increased the slag viscosity due to the polymerization of the aluminate structures. At fixed Al2O3 of 15 and 20 mass pct, increasing the CaO/SiO2 from 0.8 to 1.3 resulted in lower viscosity due to the depolymerization of the aluminate structure. 相似文献
17.
CaO—SiO2—MgO—Al2O3精炼渣的脱硫性能 总被引:8,自引:1,他引:7
在实验室用模拟装置研究了CaO-SiO2-MgO-Al2O3精炼渣脱硫的性能。碱度和助溶剂CaF2含量对硫分配比Ls影响较为显著,并分析了MgO、Al2O3对脱硫反应的作用。 相似文献
18.
The present work is carried out to study the evaporation of Na2O from CaO–Al2O3–SiO2–TiO2–MgO–Na2O slags with high basicity and high alumina in the temperature range of 1500–1560°C. The ratio of evaporation was determined by monitoring the Na2O content change of the slag melt under isothermal reduction conditions. The results show that the evaporation ratio increases with increasing the temperature. Higher basicity and increasing concentrations of Na2O, Al2O3 are also found to increase the evaporation ratio of Na2O, while MgO addition only slightly enhances the evaporation ratio. With TiO2 content increasing, the evaporation ratio first increases and then decreases. The evaporation rate of Na2O appears to be controlled by chemical reaction at the slag/gas interface in the beginning, followed by a mixed reaction-mass transfer regime, and finally a liquid-phase mass transport step. The apparent activation energy is 134.74?kJ?mol?1 for the chemical reaction regime and 268.53?kJ?mol?1 for the liquid-phase mass diffusion step. 相似文献
19.
The new CaO–Al2O3–SiO2–Li2O–B2O3–Ce2O3 mould flux was devised to realise smooth continuous casting of Ce-bearing heat-resistant steel. The new devised mould flux was based on calcium-aluminate system, so the w(CaO)/w(Al2O3) has great influence on the properties of the slag, which is similar to the basicity in the silicate system. The melting temperature, viscous properties, slag structure and crystalline phases with different w(CaO)/w(Al2O3) were investigated. The melting temperature of the mould flux could remain relatively steady with w(CaO)/w(Al2O3) in the range of 1.0–1.82. The main network former in the new slag was [AlO4]-tetrahedron. The network formed by [AlO4]-tetrahedron was destroyed by increasing w(CaO)/w(Al2O3), the viscosity decreased consequently. The mould flux show weaker crystallisation tendency with increasing w(CaO)/w(Al2O3). When the temperature decreased to 1100°C, the change of the fully crystallised phases with increasing w(CaO)/w(Al2O3) was as follows: Li2O·Al2O3?+?2CaO·Al2O3·SiO2?→?Li2O·Al2O3?→?Li2O·Al2O3?+?3CaO·Al2O3?+?CaCeAlO4. 相似文献
20.
Gert Bartzsch Rennie Christian Soumya Ranjan Mohanty Ajay Kumar Shukla Olena Volkova 《国际钢铁研究》2023,94(6):2200798
The influence of Al2O3 in the range of 10–20 mass% and TiO2 in the range of 0.55–5 mass% on the flow behavior, viscosity, density, and surface tension of molten industrial blast furnace slag with CaO/SiO2 = 1.13 is investigated using a high-temperature microscope, a rotating viscometer, and the maximum bubble pressure method. The measurement results show that Al2O3 acts as a network former in the studied CaO–SiO2–MgO–Al2O3–TiO2 slags. With an increase in the Al2O3 content from 10 to 20 mass%, the viscosity and surface tension of the slags increase and the density decreases. In contrast to Al2O3, the TiO2 acts as a surfactant and network breaker in the range of up to 15 mass%. The addition of TiO2 up to 15 mass% results in a decrease in the viscosity in the liquid-dominated region and a decrease in the surface tension of the studied slags. Therefore, the density increases with the addition of TiO2 due to increasing molar volume. The behavior of the breakpoint temperature on all the viscosity curves is in complete agreement with the behavior of the flow point temperature and crystallization temperatures of melilite and perovskite. 相似文献