scholarly journals Phase Equilibria in the System CaO-SiO2-La2O3-Nb2O5 at 1400 °C

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1892
Author(s):  
Chengjun Liu ◽  
Jiyu Qiu ◽  
Zhengyue Liu
Keyword(s):  
Phase Diagram ◽  
Slag System ◽  
Original Data ◽  
Tangent Plane ◽  
Primary Phase ◽  
Tangent Line ◽  
Reaction Type ◽  
Quaternary Phase ◽  
Phase Fields ◽  
Crystallization Reaction

CaO-SiO2-La2O3-Nb2O5 system is of great significance for the pyrometallurgical utilization of Bayan Obo tailing resources. In the present work, the phase equilibrium of this quaternary system at 1400 °C was determined by a thermodynamic equilibrium experiment. On the basis of the recently determined CaO-La2O3-Nb2O5 phase diagram, some boundary surfaces of primary phase fields of CaO-SiO2-La2O3-Nb2O5 phase diagram were modified; then, the 1400 °C isothermal surface in the primary phase fields of SiO2, CaNb2O6, Ca2Nb2O7, and LaNbO4 was constructed, respectively. On this basis, CaO-SiO2-Nb2O5 pseudo-ternary phase diagrams with w(La2O3) = 5%, 10%, 15%, and 20% were determined, respectively. Considering the importance of equilibrium crystallization reaction type, we proposed a new rule named Tangent Line Rule to judge the univariant reaction type in the quaternary phase diagram. By applying Tangent Line Rule and Tangent Plane Rule previously proposed, some univariant and bivariant crystallization reaction types in the CaO-SiO2-La2O3- Nb2O5 phase diagram were determined, respectively. The current work can provide original data for the establishment of a thermodynamic database of Nb-bearing and REE-bearing slag system; the proposed Tangent Line Rule will promote the application of a spatial quaternary phase diagram.

Quaternary phase diagrams as a tool for ionic cocrystallization: the case of a solid solution between a racemic and enantiopure ionic cocrystal

CrystEngComm ◽  
2020 ◽  
Vol 22 (14) ◽  
pp. 2537-2542
Author(s):  
Lixing Song ◽  
Fucheng Leng ◽  
Koen Robeyns ◽  
Tom Leyssens
Keyword(s):  
Phase Diagram ◽  
Solid Solution ◽  
Phase Diagrams ◽  
Solid Solution Formation ◽  
Quaternary Phase ◽  
Solution Formation ◽  
Contour Lines

Quaternary phase diagram of ionic cocrystals with solid solution formation is generated and dissolution surface is depicted clearly by contour lines.

Single-crystal growth of the Al–Cu–Fe icosahedral quasicrystal from the ternary melt

2001 ◽  
Vol 16 (11) ◽  
pp. 3038-3041 ◽  
Author(s):  
J. Q. Guo ◽  
A. P. Tsai
Keyword(s):  
Phase Diagram ◽  
Crystal Growth ◽  
Liquid Phase ◽  
Single Crystal ◽  
Peritectic Reaction ◽  
Maximum Size ◽  
Single Crystal Growth ◽  
Primary Phase ◽  
Partial Phase Diagram ◽  
Icosahedral Quasicrystal

An Al–Cu–Fe partial phase diagram involving the icosahedral quasicrystal has been constructed along an Al62.5Cu37.5−xFex (x = 2.5 to 25 at.%) isopleth. The icosahedral quasicrystal forms at 850 °C via a peritectic reaction between a liquid and (Al,Cu) 13Fe4 phase and coexists with a liquid phase at temperature below the peritectic reaction. The icosahedral quasicrystal crystallizes as a primary phase in the temperature range of 760 to 850 °C from alloys surrounded by composition points of Al–Cu–Fe: 62.5–33–4.5, 62.5–34.5–3, 57.5–39.5–3 and 57.5–38.0–4.5 at.%. On the basis of the phase diagram, single grains of the Al–Cu–Fe icosahedral quasicrystal with a maximum size of 5 mm were successfully grown from Al–Cu–Fe melts.

scholarly journals Viscosity and Structure of a CaO-SiO2-FeO-MgO System during a Modified Process from Nickel Slag by CaO

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2562 ◽  
Author(s):  
Yingying Shen ◽  
Junkai Chong ◽  
Ziniu Huang ◽  
Jianke Tian ◽  
Wenjuan Zhang ◽  
...  
Keyword(s):  
Mole Fraction ◽  
Solid Phase ◽  
Molar Fraction ◽  
Slag System ◽  
Softening Temperature ◽  
Degree Of Polymerization ◽  
Primary Phase ◽  
Basic Oxide ◽  
High Iron Content ◽  
Critical Viscosity

There is a high iron content in nickel slag that mainly exists in the fayalite phase. Basic oxide can destroy the stable structure of fayalite which is beneficial to the treatment and comprehensive utilization of nickel slag. The research was based on the composition of the raw nickel slag, taking the CaO-SiO2-FeO-MgO system as the object and CaO as a modifier. The effect of basicity on the melting characteristics, viscosity and structure of the CaO-SiO2-FeO-MgO system was studied. The relationship between the viscosity and structure of the CaO-SiO2-FeO-MgO system was also explored. The results show as follows: (1) When the basicity is lower than 0.90, the primary phase of the slag system is olivine phase. When the basicity is greater than 0.90, the primary phase of the slag system transforms into monoxide. When the basicity is 0.90, olivine and monoxide precipitate together as the temperature continues to decrease. At the same time, the liquidus temperature, softening temperature, hemispherical temperature, and flow temperature all reach the lowest value. (2) With the increase of basicity, the critical viscosity temperature of the CaO-SiO2-FeO-MgO system decreases first and then increases. Critical viscosity temperature is the lowest at the basicity of 0.90, which is 1295 °C. (3) When the slag system is heterogeneous, the viscosity of the molten slag increases rapidly because of the quantity of solid phase precipitated from the CaO-SiO2-FeO-MgO system. (4) When the slag system is in a homogeneous liquid phase, the molar fraction of O0 decreases with the increase of basicity and the mole fraction of O−, and O2− increases continuously at the basicity of 0.38~1.50. The silicate network structure is gradually depolymerized into simple monomers, resulting in the degree of polymerization, and the viscosity, being reduced. The mole fraction of different kinds of oxygen atoms is converged to a constant value when the basicity is above 1.20.

Quaternary Phase Equilibria in the Ti-Si-N-O System: Stability of Metallization Layers and Prediction of Thin Film Reactions

1989 ◽  
Vol 148 ◽  
Author(s):  
A.S. Bhansali ◽  
R. Sinclair
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Diagram ◽  
Phase Equilibria ◽  
System Stability ◽  
Multicomponent Systems ◽  
Phase Rule ◽  
Quaternary Phase ◽  
Circuit Fabrication ◽  
Quaternary Phase Equilibria

ABSTRACTDuring high temperature circuit fabrication, metallization layers can come in contact with both solids and gases. Their stability can be addressed with the aid of phase equilibria. Using the Gibbs phase rule as a basis, a method for generating phase diagrams for multicomponent systems can be established. This procedure is described and illustrated by reference to the quaternary phase diagram of Ti-Si-N-O. This phase diagram can then be used to predict stability and/or reactions in metallization layers and thin films.

Calculation of Aluminum Equivalent Based on Thermo-Calc Software in Ti-Al-Nb Ternary System

2014 ◽  
Vol 788 ◽  
pp. 144-149 ◽  
Author(s):  
Hui Min Yang ◽  
Liang Shun Luo ◽  
Mei Hui Song ◽  
Hai Qun Qi ◽  
Chun Yan Wang ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Ternary Phase ◽  
Ternary Phase Diagram ◽  
Primary Phase ◽  
Ternary Alloys ◽  
Al Content ◽  
Β Phase ◽  
Thermo Calc Software ◽  
Vertical Sections ◽  
Aluminum Equivalent

Ti-Al-Nb ternary phase diagrams were calculated by Thermo-Calc software. The analysis of the calculated vertical sections of Ti-Al-Nb phase diagram indicated that when Nb content is fixed at 5at.% and Al content is lower than 52.3at.%, the primary phase would be β phase during solidification. With 10 at.%Nb and Al content lower than 55.8at.%, or with 15 at.%Nb and Al content lower than 56.9at.%, the primary phase would be β phase. The vertical sections of Ti-Al-Nb ternary phase diagram were further simplified into pseudo-Ti-Al binary phase diagram. According to the pseudo-Ti-Al diagram, the expression of the aluminum equivalent was obtained in Ti-Al-5Nb ternary alloys.

Reaction between niobium and silicon carbide at 1373 K

1990 ◽  
Vol 5 (10) ◽  
pp. 2197-2208 ◽  
Author(s):  
D. L. Yaney ◽  
A. Joshi
Keyword(s):  
Phase Diagram ◽  
Silicon Carbide ◽  
Reaction Layer ◽  
Substrate Surface ◽  
Depth Profiling ◽  
Vacuum System ◽  
Layer Sequence ◽  
Quaternary Phase ◽  
Transmission Electron ◽  
Free Energy Of Formation

The reaction zone formed between niobium and silicon carbide during heating for 4 h at 1373 K was examined by transmission electron microscopy (TEM) and Auger electron spectroscopy (AES). The typical reaction layer sequence is SiC/Nb5Si4C/Nb5Si3/Nb2C/NbO/Nb. However, in one area of the specimen, the first reaction layer was NbC rather than Nb5Si4C. The high oxygen and carbon concentrations near the outer surface were shown by AES depth profiling to result from carbon and oxygen contamination from the vacuum system during annealing. In order to determine if the observed reaction layer sequence is consistent with conditions of local thermodynamic equilibrium, the quaternary Nb–Si–C–O phase diagram was calculated from available thermodynamic data. A minimum (most negative) free energy of formation for the ternary compound Nb5Si4C of −582 kJ/mole was estimated assuming that the equilibrium between NbSi2 and SiC observed experimentally at 1573 K1 also exists at 1373 K. Except for the region immediately adjacent to the substrate, the observed reaction layer sequence was in agreement with the calculated quaternary phase diagram. However, it was noted that agreement with the quaternary phase diagram would be obtained if a thin layer of either SiO2 or NbC were present at the substrate surface.

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