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Equilibrium diagrams for the systems NiO-SiO2, NiO-Al2O3, NiAl2O4-SiO2, Ni2SiO4-NiAl2O4, and NiAl2O4-Al6Si2O13 were drawn from data obtained by quenching and direct observational techniques. The only intermediate compound in the binary system NiO-SiO2 is Ni2SiO4, which has the olivine structure. Unlike other olivines which melt congruently, nickel olivine has an upper temperature of stability (1545°C) and at temperatures between 1545° and 1650°C, NiO and SiO2 coexist in equilibrium. The only compound in the binary system NiO-Al2O3 is NiAl2O4, which has a spinel structure. The nickel aluminate spinel varies in composition from 50 to 35 mole % Al2O3 at 1800°C, and the stoichiometric NiAl2O4 composition has a melting point near 2110°C. Of the joins within the ternary system NiO-Al2O3-SiO2 which were studied, only Ni2SiO4-NiAl2O4 is not binary. In this join, crystals of NiO exist in equilibrium with liquid and a ternary assemblage of NiO + NiAl2O4+ liquid is stable to 1775°C. The decomposition temperature of Ni2SiO4 is decreased from 1545°C in the binary system to approximately 1490°C, presumably the result of solubility of NiAl2O4 in Ni2SiO4. The join NiAl2O4-SiO2 is binary in that the compositions of crystalline phases can be expressed in terms of the chosen components. The eutectic temperature in the system is 1495°C. The join NiAl2O4-Al6Si2O13 is binary for the same reasons and has a eutectic temperature at 1720°C. Using the data obtained in this study and those published for the well-known system Al2O3-SiO2, a liquidus surface diagram for the system NiO-Al2O3-SiO2 is proposed. Nickel olivine, even though it has an upper limit of stability in the binary system, has a primary field in the ternary system NiO-Al2O3-SiO2. This is the only refractory oxide system known to illustrate this so-called “typical case,” the governing principles of which have been clearly presented in discussions of phase equilibria. 相似文献
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A phase diagram of the system A12 O3 -A14 C3 is proposed. Two intermediate oxycarbides, A14 O4 C and A12 OC, were established. Eutectic melting between alumina and A14 O4 C occurred at 1840° C. No other low melting was observed. The alumina phase was not corundum but was similar to delta-alumina. Because of the high reactivity of aluminum carbide and all the intermediate compounds with moisture and oxygen, use of refractories based on the system A12 O3 -A14 C3 must be limited to applications where these agents are excluded. The behavior of high-alumina refractories in the presence of carbon is explained. 相似文献
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Antonio H. de Aza Juan E. Iglesias Pilar Pena Salvador De Aza 《Journal of the American Ceramic Society》2000,83(4):919-927
Solid-state compatibility and melting relationships in the subsystem Al2 O3 —MgAl2 O4 —CaAl4 O7 were studied by firing and quenching selected samples located in the isopletal section (CaO·MgO)—Al2 O3 . The samples then were examined using X-ray diffractomtery, optical microscopy, and scanning and transmission electron microscopies with wavelength- and energy-dispersive spectroscopies, respectively. The temperature, composition, and character of the ternary invariant points of the subsystem were established. The existence of two new ternary phases (Ca2 Mg2 Al28 O46 and CaMg2 Al16 O27 ) was confirmed, and the composition, temperature, and peritectic character of their melting points were determined. The isothermal sections at 1650°, 1750°, and 1840°C of this subsystem were plotted, and the solid-solution ranges of CaAl4 O7 , CaAl12 O19 , MgAl2 O4 , Ca2 Mg2 Al28 O46 , and CaMg2 Al16 O27 were determined at various temperatures. The experimental data obtained in this investigation, those reported in Part I of this work, and those found in the literature were used to establish the projection of the liquidus surface of the ternary system Al2 O3 —MgO—CaO. 相似文献
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JOYDEB MUKERJI 《Journal of the American Ceramic Society》1965,48(4):210-213
Differential thermal analysis and quenching experiments were used to establish the ternary phase diagram CaO-CaF2 -2CaO.SiO2 . Hermetically-closed platinum capsules were used to prevent fluorine loss in the form of HF, SiF4 , and CaF2 by reaction of the CaF2 with water vapor or SiO2 , or by evaporation. The melting point of pure CaF2 was 1419°± 1°C. There is one binary eutectic in the system CaO-CaF2 and there are two ternary eutectics in the system CaO-CaF2 -2CaO.SiO2 . The results of the present study were combined with literature data to construct the phase diagram CaO-CaF2 -SiO2 . 相似文献
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The 1600° and 1700°C. liquidus lines in the CaO·2Al2 O3 and A12 O3 stability fields of the system CaO-Al2 O3 -SiO2 are determined from the chemical analyses of saturated slags at these temperatures. 相似文献
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J. P. COUTURES 《Journal of the American Ceramic Society》1985,68(3):105-107
A tentative phase diagram for the system Al2 03 -Nd2 O3 is presented. Three compounds were obtained: a β -A12 O3 -type compound, the perovskite NdAlO3 , and Nd4 Al2 O9 . The perovskite melts congruently (mp 2090°C), and the two other compounds exhibit incongruent melting behavior: β -Nd/Al2 O3 , mp 1900°C; Nd4 Al2 O9 , mp 1905°C. Two eutectics exist with the following compositions and melting points: 80 mol% Al2 O3 , 1750°C; 23 mol% Al2 O3 ,1800°C. Nd4 Al2 O9 decomposes in the solid state at 1780°C. 相似文献
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The binary system Nb2 O5 — SiO2 has been shown to include an extensive two-liquid region over the range 5 to 80% Nb2 O5 . The minimum temperature of the two-liquid area is 1695°C. A eutectic composition occurs at 95% Nb2 O5 and 1448°C. and another at approximately 5% Nb2 O5 and 1695°C. The experimental results were obtained by the cone-fusion method. 相似文献
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PERRY A. FOSTER Jr. 《Journal of the American Ceramic Society》1960,43(8):437-438
THE electrolyte that is employed in the commercial production of aluminum generally consists of a fused mixture of cryolite, aluminum fluoride, calcium fluoride, and alumina. The aluminum fluoride is added to alter the cryolite ratio (3NaF/AlF3 )* from the stoichiometric value of 1.5 to some lower value. Calcium fluoride is added to permit lower operating temperatures. Typically, the calcium fluoride content of the commercial electrolyte is usually between 7 and 9%. Alumina, of course, is continually being consumed in the production of aluminum. Periodic additions of alumina to the cell maintain the level between 2 and 50%. 相似文献
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Bertha Alicia Vázquez Angel Caballero Pilar Pena 《Journal of the American Ceramic Society》2003,86(12):2195-2199
Compatibility relations of Al2 O3 in the quaternary system Al2 O3 –CaO–MgO–SiO2 were studied by firing and quenching followed by microstructural and energy-dispersive X-ray examination. A projection of the liquidus surface of the primary phase volume of Al2 O3 was constructed in terms of the CaO, SiO2 , and MgO contents of the mixtures recalculated to 100 wt%. Two invariant points, where four solids coexist with a liquid phase, were defined, and the positions of the isotherms were tentatively established. The effect of SiO2 , MgO, and CaO impurities on Al2 O3 growth also was studied. 相似文献
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Results are presented of a study of phase equilibria among crystalline and liquid phases in the quaternary system CaO–MgO-Al2 O3 –SiO2 at Al2 O3 contents greater than 35%. Equilibrium diagrams shown are for the five triangular joins CaAl2 Si2 O3 -Ca2 Al2 SiO7 -MgAl2 O4 , Ca2 Al2 SiO7 -MgAl2 O4 -Al2 O3 , CaAl2 Si2 O8 -MgO-Al2 O3 , CaAl2 Si2 O8 -Mg2 SiO4 -MgAl2 O4 , and CaAl2 Si2 O8 -MgO-Mg2 SiO4 . The composition and nature of the four quaternary peritectic points and the relationships of univariant lines and primary phase volumes are discussed. 相似文献
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Satoshi Uda Etsuro Asakura Masahisa Nagashima 《Journal of the American Ceramic Society》1998,81(3):725-729
The influence of the additive SO3 on the phase relationships in the quaternary system CaO-SiO2 -Al2 O3 -Fe2 O3 was investigated by observing the change of volume ratio of 3CaOSiO2 (C3 S) to 2CaOSiO2 (C2 S) + CaO (C) in the sintered material with the increase of SO3 content. The primary phase volume of C3 S in the quaternary phase diagram shrank with the increase of SO3 and disappeared when the SO3 content exceeded 2.6 wt% in the sintered material. Changes in the peritectic reaction relationship between CaO (C), 2CaOSiO2 (C2 S), 3CaOSiO2 (C3 S), 3CaOAl2 O3 (C3 A), 4CaOAl2 O3 Fe2 O3 (C4 AF), and liquid were also observed and discussed. 相似文献
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Shyan-Lung Chung Yu-Cheng Sheu Ming-Shyong Tsai 《Journal of the American Ceramic Society》1992,75(1):117-123
SiO2 , Al2 O3 , and 3Al2 O3 .2SiO2 powders were synthesized by combustion of SiCl4 or/and AlCl3 using a counterflow diffusion flame. The SiO2 and Al2 O3 powders produced under various operation conditions were all amorphous and the particles were in the form of agglomerates of small particles (mostly 20 to 30 nm in diameter). The 3Al2 O3 .2SiO2 powder produced with a low-temperature flame was also amorphous and had a similar morphology. However, those produced with high-temperature flames had poorly crystallized mullite and spinel structure, and the particles, in addition to agglomerates of small particles (20 to 30 nm in diameter), contained larger, spherical particles 150 to 130 nm in diameter). Laser light scattering and extinction measurements of the particle size and number density distributions in the flame suggested that rapid fusion leading to the formation of the larger, spherical particles occurred in a specific region of the flame. 相似文献
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This paper deals with a study of the equilibrium relations of mixtures of pure alumina and silica at high temperatures. The results are expressed concisely in the form of an equilibrium, diagram and their bearing on ceramic problems is discussed. The principal feature of the diagram is the absence of the compound Al2O3.SiO2, the only compound being 3Al2O3.2SiO2. Crystals of this latter compound occur in all alumina-silica refractories. The optical properties of these crystals have been determined and are compared with those of sillimanite, Al2O3.SiO2, which has hitherto been regarded as the crystalline compound occurring in refractories and clay bodies in general. The behavior of natural sillimanite on heating is discussed. 相似文献
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ARNULF MUAN 《Journal of the American Ceramic Society》1957,40(12):420-431
Phase equilibrium data at liquidus temperatures are presented for mixtures in the system FeO–Fe2 O3 –Al2 O3 –SiO2 . The volume located between the 1 and 0.2 atm. O2 isobaric surfaces of the tetrahedron representing this system was studied in detail. Scattered data were obtained at lower O2 pressures. Results obtained in the present investigation were combined with data in the literature to construct a phase equilibrium diagram, at liquidus temperatures, for the entire system FeO–Fe2 O3 –Al 2 O3 –SiO2 . Methods for interpretation of the diagram are explained. 相似文献
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A. T. PRINCE 《Journal of the American Ceramic Society》1951,34(2):44-51
The system MgO–Al2 O3 –2CaO·SiO2 comprises a plane through the tetrahedron CaO–MgO–Al2 O3 –SiO2 . A total of 108 compositions were prepared having an alumina content below the line joining 2CaO·Al2 O3 SiO2 (gehlenite) and MgO·Al2 O3 (spinel). Quenching experiments were carried out on 96 of these compositions at temperatures up to 1590°C. Three binary eutectic systems and two ternary eutectic systems are described. Compositions on this plane are of significance in an investigation of the constitution of basic refractory clinkers made from Canadian dolomitic magnesites. They also concern the compositions of certain blast furnace slags. 相似文献