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1.
Bertha Alicia Vázquez Ángel Caballero Pilar Pena 《Journal of the American Ceramic Society》2005,88(7):1949-1957
Solid-state compatibility and melting relations of MgAl2 O4 in the quaternary system Al2 O3 –CaO–MgO–SiO2 were studied by firing and quenching selected samples located in the 65 wt% MgAl2 O4 , plane followed by microstructural and energy dispersive X-ray analysis. A projection of the liquidus surface of the primary crystallization volume of MgAl2 O4 was constructed from CaO, SiO2 and exceeding Al2 O3 , not involved in stoichiometric MgAl2 O4 formation; those three amounts were recalculated to 100 wt%. The temperature and character of six invariant points, where four solids co-exist with a liquid phase, were defined. One maximum point was localized and the positions of the isotherms were tentatively established. The effect of CaO, SiO2 , and Al2 O3 impurities on the high temperature behavior of spinel materials was also discussed. 相似文献
2.
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
3.
Cristina Siligardi Luca Lusvarghi Monia Montorsi Cecilia Vernia 《Journal of the American Ceramic Society》2008,91(3):990-995
In this work several complementary techniques have been employed to carefully characterize the sintering and crystallization behavior of CaO–Al2 O3 –ZrO2 –SiO2 glass powder compacts after different heat treatments. The research started from a new base glass 33.69 CaO–1.00 Al2 O3 –7.68 ZrO2 –55.43SiO2 (mol%) to which 5 and 10 mol% Al2 O3 were added. The glasses with higher amounts of alumina sintered at higher temperatures (953°C [lower amount] vs. 987°C [higher amount]). A combination of the linear shrinkage and viscosity data allowed to easily find the viscosity values corresponding to the beginning and the end of the sintering process. Anorthite and wollastonite crystals formed in the sintered samples, especially at lower temperatures. At higher temperatures, a new crystalline phase containing ZrO2 (2CaO·4SiO2 ·ZrO2 ) appeared in all studied specimens. 相似文献
4.
W. C. LUTH 《Journal of the American Ceramic Society》1967,50(4):174-176
Schairer's study (1954) on phase relations in the system KalSi2 O6 –Mg2 SiO4 –SiO2 was extended to include the system KalSiO4 –Mg2 SiO4 –KalSi2 O6 . It is shown that this join is ternary; however, the relatively high vapor pressure of the condensed phases prohibits study by the usual quenching techniques. The apparent intersection of the (KalSiO4 –Mg2 SiO4 –SiO3 ) join with the primary phase volume of spinel is attributed to loss of the alkali-silicate constituents by vapor transport. This results in the effective bulk composition being moved away from this join toward the primary phase volume of spinel in the system K2 O–MgO–Al2 O3 –SiO2 . 相似文献
5.
Masahide Okamoto Hironori Kodama Kazuo Shinozaki 《Journal of the American Ceramic Society》2008,91(4):1110-1114
The sintering of a composite of MgO–B2 O3 –Al2 O3 glass and Al2 O3 filler is terminated due to the crystallization of Al4 B2 O9 in the glass. The densification of a composite of MgO–B2 O3 –Al2 O3 glass and Al2 O3 filler using pressureless sintering was accomplished by lowering the sintering temperature of the composite. The sintering temperature was lowered by the addition of small amounts of alkali metal oxides to the MgO–B2 O3 –Al2 O3 glass system. The resultant composite has a four-point bending strength of 280 MPa, a coefficient of thermal expansion (RT—200°C) of 4.4 × 10−6 K−1 , a dielectric constant of 6.0 at 1 MHz, porosity of approximately 1%, and moisture resistance. 相似文献
6.
Phase relations and lattice constants in the MgO–Al2 O3 –Ga2 O3 system at 1550°C have been determined experimentally. In a large part of this system, only a nonstoichiometric spinel is stable. Compositions as extreme as 12.5 mol% MgO–20.5 mol% Ga2 O3 –67 mol% Al2 O3 for a homogeneous spinel are possible. In the bordering phase diagrams of MgO–Al2 O3 and MgO–Ga2 O3 , the composition of the spinel is as high as 63 mol% Al2 O3 or Ga2 O3 , respectively. The contributions of all simple ionic exchange reactions on the lattice constant of the spinel have been deduced from X-ray diffractometry data. 相似文献
7.
8.
Teresa Durán Sara Serena Pilar Pena Ángel Caballero Salvador De Aza Antonio H. De Aza 《Journal of the American Ceramic Society》2008,91(2):535-543
The isoplethal sections CaAl2 O4 –MgO and CaAl4 O7 –MgO of the Al2 O3 –MgO–CaO ternary system have been experimentally established at 1 bar total pressure and air of normal humidity. The sections obtained provide new data and information that are in disagreement with thermodynamic evaluations and optimizations of the Al2 O3 –MgO–CaO ternary system published to date. These differences arise mainly from the inclusion, or exclusion, of the binary compound Ca12 Al14 O33 , mayenite, as a stable phase in the reported studies of the system. The presence or absence of this compound within the system has an important impact on the solid state and melting relationships of the whole ternary system. The present study confirms the solid-state compatibility CaAl2 O4 –MgO and CaAl2 O4 –MgO–MgAl2 O4 up to 1372°± 2°C, the peritectic melting point of the later mentioned subsystem. 相似文献
9.
I. Prakash P. Muralidharan N. Nallamuthu N. Satyanarayana M. Venkateswarlu David Carnahan 《Journal of the American Ceramic Society》2006,89(7):2220-2225
NiAl2 O4 /SiO2 and Co2+ -doped NiAl2 O4 /SiO2 nanocomposite materials of compositions 5% NiO – 6% Al2 O3 – 89% SiO2 and 0.2% CoO – 4.8% NiO – 6% Al2 O3 – 89% SiO2 , respectively, were prepared by a sol–gel process. NiAl2 O4 and cobalt-doped NiAl2 O4 nanocrystals were grown in a SiO2 amorphous matrix at around 1073 K by heating the dried gels from 333 to 1173 K at the rate of 1 K/min. The formations of NiAl2 O4 and cobalt-doped NiAl2 O4 nanocrystals in SiO2 amorphous matrix were confirmed through X-ray powder diffraction, Fourier transform infrared spectroscopy, differential scanning calorimeter, transmission electron microscopy (TEM), and optical absorption spectroscopy techniques. The TEM images revealed the uniform distribution of NiAl2 O4 and cobalt-doped NiAl2 O4 nanocrystals in the amorphous SiO2 matrix and the size was found to be ∼5–8 nm. 相似文献
10.
R. A. EPPLER 《Journal of the American Ceramic Society》1963,46(2):97-101
The stability of the vitreous state in the lithium metasilicate region of the system Li2 O–Al2 O3 –SiO2 was found to be a function of the concentration of lithia. The higher the lithia content, the less stable was the glass. The devitrification of glasses in this system was studied. In addition to the phases present at or near the liquidus, it was found that the β -eucryptite– β -quartz solid solution phase was metastable over most of the region. The Li2 O–SiO2 , β -Li2 O–Al2 O3 –4SiO2 solid solution, β -Li2 O–Al2 O3 –2SiO2 solid solution triple point was estimated to be near 62.5% SiO2 , 17% Al2 O3 , and 20.5% Li2 O (by weight). The thermal expansions of bodies in this region were measured and the values obtained are explained in terms of the phases present. 相似文献
11.
In this study, the isothermal section of a Cu2 O–Al2 O3 –SiO2 pseudo-ternary phase diagram at 1150°C was analyzed by means of a scanning electronic microscope and powder X-ray diffraction of the quenched samples qualitatively, and the compositions of the tie-points of the tie-planes as well as their regions were determined by in situ high-temperature quantitative X-ray diffraction analysis and energy-dispersive X-ray spectroscopy. Then, the isothermal section of the Cu2 O–Al2 O3 –SiO2 pseudo-ternary phase diagram at 1150°C was constructed; it was found that the isothermal section is composed of two single liquid-phase regions, five two-phase regions, and six three-phase regions. 相似文献
12.
Sander Arnout Dirk Durinck Muxing Guo Bart Blanpain Patrick Wollants 《Journal of the American Ceramic Society》2008,91(4):1237-1243
In this work, the liquidus of synthetic CaO–SiO2 –MgO–Al2 O3 –CrO x slags is evaluated in the industrially relevant compositional domain. Equilibrium experiments are carried out at 1500°C and partial oxygen pressure ( p O2 ) 10−11.04 atm, and at 1600°C and p O2 =10−10.16 and 10−9.36 atm. The studied basicities (CaO/SiO2 ) are 1.2 and 0.5. Al2 O3 levels range from 0 to 30 wt%. Oversaturated liquid is sampled and phase relations are measured with quantitative electron probe microanalysis–wavelength dispersive spectroscopy (EPMA–WDS). The results are compared with the commercially available FactSage thermodynamic databases. Qualitative agreement is always obtained. Also a good quantitative agreement is found at the higher basicity, especially for the spinel liquidus. A minor but systematic deviation can be observed for the eskolaite liquidus. At the lower basicity, the calculated phase diagram deviates strongly from the experimental results, probably due to missing ternary interactions in the database. 相似文献
13.
The cell dimensions of pure triclinic 3CaO·SiO2 and monoclinic 3CaO·SiO2 solid solution (54CaO·16SiO2 ·Al2 O3 ·MgO) were determined and the powder diffraction patterns were indexed by the method of precise measurement of the spacings. The lattice constants are expressed in terms of triclinic or monoclinic cells corresponding to pseudo-orthorhombic cells derived from Jeffery's trigonal cell. The apparent lattice constants for pure 3CaO·SiO2 are a = 12.195 a.u., b = 7.104 au., c = 25.096 a.u., α= 90°, β= 89°44'γ= 89°44'; for 54CaO·16SiO2 .-Al2 O3 MgO, a = 12.246 a.u., b = 7.045 a.u., c = 24.985 a.u., β= 90°04'. Precise lattice constants of Jeffery's monoclinic lattice for 54CaO.-16SiO2 -Al2 O3 ·MgO are derived as a = 33.091 a.u., b = 7.045 a.u., c = 18.546 a.u., β= 94°08'. High-temperature X-ray patterns showed that pure triclinic 3CaO·SiO2 transformed to a monoclinic form at about 920°C. and then to a trigonal form at about 970°C. Monoclinic 54CaO.16SiO2 ·Al2 O3 –MgO transformed to trigonal at about 830°C. These transitions were reversible and reproducible and were accompanied by only slight deformation of the structure forms. 相似文献
14.
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
15.
On the basis of 190 runs made up to 1860°C in sealed noble-metal containers the following revisions have been made in the equilibrium diagram for the system A12 O3 –SiO2 . Mullite melts congruently at 1850°C. The extent of equilibrium solid solution in mullite at solidus temperature is from approximately 60 mole % Al2 O3 (3/2 ratio) to 63 mole % A12 O3 . Metastable solid solutions can be prepared up to about 67 mole % Al2 O3 . There is no evidence for stable solubility of excess SiO2 beyond the 3/2 composition at pressures below 3 kbars. Refractive indices are presented for glasses containing up to 60 mole % Al2 O3 and from them the composition of the eutectic is confirmed at 5 mole % SiO2 . The variation in lattice constants of the mullite solid solution is not an unequivocal guide to composition since mullites at one composition produced at different temperatures show differences in spacing, no doubt reflecting Al-Si ordering phenomena. The possibility of quartz and corundum being the stable assemblage at some low temperatures and pressures cannot be ruled out. A new anhydrous phase in the system is described, which was previously thought to be synthetic andalusite; it is probably a new polymorph of the Al2 SiO5 composition with ortho-rhombic unit-cell dimensions a =7.55 A, b =8.27 A, and c = 5.66 A. 相似文献
16.
Activity–composition relations of FeCr2 O4 –FeAl2 O4 and MnCr2 O4 –MnAl2 O4 solid solutions were derived from activity–composition relations of Cr2 O3 –Al2 O3 solid solutions and directions of conjugation lines between coexisting spinel and sesquioxide phases in the systems FeO–Cr2 O3 –Al2 O3 and MnO–Cr2 O3 –Al2 O3 . Moderate positive deviations from ideality were observed. 相似文献
17.
Sang Il Seok Mi Ae Lim Jung-Jin Ju Myung-Hyun Lee 《Journal of the American Ceramic Society》2005,88(9):2380-2384
Er-doped Al2 O3 –SiO2 (1/9 in mol ratio of Al2 O3 /SiO2 ) thin films were prepared by using a modified sol–gel process. The modified process entails the precipitation and digestion of Er(OH)3 , obtained from the reaction between Er ions and NH4 OH in solution. Thin films were deposited on Si wafers by using a spin coating technique (3000 rpm) and the coated films were heat treated at different temperatures for 1 h in an oxygen-purged furnace. All the films were structurally characterized by the X-ray diffraction technique using Cu K α radiation. Refractive indices and the morphologies of the films were studied using a spectroscopic phase modulated ellipsometer and atomic force microscopy, respectively. It was observed that the films were crack free and of about 0.4 μm thickness in a single spin coating and both the lifetime and the photoluminescence intensity of Er ions increased with increasing the annealing temperature. The luminescence properties of the Er-doped Al2 O3 –SiO2 made by a conventional and our modified doping process were compared and discussed from the stand point of peak intensities and lifetimes as a function of annealing temperatures. It is to be noted here that our modified process was found to be more effective in reducing the clustering of Er ions in Al2 O3 –SiO2 materials as compared to that of the conventional method. 相似文献
18.
Chen-Feng Chan Bernard B. Argent William E. Lee 《Journal of the American Ceramic Society》1998,81(12):3177-3188
The microstructures of Al2 O3 –SiO2 –SiC–C refractory matrices with aluminum, silicon, Si3 N4 , BN, B2 O3 , and B4 C additives are characterized before and after a crucible slag test, and the phases present are compared to those expected at thermodynamic equilibrium. The carbon content dominates the resistance to CaO–MgO–Al2 O3 –SiO2 slag penetration, while the viscosity of liquid phases present has a significant influence when the matrix carbon contents are similar. Silicon and Si3 N4 additives reduce slag penetration resistance because of indirect oxidation of carbon to form SiC. B4 C, in particular, and B2 O3 also reduce slag penetration resistance because of formation of a more fluid boron-containing liquid, while aluminum and BN addition have no significant effect. Carbon and BN hardly react with the slag, while SiC partially reacts with it, leading to deposition of carbon as a dense layer. Corundum present in the refractories also readily dissolves in the slag. Microstructurally, slag penetration resistance is associated with the dense carbon layer located at the slag-refractory interface. 相似文献
19.
Zhen-Kun Huang Steve D. Nunn Irene Peterson Tseng-Ying Tien 《Journal of the American Ceramic Society》1994,77(12):3251-3254
Formation of N-phase in the system Mg,Si,Al/N,O was studied. Its composition was confirmed to be MgAl2 Si4 O6 N4 (2Si2 N2 OMgAl2 O4 ). Subsolidus phase relationships in the MgO–Si2 N2 O-Al2 O3 system were determined. The results are discussed by comparing with two similar systems, CaO-and Y2 O3 –Si2 N2 O–Al2 O3 . 相似文献
20.
P. L. ROEDER F. P. GLASSER† E. F. OSBORN 《Journal of the American Ceramic Society》1968,51(10):585-593
Liquidus phase equilibrium data are presented for the system Al2 O3 -Cr2 O3 -SiO2 . The liquidus diagram is dominated by a large, high-temperature, two-liquid region overlying the primary phase field of corundum solid solution. Other important features are a narrow field for mullite solid solution, a very small cristobalite field, and a ternary eutectic at 1580°C. The eutectic liquid (6Al2 O3 -ICr2 O3 -93SiO2 ) coexists with a mullite solid solution (61Al2 O3 -10Cr2 O3 -29SiO2 ), a corundum solid solution (19Al2 O3 -81Cr2 O3 ), and cristobalite (SO2 ). Diagrams are presented to show courses of fractional crystallization, courses of equilibrium crystallization, and phase relations on isothermal planes at 1800°, 1700°, and 1575°C. Tie lines were sketched to indicate the composition of coexisting mullite and corundum solid solution phases. 相似文献