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1.
F. F. LANGE 《Journal of the American Ceramic Society》1978,61(1-2):53-56
Phase relation studies of Si3 N1 , SiO2 , and MgO have established three important subsolidus tie lines, viz. Si3 N4 -MgO, Si3 N4 -Mg2 SiO4 , and Si2 N2 O-Mg2 SiO4 for nonoxidizing fabrication conditions. Strength measurements at 1400°C show that optimum strengths are obtained for compositions approaching the Si3 N4 -MgO and Si3 N4 -Si2 N2 O tie lines and that inferior strengths are obtained for compositions approaching the Si3 N4 -Mg2 SiO4 tie line. Oxidation measurements at 1375°C show that the oxidation kinetics depend on the content of MgO and Mg2 SiO4 phases. Optimum oxidation resistance is observed for compositions approaching the Si3 N4 -Si2 N2 O tie line. Strength and oxidation results are discussed with regard to phase equilibrium considerations. 相似文献
2.
Immiscibility temperatures of Na2 O-B2 O3 -SiO glasses, with andwithout 1 mol% MoO3 , additions, were determined and the effect of MoO3 additions on the 65O°C immiscibility isotherms was established. In addition, immiscibility temperature and phase-separation morphology of an Na2 O-B2 O3 -SiO2 glass with progressive additions of MoO3 , were investigated. It was found that the addition of small amounts of MoO3 extends the immiscibility boundary of the system and raises the immiscibility temperature by ∼l8°C for each mol % MoO3 , addition. Analysis of phase-separation morphology suggests that the MoO3 , additions do not significantly alter the tie lines of phase separation in the system, although such additions cause a lowering of the viscosities and the glass-transition temperatures of these glasses. 相似文献
3.
Phase relations in air at 1300°C were determined for the system MgO-Cr2 O3 −Fe2 O3 by conventional quenching techniques. Details of the phase equilibria were established for: (1) the sesquioxide solid solution between Cr2 O3 and Fe2 O3 , (2) the spinel solid solution field between MgCr2 O4 and MgFe2 O4 , and (3) the periclase solid solution field for MgO. Selected tie lines connecting coexisting compositions were established with X-ray diffractometer data. Diffuse reflectance spectra, diffractometer intensity ratios, and lattice parameter measurements were obtained for quenched samples to study the structural inversion in the spinel series MgCr2 O4-MgFe2 O4 . 相似文献
4.
A detailed study of the system Pb0–B2 03 –Si02 was undertaken because of the interest in lead borosilicate fluxes and the possibility of producing opaque low-melting enamels by controlled liquid-phase separations. Studies in the portion of the system containing greater than 60% PbO produced little change from previous work. The shape of the liquidus surface beneath the two-liquid region and the shape of the immiscibility dome were determined. Much of the observed immiscibility is metastable, particularly for compositions containing greater than 40% SiO2 . Using the electron microscope provided information on the way the rate of formation, stability, and texture of the immiscible liquids are affected by composition, time, and temperature. Finally, a high-temperature centrifuge was constructed to separate the immiscible liquids and thus define tie lines within the immiscibility dome. 相似文献
5.
J. P. GUHA 《Journal of the American Ceramic Society》1977,60(5-6):246-249
Subsolidus phase relations in the system Ba0-Ti02-Ge02 were investigated using conventional solid-state reaction techniques and X-ray powder diffraction. The existence of 2 ternary compounds, BaTiGe309 and BazTiGeZ08, was confirmed and their X-ray crystallographic data are presented. The compound BaTiGe3 09 has a lower limit of stability at 1135°C and melts incongruently at 1232°C; Ba2 TiGe2 O2 melts congruently at 1228°C. Subsolidus compatibility relations in the ternary system were established and tie lines between the various phases which constitute a total of 12 compatibility triangles at 1000°C are shown in a subsolidus phase diagram. 相似文献
6.
The ternary phase diagram of Al2 O3 -La2 O3 -TiO2 at 1400°C was determined with 12 compatibility triangles. Al2 O3 stabilizes the A-site-deficient La2/3 TiO3 perovskite structure. According to XRD and microstructural investigations, the solid solution extends along the La2/3 TiO3 -LaAlO3 tie line from at least 4 mol% LaAlO3 to pure LaAlO3 . With increasing LaAlO3 content, the stabilized La2/3 TiO3 structure changes from orthorombic via tetragonal to cubic. 相似文献
7.
Solid-liquid equilibria at 1750°C and subsolidus phase relations in the system Si3 N4 −AlN-SiO2 −Al2 O3 were determined for the composition region bounded by the β-Si3 N4 solid solution line and silica-alumina join X-ray diffraction and optical microscopy were used to determine the phases present in specimens cooled rapidly after equilibration. The extent of a single liquid-phase region and the tie lines for the βsolid solution + liquid field at 1750°C were established from quantitative X-ray diffractometry and lattice parameter measurements of βsolid solutions in equilibrium with liquid. The results were corroborated by optical microscopy and melting behavior observations. A new composition, Si12 Al18 O3 9N8 , is suggested for the x1 phase. The lowest melting temperature in the system is ≅ 1480°C and the corresponding composition is 10 eq% Al-90 eq%O. 相似文献
8.
Phase equilibrium relations in the system PbO–TiO2 –ZrO2 were studied by quenching in the range where the PbO content is 50 mole % and more. Isotherms were examined at 1100°, 1200°, and 1300°C and tie lines were determined between the liquid and solid solution in equilibrium. The incongruent melting point of PbZrO3 was 1570°C and the equilibrium between liquid, PbO-type solid, and PbZrO3 is peritectic. Pb(Zr,Ti)O3 solid solutions containing more than 14 mole % PbZrO3 decomposed to liquid, ZrO2 , and Pb(Zr,Ti)O3 and the decomposition temperature rises from 1340° to 1570°C with increasing PbZrO3 content. The system PbTiO3 –PbZrO3 should not be treated as a binary, but as a section of the ternary system. 相似文献
9.
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
10.
The solid phases formed at 1400°C. in air in the three-component systems BaO-SrO-TiO2 , BaO-CaO-TiO2 , and SrO-CaO-TiO2 are described. Besides solid solutions of components with known structures, some new ternary compounds have been studied. The dielectric constants and loss factors of a number of specimens are given. Crystallographic data of the compounds BaCaTiO4 , Ba3 Ca2 Ti2 O9 , and Ca3 Ti2 O7 and of the solid solution series (Ba, Sr), TiO4 are presented. The preparation of the new compounds is described in detail. 相似文献
11.
Tsuyoshi Honma Yasuhiko Benino Takumi Fujiwara Takayuki Komatsu Ryuji Sato 《Journal of the American Ceramic Society》2005,88(4):989-992
The glass formation region, crystalline phases, second harmonic (SH) generation, and Nd:yttrium aluminum garnet (YAG) laser-induced crystallization in the Sm2 O3 –Bi2 O3 –B2 O3 system were clarified. The crystalline phases of Bi4 B2 O9 , Bi3 B5 O12 , BiBO3 , Sm x Bi1− x BO3 , and SmB3 O6 were formed through the usual crystallization in an electric furnace. The crystallized glasses consisting of BiBO3 and Sm x Bi1− x BO3 showed SH generations. The formation of the nonlinear optical BiB3 O6 phase was not confirmed. The formation (writing) region of crystal lines consisting of Sm x Bi1− x BO3 by YAG laser irradiation was determined, in which Sm2 O3 contents were∼10 mol%. The present study demonstrates that Sm2 O3 –Bi2 O3 –B2 O3 glasses are promising materials for optical functional applications. 相似文献
12.
Shara S. Shoup Tamara J. Haverlock Carlos E. Bamberger 《Journal of the American Ceramic Society》1995,78(5):1261-1264
A region of selected SrO-LnO1.5 -TiO2 (Ln = La, Ce, Pr, or Nd) systems was studied experimentally using X-ray diffractometry (XRD). A series of solid solutions with composition Sr4 x Ln2 x/ 3 Ti4 O12 having tetragonally distorted per-ovskite structures was found to exist along the tie line connecting SrTiO3 and Ln2 Ti3 O9 . Reactions of SrLn2 Ti4 O12 , representative compounds of the series, with SrO were also studied. Additionally, the solubility of TiO2 in Ln2 O3 -(3TiO2- m (Ln = La, Pr, or Nd) at 1300°C was investigated using XRD. 相似文献
13.
JONG-HEE PARK WAYNE E. KING STEVEN J. ROTHMAN 《Journal of the American Ceramic Society》1987,70(12):880-885
The cation diffusivities in the lattice and along dislocations and grain boundaries have been measured on sintered polycrysals of Cr2 O3 ; and Cr2 Cr2 O3 -0.09 wt% Y2 O3 at1100°C and at the pO2 corresponding to that of Cr/Cr2 O3 equilibrium at that temperature. Results for lattice and dislocation diffusivities in pure Cr2 O3 are in good agreement with previous work. The present results indicate that yttrium additions have negligible effect on lattice and dislocation diffusion. However, grain-boundary diffusion in pure Cr2 O3 is significantly slower than grain-boundary diffusion in Cr2 O3 -0.09 wt% Y2 O3 . The results are discussed in terms of their implications for the reactive-element effect in high-temperature oxidation of chromium-containing alloys. 相似文献
14.
Elena R. Andrievskaya Lidia M. Lopato Vasily P. Smirnov 《Journal of the American Ceramic Society》1996,79(3):714-720
A mathematical model of the liquidus surface based on a reduced polynomial method was proposed for the system HfO2 -Y2 O3 -Er2 O3 . The results of calculations according to this model agree fairly well with the experimental data. Phase equilibria in the system HfO2 -Y2 O3 -Er2 O3 were studied on melted (as-cast) and annealed samples using X-ray diffraction (at room and high temperatures) and micro-structural and petrographic analyses. The crystallization paths in the system HfO2 -Y2 O3 -Er2 O3 were established. The system HfO2 -Y2 O3 -Er2 O3 is characterized by the formation of extended solid solutions based on the fluorite-type (F) form of HfO2 and cubic (C) and hexagonal (H) forms of Y2 O3 and Er2 O3 . The boundary curves of these solid solutions have the minima at 2370°C (15. 5 mol% HfO2 , 49. 5 mol% Y2 O3 ) and 2360°C (10. 5 mol% HfO2 , 45. 5 mol% Y2 O3 ). No compounds were found to exist in the system investigated. 相似文献
15.
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
16.
Adrish Ganguly Michel W. Barsoum Roger D. Doherty 《Journal of the American Ceramic Society》2007,90(7):2200-2204
In this work, we report on the interdiffusion of Ge and Si in Ti3 SiC2 and Ti3 GeC2 , as well as that of Nb and Ti in Ti2 AlC and Nb2 AlC. The interdiffusion coefficient, D int , measured by analyzing the diffusion profiles of Si and Ge obtained when Ti3 SiC2 –Ti3 GeC2 diffusion couples are annealed in the 1473–1773 K temperature range at the Matano interface composition (≈Ti3 Ge0.5 Si0.5 C2 ), was found to be given by
Dint increased with increasing Ge composition. At the highest temperatures, diffusion was halted after a short time, apparently by the formation of a diffusion barrier of TiC. Similarly, the interdiffusion of Ti and Nb in Ti2 AlC–Nb2 AlC couples was measured in the 1723–1873 K temperature range. The D int for the Matano interface composition, viz. ≈(Ti0.5 ,Nb0.5 )2 AlC, was found to be given by
At 1773 K, the diffusivity of the transition metal atoms was ≈7 times smaller than those of the Si and Ge atoms, suggesting that the former are better bound in the structure than the latter. 相似文献
D
At 1773 K, the diffusivity of the transition metal atoms was ≈7 times smaller than those of the Si and Ge atoms, suggesting that the former are better bound in the structure than the latter. 相似文献
17.
In the system Bi2 O3 -SiO2 -GeO2 , good glasses can be formed only from limited compositional regions consisting of 2 narrow strips along the lines x Bi2 O3 -(100-:t) GeO2 ( x ≤40) and 40Bi2 O3 y SiO2 (60- y )GeO2 (mol%); such glass is dark brown. Compositions from a large region (Bi2 O3 content <40 mol%) showed immiscibility. In the binary system Bi2 O3 -GeO2 , density and refractive index vary linearly with composition (mol%). Negative deviations of molar volume from ideality suggest that the coordination of a significant number of Ge ions is changing from 4-fold to 6-fold. Thermal expansion and electrical resistivity data are also reported. 相似文献
18.
Glasses in the system Pb0–Al2 O3 -B2 O3 -SiO2 are chemically stable over a wide composition range and have very desirable electrical characteristics such as high electrical resistivities and activation energies for conduction. Variations in these electrical properties were studied as a function of composition changes within the system, the object being to identify the role of the constituent oxides in achieving the highest activation energy and resistivity values consistent with moderate preparation temperatures. Measurements were made in the temperature range 25° to 400°C on carefully prepared glass disks in which the individual oxide components or different oxide ratios such as PbO/SiO2 , Al2 O3 /SiO2 , and Bs O3 /SiO1 were systematically varied. The activation energy and resistivity values obtained ranged from 1.2 to 1.6 ev and 10° to 1014 ohm-cm, with dielectric constants ranging from 9 to 19 and densities from 4.30 to 4.50 g/cmY. Indications were that, for the composition range studied, the behavior manifested was basically that of the binary PbO-SO2 glass with additions of Al2 O3 or B2 O3 , even in small concentrations, sharply increasing the activation energy for conduction while lowering the density. 相似文献
19.
Keiji Kobayashi 《Journal of the American Ceramic Society》1990,73(11):3500-3502
F− - and OH− -free ZnO-B2 O3 -SiO2 -Al2 O3 -P2 O5 glasses used for semiconductor-device passivation or insulation are investigated with regard to compositional dependencies for thermal expansion, viscosity points, and metal oxide semiconductor (MOS) capacitor properties. The experimental data show that thermal expansion increases, and flow points decrease, when P2 O5 is substituted for B2 O3 . MOS capacitors passivated by OH− - and F− -free ZnO-based glasses exhibit normal capacitance-voltage curves. 相似文献
20.
Activities of NiO were measured in the oxide and spinel solutions of the system MnO–NiO–Al2 O3 at 1300° and 1400° C with the aim of deriving information on the thermodynamic properties of the spinel phases. Synthetic samples in selected phase assemblages of the system were equilibrated with metallic nickel and a gas phase of known oxygen partial pressures at a total pressure of 1 atm. The data on NiO activities and directions of conjugation lines between coexisting oxide and spinel phases were used to establish the activity–composition relations in spinel solid solutions at 1300° and 1400°C. The MnAl2 O4 –NiAl2 O4 solid solutions exhibit considerable negative deviations from ideality at these temperatures. The free energy of formation of MnAl2 O4 from its oxide components (MnO + Al2 O3 ) at 1300° and 1400°C is calculated to be −24.97 and −26.56 kJ. mol−1 , respectively. The activities determined in the stoichiometric spinel solid solutions are more negative as compared with those predicted from cation distribution models. 相似文献