共查询到20条相似文献,搜索用时 15 毫秒
1.
Mark I. Pownceby Keri K. Constanti-Carey Michael J. Fisher-White 《Journal of the American Ceramic Society》2003,86(6):975-980
Subsolidus phase equilibria in the system Fe2 O3 –Al2 O3 –TiO2 were investigated between 1000° and 1300°C. Quenched samples were examined using powder X-ray diffraction and electron probe microanalytical methods. The main features of the phase relations were: (a) the presence of an M3 O5 solid solution series between end members Fe2 TiO5 and Al2 TiO5 , (b) a miscibility gap along the Fe2 O3 –Al2 O3 binary, (c) an α-M2 O3 ( ss ) ternary solid-solution region based on mutual solubility between Fe2 O3 , Al2 O3 , and TiO2 , and (d) an extensive three-phase region characterized by the assemblage M3 O5 +α-M2 O3 ( ss ) + Cor( ss ). A comparison of results with previously established phase relations for the Fe2 O3 –Al2 O3 –TiO2 system shows considerable discrepancy. 相似文献
2.
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
3.
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
4.
Koichiro Fukuda Iwao Maki Kazuhiro Toyoda Suketoshi Ito 《Journal of the American Ceramic Society》1993,76(7):1821-1824
The α-to-α'H transition of Ca2 SiO4 solid solutions (C2 S(ss)) is a nucleation and growth process. This process was shown on time–temperature–transformation (TTT) diagrams for C2 S(ss) with different concentrations of foreign oxides (Na2 O, Al2 O3 , and Fe2 O3 ). The kinetic cutoff temperature and the activation energy for growth of the α'H phase increase steadily with increasing concentration of impurities. The activation energy for nucleation also increases above 950°C. The α'H phase, which exists in equilibrium with the α phase at 1280°C, is formed at a maximum rate at around 1100°C regardless of the chemical composition. The TTT diagrams enable us to predict, as a function of cooling rate, the phase constitution of C2 S(ss) at ambient temperature. 相似文献
5.
Koichiro Fukuda Iwao Maki Suketoshi Ito Hideto Yoshida 《Journal of the American Ceramic Society》1995,78(12):3387-3389
A pseudobinary phase equilibrium diagram has been established for the P2 O5 -bearing Ca2 SiO4 -CaFe4 O7 system to confirm the occurrence of remelting reaction in α-Ca2 SiO4 solid solutions (C2 S(ss)). The reaction started at 1290°C immediately after the α-to-α'H transition and finished at 1145°C. The reaction products were made up of about 1 wt% of liquid and 99 wt% of solid α'H -C2 S(ss). The liquid exsolved at 1290°C was rich in Fe2 O3 , consisting of about 30 wt% of Ca2 SiO4 and 70 wt% of CaFe4 O7 . The liquid coexisting with α-C2 S(ss) precipitated new α'-phase crystals in association with the remelting reaction. 相似文献
6.
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
7.
The phase domain of Ti3 O5 –Ti2 O3 –Ti(CO) at 1580 K was determined from the formation energies of Ti(C x O y ), as calculated via the Gibbs–Duhem equation. An extensive Ti(CO) domain is attributed to the high affinity between TiC and TiO. The phase domain of Ti3 O5 –Ti2 O3 –Ti(CN) was obtained at 1673 K using the formation energies of Ti(C x N y ). This study shows that the stable region for Ti2 O3 is significantly small in the Ti3 O5 –Ti2 O3 –Ti(CN) phase domain. It demonstrates the absence of TiO and Ti2 O3 in the normal syntheses of TiC and Ti(CN) from TiO2 , respectively. 相似文献
8.
Hyun M. Jang Jong H. Moon Cheol W. Jang 《Journal of the American Ceramic Society》1992,75(12):3369-3376
Al2 O3 –ZrO2 –SiC whisker composites were prepared by surface-induced coating of the precursor for the ZrO2 phase on the kinetically stable colloid particles of Al2 O3 and SiC whisker. The fabricated composites were characterized by a uniform spatial distribution of ZrO2 and SiC whisker phases throughout the Al2 O3 matrix. The fracture toughness values of the Al2 O3 –15 vol% ZrO2 –20 vol% SiC whisker composites (∼12 MPa.m1/2 ) are substantially greater than those of comparable Al2 O3 –SiC whisker composites, indicating that both the toughening resulting from the process zone mechanism and that caused by the reinforced SiC whiskers work simultaneously in hot-pressed composites. 相似文献
9.
The phase diagrams in the Al2 O3 –Cr2 O3 and V2 O3 –Cr2 O3 systems have been assessed by thermodynamic modeling with existing data from the literature. While the regular and subregular solution models were used in the Al2 O3 –Cr2 O3 system to represent the Gibbs free energies of the liquid and solid phases, respectively, the regular solution model was applied to both phases in the V2 O3 –Cr2 O3 system. By using the liquidus, solidus, and/or miscibility gap data, the interaction parameters of the liquid and solid phases were optimized through a multiple linear regression method. The phase diagrams calculated from these models are in good agreement with experimental data. Also, the solid miscibility gap and chemical spinodal in the V2 O3 –Cr2 O3 system were estimated. 相似文献
10.
Yung-Chao Ko 《Journal of the American Ceramic Society》2000,83(9):2333-2335
The XRD patterns at ambient temperature and at 1500°C showed that the spinel in the Al2 O3 –MgO castables fired at 1500°C for 3 h has the higher peak intensity, compared to those in Al2 O3 –spinel castables; the interplanar distance in the set (311) is 2.43 Å for the spinel in Al2 O3 –MgO castables as well as the spinels in Al2 O3 –spinel castables using spinels containing 73, 90, and 94 wt% Al2 O3 , respectively. The corresponding alumina contents of the spinels in these castables were estimated to be around 75 wt%. The smaller grain size of the spinel in Al2 O3 –MgO castables compared to that in Al2 O3 –spinel castables is evidenced by the recrystallization of the in situ spinel only occurring in Al2 O3 –MgO castables as revealed by the XRD patterns at ambient temperature and at 1500°C. The larger amount and smaller grain size of the in situ spinel in the matrix mostly account for the better slag resistance of Al2 O3 –MgO castables, compared to Al2 O3 –spinel castables. 相似文献
11.
Kentaro Fukuda Teiichi Hanada Setsuhisa Tanabe Takeshi Yao 《Journal of the American Ceramic Society》2002,85(4):915-920
Amorphous films in the system Al2 O3 –Y2 O3 were prepared by the rf sputtering method in the range of 0–76 mol% Y2 O3 , and their density, refractive index, and elastic constants were measured. All of the physical properties of the amorphous Al2 O3 –Y2 O3 films had a similar compositional dependence; that is, they increased continuously, but not linearly with increasing Y2 O3 content. To confirm the coordination states of aluminum and yttrium ions in the amorphous Al2 O3 –Y2 O3 films, the Al K α X-ray emission spectra and the X-ray absorption near edge structures (XANES) were measured. The average coordination number of aluminum ions in the amorphous films containing up to about 40 mol% Y2 O3 content was 5, that is a mixture of 4-fold- and 6-fold-coordinated states. In the region of more than about 50 mol% Y2 O3 , the fraction of the 6-fold-coordinated aluminum ions increased with increasing Y2 O3 content, while the results led to the conclusion that the coordination number of yttrium ions was always 6, regardless of composition. These results indicate that, in amorphous films in the system Al2 O3 –Y2 O3 , the change of the coordination state of aluminum ions has an important effect on physical properties. 相似文献
12.
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
13.
A. Ravikiran Vikram Jayaram Sanjay K. Biswas 《Journal of the American Ceramic Society》1997,80(1):219-224
The sliding-wear behavior of Al2 O3 –SiC–Al composites prepared by melt oxidation against a steel counterface has been recorded in a pin-on-disk machine. At high speeds and pressures (10 m/s, 20 MPa), friction and wear appear to be principally controlled by the in-situ formation of an interfacial film that consists of a layer of Fe3 O4 . The formation of this film is examined as a function of sliding speed, lubrication, and composite microstructure. A model is proposed in which high surface temperatures cause the preferential extrusion of aluminum from the composite onto the pin/disk interface. This promotes the adhesive pickup of iron and its oxidation to form a stable tribologically beneficial layer of Fe3 O4 . 相似文献
14.
Yangyang Ji Jingkui Liang Zhan Chen Sishen Xie 《Journal of the American Ceramic Society》1991,74(2):444-446
The phase relations at a temperature below "subsolidus" in the system Al2 O3 –B2 O3 –Nd2 O3 are reported. Specimens were prepared from various compositions of Al2 O3 , B2 O3 , and Nd2 O3 of purity 99.5%, 99.99%, and 99.9%, respectively, and fired at 1100°C. There are six binary compounds and one ternary compound in this system. The ternary compound, NdAl3 (BO3 )4 (NAB), has a phase transition at 950°C ± 15°C. The high-temperature form of NAB has a second harmonic generation (SHG) efficiency of KH2 PO4 (KDP) of the order of magnitude of the form which has been used as a good self-activated laser material, and the low-temperature form of NAB has no SHG efficiency. 相似文献
15.
Tomoyuki Adachi Naoki Wakiya Naonori Sakamoto Osamu Sakurai Kazuo Shinozaki Hisao Suzuki 《Journal of the American Ceramic Society》2009,92(S1):S177-S180
Fe3 O4 –BaTiO3 composite particles were successfully prepared by ultrasonic spray pyrolysis. A mixture of iron(III) nitrate, barium acetate and titanium tetrachloride aqueous solution were atomized into the mist, and the mist was dried and pyrolyzed in N2 (90%) and H2 (10%) atmosphere. Fe3 O4 –BaTiO3 composite particle was obtained between 900° and 950°C while the coexistence of FeO was detected at 1000°C. Transmission electron microscope observation revealed that the composite particle is consisted of nanocrystalline having primary particle size of 35 nm. Lattice parameter of the Fe3 O4 –BaTiO3 nanocomposite particle was 0.8404 nm that is larger than that of pure Fe3 O4 . Coercivity of the nanocomposite particle (390 Oe) was much larger than that of pure Fe3 O4 (140 Oe). These results suggest that slight diffusion of Ba into Fe3 O4 occurred. 相似文献
16.
R. F. FELDMAN V. S. RAMACHANDRAN P. J. SEREDA 《Journal of the American Ceramic Society》1965,48(1):25-30
The influence of CaCO3 on the hydration of 3CaO Al2 O3 containing about 90% C3 A is studied with compacts of their mixtures proportioned to 0, 2.5, 10, 20, and 50 wt% CaCO3 . The compacts are exposed to H2 O in liquid and in vapor phase, the attendant expansion being measured as a function of time. Differential thermal analysis, infrared absorption, and X–ray diffraction are used in conjunction with this technique. It is shown that the hydration reaction of 3 CaO · Al2 O3 is suppressed by CaCO3 additions and that this is due primarily to the formation of the low form of calcium carboaluminate on the surface of the C3 A grains. Expansion measurements of the compacts during the reactions show that this technique indicates the progress of hydration and detects the formation of the carboaluminate at an early stage of the reaction. Using the same technique, a study at 50% relative humidity provides the basis for the conclusion that C3 A reacts with CaCO3 under these conditions by a direct mechanism. 相似文献
17.
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
18.
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
19.
Electroconductive Al2 O3 –NbN ceramic composites were prepared by hot pressing. Dense sintered bodies of ball-milled Al2 O3 –NbN composite powders were obtained at 1550°C and 30 MPa for 1 h under a nitrogen atmosphere. The bending strength and fracture toughness of the composites were enhanced by incorporating niobium nitride (NbN) particles into the Al2 O3 matrix. The electrical resistivity of the composites decreased with increasing amount of NbN phase. For a 25 vol% NbN–Al2 O3 composite, the values of bending strength, fracture toughness, Vickers hardness, and electrical resistivity were 444.2 MPa, 4.59 MPa·m1/2 , 16.62 GPa, and 1.72 × 10−2 Ω·cm, respectively, making the composite suitable for electrical discharge machining. 相似文献
20.
Ho-Yong Lee Yeong-Kyeun Pack Byoung-Ki Lee Suk-Joong L. Kang 《Journal of the American Ceramic Society》1995,78(8):2149-2152
When sintered 85Al2 O3 –15Fe2 O3 (in wt%) specimens consisting of corundum grains and spinel particles were annealed at temperature where only a corundum phase was stable, phase transformation of spinel into metastable FeAIO3 and subsequently complete dissolution of the metastable phase occurred together with the migration of grain boundaries at the surface of the specimens. Since the grain boundary migration was induced by grain boundary diffusion of Fe2 O3 from the transforming and dissolving particles, the boundary migration by temperature decrease corresponds to a discontinuous dissolution of the spinel particles and a chemically induced grain boundary migration by temperature change. Inside the specimens, however, the transformation—dissolution and the grain boundary migration were suppressed because of unavailable accommodation of the volume expansion due to the transformation. 相似文献