共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
Takashi Harada Hiromichi Takebe Makoto Kuwabara 《Journal of the American Ceramic Society》2006,89(1):247-250
The glass transition temperature increases and the thermal expansion coefficient and density decrease with increasing B2 O3 concentration in a series of (100− x )(50BaO–50P2 O5 )− x B2 O3 where x =0–10 mol% for bulk samples. According to Raman spectroscopy, the bulk BaO–P2 O5 –B2 O3 (BaP–B) glasses consist of metaphosphate Q 2 units with ring-type metaborate, diborate, and PO4 –BO4 groups. X-ray photoelectron spectroscopy results reveal qualitatively that P–O–B bonds are formed at the surface of BaP–B glass samples ground in laboratory air over 6 mol% B2 O3 only. The P–O–B bonds are related to the suppression of the crystallization of powdered BaP–B glasses with >6 mol% B2 O3 during differential thermal analysis. 相似文献
3.
Takashi Harada Hiroyuki In Hiromichi Takebe Kenji Morinaga 《Journal of the American Ceramic Society》2004,87(3):408-411
The effect of B2 O3 addition on the thermal stability of BaO–P2 O5 glasses is studied by differential thermal analysis (DTA), X-ray diffraction (XRD) analysis, scanning electron microscopy, and micro-Raman spectroscopy. The difference between glass-transition and onset-crystallization temperatures increases monotonically with increasing B2 O3 concentration. The DTA result reveals that no exothermic peak due to surface crystallization exists in the BaO–P2 O5 glass doped with 3 mol% B2 O3 . A single-mode BaO–P2 O5 -B2 O3 glass fiber could be fabricated by a rod-in-tube technique. The modification of glass structure due to B2 O3 addition is qualitatively discussed. 相似文献
4.
Comparing the crystallization mechanism of stoichiometric and B2 O3 and P2 O5 containing glass reveals that the additives extend the gap between the glass transition and crystallization temperatures and suppress formation of μ, cordierite while promoting direct crystallization of α cordierite. Detailed TEM analysis of nucleation and growth of crystals in hot-pressed pellets of B2 O3 /P2 O5 -containing glass particles shows that nucleation occurs on unidentified heterogeneous nuclei at the sites of the previous particle surfaces. Growth of α cordierite with a cellular morphology or μ cordierite with a dendritic morphology is most likely controlled by the glass composition directly ahead of the growth front. 相似文献
5.
Takashi Wakasugi Rikuo Ota Jiro Fukunaga 《Journal of the American Ceramic Society》1992,75(11):3129-3132
In order to evaluate the crystallization tendency of glasses, the ratio of the crystallization temperature to the liquidus temperature ( T c / T L ) was obtained by DTA measurement for the Na2 O–B2 O3 and Na2 O–B2 O3 –Al2 O3 systems. The critical cooling rate for glass formation ( Q *) was also measured. The measurements were performed in the composition range of (100 − x )Na2 O–( x )B2 O3 , ( x = 25–35 and 60–100 mol%), and (100 − y )0.5Na2 O·0.5B2 O3 −( y )Al2 O3 , ( y = 6–34 mol%). The relationship between T c / T L and Q * was discussed. A linear relationship between T c / T L and log Q * for these systems was found. Furthermore, the relationship between T c / T L and Q * was verified by computer simulation based on the crystallization kinetics of glass or supercooled liquid. 相似文献
6.
The microstructural development and phase-transformation kinetics of stoichiometric cordierite glasses containing B2 O3 and/or P2 O5 additives were highly affected by the microstructural characteristics of the μ-cordierite and the type of additives. The addition of B2 O3 tended to cause the formation of μ-spherulitic dendrites with thin dendritic arms, which promoted the formation of α-cordierite, either from crystallization of the residual glass or from transformation of μ-cordierite. P2 O5 had the opposite effect: Increasing the temperature increased the growth rate of α-cordierite more than that of μ-cordierite. 相似文献
7.
R. K. Datta 《Journal of the American Ceramic Society》1987,70(10):288-C
Literature data for the 12CaO°7Al2 O3 phase show certain discrepancies in the structure, thermal stability, and mean linear thermal expansion obtained by different techniques. Phase-pure, cubic, polycrystallin I2CaO°7Al2 O3 was synthesized by annealing a stoichiometric melt in air. Infrared spectrophotometry indicated stabilization by moisture. Differential thermal analysis and thermogravimetric analysis showed the cubic phase to be stable up to at least 1200° C. High-temperature X-ray diffraction analysis of a polycrystalline sample and dilatometric measurement of sintered pellets indicated a linear thermal expansion of 41 × 10-7 to 43X10-7 /°C in the temperature range 200° to 800°C. 相似文献
8.
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
9.
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
10.
Yanping Long Yilin Wang Wenjun Wu Dong Wang Yongxiang Li 《Journal of the American Ceramic Society》2009,92(11):2630-2633
The effect of B2 O3 –SiO2 liquid-phase additives on the sintering, microstructure, and microwave dielectric properties of LiNb0.63 Ti0.4625 O3 ceramics was investigated. It was found that the sintering temperature could be lowered easily, and the densification and dielectric properties of LiNb0.63 Ti0.4625 O3 ceramics could be greatly improved by adding a small amount of B2 O3 –SiO2 solution additives. No secondary phase was observed for the ceramics with B2 O3 –SiO2 additives. With the addition of 0.10 wt% B2 O3 –SiO2 , the ceramics sintered at 900°C showed favorable microwave dielectric properties with ɛr =71.7, Q × f =4950 GHz, and τf =−2.1 ppm/°C. The energy dispersive spectra analysis showed an excellent co-firing interfacial behavior between the LiNb0.63 Ti0.4625 O3 ceramic and the Ag electrode. It indicated that LiNb0.63 Ti0.4625 O3 ceramics with B2 O3 –SiO2 solution additives have a number of potential applications on passive integrated devices based on the low-temperature co-fired ceramics technology. 相似文献
11.
The monolithic glass-forming region of the low phonon and low softening point antimony glasses containing high Sb2 O3 (40–75 mol%) in the novel quaternary K2 O–B2 O3 –Sb2 O3 –ZnO system has been found with the help of X-ray diffraction (XRD) analysis. The structure of a series of glasses with the general composition of (mol%) 15K2 O–15B2 O3 –(70− x )Sb2 O3 – x ZnO (where x =5–25) has been evaluated by infrared reflection spectral (FT-IRRS) analyses. All the glasses are found to possess a low phonon energy of around 600 cm−1 , as revealed by FT-IRRS. Their softening point ( T s ), glass transition temperature ( T g ), and coefficient of thermal expansion (CTE) have been found to vary in the ranges of 351°–379°C, 252°–273°C, and 195–218 × 10−7 K−1 , respectively. These properties are found to be controlled by their fundamental property, like the covalent character of the glasses, which is found to increase with an increase in Sb2 O3 content. In addition, the devitrified glasses have been characterized by XRD and field emission scanning electron microscopy, which manifests the presence of nanozinc antimony oxide crystals with sizes of 21–43 nm. The exhibited properties have revealed that they are a new class of versatile materials. 相似文献
12.
Ahmed G. Solomah Reinhard Odoj Christoph Freiburg 《Journal of the American Ceramic Society》1983,66(10):c182-c183
A new identification and indexing for the phase BaAl2 Ti5 O14 were accomplished using an X-ray diffraction technique. The new lattice parameters for the tetragonal lattice structure are: a0 =9.990 × 10-10 m and c0 =12.264 × 10-10 m, with a corresponding volume 1.224 × 10-27 m3 . The data provided by the Joint Committee on Powder Diffraction Standards are inconsistent both in lattice parameter values and Miller indices. The X-ray powder diffraction pattern of BaAl2 Ti5 O14 was indexed using the LSUCR (least-squares unit cell refinement) computer program. 相似文献
13.
Synthesis of BaCu(B2 O5 ) Ceramics and their Effect on the Sintering Temperature and Microwave Dielectric Properties of Ba(Zn1/3 Nb2/3 )O3 Ceramics 总被引:1,自引:0,他引:1
Min-Han Kim Jong-Bong Lim Jae-Chul Kim Sahn Nahm Jong-Hoo Paik Jong-Hee Kim Kyeong-Soon Park 《Journal of the American Ceramic Society》2006,89(10):3124-3128
BaCu(B2 O5 ) ceramics were synthesized and their microwave dielectric properties were investigated. BaCu(B2 O5 ) phase was formed at 700°C and melted above 850°C. The BaCu(B2 O5 ) ceramic sintered at 810°C had a dielectric constant (ɛr ) of 7.4, a quality factor ( Q × f ) of 50 000 GHz and a temperature coefficient of resonance frequency (τf ) of −32 ppm/°C. As the BaCu(B2 O5 ) ceramic had a low melting temperature and good microwave dielectric properties, it can be used as a low-temperature sintering aid for microwave dielectric materials for low temperature co-fired ceramic application. When BaCu(B2 O5 ) was added to the Ba(Zn1/3 Nb2/3 )O3 (BZN) ceramic, BZN ceramics were well sintered even at 850°C. BaCu(B2 O5 ) existed as a liquid phase during the sintering and assisted the densification of the BZN ceramic. Good microwave dielectric properties of Q × f =16 000 GHz, ɛr =35, and τf =22.1 ppm/°C were obtained for the BZN+6.0 mol% BaCu(B2 O5 ) ceramic sintered at 875°C for 2 h. 相似文献
14.
Daniel Caurant Odile Majérus Edward Fadel Marion Lenoir Christel Gervais Olivier Pinet 《Journal of the American Ceramic Society》2007,90(3):774-783
Crystallization of the poorly durable Na2 MoO4 phase able to incorporate radioactive cesium must be avoided in SiO2 –Al2 O3 –B2 O3 –Na2 O–CaO glasses developed for the immobilization of Mo-rich nuclear wastes. Increasing amounts of B2 O3 and MoO3 were added to a SiO2 –Na2 O–CaO glass, and crystallization tendency was studied. Na2 MoO4 crystallization tendency decreased with the increase of B2 O3 concentration whereas the tendency of CaMoO4 to crystallize increased due to preferential charge compensation of BO4 − entities by Na+ ions. 29 Si MAS NMR showed that molybdenum acts as a reticulating agent in glass structure. Trivalent actinides surrogate (Nd3+ ) were shown to enter into CaMoO4 crystals formed in glasses. 相似文献
15.
An investigation of the properties of high-purity (>99 wt%) tantalum tungstates (Ta22 W4 O67 , Ta, WO8 , and Ta16 W18 O94 ) included determination of density (bulk and theoretical), refined lattice constants, maximum use temperatures, micro-hardness, heat capacity, thermal expansion (contraction) and diffusivity, calculated thermal conductivity, and electrical resistivity. Usable to ∼ 1700 K in air or inert atmospheres, these tantalum tungstates have theoretical densities of 7.3 to 8.5 g/cm3 , are relatively soft (120 to 655 kg/mm2 hardnesses), and are electrical insulators (6× 103 to 2× 108 Ω. cm resistivities). The distinguishing properties of the materials are their thermal expansion (average CTE values from + 0.6×10−8 /K to −5.1× 10−6 /K at 293 to 1273 K), thermal expansion hysteresis with minimal observable microcracking, and thermal diffusivity 相似文献
16.
Bing Zhang Qi Chen Li Song Huiping Li Fengzhen Hou 《Journal of the American Ceramic Society》2008,91(6):2036-2038
The influence of 0–16 mol% Sb2 O3 substitution for P2 O5 on the properties of ZnO–P2 O5 glasses has been investigated. It was shown that Sb2 O3 could participate in the glass network and thermal stability of the glasses decreased with increasing Sb2 O3 content. Glass transition temperature T g , softening temperature T s , and water durability all decreased firstly (up to 6 mol% Sb2 O3 added) and then increased. Substitution of 12 mol% Sb2 O3 led to a 16°C decrease in T g and 30°C decrease in T s , and weight loss of the glass was only 0.42 mg/cm2 , which is ∼11 times lower than that of the glass without Sb2 O3 after immersion in deionized water at 90°C for 1 day. The glass containing 12 mol% Sb2 O3 might be a substitute for Pb-based glasses in some applications. 相似文献
17.
The glassforming region in the system was roughly outlined and liquidus data were obtained for the three joins LiPO3 -BPO4 , Li4 P2 O7 -BPO4 , and Li3 PO4 -Li2 B4 O7 . Compatibility relations for the ternary subsystems Li4 P2 O7 -BPO4 -P2 O5 and Li2 O-Li3 PO4 -Li2 B8 O13 were established. Two ternary compounds with the probable compositions 22Li2 O - 11B2 O3 - 13P2 O5 and 2Li2 O 3B2 O3 P2 O5 were detected. 相似文献
18.
The crystallization and phase transformation of glassy Na2 O·2B2 O3 have been studied by X-ray diffraction, infrared spectroscopy, thermal analysis, and density measurement. By employing proper thermal treatment methods, three metastable and two relatively stable polymorphs of Na2 O·2B2 O3 are obtained, as well as two other compounds, Na2 O·B2 O3 and 2Na2 O·5B2 O3 . The possible structural groups of these phases are deduced, which are found to be similar to that existing in the glass. Current glass models which imply the existence of structural "granularity" satisfactorily describe the crystallization behavior. The phase transformation is observed to depend not only on temperature, but also on the density of the phase. 相似文献
19.
Mathias Herrmann Hans-Joachim Kleebe Jan Raethel Kerstin Sempf Stefan Lauterbach Mathis M. Müller Iakovos Sigalas 《Journal of the American Ceramic Society》2009,92(10):2368-2372
B6 O is a possible candidate of superhard materials with a hardness of 45 GPa measured on single crystals. Up to now, densification of these materials was only possible at high pressure. However, recently it was found that Al2 O3 can be utilized as an effective sintering additive, similar to the addition of Y2 O3 /Al2 O3 that was used in this work. The densification behavior of the material as a function of applied pressure, its microstructure evolution, and the resulting mechanical properties were investigated. A strong dependence of the densification with increasing pressure was found. The material revealed characteristic triple junctions filled with amorphous residue composed of B2 O3 , Al2 O3 , and Y2 O3 , while no amorphous grain-boundary films were observed along internal interfaces. Mechanical testing revealed on average a hardness of 33 GPa, a fracture toughness of 4 MPa·m1/2 , and a strength value of 520 MPa. 相似文献
20.
Hyunho Shin Sang-Gon Kim Jong-Sung Park Jae-Sul An Kug Sun Hong Hyungsun Kim 《Journal of the American Ceramic Society》2006,89(10):3258-3261
The influence of co-additions of crystalline TiO2 and SiO2 fillers (10 wt% addition in total) to BaO–ZnO–B2 O3 –SiO2 glass on resultant properties was investigated from the viewpoint of applying the material to the barrier ribs of plasma display panels. The substitution of SiO2 for TiO2 reduced the dielectric constant significantly, while it maintained high optical reflectance and appropriate coefficient of thermal expansion (CTE) in the case when TiO2 alone was used. A 5–7.5 wt% SiO2 addition with 2.5–5 wt% TiO2 under the constraint of 10 wt% total fillers demonstrated an optical reflectance of about 55%, a CTE of about 8.3 × 10−6 K−1 (compatible with glass panels), and a dielectric constant of about 7.5, which are promising properties for the barrier rib application. 相似文献