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The phase relationships in the system K2O · AL2O3-Al2O3 between 1200 and 1700° C have been experimentally established. The homogeneity range of potassium -alumina is limited by the 83 and 91 mol % Al2O3 compositions. The eutectic point between the K2O-Al2O3 and -alumina was found to be at 1450° at about 62 mol % Al2O3 composition. An X-ray diffraction pattern analysis of potassium -alumina is shown. 相似文献
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低温沉积α-Al2O3薄膜是拓展其实际工程应用的关键。本研究以Al、α-Al2O3和Al + 15wt% α-Al2O3为靶材, 用射频磁控溅射在Si(100)基体上沉积氧化铝薄膜。用掠入射X射线衍射(GIXRD)、透射电子显微镜(TEM)、能谱仪(EDS)对所沉积薄膜的相结构和元素含量进行研究, 用纳米压痕技术测量薄膜硬度。结果表明, 在550 ℃的基体温度下, 反应射频磁控溅射Al+α-Al2O3靶可获得单相α-Al2O3薄膜。靶中的α-Al2O3溅射至基片表面能优先形成α-Al2O3晶核, 在550 ℃及以上的基体温度下可抑制γ相形核, 促进α-Al2O3晶核同质外延生长, 并最终形成单相α-Al2O3薄膜。 相似文献
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玻璃陶瓷属于一类多晶陶瓷材料.通过调整玻璃基质和晶相组成可以制备出具有良好的力学、热学、电学和光学性能的玻璃陶瓷材料.采用传统的熔融和退火技术制备出含B2O3-Al2O3-SiO2-Li2O-K2O组分的硼铝硅玻璃,并通过成核和长晶工艺最终制备出透明玻璃陶瓷.配合料在铂金坩埚中于1450℃下熔融2h,然后经两步热处理制度控制晶核的生成和晶粒的长大.采用差热分析技术确定成核和长晶温度.采用X射线衍射技术对不同热处理制度下的玻璃陶瓷样品进行分析,以确定最佳成核和长晶条件.采用扫描电子显微镜分析玻璃陶瓷形态,晶粒尺寸及其在残余玻璃相中的分布.采用UV-Vis-Nir分光光度计测定玻璃陶瓷样品的透过率. 相似文献
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以纳米η-Al2 O3为原料,氧化镁(MgO)为稳定剂,采用双组元法制备Na-β″-Al2 O3固体电解质.通过Archimedes法,SEM和三点抗弯法研究试样的致密性、显微结构和力学性能;采用XRD和交流阻抗谱仪研究试样的β″-Al2 O3相含量和离子电导率.结果表明:双组元法有利于提高试样的结构均匀性;纳米η-Al2 O3比高纯α-Al2 O3更易于合成Na-β″-Al2 O3固体电解质;适量MgO的加入有利于提高试样中β″-Al2 O3相的含量和试样的致密性,减小试样的晶界电阻,提高试样的离子电导率;过多的Mg O掺杂量导致晶内气孔尺寸的长大,反而增大了试样的晶粒电阻,导致试样的离子电导率降低.当MgO的加入量为2%(质量分数)时,试样在300℃时的离子电导率最大,为0.0396 S·cm-1. 相似文献
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在氧气中焙烧C/γ-Al2O3复合物快速制备α-Al2O3微粉 总被引:1,自引:0,他引:1
提出了一种快速制备α-Al2O3微粉的方法, 以淀粉为碳源、γ-Al2O3为前体制备了C/γ-Al2O3复合物, 然后在800℃、氧气氛中焙烧制备α-Al2O3微粉. N2物理吸附及SEM分析结果表明, 所制得的α-氧化铝颗粒细小, 约为2μm. 该方法具有焙烧温度低、焙烧时间短的优点, 同时, 淀粉及γ-Al2O3均为廉价的工业原料, 且该方法所需淀粉量较少, 最少仅需0.3g/g γ-Al2O3, 对应的C/γ-Al2O3复合物碳含量约为6wt%, 因而极具工业化应用前景. 相似文献
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In this article, electron emission is used to study the defect structure of alumina. The need of a direct measurement of the position of the Fermi level (or the electron concentration in the conduction band) is shown by discussing the actual electrical data on alumina. The emission has been measured over a large temperature range (1400 to 2400 K) and the emission of a technical polycrystalline alumina is reported up to the melting temperature under a controlled oxygen partial pressure. Additional results are reported for titanium- and iron-doped polycrystalline aluminas. The results are discussed from two points of view. First the quantitative data concerning the work function are taken into account and the contribution of the surface layer is discussed. Secondly, the dependency of the electron emission on the oxygen partial pressure is explained by the defect chemistry of the oxide. The absence of variation of the electron concentration in a certain range of
is due to a self compensation between donor and acceptor impurities. 相似文献
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爆轰法制备纳米α-Al2O3 总被引:4,自引:0,他引:4
纳米粉体材料是上世纪80年代中期以后发展起来的一种新型固体材料,它由尺寸在(1-100)mm的固体颗料组成.由于纳米材料具有良好的表面效应、体积效应、量子尺寸效应和宏观量子隧道效应,在材料、机械、化工、医药、军事等领域都有广泛的用途. 相似文献
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R. Kvachkov A. Yanakiev C. N. Poulieff I. Balkanov P. D. Yankulov E. Budevski 《Journal of Materials Science》1981,16(10):2710-2716
The influence of the morphology and the size of the particles of various types of starting Al2 O3 material on the synthesis and characteristics of Li-stabilized'-Al2O3 ceramics have been investigated. The use of highly dispersed oxides makes it possible to attain higher densities in the fired ceramic bodies due to their higher reactivity. In the case of oxides obtained from ammonium alum, the degree of dispersion and the reactivity may be increased by raising the amount of-Al2O3 up to a certain limit. Alumina prepared from Al2 (OH)5 NO3 by slurry solution spray-drying also gives satisfactory results despite its lower degree of dispersion. This is connected with the morphology of the particles. In the case of synthesized materials containing an insufficient amount ofAl2O3-NaAlO2 eutectic, high densities may also be achieved by applying a two-step firing schedule at temperatures above the melting point of the eutectic. 相似文献
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I. I. M. Tijburg H. De Bruin P. A. Elberse J. W. Geus 《Journal of Materials Science》1991,26(21):5945-5949
Sintering of pseudo-boehmite, acicular-Al2O3 produced by dehydration of pseudo-boehmite, and-Al2O3 ex alum was investigated. The sintering process was studied by X-ray diffraction, transmission electron microscopy with selected area electron diffraction and BET surface area measurements. The solid state reaction to-Al2O3 causes a steep drop of the surface area to less than 10 m2g–1. The acicular pseudo-boehmite and-Al2O3 supports exhibit an intermediate state where the acicular particles assume a rod-like shape and the surface area falls from about 300 to 100 m2g–1. It was established that reaction to -Al2O3 and, hence, sintering proceeds via a nucleation and growth mechanism. The rate-limiting step is nucleation of -Al2O3. Consequently, the contacts between the elementary alumina particles dominate the sinter process. The contact between the acicular elementary particles of pseudoboehmite and-Al2O3 studied leads to the reaction to -Al2O3 to be almost complete after keeping samples for 145 h at 1050 °C. Decomposition of alum produces very small particles showing negligible mutual contacts. Consequently an elevated thermal stability is exhibited. Treatment of the alumina ex alum with water and drying results in a xerogel in which contact between elementary particles is much more intimate. Accordingly, treatment at 1050 °C causes a sharp drop in surface area. 相似文献
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微波酸消解α-Al2O3研究 总被引:1,自引:0,他引:1
使用MARS-5微波高压消解系统采用HCI或HNO3成功地溶解了α-Al2O3样品,指出当溶剂温度上升至240℃时,HCI或HNO_3对α-Al2O3样品具有较强的溶解能力.当溶剂量固定时,样品量的大小与溶样时间大致成正比关系. Al2O3样品中α相比率越高,消解时间越长. 相似文献
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《Nanostructured Materials》1994,4(4):371-385
The densification and phase transformation behavior of gas condensation synthesized nanocrystalline γ-A12O3 sintered with microwave radiation has been studied. The polymorphic nucleation and growth phase transformations which occurred as the material was heated through the temperature range of 800–1300°C present significant obstacles in the achievement of specimens which possess high bulk densities. These phase transformations are accompanied by a change in particle morphology, crystallite size, and surface area. Alumina derived from a chemically synthesized boehmite precursor has been shown to exhibit the same nucleation and growth phase transformation behavior when conventionally heated. It is concluded that nanocrystalline γ or δ alumina will not be a viable starting material for the production of dense bodies with grain sizes of less than 100 nm. 相似文献
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B2O3-Al2O3-SiO2系微晶玻璃析晶动力学研究 总被引:1,自引:0,他引:1
采用差示扫描量热(DSC)分析法对B2O3-Al2O3-SiO2系统微晶玻璃的析晶动力学参数进行了测定,研究了该系统微晶玻璃的析晶动力学。结果表明:随着B2O3/SiO2比的降低,该系统玻璃的析晶活化能E呈先升高后降低的变化趋势,当B2O3/SiO2比为11:5时,析晶活化能最小,Emin=375.4kJ/mol,晶化指数n则先减小后增大,但均〉4,表明该系统玻璃可整体析晶。 相似文献
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研究了应用于阳极支撑型的中温固体氧化物燃料电池(ITSOFC)密封的SrO-La2O3-Al2O3-B2O3-SiO2体系微晶玻璃不同组分的线膨胀率,结果表明当微晶玻璃粉组成SrCO3 28.14%(摩尔分数),La2O3 21.17%(摩尔分数),Al2O3 7.22%(摩尔分数),H2BO3 41.72%(摩尔分数),SiO2 1.76%(摩尔分数)(SLABS3) 时,最符合ITSOFC密封要求.差热分析结果表明SLABS3的玻璃转变温度在670℃~760℃之间,结晶温度在813~840℃之间,玻璃软化点约在900℃,XRD测试表明微晶玻璃与Ni-La0.3Ce0.7O1.85(Ni-LDC)阳极化学相容性好,将微晶玻璃和Ni-LDC在850℃烧结100h后,SEM观察界面粘附性好,EPMA测试界面的元素含量结果表明,虽然阳极的Ce会向微晶玻璃扩散10μm的深度,但观察不到微晶玻璃的元素向Ni-LDC扩散现象.用SLABS3密封模拟电池,测试开路电压结果表明SLABS3的密封效果和稳定性良好. 相似文献
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Le Yong Ma Xiaochen Wang Di Xiao Hongdi Luan Caina Zhang Biao Ma Jin 《Journal of Materials Science: Materials in Electronics》2022,33(3):1503-1510
Journal of Materials Science: Materials in Electronics - The heteroepitaxial δ-Ta2O5 films were deposited on α-Al2O3 (0001) by MOCVD. As the growth temperature increases from... 相似文献
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