Cr_2O_3-Al_2O_3砖中不同组成Cr_2O_3-Al_2O_3电熔颗粒料的抗侵蚀研究

首先以不同比例的铬绿和氧化铝粉电熔制得Cr2O3质量分数分别为15%、40%、50%、60%、85%、99%的6种Cr2O3-Al2O3电熔颗粒料(其编号依次为CR15、CR40、CR50、CR60、CR85和CR99),然后采用回转渣蚀法研究了此电熔颗粒料(4~1 mm)的抗侵蚀性。结果显示:电熔颗粒料的抗侵蚀性随Cr2O3含量的增加及颗粒尺寸的增大而增强;高Cr2O3含量的CR99、CR85颗粒料在渣面层被侵蚀,主要是渣中的FeO和Al2O3对颗粒料的侵蚀,FeO与骨料中的Cr2O3反应,首先形成(Fe,Cr)3O4尖晶石,再与其他物相反应形成了复合尖晶石,当FeO耗尽后,渗入到颗粒内的Al2O3开始和Cr2O3反应,在颗粒表面形成铝铬固溶体;CR60颗粒料在渣面层和渗透层都存在侵蚀,渗透层的侵蚀主要是CaO、SiO2对颗粒料中铝铬固溶体中Al2O3的熔蚀,形成钙长石、钙黄长石以及玻璃相;Cr2O3含量较低的CR50、CR40、CR15颗粒料在渗透层内的侵蚀机制和CR60颗粒料的相同。     

High oxide ion conduction in sintered oxides of the system Bi2O3-Y2O3

The ionic conduction in sintered Bi₂O₂-Y₂O₃ was investigated by measuring the conductivity and the emf of an oxygen concentration cell using the specimen tablet as electrolyte. The face centred cubic phase in this system was found to show high oxide ion conduction accompanied by a little electronic conduction when exposed to air. This phase was stable with a composition of 25 ～ 43 mol % Y₂O₃ over a wide range of temperatures, and the oxide ion conductivity increased with decrease in Y₂O₃. The conductivities of (Bi₂O₃)_0.75 (Y₂O₃)_0.25 were 1.6×10^?1 Ω^?1 cm^?1 at 700°C and 1.2×10^?2 Ω^?1 cm^?1 at 500°C values which are many times higher than those of stabilized zirconia (ZrO₂)_0.90(Y₂O₃)_0.10 at corresponding temperatures. Specimens containing less than 25 mol % Y₂O₃ showed a phase transition at 700 ～ 580°C and the conductivities decreased remarkably below these temperatures. High oxide ion conduction in the fcc phase is attributed to the migration of oxide ion vacancies which were present in an appreciable amount.     

Cr2O3-Al2O3-ZrO2高铬制品

介绍了Cr2O3-Al2O3-ZrO2制品的组成及各组成的作用、烧成气氛、制品的显微结构特征和性能指标.着重论述了影响制品性能的烧成工艺和以电熔、烧结两种Cr2O3颗粒生产的Cr2O3-Al2O3-ZrO2制品的显微结构差异,表明在还原气氛下烧成的Cr2O3-Al2O3-ZrO2制品性能优良,而采用电熔Cr2O3料生产的Cr2O3-Al2O3-ZrO2制品性能优于使用烧结Cr2O3料生产的.     

A strong ceramic in the Al2O3-ZrO2-Y2O3 system

Conclusions A highly dense ceramic based on the eutectic composition of the Al₂O₃-ZrO₂ system was obtained using 3 mole % Y₂O₃ addition. The ceramic has a fine-grained structure and high hardness and strength.Translated from Ogneupory, No. 2, pp. 8–10, February, 1987.     

Combustion synthesis of SiC-MoSi2-Al2O3 composites

Combustion synthesis of SiC-MoSi₂-Al₂O₃ composites by using highly exothermic reactive system of MoO₃-Al-Si-SiO₂ was investigated. It has been shown that, by using the combustion synthesis method, it is feasible to prepare, at 1500 °C, an electrical heating element with room temperature resistivity and element watt loading of 12 Ω cm and 20 W/cm² respectively. The colloid containing nano-sized material 30 wt% SiO₂, was used as the plasticizer medium as well as combustion source. The β-SiC functioned as a filler material to control the combustion reaction and also constituted part of the final product. The amount of SiC additive varied in the range from 45% to 65% wt. and was optimized with respect to porosity level, reaction conversion and net-shape quality of the heating elements. The element containing about 60% wt. SiC reveals low porosity level, with full conversion for the reaction and superior net-shape quality. However, despite the relatively high level of porosity present in the final synthesized product, it can be used as an electrical heating element in accordance with the investigation at the element temperatures up to 1500 °C.     

水煤浆气化炉用Cr2O3-ZrO2-Al2O3砖的蚀变过程

利用扫描电镜及能谱仪对水煤浆气化炉用进口铬锆铝砖的蚀变过程进行了显微观察与分析.结果表明此砖在水煤浆气化炉环境条件下的侵蚀主要由熔渣中的SiO2、CaO和P2O5引起;Cr2O3对这种渣蚀表现出很强的化学惰性,溶蚀很小,其使用过程中的主要变化是高温蒸发和在砖内蚀变液相作用下的溶蚀、溶析;而氧化锆蚀变生成的系列产物不仅在蚀变初期有利于保持砖结构致密,并且对蚀变后期基质连续网络结构的形成和保持也起了重要的作用.     

热疗用Fe2O3-SiO2-Y2O3-Al2O3微晶玻璃微球的制备与性能

采用火焰漂浮法制备新型含钇铁磁微晶玻璃微球(ferromagnetic glass ceramic microspheres,FGCMs),用以放疗与热疗相结合的医疗用途.通过热分析和X射线衍射(X-ray diffraction,XRD)研究热处理温度对FGCMs性能的影响.使用偏光显微镜观察FC-CMs的形貌.用振...     

Combustion synthesis of compounds in the Y2O3-Al2O3 system

In the Y₂O₃-Al₂O₃ system, compounds Y₃Al₅O₁₂ (yttrium aluminum garnet, YAG), YAlO₃ (yttrium aluminum perovskite, YAP), and Y₄Al₂O₉ (yttrium aluminate monoclinic, YAM) are well known. YAG and YAP are of considerable technological importance. Conventional solid-state reaction techniques require high sintering temperatures (above 1800°C) to prepare phase-pure compounds. Though several soft chemical routes have been explored for synthesis of YAG, YAP and YAM, most of these methods are complex. Moreover, phase-pure materials are not obtained in one step and prolonged annealing at temperatures around 1000°C is necessary. In this paper, one-step combustion synthesis of these compounds is reported using a modified procedure and employing mixed (glycine + urea) fuel. Phosphors based on Ce³⁺ activation were also prepared and exhibited characteristic photoluminescence.     

Change of pigment color in the system CoO-Cr2O3-Al2O3

Translated from Steklo i Keramika, No. 11, pp. 22–23, November, 1991.     

Structure and magnetic properties of BeO-Fe2O3-Al2O3-TeO2 glass-ceramic composites

In this work, glass-ceramics in the xBeO–20Fe₂O₃–(80-x)TeO₂ system with x = 0–25 mol% were synthesized by the traditional melt quenching route and studied by inductively coupled plasma optical emission spectroscopy, X-ray diffraction, confocal microscopy, infrared and Raman spectroscopy. BeO addition was found to support the crystallization process of Fe₂O₃ during melting, and an increased BeO content was associated with an increased fraction of the crystalline Fe₂O₃ phase and an increased size of these crystallites. Furthermore, samples doped with BeO exhibit an increasing polymerization of the residual tellurite glass network compared to the undoped sample. The magnetic properties and specific heat of all synthesized materials were measured, and the results show that all studied samples behave as spin-glasses. Also, the Morin transition of hematite was observed at 260 K with intensity depending on the material content in Fe₂O₃ crystalline phase, the formation of which correlates with the amount of added BeO.