Preparation and Photoproperties of a Transparent Alumina Film Doped with Energy-Transfer-Type Laser Dye Pair

Doping of an energy-transfer-type laser dye pair into an alumina film was tried in order to increase the efficiency of its photoproperties. A transparent alumina film was prepared from an aqeous sol solution by the sol—gel process. Changes in the fluorescence of the pyranine were monitored during the process from aqueous sol solution to the dried gel. The undesirable dye aggregation usually observed in aqueous solution was largely reduced in the film. The laser emission of rhodamine B by N₂ laser pumping can be increased by the addition of rhodamine 6G, which enhances pumping efficiency. It indicates that this doped film operates as a compact dye laser film.     

Luminescence of Eu‐Doped Transparent LuPO4 Glass‐Ceramics

Dual valence Eu‐doped transparent glass‐ceramics containing LuPO₄ nanocrystals were fabricated by melt‐quenching technique in air atmosphere. Their luminescent properties were systematically investigated by excitation, emission spectra, and decay lifetime measurements. The prominent Stark splitting, low forced electric‐dipole ⁵D₀ – ⁷F₂ transition and long decay lifetimes of Eu^{3 +} emission for glass‐ceramics reveal the incorporation of Eu^{3 +} into LuPO₄ nanocrystals. The enhanced Eu^{2 +} emission and reduction mechanism of Eu^{3 +} to Eu^{2 +} after crystallization are discussed briefly. Our results indicate that transparent LuPO₄ glass‐ceramics may find applications in photonics.     

氧化铝陶瓷表面化学气相沉积钛涂层的制备及性能

利用卤化物还原原理,以Ti粉和I2粉为反应原料,通过化学气相沉积的方法在Al2O3陶瓷基体上制备了金属Ti涂层。考察了原料配比、加热温度及保温时间等工艺参数对涂层沉积的影响。通过X射线衍射仪分析了涂层的物相组成。利用扫描电子显微镜及能谱仪对涂层的微观组织形貌及成分进行了分析。采用座滴法考察铜与沉积了涂层的氧化铝陶瓷间的润湿性。研究结果表明,化学气相沉积法在氧化铝陶瓷表面制备Ti涂层的适宜工艺参数为:Ti与I2的质量比=1∶3,沉积温度为1 100℃,沉积时间为60min。所获得的Ti涂层纯度较高,具有明显的(110)晶面择优取向性,涂层与陶瓷结合良好。铜与涂层间的润湿角在1 113℃时为57°。     

Tb3+掺杂钼酸盐玻璃陶瓷的制备及发光性能表征

采用熔融-晶化法制备了Tb3+掺杂的CaMoO4为主晶相的透明钼酸盐玻璃陶瓷。利用DSC、XRD、SEM确定了该体系玻璃样品的最佳热处理制度：715℃保温2.5 h;随着热处理时间的增加,玻璃陶瓷中的晶粒尺寸逐渐变大;利用UV-Vis-NIR得到样品玻璃陶瓷在可见光区的透过率可达80%;并利用荧光光谱讨论了在相同热处理条件下,不同Tb3+掺杂浓度对玻璃陶瓷样品发光性能的影响,研究表明Tb3+掺杂浓度为7.0mol%时样品的荧光强度最大。     

Optical Characterizations of Hot‐Pressed Erbium‐Doped Calcium Fluoride Transparent Ceramic

Nanoparticles of erbium‐doped calcium fluoride were synthesised by the coprecipitation method. Micromorphology of the obtained nanoparticles was observed by transmission electron microscopy. The nanoparticles were hot‐pressed in a vacuum environment to achieve Er:CaF₂ transparent ceramic. X‐ray diffraction analysis confirmed the crystallization of a single fluorite phase after sintered. Transmittance spectrum of Er:CaF₂ ceramic sample was measured, and the transmittance at 1200 nm reached about 87%. Microstructures were characterized using field‐emission scanning electron microscopy. The luminescence spectrum of Er:CaF₂ transparent ceramics under 488‐ and 978‐nm excitation was measured and discussed. It was evidenced that strong cross‐relaxation processes between Er³⁺ ions occur at high dopant concentration, and favoring the red emission at the expense of the green one.     

氧化铝陶瓷的应用

随着科学技术与制造技术日新月异的发展,氧化铝陶瓷在现代工业中得到了深入的发展和广泛的应用。本文介绍了氧化铝陶瓷在各个研究领域的应用及其制备工艺,以氧化铝陶瓷性能为基础,综述了它在所应用领域的发展状况。     

Transparent Alumina with Submicrometer Grains by Float Packing and Sintering

Commercially available α-alumina powder with high-purity, submicrometer particle size and narrow particle-size distribution is used as starting material to prepare dense ceramic parts with transparent properties. The powder is dispersed and stabilized in a water-based suspension. Controlled consolidation and drying by float packing leads to homogeneous green compacts, which can be densified without additives by sintering in air at 1275°C to transparency, while the mean grain size remains at 0.4 μm. The in-line transmittance for wavelengths of 300–450 nm is comparable to commercial polycrystalline alumina tubes for lighting technologies, whose grain sizes are larger by a factor of 40.     

Thermostable Transparent Lithium-Aluminosilicate Sitall Doped with Neodymium Oxide

Glass and Ceramics - The effect of adding the oxide Nd2O3(0.1 – 3.0 mol.%) on the synthesis conditions, crystallization, and spectral properties of a thermostable...     

Ceramic Composites of Monazite and Alumina

A new family of high-temperature, oxidation-resistant, ceramic composites, with (La)-monazite (LaPO₄) serving as a weakly bonded interphase, is proposed. Monazite is stable and phase-compatible with alumina at temperatures at least as high as 1750°C in air. Especially important for use in high-toughness composites, the monazite-alumina interface is shown to be sufficiently weak that interfacial debonding prevents cracks from growing from monazite into alumina. Observations of fracture responses of fibrous and laminar reinforcements are presented.     

Singular Grain Boundaries in Alumina Doped with Silica

Pure Al₂O₃ powder compact sintered at 1400°C after adding 100 mol ppm of SiO₂ shows grain boundaries that are flat, even across the triple junctions. TEM observations show that these flat grain boundaries are parallel to the basal planes of the grains on one side. These flat grain boundaries must be singular. At such a low SiO₂ concentration and a low temperature, it is very unlikely that any liquid phase is present at these grain boundaries to cause such flat boundary shapes.     

Sintering of Ultra-High-Purity Alumina Doped Simultaneously with MgO and FeO

The use of ultra-high-purity powder processing and multiple solid-solution additive doping has been evaluated as an effective approach for the fabrication of alumina ceramics. MgO was found to inhibit grain growth more strongly in very pure powders because of its stronger solute drag effect. The degree of inhibition was severe enough to render grain growth insensitive to porosity. By diminishing the dragging influence of pores on grain-boundary motion, MgO guards against abnormal grain growth due to inhomogeneous densification. FeO acted singly in alumina to promote grain growth more than densification. FeO was not, therefore, an effective sintering additive for undoped alumina. FeO did, however, Ceramic benefit the sintering of MgO-doped alumina.     

多孔Al2O3陶瓷底膜的表征方法

研究了Al2O3陶瓷底膜的表征方法。首先，根据毛细管作用原理、润湿现象及Laplace方程，采用异丙醇作为润湿剂，求出底膜的孔径、干膜流量和湿膜流量，用这些数据，导出孔径分布函数，并作出孔径分布函数与孔径关系图，其次，采用GB1966-80的方法，测定了Al2O3陶瓷底膜的孔隙率。     

氧化铝陶瓷磨加工常见缺陷及原因分析

介绍了氧化铝陶瓷零件磨削加工中数种常见的缺陷,对出现问题的原因进行了分析,为陶瓷工件磨加工质量的提高提供了参考。     

Abnormal Grain Growth in Barium Titanate Doped with Alumina

The effect of additions of ≤1 mol% Al₂O₃ on abnormal grain growth in BaTiO₃ sintered for periods of ≤60 min at 1350°C has been studied. Addition of ≤0.2 mol% Al₂O₃ caused an increase in the nucleation and growth rates of abnormal grains, with further additions causing a decrease. This behavior is explained by interface-controlled growth. Dopant adsorption reduces both the edge free energy and the step velocity of a grain, causing the nucleation and growth rates of abnormal grains to increase, pass through a maximum, and then decrease with increasing dopant concentration.     

SiC掺杂氧化铝耐磨陶瓷摩擦盘材质的研制

通过向氧化铝中加入适量的亚微米级SiC并掺杂少量的MgO来抑制氧化铝晶粒的异常生长以便形成细晶结构,提高制品的力学性能,从而得到耐磨性能优异的陶瓷摩擦盘材质。     

氧化铝陶瓷介电性能的提高

研究了含Al2O395%的BK95-1型真空致密的氧化铝陶瓷。SiO2、Al2O3、MgO及B2O3等形成了陶瓷中的玻璃相。查明,向陶瓷配料中加入SrO和CaO等氧化物可以显著地改善材料的介电性能:体积电阻系数提高一个数量级,特别是高温下的介质损耗显著降低。这可能与锶及钙离子的屏蔽作用有关,它可以阻止碱金属离子的迁移。     

Single and Polycrystalline Transparent Ceramic Armor with Different Crystal Structure

Contrary to the moderate ballistic advantage of Al₂O₃ ceramics over MgAl₂O₄ polycrystals, the present study shows a reverse ratio of the ballistic strength of alumina and spinel single crystals: Spinel single crystals outperform sapphire and exhibit a similarly high stability as submicrometer Al₂O₃ ceramics. The results correlate with different cleavage of single crystalline spinel and sapphire, changing the fragmentation on ballistic impact.     

Dy和Er掺杂对AlN陶瓷显微结构及性能的影响

在AlN粉末中添加稀土氧化物Dy2O3和Er2O3,采用高温烧结方法制备氮化铝陶瓷,研究了稀土掺杂对陶瓷烧结性能、显微结构及导热性能的影响。结果表明:纯氮化铝陶瓷相对密度只有90.7%,导热率为45.7W/(m·K),而添加3%的Dy2O3的AlN陶瓷相对密度为99.4%%,导热率为84.1W/(m·K),添加3%的Er2O3可使氮化铝陶瓷相对密度提高到99.1%,导热率达到115.4W/(m·k);添加Er2O3可有利于消除氮化铝陶瓷的晶界相,减少氮化铝晶粒缺陷及提高声子在晶体中的传播路程,并显著提高氮化铝陶瓷的结构致密性和导热性能。