Bonding of Al2O3 ceramic and Nb using transient liquid phase brazing

The brazing of Al2O3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni-5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1423-1573 K for 1-120 min. The results show that the shear strength of the joint first increases and then decreases with increasing holding time and brazing temperature. The joint interface microstructure and elements distribution were investigated. It can be concluded that a composite structure, in which the base metals are solid solution Nb(V) and Nb(Ti) reinforced by Ni3Ti, is formed when the brazing temperature is 1473 K and holding time 15 min, and a satisfactory joint strength can be achieved. The interaction of Ti foil and Ni-5V foil leads to the formation of liquid eutectic phase with low melting point, at the same time the combination of Ti come from the interlayer with O atoms from Al2O3 results in the bonding of Al2O3 and Nb.     

扩散处理对Si3N4陶瓷与金属钎焊接头的强化作用

用扫描电子显微镜、能谱仪及X射线衍射仪分析和讨论了复合电镀Ni-Ti陶瓷与金属钎焊接头的强度、微观结构和其界面结合机制。试验表明：扩散处理对陶瓷与金属钎焊接头有强化作用。经辉光扩散处理后，Ti向陶瓷界面扩散，Ni-Ti层与陶瓷发生界面反应。     

牙科着色玻璃渗透氧化铝陶瓷的性能研究

在1400℃下熔融2h制备4种定制颜色的着色渗透玻璃，并将玻璃于1120℃渗透入预烧结氧化铝多孔基体，采用分光光度计测定渗透后的透射比和颜色参数，渗透后的复合材料作三点弯曲强度及断裂韧性测试，断裂面进行扫描电镜观察。结果表明：玻璃渗透后铝瓷的颜色参数范围：L^＊：68．80-78．44，a^＊：1．32～4．75，b^＊：16．86-21．86。三点弯曲强度为（420-27．72）MPa，断裂韧性为（3．70-0．13）MPa·m^1/2。     

缠绕型全自动液压压砖机机架钢丝预紧力的设计

通过建立钢丝缠绕型液压压砖机机架的力学模型，推导出钢丝绕层和钢丝预紧力的计算方法，并用有限元分析方法验算了某一缠绕型全自动液压压砖机机架钢丝预紧力的大小。     

Synthesis and characterization of La0.8Sr0.2MO3−δ (M=Mn, Fe, or Co) cathode materials by induction plasma technology

In this work, nanopowders of perovskite cathode materials (La_0.8Sr_0.2MnO_3−δ, La_0.8Sr_0.2FeO_3−δ, and La_0.8Sr_0.2CoO_3−δ), for use in solid oxide fuel cells (SOFC), were successfully synthesized, using induction plasma techniques. Their compositions, structures, morphology, particle size distributions, and BET specific surface areas were determined for comparison with their counterparts prepared by the Pechini method and by the glycine-nitrate combustion (GNC) technique. The particle sizes of the plasma-synthesized powders are mostly around 63 nm. These plasma-synthesized powders are generally globular, their BET specific surface areas being about 26 m²g⁻¹, approximately twice those of powders prepared by the GNC and Pechini methods. These plasma-synthesized powders are readily reproducible and are not agglomerated. Their individual particle sizes and distributions are very independent of their composition.     

陶瓷与金属扩散连接的研究现状

陶瓷与金属的连接技术是材料工程领域的热点研究课题,而扩散连接方法被认为是陶瓷与金属连接最适宜的方法。本文综述了陶瓷与金属扩散连接的研究现状,重点介绍了界面反应研究、残余应力分析和连接工艺研究等内容,并在此基础上指出了研究中所存在的问题。     

Characterization of microstructure of Nano-TiO2 coating deposited by vacuum cold spraying

Control of the microstructure of TiO₂ coatings through preparation methods significantly influences the coating performance. In this study, a vacuum cold-spray process, as a new coating technology, is used to deposit nanocrystalline TiO₂ coatings on conducting glass and stainless steel substrates. TiO₂ deposits were formed using two types of nanocrystalline TiO₂ powders with mean particle diameters of 200 and 25 nm. Coating microstructures were characterized by scanning electron microscopy and x-ray diffraction analysis. Results demonstrate that a thick nanocrystalline TiO₂ coating can be deposited by the vacuum cold-spray process. The coating was found to consist of particles stacked as agglomerates that build up to several hundred nanometers. The coating also presents a mesoporous microstructure that could be effective in such applications as photocatalytic degradation and dye-sensitized solar cells. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

渗钛Si3N4/Q235钎焊界面反应对接头强度的影响

说明了渗钛Ｓｉ３Ｎ４／Ｑ２３５钎焊界面反应与微观结构对接头强度的关系，并对各主要工艺因素对砂强度的影响规律进行了探讨，为渗钛陶瓷／金属钎焊规范的优化选择提供了试验及理论依据。     

Joining alumina to inconel 600 and UMCo-50 superalloys using an Sn10Ag4Ti active filler metal

Alumina ceramics were brazed to Inconel 600 and UMCo-50 superalloys at 900 °C for 10 min using an Sn10Ag4Ti active filler metal. The brazing filler showed good wettability on alumina and superalloys. The flexural strengths were 69 and 57 MPa for alumina/Inconel 600 and alumina/UMCo-50 joints, respectively. In both cases, the brazed specimens fractured along the Sn10Ag4Ti/superalloy interfaces after four-point bending tests. Electron probe microanalysis (EPMA) elemental mapping revealed that the Ni of Inconel 600 and the Co of UMCo-50 dissolved into Sn10Ag4Ti filler metal, which serves to reinforce the weak Sn10Ag4Ti matrix.     

Technical note: Plasma-sprayed ceramic thermal barrier coatings for smooth intermetallic alloys

A durable ceramic thermal barrier coating is applied directly to a smooth, highly oxidation resistant intermetallic alloy in two layers. The first layer of ceramic is applied by low pressure plasma spraying and the second layer is applied by conventional atmospheric pressure plasma spraying. This approach would allow the use of plasma sprayed ceramic coatings in applications where a metallic bond coat is not desirable.