金属氢化物热泵及其在载人航天生保系统中的应用

介绍了金属氢化物热泵系统的工作原理和研究现状，分析了该系统在载入航天生命保障系统，特别是出舱航天服生命保障系统中应用的可能性，着重从系统体积，重量、物质消耗，再生时间和技术成熟度等方面比较了水升华器，相变储热，金属氢化物热泵等几种冷源各自的优缺点，说明了金属氢化物热泵系统在载入航天生命保障系统中应用的巨大潜力和需要研究的关键性技术问题。     

Friction Stir Welding of Metal Matrix Composites for use in aerospace structures

Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as the Orion Crew Exploration Vehicle. A current focus of FSW research is to extend the process to new materials which are difficult to weld using conventional fusion techniques. Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramics and have a very high strength to weight ratio, a property which makes them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Since FSW occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This work characterizes the effect of process parameters (spindle speed, traverse rate, and length of joint) on the wear process. Based on the results of these experiments, a phenomenological model of the wear process was constructed based on the rotating plug model for FSW. The effectiveness of harder tool materials (such as Tungsten Carbide, high speed steel, and tools with diamond coatings) to combat abrasive wear is explored. In-process force, torque, and vibration signals are analyzed to assess the feasibility of on-line monitoring of tool shape changes as a result of wear (an advancement which would eliminate the need for off-line evaluation of tool condition during joining). Monitoring, controlling, and reducing tool wear in FSW of MMCs is essential to the implementation of these materials in structures (such as launch vehicles) where they would be of maximum benefit.     

弱界面粘结对复合材料有效性能的影响

采用非线性弹簧元模拟界面,用细观力学有限元法计算分析了不同界面特性下弱界面粘结的纤维增强金属基复合材料的宏细观性能。并考虑了3种不同的界面模型。结果表明弱界面粘结的存在使复合材料宏观性能下降。在常响应界面情况下,复合材料横向拉伸应力-应变曲线存在明显的转折点,对应于界面分离的起始点,转折点的位置取决于界面粘结强度。当存在渐进适应界面时,复合材料横向拉伸应力-应变曲线存在3个阶段。      

行波机理对低散射目标支架雷达散射截面的影响研究

针对雷达低散射支架,文中首先采用天线机理分析行波对雷达散射截面(RCS)的贡献,并且使用等效相速度的概念求出双弧线外形目标支架在远区的辐射场,最后分析得出低散射支架行波辐射特性,并讨论行波对目标支架RCS的影响。     

SiCp增强体表面改性对铁基复合材料组织性能的影响

为了改善粉末冶金方法制得的SiCp/Fe复合材料性能，采用化学镀的方法，成功地在SiCp表面沉积镍，考察了颗粒表面改性对铁基复合材料组织性能的影响。结果表明，镀镍层的作用明显：第一，阻碍了SiCp/Fe界面的过度反应以及Si原子向基体中的扩散；第二，镀镍层的存在改善了颗粒与基体的界面状况，使得颗粒能够更好地发挥增强体的作用。     

钨渗铜材料在真空高压开关上的应用

为适应高压真空开关抗熔焊、耐电蚀、高电导、低含气量等要求，对传统的生产工艺作了一系列改进，采用纯钨粉经模压成型、高温烧结，然后一次完成渗铜和覆铜。结果表明，钨骨架强度高，钢呈网状分布，基体组织细小均匀，气体含量低，覆铜层与钨铜基体结合紧密，从而满足了使用要求，降低了成本，获得了较好的经济效益。     

Effective metal mold method for the production of bionic adhesives based on electrochemical modifications

Bionic adhesives with tip-expanded microstructural arrays have attracted considerable interest owing to their high adhesive performance at low preloads. Their mainstream manufacturing method is molding. Due to most molds are made of silicon or silicon-based soft templates, and have poor wear resistant or vulnerability to high temperature, limiting their use in large-scale manufacturing. Nickel is widely used as an embossing mold in the micro/nano-imprint industrial process owing to its good mechanical properties. However, the processing of metal molds for the fabrication of tip-expanded microstructural arrays is extremely challenging. In this study, using electrodeposition techniques, the shape of the micropores is modified to obtain end-controlled pores. The effect of the non-uniformity of the electric field on the microporous morphology in the electrodeposition process is systematically investigated. Furthermore, the mechanism of non-uniformity evolution of the microporous morphology is revealed. The optimized microporous metal array is used as a mold to investigate the cavity evolution laws of the elastic cushions under pre-load during the manufacturing process. As a result, typical bionic adhesives with tip-expansion are obtained. Moreover, corresponding adhesion mechanics are analyzed. The results show that electrochemical modifications have broad application prospects in the fabrication of tip-expanded microstructures, providing a new method for the large-scale fabrication of bionic adhesives based on metal molds.     

一起典型的FJ44-1A发动机金属末故障分析

航空发动机滑油系统发现金属末意味着这发动机部件之间出现了过度磨损,这类故障严重影响飞行安全,必须查明故障原因并纠正。本文根据多次发动机热端部件检查的实践经验,对一起由于安装不当造成发动机轴承磨损的故障进行了分析,并总结了FJ44-1A发动机热端部件装配的若干经验。     

金属粉末燃烧装置凝相产物反弹特性实验研究

为获得金属粉末燃烧装置燃烧产物的反弹特性,进而为金属凝相燃烧产物收集装置的设计提供指导,在收集并分析了铁粉燃烧产物特性的基础上,搭建了壁面碰撞反弹装置,开展了凝相燃烧产物与石墨板反弹特性实验研究,获得了铁粉燃烧产物与石墨板碰撞反弹后的法向反弹系数（en）与切向反弹系数（et）随粒子入射速度、入射角度的影响规律,并拟合了反弹系数多项式。结果表明：真实燃烧产物实验条件下,铁粉凝相燃烧产物的入射速度对en和et影响不显著,但入射角度对en和et的影响较大,表现为en随入射角度的增加而增大,et随入射角度的增加先减后增,但增幅较小,当入射角度大于58°时,et又出现减小的趋势。     

AP/KP/GAP富燃料推进剂的热分解特性

用差示扫描量热实验和高压差热分析法，分析，研究了GAP模拟富燃料推进剂的常压和高压热分解特性，同时考虑了过渡金属氧化物（TMO）催化剂对GAP模拟富燃料热分解特性的影响，实验结果表明，TMOwwyjcf GAP,AP和KP的催化作用不同，同一催化剂在不同压强下的催化作用也不同。