Five-year update: nickel hydrogen industry survey

A 1984 survey of the nickel hydrogen (NiH₂) battery industry is updated. Late 1980s and early 1990s issues are identified, and usage and testing results of the survey are summarized. NiH₂ is the system of choice for new geosynchronous-earth-orbit (GEO) satellites and is being seriously considered for low-earth-orbit (LEO) applications. In five years, the annual cell production rate has doubled from approximately 1000 to 2000 cells. A number of cells under test have exceeded 20000 cycles at 40% DOD in LEO regimes, while other cells have achieved over 35 seasons in accelerated GEO regimes. The LEO database clearly indicates that NiH₂ performance is at least as good as the best conventional nickel-cadmium performance demonstrated under test     

Status of the Air Force nickel hydrogen low earth orbit life test

The US Air Force NiH₂ LEO (low earth orbit) life test consists of 200 cells undergoing real-time LEO cycling, pulse discharge testing, and storage testing. To date, three of the program's four objectives have been met: NiH₂ performance in LEO applications has been demonstrated. A significant number of cells have completed more than 20,000 cycles at 40% DOD. A database for cells of both 3.5 in. and 4.5 in. diameter has been generated. There have been no indications of any performance problems related to scaling up in terms of cell size. Initial data on the pulse discharge performance of a small number of cells has been demonstrated. Concerning the goal of achieving 20,000 cycles at 60% DOD, the data are mixed. Overall, it appears highly unlikely that cell designs such as those currently in the US Air Force test can achieve 20,000 cycles at 60%     

Advances in the development of ovonic nickel metal hydridebatteries for industrial and electric vehicles

The environmental advantages of ovonic NiH₂ batteries, due to the nontoxicity of ovonic alloys, are briefly discussed, and their general performance is described. Commercial progress in their development is summarized. Their use in electric vehicles is examined     

PowerCore combining structure and batteries for increased energy toweight ratio

Much of the mass of a battery is comprised of nonreactive materials. In an NiH₂ battery, this includes the pressure vessel and 50% of the positive electrode. PowerCore reconfigures the battery materials to serve as a structural sandwich panel. The effective specific energy of the new device can exceed 100 Wh/kg. PowerCore is intended to handle power demands of low Earth orbiting communications satellites such as IRIDIUM. This paper describes the concept and development progress     

Advanced developments in NiH2 Dependent Pressure Vessel(DPV) cell and battery technology

The Dependent Pressure Vessel (DPV) Nickel-Hydrogen (NiH₂ ) design is being developed by Eagle-Picher Industries, Inc. (EPI) as an advanced battery for military and commercial, aerospace and terrestrial applications. The DPV cell design offers high specific energy and energy density as well as reduced cost, while retaining the established Individual Pressure Vessel (IPV) technology flight heritage and database. This advanced DPV design also offers a more efficient mechanical, electrical and thermal cell and battery configuration and a reduced parts count. The DPV battery design promotes compact, minimum volume packaging and weight efficiency, and delivers cost and weight savings with minimal design risks     

Lightweight (AlGaAs)GaAs/CuInSe2 tandem junction solarcells for space applications

Mechanically stacked tandem cells consisting of GaAs thin-film upper cells and CuInSe₂ thin-film lower cells have been developed to meet the increasing power needs projected for future spacecraft. The authors report the fabrication of the first highly efficient lightweight GaAs/CuInSe₂ tandem cell on a 2-mil thick substrate, update recent performance improvements in thin-film GaAs/CuInSe₂ tandem cells, and discuss their application to space power systems. The efficiency of 4-cm² cells has improved to 21.6% AM0, the highest ever reported for a thin-film photovoltaic cell. Lightweight 4-cm² tandem cells have been successfully fabricated with efficiencies as high as 20.8%. These cells weighed about 180 mg without optimized substrate trimming. Radiation and operating temperature effects on GaAs/CuInSe₂ tandem cells are also discussed, and an interconnect scheme to form a voltage-matched string is described     

Hybrid electric vehicles: year 2000 status

In the year 2000, the automotive manufacturers turned their attention to Hybrid Electric Vehicles (HEV). This re-direction of Electric Vehicle (EV) development effort was highlighted at the North American International Auto Show (NAIAS 2000), where, the World's major automobile manufacturers displayed twenty three HEVs. Thirteen HEV were configured with an internal combustion piston engine and electric traction motor, while, ten additional HEV were configured as fuel cell and battery pack hybrid vehicles (FCHV). Furthermore, the FCHV were fueled with hydrogen (H₂) from H₂ absorption metal hydride fuel tanks, or, from liquified hydrogen cryogenic fuel tanks. One conclusion for HEV was that the preferred configuration includes a compression ignition engine paired with an electric motor, and, four speed manual transmission with automatic shift. A second conclusion for FCHV was that the fuel of choice is H₂, and furthermore, these H₂ fueled FCHV were the precursor vehicles foreshadowing deployment of a hydrogen fuel infrastructure within the first quarter of the 21^st Century     

样本量为2的极小样本相容性检验方法

在航空航天领域由于成本、时间周期等原因进行疲劳寿命及可靠性评估时样本量通常极少（m=1或2）,利用相容性检验方法可对样本量进行扩充。常规的Wilcoxon秩和检验和K-S（Kolmogorov-Smirnov）检验适用于小样本情形,而极小样本相容性检验方面研究较少,且缺乏对方法合理性的详细说明和对不同方法检验功效优劣的比较。航空航天产品疲劳寿命多服从正态分布,因此本文主要以正态分布作为研究对象。利用Monte Carlo仿真发现从某一正态分布N（μ,σ²）中随机抽取两个样本x₁、x₂计算均值μ₁和标准差σ₁后构建新正态分布N（μ₁,σ₁²）,其±σ₁、±2σ₁和±3σ₁范围内的点落在原正态分布N（μ,σ²）±3σ范围内的概率依次为99.80%、98.13%和97.37%。在此基础上针对现场试验数据样本量为2的情况,本文提出利用3σ原则对先验信息数据进行相容性检验从而扩充样本量的方法。将该方法与两种文献方法对比后发现其误差率明显更低并呈现出检验性能随先验数据增加而不断提高的优势。     

Prismatic lithium-ion batteries

Lithium-ion (Li-ion) batteries have demonstrated the ability to fulfill the energy storage needs of many new technologies. The most significant drawbacks of currently available technologies, such as LiCoO ₂ based Li-ion cells, is their high cost and significant environmental hazards. Li-ion cells which use a lithium manganese oxide (LiMn₂O₄) spinel based cathode material should be much less costly and safer than LiCoO₂ based cells. Performance data from prismatic design cells which use a LiMn₂O₄ based cathode material is presented and shown to meet many military performance criteria. The most significant drawback of this technology is the short cycle life     

GPS C/N/sub 0/ estimation in the presence of interference and limited quantization levels

The carrier-to-noise density ratio (C/N₀) is considered an important parameter describing the GPS receiver performance. This paper compares the performance of two popular coarse-acquisition (C/A) C/N₀ algorithms appearing in literature: the variance summing method (VSM) (Psiaki et al., 2003, Psiaki, 2001), and the power ratio method (PRM) (Van Dierendonck, 1996, Sayre, 2003), in terms of their estimates in 1) additive white Gaussian noise (AWGN), 2) narrowband continuous wave interference (CWI), 3) their response to quantization and saturation effects, and their 4) dynamic range. The algorithms were implemented as a part of a software receiver. Two LI GPS data sets are examined; one was obtained from a GPS raw data collection setup, while the other was obtained from a GPS signal simulator. The collected set was stored with almost constant C/N₀ level while the simulated one contained variable C/N₀ levels. The effect of adding AWGN on the C/N₀ estimate was directly proportional with the noise power. The C/N₀ estimates suffered more when the CWI frequency was closer to the IF of the receiver. The PRM suffered from saturation at higher C/N₀ levels. The VSM showed good tracking at high C/N₀ levels and better immunity to limited quantization levels, while its C/N₀ estimate suffered from rapid fluctuations in power levels when sudden power steps occurred     

Thin-film Li-LiMn2O4 batteries

Thin-film rechargeable Li-LiMn₂O₄ batteries have been fabricated and characterized. Following deposition by electron beam evaporation of LiMn₂O₄, the amorphous as-deposited cathode films 1 cm² in area by 0.3to 4-μm thick were annealed at 700°C to 800°C in oxygen in order to form the crystalline spinet phase. The specific capacity of the cells between 4.5 V to 3.8 V ranged from 50 μAh/mg to 120 μAh/mg. When cycled over this range, the batteries exhibited excellent secondary performance with capacity losses as low as 0.001% per cycle. On charging to 5.3 V, a plateau with a median voltage of 5.1 V was observed. The total charge extracted between 3.8 V to 5.3 V corresponded to about 1 Li/Mn₂ O₄     

ZrO2陶瓷切向超声辅助磨削表面及亚表面损伤机制

为进一步揭示切向超声辅助磨削过程中硬脆材料的表面及亚表面损伤机理,基于应变率模型对其磨削过程中材料的动态力学性能进行分析,并在此基础上建立了硬脆材料的脆-塑转变临界切削深度模型与微裂纹损伤深度模型。研究发现,脆-塑转变临界切削深度和微裂纹损伤深度均与应变率有关,其中临界切削深度随着应变率的增加而增加,而横向裂纹损伤深度与中位裂纹损伤深度均随应变率的增加而减小。通过ZrO₂陶瓷切向超声辅助磨削试验进行验证。试验结果表明：由于切向超声振动的引入提高了材料应变率,进而提高了材料的动态断裂应力以及动态断裂韧性,从而扩大了ZrO₂陶瓷的塑性域去除范围,降低了加工表面的横向裂纹与中位裂纹损伤深度,使得ZrO₂陶瓷的表面及亚表面质量得到明显改善。试验结果与理论分析相一致,为进一步揭示切向超声辅助磨削过程中硬脆材料的表面及亚表面微观损伤机理提供了理论参考。     

航天飞行器轻质纳米材料高温隔热性能

纳米隔热材料是一种新型航天飞行器热防护材料。本文使用自行研制的高速飞行器热试验系统,对Al₂O₃纳米材料的高温隔热性能进行试验研究及数值计算,为高速航天器热防护系统的安全可靠性设计提供重要依据。研究结果表明,厚度仅为10 mm的Al₂O₃纳米材料板,当前表面温度为1 200℃时（1 800 s）,前后表面的温度差高达880.9℃,后表面温度降低了73.4%,且隔热性能稳定。另外与某空天飞行器轻质陶瓷材料进行了隔热性能的对比试验,结果显示轻质陶瓷材料板的背壁温度要比Al₂O₃纳米材料板高56%。说明Al₂O₃纳米材料的高温隔热性能非常优异,在航天器和高超声速飞行器热防护中具有重要的应用价值。由扫描电镜（SEM）图像知,当温度超过1 200℃后,Al₂O₃纳米材料颗粒快速聚集生长,颗粒间的空洞尺寸显著增大,材料内部纤维出现熔融现象,裂纹数量增多、深度及宽度显著增大,影响材料表观导热率。另外,当温度高于1 200℃时,纳米材料板边界出现了较大的收缩变形和弯曲变形。基于试验结果可知,Al₂O₃纳米隔热材料应该在小于1 200℃的热环境中使用。     

钛基稀土激光熔覆层组织细化机制及性能

采用通快TruDisk 4002光纤激光器在TC4合金表面分别制备了0wt% Y₂O₃和3wt% Y₂O₃的TC4+Ni45+Co-WC钛基耐磨复合涂层。利用XRD、SEM、EDS、EPMA、显微硬度计和摩擦磨损试验机等分析了涂层组织、显微硬度和摩擦学性能。结果表明，两种涂层表面均无裂纹孔隙等缺陷，且生成相一致，主要包括TiC、TiB₂、Ti₂Ni、WC和α-Ti；0wt% Y₂O₃涂层组织存在明显偏析，析出相尺寸粗大且方向性明显；3wt% Y₂O₃涂层组织呈均匀弥散状态分布，细化特征明显；经Bramfitt二维点阵错配度计算，（100）_Y2O3和（100）_Ti2Ni、（111）_Y2O3和（110）_TiC、（110）_Y2O3和（1010）_TiB2间的错配度分别为5.75%、6.72%和10.10%，Y₂O₃作为异质形核核心对Ti₂Ni、TiC和TiB₂的细化能力依次为Ti₂Ni > TiC > TiB₂；0wt% Y₂O₃和3wt% Y₂O₃涂层显微硬度分别为600~630 HV_0.5和470~480 HV_0.5，较基材分别提高了约62%和26%；3wt% Y₂O₃涂层耐磨减摩性最优，其磨损体积和摩擦系数较0wt% Y₂O₃涂层分别下降了约47.8%和5.0%，磨损机制主要为磨粒磨损。     

TMO复合催化剂对AP推进剂燃速催化作用研究

系统地考察了4种TMO催化剂(CuO、Fe₂O₃、Co₂O₃和Cr₂O₃)及其等质量比(1∶1)的6种TMO复合催化剂对AP/HTPB和AP/Al/HTPB两类复合固体推进剂燃烧性能的影响。实验结果表明, TMO复合催化剂对推进剂燃速的影响可分为正协同效应、无协同效应和负协同效应3类;具有正协同效应的TMO复合催化剂提高燃速效果最佳, TMO复合催化剂对AP复合推进剂燃速的影响取决于推进剂的种类, 协同效应的类属和单一TMO催化剂的催化活性。      

DSM11镍基高温合金表面三种涂层高温性能

DSM11镍基高温合金表面制备Al-Si、Al和Co-Al三种涂层,研究三种涂层在900℃下的涂盐（质量分数为5% NaCl+95% Na₂SO₄）热腐蚀性能和800℃下的疲劳性能。实验结果表明:在900℃热腐蚀200h后,Al-Si涂层和Co-Al涂层表面腐蚀区均形成了以Al₂O₃为主的连续且致密的氧化层,抑制热腐蚀反应的进行,具有一定的抗热腐蚀性能;Al涂层表面腐蚀区形成了混合型氧化层,热腐蚀反应会持续进行,抗热腐蚀性能较差。在800℃的疲劳实验后,Al-Si涂层表面生成大量的微裂纹,涂层容易发生开裂,进而引起合金试样快速断裂;Co-Al涂层和Al涂层的合金试样表现较好的抗高温疲劳性能。在高温合金的防护涂层使用中,要充分考虑到涂层的服役环境,对相关性能进行综合评价,选出最适合的防护涂层。      

Advances and trends in primary and small secondary batteries

Improvements in performance and reliability continue to be made in the traditional primary and secondary systems such as C-Zn, alkaline MnO ₂, Zn-air, Li-I, and sealed Ni-Cd and lead acid. In addition, two new secondary systems, Ni-metal hydride and lithium ion, have recently been introduced. They are growing rapidly in response to environmental concerns and the need for more energy density by devices. Two new rechargeable systems, Zn-air and lithium polymer electrolyte are nearing commercial production. One manufacturer has just introduced a rechargeable version of the alkaline MnO₂ system for consumer use. Lithium primary systems, such as Li-MnO₂, Li-FeS₂ and CF_x are gaining substantial market share, amounting to about $500 million in 1992. Li-silver vanadium primary cells have been developed to supply the higher currents needed by implantable medical devices such as defibrillators     

高超声速飞行器脆性透波材料大热流冲击下断裂性能试验

高超声速飞行器在俯冲段、高机动变轨或瞬间外露定位探测设备时,快速变化的高热流密度气动热会对天线窗、天线罩等部件产生强烈的热冲击。判断脆性材料透波部件在大热流密度冲击下是否出现断裂破坏及确定断裂时间点,对于高超声速飞行器能否最终锁定并击中目标具有极为重要的意义。本文建立石英灯红外辐射式大热流冲击试验系统,最大冲击热流密度可达1.5 MW/m²,并对SiO₂和Al₂O₃2种脆性材料进行了高速热冲击试验。热流冲击模拟准确,控制结果与预设热流的相对误差小于1.0%。同时,采用数字图像相关方法实时采集热冲击过程中脆性材料表面散斑图像的动态变化,成功捕捉并获得了断裂时间点这一重要关键参数。通过对散斑图像的分析计算,得到了脆性试验件断裂前的表面应变的变化。试验结果为高超声速飞行器透波天线窗等信号探测定位部件在高速大热流热冲击下的安全可靠性设计提供了重要依据。     

Gd2SiO5纳米粉体的并流化学共沉淀法合成

以Gd₂O₃和正硅酸乙酯(TEOS)为原材料,采用并流化学共沉淀法合成Gd₂SiO₅粉体材料。研究Gd₂SiO₅前驱体的热响应特征、Gd₂SiO₅粉体的物相组成和微观形貌,并对Gd₂SiO₅粉体的合成机理进行初步探讨。结果表明:前驱体的低Gd/Si摩尔比和反应体系的高pH值会导致Gd₂SiO₅粉体生成Gd_9.33(SiO₄)₆O₂杂质相,相反则会导致生成Gd2O3杂质相。当Gd/Si摩尔比为20∶11、pH值为9~10、合成温度为1000~1300℃时,合成的粉体纯度较高,Gd₂SiO₅颗粒呈不规则形貌特征,平均粒度为100~200 nm。Gd₂SiO₅合成过程中,前驱体以一种—[Si—O—Gd]—网络结构存在,在煅烧过程中逐渐转化为Gd₂SiO₅晶体以及Gd_9.33(SiO₄)₆O₂和Gd₂O₃杂相。     

固体火箭发动机Al_2O_3凝结及颗粒破碎的数值模拟

Al2O3凝结对固体火箭发动机Al颗粒的燃烧效率及燃气流动有很大影响。结合拉格朗日方法,建立Al2O3凝结模型,分析了在Al2O3烟雾凝结及颗粒自身破碎作用下,不同初始直径Al颗粒的燃烧效率及燃烧室流场的变化规律。计算结果与同条件下的测试数据有较好的吻合,颗粒分布符合相关实验现象。结果表明,小颗粒燃烧后,流场温度及Al2O3烟雾分布均匀;随颗粒初始直径的增加,径向出现明显分层现象;在发动机出口,小颗粒燃烧效率较高,颗粒中Al2O3质量分数较大,但破碎程度较小;随初始直径增加,颗粒燃烧效率逐渐降低,颗粒中仍含有大量未燃烧的Al,破碎程度提高,颗粒数目急剧增加。