Effects of europium doping on the photocatalytic behavior of BiVO4

Eu/BiVO₄ composite photocatalysts have been hydrothermally synthesized and characterized by XRD, XPS, SEM, EDS and DRS techniques. The photocatalytic activities of these catalysts were evaluated by the decolorization of methyl orange in aqueous solution under visible light irradiation (λ > 420 nm). It proved that the enhanced activities of Eu/BiVO₄ composites are mainly ascribed to the dopants for the effective electron–hole separation effect, and the optimum content of the doped metal can be controlled by adjusting the ratio of the rare materials in precursor.     

离子推力器寿命试验总结与展望

在充分调研国内外成熟度较高的离子推力器产品地面寿命试验的基础上,总结了关键失效磨损试验、工程型号寿命试验、产品极限寿命试验和综合评价寿命试验等四类离子推力器寿命试验的目的、方法、结果及应用.通过不同寿命试验方法之间、试验验证寿命与工程应用寿命之间、不同失效模式及其试验验证方法之间的对比分析,总结了各类寿命试验的成功经验...     

电动客车用余热回收型热泵的换热器优化及性能实验研究

本文针对热泵空调系统在冬季低温工况下制热能力衰减问题,通过换热器设计优化,研发出基于喷射补气的余热回收型热泵空调系统,并进行了性能实验研究.结果表明:研制的准二级压缩电动客车热泵空调系统在低温条件下具有较好的制热性能.在环境温度为-20℃,车内温度为20℃,余热量为1.8 kW的制热工况下,相比于无余热回收工况,系统制...     

开式液氮冷凝泵的压力分析

简要介绍了应用于等离子隐身系统中低温冷凝泵的结构设计,并在结构设计的基础上,采用真空抽气过程中的流量连续方程和计算流体力学（CFD）方法,建立了冷凝泵进气过程的压力分析方案。分析结果表明,冷凝泵轴向压力降主要发生在节流孔附近,且节流孔存在一个最佳尺寸。分析结果为低温泵的结构优化和后续的热力学分析提供参考。     

小卫星领域应用电推进技术的评述

小功率电推进已成为最有技术竞争力的小卫星应用的推进系统选择。在总结美国、俄罗斯、欧洲、日本等国家离子、霍尔、电热、PPT、FEEP等小功率电推进技术发展和小卫星应用情况的基础上,从轨道转移、大气阻尼补偿、位置保持、姿态控制、编队飞行等任务方面分析了小卫星对电推进系统的需求和应用电推进的必要性及可行性,针对小卫星主要任务需求分别提出了10 W、100 W和500 W级小功率电推进技术发展和应用方面的具体建议。     

原子氧防护涂层技术研究

原子氧是低地球轨道主要的残余气体粒子,其化学性质非常活泼,是极强的氧化剂,会对空间材料的性能产生严重的影响。介绍了低地球轨道的原子氧环境及原子氧防护方法;对有机、无机和复合原子氧防护涂层的优缺点、研究进展情况以及空间应用情况进行了详尽的阐述;最后分析了原子氧防护的发展方向。     

Synthesis,ferroelectric and piezoelectric properties of some (Na0.5Bi0.5)TiO3 system compositions

Some (Na_0.5Bi_0.5)TiO₃ (NBT) system compositions, including NBT, (Na_0.5Bi_0.5)_0.94Ba_0.06TiO₃ (NBBT) and 0.4 wt.% CoO added NBBT (NBBTC), were prepared by a citrate method. The ferroelectric and piezoelectric properties of the resulting ceramics were investigated. The results confirm that the citrate method is a feasible and advantageous route to produce NBT system ceramics. NBBT ceramic made by the citrate method exhibits a high piezoelectric constant (d₃₃) of 180 pC/N. An essential relation between the piezoelectric properties and the ferroelectric nature of the ceramics was detected. It was found that lowering the coercive field (E_c) and enhancing the remanent polarization (P_r) of NBT system ceramics simultaneously lead to desired piezoelectric properties.