In this study, polymer-stabilised cholesterol-based liquid crystal (PSLC) broadband reflective films were prepared by doping UV absorbers and chiral compounds in bilayer poly (methyl methacrylate) (PMMA) nanofiber films. Broadband reflection was achieved by diffusion of the UV absorber and chiral compounds in the bilayer nanofibers into the liquid crystal layer, which resulted in the formation of an inhomogeneous pitch distribution in the liquid crystal layer. To attain an optimal reflective effect, various factors such as polymer monomer concentration, concentration of chiral compounds in the spun film, diffusion temperature, diffusion time, and intensity of polymerised light were investigated. The effects of these factors on the reflective bandwidth were explored. The method significantly broadened the reflective bandwidth of the cholesteric phase liquid crystal layer, establishing the foundation for studying the combination of nanofiber films with cholesteric phase liquid crystals to form an adjustable pitch.

Polymer Dispersed Liquid Crystal (PDLC) films are attracting increasing attention as versatile and innovative material for use in electrical switching and flexible devices. This paper investigates the effect of a Poly(methyl methacrylate (PMMA) nanospun membrane system doped with SiO2 nanoparticles on the electro-optical properties and transmittance/voltage slopes of thiol- and acrylate-based PDLC films. Experimental samples were prepared for testing by adding mixtures of liquid crystals and crosslinkers in different proportions to liquid crystal cassettes doped with PMMA/SiO2 nanospun membranes. The size of the polymer mesh was found to influence all parameters of PDLC. The phase separation process, which determines the morphology and electro-optical properties of PDLC films, is directly affected by the doping of different components of PMMA/SiO2. The doping of the PMMA/SiO2 system resulted in improved optoelectronic properties of PDLC films, significantly enhanced weathering resistance, and increased the degree of intelligent regulation of the transmittance of PDLC films. Thus, by developing PDLC-doped reticulated nanofibre films with faster response times and better electro-optical properties, the potential for technological applications of PDLC-based devices in optical windows, displays, energy storage and flexible devices can be significantly enhanced. [GRAPHICS] .

The advancement of multi-functional displays with outstanding electro-optical properties is particularly essential at present. However, conventional integral all-area driven transparent displays are gradually failing to meet current demands. Herein, sub-regional electrostatic spinning of nanofibers as a novel fabrication method was introduced into polymer-dispersed liquid crystal (PDLC) to achieve stepwise display in concert with loaded WO3 nanoparticles, addressing the aforementioned drawback. The use of nanofibers played a crucial role in ensuring fine dispersion of nanoparticles, resulting in a reduction of the saturation voltage of the PDLC film from 28.9 V to 19.7 V and an increase in contrast ratio from 105.7 to 194.3. Meanwhile, experimental findings and theoretical considerations have revealed that variations in microscopic pore size can significantly influence the electro-optical behaviour of PDLC film. Next, the stepwise PDLC film was prepared by electrostatically spinning nanofibers onto half of the LC cell region, leading to different voltage-transmittance responses between the two regions. Consequently, under appropriate driving voltages, the PDLC film can realise three different optical states: total scatter, half-transparency, and total transparency. In addition, the PDLC film exhibited excellent anti-thermal ageing performance, allowing it to excel in various advanced display applications.

In this study, the polymer-stabilised cholesterol-based liquid crystal (PSCLC) films with broad-wave reflection were prepared via PVA nanofibers as carriers loaded with Fe3O4 nanoparticles. Fe3O4 nanoparticles have absorption properties in the UV region. When UV light is irradiated along the thickness of the liquid crystal cell, the resulting gradient distribution of UV light intensity induces a gradient distribution of spacing and thus a broad-wave reflection. Specifically, the effects of nanoparticles content loaded in nanofibers, magnetic field strength, polymerisation time and temperature, UV light intensity and polymerised monomer content were studied. The result shows that the proper contents of Fe3O4 nanoparticles and the polymerisation conditions have favourable impacts on the broad-wave reflection of PSCLC films. To clarify the mechanism of formed broad-wave reflection, the morphology of nanofibers was observed by scanning electron microscopy (SEM). The modification of nanoparticles was collected by transmission electron microscopy (TEM) and infrared spectroscopy. The texture of PSCLC films was observed by POM. The broad-wave reflection were measured by UV-Vis spectrophotometer. This strategy broadens the broad-wave reflection of PSCLC films from 300 nm to 476 nm increasing its application potential in UV shielding devices, and infrared thermal control devices.

Carbon fibers were multiphase polycrystalline materials. To study the influence of microcrystalline structure characteristics on thermal conductivity, the characteristics of the microstructure of carbon fiber, the relationship between thermal conductivity and microstructure was studied by XDR. The results highlight that the thermal conductivities increases with the increase of lateral size（La）, stacking thickness（Lc）, average stacking layers（N） of graphitic microcrystals and decreases with the increase of porosity（Vp）. Based on the peak fitting information of Raman spectra, the graphitization degree of carbon fibers was analyzed. The results reveal that the higher the graphitization degree of carbon fiber, the higher the thermal conductivity.

To investigate the influence of space irradiation on the properties of J312L structural adhesive, micromorphology, molecular structure, heat resistance, vacuum pollution and mechanical properties of J312L were analyzed by SEM, FT-IR, XPS, TGA, DSC, vacuum outgassing and mechanical test. The irradiation aging mechanism of material was investigated. The results show that the total dose irradiation has a significant effect on the thermal stability, vacuum outgassing and mechanical properties of J312L adhesive. After 1. 5×10~9 rad（Si） γ-ray irradiation from 60Co, the tensile shear strength is 4. 8 MPa, and the total vacuum mass loss（TML） is 2. 36%. Compared to that of the initial, the glass transition temperature and the thermal decomposition temperature（Td 5%） are reduced by 31 ℃ and 84 ℃, respectively, indicating that the J312L adhesive is dominated by the degradation reactions within high-dose radiation.

The substrate was the installation basis of solar cell for spacial solar array. "Upper and lower grid panel of carbon fiber composite + aluminum honeycomb core + polyimide film" was a typical structure of the substrate. As the key raw material of the solar array, high-modulus carbon fiber must be autonomous and controllable. To this end, the research of domestic high-modulus carbon fiber CCM40J-6K/epoxy composite applied to solar array′s substrate had been carried out. And three key links, including macro mechanics, pull-off resistance of micro mesh, and adhesion performance of polyimide film of CCM40J-6K/epoxy composites in substrate applications, had been proposed. Five aspects of testing and verification items, including mechanical properties, bonding force of mesh panel node, bondingperformance of polyimide film, and thermal-cycle performance of substrate structures, had been carried out. The verification results show that the mechanical properties of solar array′s substrate using the domestic carbon fiber-CCM40J-6K are equivalent to those of the imported M40JB-6K, and the original related molding process of substrate by M40JB-6K can be followed. Test pieces of single-layer and multi-layer laminate substrate can withstand thermal shock and thermal cycling tests, whose mechanical properties have no obvious change before and after the test, and the polyimide film has no debonding phenomenon. The tensile strength of the grid node of the domestic carbon fiber is 18. 9% higher than that of the imported carbon fiber. It shows that the domestic carbon fiber CCM40J-6K can be applied to the development of the substrate structure for solar array.

文献计量学是针对某一时期某一领域研究成果(论文),利用数学统计方法呈现研究现状、评述技术热点、分析预测发展趋势的一门学科[1-2].文献计量方法始于1917年,最早应用于解剖学领域[2].近年来,随着计算机和网络技术的发展,文献计量方法已广泛应用于图书馆学、情报学、经济学、医学、药学、科学学、材料学等人文社科和科学技术领域3-7],通过国家(区域)、学科、机构、作者、主题词、关键词等挖掘和计量分析,获取研究脉络、发展趋势、研究布局、合作关系等信息,以此为基础可进一步实现前沿研究技术方向(包括领域、项目课题、目标、指标等)的遴选和规划[8],以及科技竞争力的评估和比较[9].此外,文献计量分析作为技术预见方法之一,已成功用于国家层面的战略决策和科技前瞻[10],以及行业层面的发展规划布局[11]和企业层面的技术预测[12].

The spacial thermal-cycle tolerance of the substrate based on domestic high-modulus carbon fiber（CCM40J-6K） was a key factor that determine whether it can be applied to solar cell panels on a large scale, and the matching between the panel and the solar cell and the on-orbit service life for solar cell panel in the alternating thermal environment must be solved. The solar cell panel based on domestic high-modulus carbon fiber/epoxy composite of CCM40J-6K was taken as the research object, and the test research of thermal-cycle environmental adaptability was carried out. In this paper, tests had been carried out from three aspects: the comparison of domestic and imported carbon fiber substrates for adapting to the capacity of high and low temperature alternating, the ability of domestic carbon fiber substrates to adapt to thermal environment after laying solar circuits, and the on-orbit service life of solar cell panels. The test results show that the comprehensive performance of the solar cell panel based on domestic carbon fiber CCM40J-6K is comparable to that of the imported M40JB-6K. The CCM40J-6K substrate has a good matching with the triple-junction GaAs solar cell. The change rates of open-circuit voltage and short-circuit current of solar cell panels based on domestic carbon fiber after fatigue thermal cycling are 0. 55% and 0. 24%, respectively. The appearance of the solar cell and cover glass is intact, the solar cell circuit is insulated from the polyimide surface of the substrate, and the surface of carbon fiber has no debonding phenomenon. It shows that the domestic carbon fiber CCM40J-6K can be used in the development of solar cell panels for solar array.

一体化试验鉴定的概念最早由美军提出,最初源于美军武器系统装备采办发展需求,目的是减少冗余、便于管理.一体化试验鉴定要求装备采办全流程链条上的所有相关机构共同参与合作,包括生产厂家、外协承包商以及官方组织机构,对研制鉴定各阶段的试验鉴定进行统一规划、统一实施、数据共享.

30％SiCp/Al复合材料具有较高的比强度和比刚度,应用于火星车驱动组件需满足空间环境温度下的高强韧性和高尺寸稳定性需求.文章对粉末冶金法制备的铝基碳化硅复合材料开展了空间环境地面模拟试验,分别从力学性能、组织结构和热物理性能等方面对材料的大温域空间环境适应性进行系统分析.结果表明,材料的力学性能和热物理性能随温度呈现规律性的变化,且具有各向异性:低温条件下抗拉强度提高,线膨胀系数降低;高温条件下冲击韧性提高,导热系数降低;经高低温循环后残余应力降低,抗拉强度提高,线膨胀系数各向异性降低.在此基础上,初步分析了铝基碳化硅复合材料受不同空间温度环境影响,力学性能和热物理性能发生变化的内在机理.

高强高模聚酰亚胺(PI)纤维是近年来出现的一种新型高性能有机纤维,具有优异的力学性能、耐高低温性能、低介电、高绝缘、高阻燃、耐辐照等综合性能,在航天、航空、安全防护、核工业等领域具有广阔的应用前景.本工作着重针对高强高模PI纤维在航天领域中的应用需求,特别是在空间环境中的应用特点,分析了其在极端温度、交变温度、粒子辐照、高真空以及长期负载等环境下的性能表现,初步考核了其空间环境适应性,以期为其相关应用提供设计依据.研究结果显示,高强高模PI纤维表现出优异的力学性能、耐高低温、耐粒子辐照、抗蠕变等综合性能,在350℃条件下其拉伸强度和拉伸模量仍分别可达到1.55 GPa和27.74 GPa,经1.0×108 rad(Si)剂量粒子辐照后,拉伸性能保持率高于98％.此外,本工作还结合PI纤维的综合性能表现对其在航天领域的应用前景进行了展望.

Micro solder joints are common in high-end microelectronics. Their load-bearing capacity and mechanical reliability have become the key factors affecting the performance of products. Herein, the mechanical properties of different regions in the welding interface of low-silver lead-free micro joints were explored by nanoindentation tests. The results showed that the hardness, modulus and yield strength of interfacial IMC regions were higher than those of solder body region. The interfacial IMC regions also displayed better creep resistance than the body region. The research results lent support for the reliability evaluation of Sn1.0Ag0.5Cu low-silver lead-free solders.

分析了火星探测器任务环境复杂、软件自主性高、验证任务重、材料选用控制难等特点,总结了天问一号火星探测器在狠抓风险识别与管控、聚焦软件系统设计源头,严格试验考核,以及严控材料选用及验证等方面采取的主要产品保证工作措施.上述措施有效保证了天问一号火星探测器的产品质量,可为后续火星探测器及其他行星际探测器研制过程的产品保证工作提供借鉴.

随着我国首次月球采样返回和火星探测器"天问一号"任务的圆满完成,我国深空探测进入了新的发展阶段.本文首先对我国深空探测的现状和发展趋势进行了分析,进而对深空探测面临的极端温度、强太阳电磁辐射、强粒子辐射、尘与尘暴、酸性大气等环境及对深空探测任务的影响进行了梳理,进而从材料及结构的轻量化、高效热控制、可靠的辐射防护与抗辐射能力、提供可持续的能源、具有较强的耐腐蚀性能、具有较好抗尘与尘暴损伤性能、在轨组装与制造等角度梳理了深空探测对航天材料与工艺的需求,最后从轻质结构机构材料、高效热控制材料、组合辐射防护及耐辐射材料、耐腐蚀材料、耐尘与尘暴材料、高可靠能源材料、3D/4D打印技术等方面给出了深空探测材料与工艺的发展方向.

Herein, a method for measuring the volume coefficient of expansion of micro/nano-scale crystalline materials is proposed in order to solve the problem that the parameter is difficult to obtain directly. The volume coefficient of expansion of materials is calculated by using the linear expansion coefficient of crystal axes of each phase, which is available through linear fitting of lattice constant with temperature based on the calculated lattice constants from the XRD diffraction patterns at different temperatures. The examples of single-phase tin solder and multi-phase PbSn solder balls have proved the feasibility and effectiveness of the proposed method.This method can be used to measure the volume coefficient of expansion of micro/nano-scale samples,including the micro-sized structures, film materials, lead wires, solders and other materials for electronic components. This method is simple and efficient in operation without any specimen requirements. Therefore,the study provides a new way to measure the thermal expansion coefficient of micro/nano-scale materials,which has tremendous applicable value.

建模与仿真是产品试验鉴定的重要手段,基于数学理论方法,利用计算机系统实现多模型建模、多模态预测,可将试验前伸到产品研制初期,从而使试验设计更具针对性.建模与仿真理论以及模型验证评估技术在装备研制与试验鉴定和航天领域的材料评价验证工作中得到了大规模应用.例如,认定、分析工作的环境适应性试验、应用验证工作的应用可靠性验证等,常常会涉及动力学研究;热老化、热分解、辐射交联、真空出气、污染等,需要通过数值模拟、建模仿真来实现对材料性能的预测.仿真模型的可信度尤为关键,可直接影响材料应用边界的准确性.特别是建模与仿真的可信性评估,关乎材料保证与应用验证试验结果的决策价值.因此,在建模仿真的基础上,必须针对仿真模型开展校核、验证与确认(VV&A)研究,以评估仿真可信度.综上,笔者旨在通过文献分析,厘清仿真模型VV&A研究领域的技术发展脉络和趋势,为进一步研究仿真模型VV&A技术奠定基础.

随着我国空间探测卫星、深空探测飞行器等国家战略装备的快速发展,宇航材料的服役环境越来越苛刻,常常面临极端低温的考验.然而低温下材料的力学/物理性能和常温相比有很大差异,极低温使役环境下材料力学/物理性能评价成为人们关注的重点问题.本文着重对基于力-热能量密度等效原理而发展的深空极低温服役环境下材料屈服强度、弹性模量、理想拉伸强度、硬度等力学性能的低成本快速评价方法研究进展进行了总结和回顾;同时,介绍了力-热能量密度等效原理在低温下半导体材料的带隙能、折射率、拉曼频移,金属材料磁晶各向异性常数等物理性能的低成本快速评价方面的推广应用情况.该评价方法为实现地面实时监测在轨航天器中关键材料的主要力学/物理性能提供了有效途径,为国家高端技术装备建设中关键材料的设计、可靠性评价和实时性能监测等提供重要的手段.

橡胶制品广泛应用于各个领域,常用作密封、隔离、屏蔽、传导、阻尼减震等用途.因其具有易老化的化学特性,橡胶的性能往往决定了整件产品的功能与寿命,是产品质量的薄弱环节.文章阐述了橡胶的作用特点与评价检验的意义,详细介绍了橡胶制品的评价检验项目内容.

月球是深空探测的热点,也是美、欧等国家航天技术的竞技场.随着我国"绕、落、回"探月工程的成功实施,建设月球基地和月球空间站已成为新任务的论证热点,这将对材料提出新的需求和发展方向.本文在概述月球环境对航天材料的影响的基础上,分析我国未来探月工程的任务难点,并从轻量化结构、高效热管理、先进热防护、低温润滑、防尘、缓冲吸能等不同角度提出了探月工程对航天材料的新需求,最后给出了后续如何发展探月工程新材料新技术的建议.