In recent years,the use of space flexible antennas has attracted more and more attention.However,the fabri-cation technology of large-area thin film antenna arrays still requires further research.Here we report exploration of key tech-nologies for the preparation of thin-film flexible antennas.Using magnetron sputtering technology,copper films with metal-lic surface and different thicknesses were deposited on flexible substrates by adjusting the sputtering energy and strip tension and speed.By optimizing the ablation energy of etching femtosecond laser,the patterned array arrangement was realized without damaging the flexible substrate.We found that the modified polyimide has higher splicing strength and better resis-tance to a temperature at range of-100～100℃compared with the commonly used 3M92 tape,so we believe that the former one has potential in splicing thin film arrays.In addition,the microstructure shows that femtosecond laser cutting can obtain a smoother section compared with nanosecond laser,and there are no burrs and ablations.Our results provide further under-standing for the fabrication of space flexible antennas.
The work aims to achieve the controlling preparation of high-performance CrSiN films at low deposition tem-perature,the HiPIMS technique was utilized to prepare CrSiN nano-composite films by regulating the synchronized pulsed-bias.The effects of the synchronized pulsed-bias on the microstructure,mechanics,tribology and corrosion resistance of films deposited at low temperature were studied.With the increase of the synchronized pulsed-bias,the content of light elements decreased slightly,which can be attributed to the energetic bombardment of the ions as well as the"re-sputtering effect"on the film growing surface.Meanwhile,the diffraction peak of c-CrN(111)disappeared and the preferred orientation of c-CrN(200)can be obtained.Due to the grain refinement and films density increase,the mechanical and corrosion resistance properties improved significantly.The film deposited at-500 V bias has maximum hardness of 16.5 GPa and minimum Icorr of 2.09×10-10 A/cm2.Under high speed and room temperature tribological situation,the abrasive and adhesive wear were the major wear mechanism for the CrSiN films.The study achieved the controlling preparation of the CrSiN films with excellent corrosion resistance properties at low temperature by utilizing the synchronized pulsed-bias,which provides the new study ideas as well as the solution ways for broadening applications of CrSiN films on the thermal sensitive matrix.
To obtain ZrCoRE(RE is rare earth elements La and Ce)getter films with good adsorption performance,DC magnetron sputtering was used to prepare ZrCoRE films with different structures in argon and krypton gas by changing the deposition pressure.The effects of sputtering gas on the microstructure of the films were analyzed by field emission scanning electron microscopy and X-ray diffraction.The hydrogen absorption properties of the films deposited in argon and krypton were tested by dynamic constant pressure method.The effect of sputtering gas and film structure on hydrogen absorption per-formance was analyzed.The results show that the films deposited in argon gas were relatively dense,while films deposited in krypton sputtering gas had more clusters and cracks in the microstructure.The films had an obvious columnar structure,and a lot of interfaces and gaps are distributed among the columnar structures,providing more paths for gas diffusion.Argon and krypton sputtering gas pressure increases,the film contains more cracks and gap structure,continuous columnar structure growth more obvious,and cracks deeper and wider.The structure had larger specific surface area,which is conducive to im-proving the hydrogen absorption performance of the films.
The specimens of MoS2-Ti film on substrate of 9Cr18 were prepared by the method of unbalanced magnetron sputtering,and then different kinds of irradiation experiments were conducted for five group specimens,which of them were no irradiation,electron,electron/proton,electron/proton/ultraviolet,electron/proton/ultraviolet/atomic oxygen.Through the characterizations of SEM,XRD,XPS profile analysis and friction tests,the influence of each irradiation on the film's mi-crostructure,chemical components and tribological performance in vacuum was studied comprehensively.The results re-vealed there were not great effects on the microstructure,surface morphology and tribological performance,caused by the ir-radiation of electron,proton,ultraviolet.The atomic oxygen with an energy of 5 eV showed strong damage effects on the film,leading to the'blanket-like'surface morphology,the oxidation of Mo,S,Ti,which resulted in the increase of friction coefficient at initial and middle stages,fluctuation at middle states,as well as the increase of specific wear rate.
The continuous development of high-energy laser technology has gradually become a practical threat to the safety of satellites in orbit.This article introduces the research progress on the damage mechanism of high-energy laser weapons on satellites,and clarifies the damage mechanisms of high-energy continuous laser and pulse laser.And based on the protection characteristics of optical systems such as satellite solar cell arrays,cameras,star sensors,as well as non-optical key structures such as thermal control multilayer and composite propellant storage tanks,the main principles,development status,and technical characteristics of various high-energy laser protection technologies such as linear optical protection films,non-linear optical protection films,phase change materials,mechanical shutters,high damage threshold films,and protective cov-ers were summarized and analyzed.
In order to provide theoretical support for the process optimization and preparation of SiC intermediate layer in high-temperature oxidation resistance composite coating system,the reaction characteristics and deposition process of SiC coating prepared by chemical vapor deposition technology were simulated using COMSOL software and Reax FF software,that based on the finite element principle and the molecular dynamics simulation principle,respectively.The results indicated that the chemical vapor deposition process of SiC coating include the diffusion process and the thermal decomposition reac-tion process of precursor trichloromethylsilane(CH3SiCl3).The SiC coating does not grow during the diffusion process,it only starts to grow from the thermal decomposition reaction process after 10-4 s,that is accompanied with the dissociation process of SiC coating.With the increase of incident particle energy,the number of Si and C particles deposited on the sub-strate surface per unit time continuously increases.Increasing the incident energy of particle is beneficial to improve the den-sity of SiC coating.The uniform growth of SiC coating can be achieved when the incident energy of particles is higher than 2 eV.However,the number of dissociated Si and C particles increases when the incident energy is higher than 6 eV,which is not conducive to the deposition of SiC coating.In summary,the comprehensive properties of SiC coating prepared by chemi-cal vapor deposition technology are the best when the incident energy is 3 eV.
The TiAlSiN hard coatings preparing by arc ion plating has high hardness,good compactness,and excellent adhesion,which has a wide application market in the tool industry.Among the many characteristics of TiAlSiN hard coatings,the residual stress of the coating will affect the hardness,adhesion,and cutting life.This article investigates the effect of the magnetic field intensity of TiSi targets on internal stress of the coating.When the magnetic field of the TiSi targets is changed from MAG3 to MAG6,the magnetic field intensity is weakened,so the ionization fraction of the target is reduced,and the in-ternal stress of the TiAlSiN coating is reduced from-5.84 GPa to-3.16 GPa.Otherwise,the adhesion and hardness of the coating do not decrease,and the cutting life is increased by 30%.The results indicate that adjusting magnetic intensity of TiSi target material can effectively adjust the internal stress of TiAlSiN coating and improve the cutting life.
Compared to conventional methods of preparing protective films,the plasma polymerization approach is a more efficient,dry,and simple preparation procedure that allows the preparation of dense thin films with a thickness of hun-dreds of nanometers on a variety of substrates.In this paper,anti-atomic oxygen polysiloxane thin film were prepared on large-area flexible Kapton substrate by plasma-enhanced chemical vapor deposition(PECVD).The effect of electrode spac-ing on the properties of anti-atomic oxygen polysiloxane thin film was investigated using SEM,AFM,FTIR and XPS.The re-sults show that the reduction of electrode spacing accelerates the degree of monomer dissociation and the oxidation process of carbon-based components.With the decrease of electrode spacing,the deposition rate of the film increases,and the film trans-forms from organic-inorganic polysiloxane film(SiOxCyHz)to inorganic film(SiO2).The increase of high dissociation ener-gy Si-O bonds in the as-deposited films reduces the erosion rate of atomic oxygen of the films.This paper also establishes a technical foundation for the adjustment of the properties of other organosilicon functional films prepared by PECVD.
With the increasing demand for materials,it has become a trend to deposit excellent films on the surface of materials to improve the performance of materials.Diamond-like carbon film has the advantages of high hardness,strong cor-rosion resistance,low friction coefficient,good wear resistance,and attracts more and more attention in the field of industrial manufacturing.This paper introduces the principle of electronic rotary resonance plasma source and surface wave plasma source and their application in the preparation of DLC film,analyzes the main factors affecting the performance of the DLC film during deposition,points out the existing problems,and summarizes that microwave plasma source can produce large area of high density plasma,without electrode contamination,which provides reference for promoting the preparation and application of high-performance DLC film.
Low surface energy fluorocarbon polymer coating is a key material to inhibit the creep and loss of space grease lubricants.The application of this material would provide technical supports for the long-life and highly reliable opera-tion of space grease lubricating moving mechanisms.In this paper,water contact angle tester,X-ray fluorescence energy spectrometer,optical microscope,etc.were used to study and analyze the properties of the developed low surface energy flu-orocarbon polymer materials before and after vacuum thermal cycling.And the creep resistance properties of low surface energy fluorocarbon polymer coatings to MACs lubricating oils were studied.The results showed that the surface energies of 9Cr18 stainless steel,2A12 aluminum alloy and TC4 titanium alloy coated with polymer coatings were 8.797 mN/m,9.083 mN/m and 9.203 mN/m,respectively.In the temperature range of-45～+90℃,after 60 vacuum thermal cycles in 30 days,the coatings still has low surface energies,which were 8.915 mN/m,9.209 mN/m and 9.266 mN/m,respectively.In addition,there presented an obvious interface between the low surface energy fluorocarbon polymer coating and MACs lubricanting oil.And no characteristic peaks of MACs lubricating oil were detected at the coating 200 μm away from the lubricating oil by XPS analysis,which exhibited that no lubricating oil creeped and diffused to the coating.The low surface energy fluorocar-bon polymer coating can play an"creep resistance"role to the MACs lubricating oil effectively.
The effect of annealing temperature on the optical and surface properties of Ta2O5 films has been investigated.The thin films were prepared on quartz substrate by electron beam evaporation technique and annealed at 200℃,400℃and 600℃respectively.The transmissibility of the films was measured by spectrograph,and the variation of refractive index and extinction coefficient were obtained by inversion calculation.The surface properties of the films were characterized by X-ray diffraction and atomic force microscopy.The results show that the maximum value of the transmittance curve of the films in-crease significantly with the increase of annealing temperature.With the increase of annealing temperature,the refractive in-dex and extinction coefficient of Ta2O5 film increase gradually,while the surface roughness of the film decreases,and the sur-face of films becomes dense.Both deposited and annealed films are amorphous.This study provides experimental data for further improving the performance of Ta2O5 thin films.
With the increasing maturity of thin film preparation methods and micro-machining technologies,thin film sensor technologies based on various thin film sensitive elements are experiencing significant development.The advantages of small size,high integration,and high sensitivity of thin film sensors make them show excellent prospects for aerospace ap-plications such as deep space exploration,spacecraft structural health monitoring,manned spaceflight,etc.In this paper,thin film temperature sensing and strain sensing technologies were discussed.According to different sensing applications in space-craft,the key technologies and research status of thin film sensing materials and devices in cryogenic/high temperature mea-surement,heat flux sensing,strain sensing at high temperature,and flexible large strain sensing,flexible intelligent skin are reviewed.Finally,the developing trends of thin film sensors are prospected.
In order to study the tribological behavior of MoS2-Ti thin films sliding against 9Cr18 steel,W-DLC and DLC thin films,MoS2-Ti,W-DLC and DLC films are deposited on 9Cr18 steel by magnetron sputtering and plasma enhanced chemical vapor deposition technology respetively.The morphology,composition and phase structure of the films are charac-terized by SEM,EDS and XRD.The hardness and tribological properties of MoS2-Ti films sliding against 9Cr18 steel,W-DLC and DLC are investigated by hardness tester and ball-on-disc tribometer respectively.The results show that the MoS2-Ti films sliding against DLC have the lowest friction coefficient and wear rate among these three mating materials.Compared to the MoS2-Ti films sliding against the 9Cr18 ball,MoS2-Ti films and W-DLC film does not reduce the friction coefficient and wear rate.The wear mechanism of MoS2-Ti films and W-DLC is adhesive wear and abrasive wear,while the wear mecha-nism of MoS2-Ti films and DLC is adhesive wear.
Antibiotics are critical weapons that were used for combating human pathogens. However, the heavy use of antibiotics leads to the increased and widely spread of antimicrobial resistance. The antimicrobial resistance is not only a medical problem, but also social and economic concerns, involving public health, environmental pollution, food safety, etc. This special issue reviewed and discussed the recent progress on antimicrobial resistance regarding the fields of clinical drug resistance and epidemiology, animal and environmental drug resistance, drug resistance mechanisms, antimicrobial drug development and drug resistance prevention and control, hoping to give a comprehensive view on basic antimicrobial resistance questions, future research directions and prevention and control strategies.
随着微小卫星任务的不断拓展,轨道机动、位置保持、姿态控制、自主离轨等任务对低功率推进系统的需求日益增加.结合微小卫星对低功率推进系统高比冲、推力精确、结构紧凑等技术需求,综述了射频离子电推进、微波离子电推进和脉冲等离子体电推进技术的研究和应用现状;通过列举各国应用案例,对比了各推进系统的性能和技术特点,总结了各推进系统的关键技术;在此基础上,分析了我国微小卫星用电推进技术发展趋势及后续攻关方向.研究结果可为微小卫星推进系统方案选择提供参考.
基于二维计算流体力学(CFD)数值模型对一款 6 W@80 K同轴斯特林型脉管制冷机进行了仿真研究.对不同运行频率和充气压力下的整机性能进行研究,发现随着运行频率的升高,制冷系数先增大后减小.随着充气压力的升高,制冷系数也随之升高.对脉管内部流动状态进行研究,发现脉管内气体呈现轴向往复振荡状态,当气体方向发生改变时,脉管两端会产生涡流,涡流大小在不同的充气压力下变化不大,随着运行频率的增大而减小.将二维仿真结果与一维仿真结果以及实验结果进行比较,发现建立的二维CFD数值模型在输入功率较大时,整机制冷量的计算结果较为准确.
微推进器在航天器姿态控制、轨道维持和阻力补偿中具有广泛应用,而应用的前提是对其推力的直接测量.微推进器产生的推力通常为mN级或更低,并且具有较低的推重比,需要使用推力架对其推力性能进行高精度测量和评估.推力架作为测量仪器,在进行推力测量前需要标定.标定过程主要是通过将精确可知的力或冲量作用在推力架上,记录响应情况,得到推力架响应与作用力或冲量之间的对应关系.随着航天技术的发展,一些高精度空间任务对推进器推力范围、分辨率和稳定性等参数的要求不断提高,同时对推力架测量能力以及相应标定技术的稳定性、精确性和可操控性提出了更高的要求.根据标定方法的不同进行分类,综述了近年来高精度推力架标定技术的研究进展.通过介绍和分析重力法、冲击力法、静电力法、电磁力法和气体分子作用力法等标定方法的原理、装置及应用情况,评述和总结了不同标定方法的适用条件和特点,并对高精度推力架标定技术的未来发展趋势进行了展望.
介绍了利用抽运-检测型铷原子磁力仪测量软磁材料剩磁矫顽力的实验装置和方法.在磁屏蔽筒中扫描通入磁化线圈的脉冲电流,置于磁化线圈中的软磁样品被磁化和退磁,利用抽运-检测型铷原子磁力仪监测软磁样品的剩磁状态,根据剩磁回线计算出样品的平均剩磁矫顽力.利用该方法测量带状坡莫合金软磁样品的剩磁矫顽力,十次测量的平均值为 1.706 mT,剩磁矫顽力测量再现性以相对标准偏差表示为 0.05%.该方法具有无零点漂移、复现性好、测量速度快、原位测量等优点,具有开发适用于环境磁学领域的磁测设备的潜力.
天基空间目标态势感知系统作为空间威胁目标运动状态监测和特性测量的重要手段,与地面感知手段相比,具有独特优势,成为当今世界航天领域的发展热点.面对空间杂光背景噪声干扰下远距离空间暗弱目标与隐身、伪装等复杂目标精确识别与测量的感知需求,依靠单一的空间态势感知手段远远不能满足未来空间对抗的发展需求.多传感器数据融合技术能弥补单个传感器感知能力的不足,使它们发挥各自的优势,形成对空间目标态势情形更加清晰、完整的多维感知描述,在扩展目标感知信息的时空覆盖性、增强目标识别能力与降低误检率方面具有明显优势.在分析主要航天国家空间目标态势感知能力及态势感知信息融合技术发展现状基础上,研究梳理相关技术与装备发展情况、未来发展趋势,并给出空间目标态势感知数据融合应用实例,最后提出我国太空态势感知系统发展的启示和建议,为我国发展天基空间目标态势感知和多源数据融合技术,加快构建天基空间态势感知一体化技术体系提供参考.
针对低温压力容器在运行过程中可能受到震动等影响导致的真空夹层泄漏、真空夹层压力上升以及内胆压力快速升高等问题,设计了一种结合群智能算法与神经网络的低温压力容器真空失效程度时序预测算法.通过对低温压力容器真空失效的过程进行简化仿真模拟,获取低温压力容器真空失效过程中的各参数变化情况,形成失效数据集.使用该数据集进行长短期记忆网络(LSTM)模型训练以预测低温压力容器真空失效程度,结合粒子群算法(PSO)对LSTM模型的超参数进行寻优.最后使用训练完成的PSO-LSTM模型对低温压力容器真空失效程度进行时序预测,并对该时序预测模型的预测效果进行了分析.
