射流式真空紫外辐照模拟设备及其应用

介绍了空间环境条件下真空紫外辐照 (VUV)的损伤效应 ,以及真空紫外辐照模拟的几种主要形式。着重讲述了射流式真空紫外辐照模拟设备的基本结构、工作原理、技术参数及特点 ,并利用该设备初步研究了几种空间材料的真空紫外辐照损伤效应。结果表明 ,VUV使EP和CF/EP产生了明显的质损 ,导致力学性能下降 ,纤维和基体表面受到明显破坏。VUV与温度交变对聚酰亚胺吸光涂层的力学性能有明显影响。     

真空紫外辐照对MQ增强硅橡胶热性能及光学性能的影响

 采用空间综合辐照模拟设备研究了真空紫外辐照对MQ增强加成型硅橡胶的表面形貌、质量损失、热性能及光学性能的影响。试验结果表明：真空紫外辐照后,硅橡胶表面出现损伤裂纹,随辐照剂量的增加,裂纹的数量增多;真空紫外辐照后,硅橡胶的质量有所损失,其质损率随辐照剂量的增加而增加;真空紫外辐照后硅橡胶的耐热性随辐照剂量的增加先增加而后下降;真空紫外辐照对硅橡胶材料的体膨胀/收缩变形影响不大,但对材料的光学性能有较大影响,随着辐照剂量的增加,材料的光学透过率下降。     

BN&Al2O3/环氧树脂复合材料粘接层对LED灯结温的影响

自制BN/EP(环氧树脂)复合材料和Al₂O₃/EP复合材料作为LED灯PCB板和散热铝块之间的粘接层材料,采用精密钻孔的方法用高精度测温仪测量LED灯正常工作时的温度分布,讨论粘接层对结温的影响,并与COMSOL Multiphysics软件模拟结果进行对比分析。实验测量LED结温与模拟结温变化趋势基本一致,结温会随着粘接层厚度的增加而上升、随着粘接层复合材料热导率的增加先快速降低而后趋于平缓。最终得到PCB板和散热铝块间最佳粘接层厚度和粘接层复合材料配比,当BN的质量分数为60%时,BN/EP复合材料粘接层的热导率最高,此时LED结温为75.2 ℃,比纯环氧树脂粘接层LED的结温降低了27.6 ℃。而Al₂O₃/EP复合材料粘接层LED的最低结温为78.2 ℃,此时Al₂O₃的质量分数为50%。     

惯性约束聚变实验用玻璃微球堵口特种胶研究

 通过对不同固化和热处理过程后的胶粘剂的剪切强度、表面形貌特征、热性能的研究，分析了增韧剂和偶联剂对环氧有机硅胶粘剂性能的影响。研究表明：随着增韧剂含量的增加，胶粘剂热分解温度下降；增韧剂质量分数为25%时，有机硅与环氧树脂相容性较好，制备的胶粘剂综合性能较好；硅烷偶联剂能改善胶层与金属界面的胶接强度，提高环氧有机硅胶粘剂的拉伸剪切强度。显微组织观察分析表明，环氧有机硅胶粘剂中环氧树脂分子链与有机硅高分子链处于一定微相分离状态。     

空间辐照环境对光学材料作用效应的模拟研究

介绍了对材料有重要影响的空间辐照环境 ,并利用地面模拟设备对某些遥感光学材料在空间辐照环境下的行为进行研究。结果表明 ,以质子、电子和太阳紫外线为代表的空间辐照环境在光学材料中产生表面剥蚀、着色、诱发表面污染和充放电等效应 ,从而使光学材料的性能在不同程度上退化     

空间材料抗原子氧有机涂层防护作用的光谱分析

用Fourier变换红外光谱(FTIR)、光电子能谱(XPS)和扫描电镜(SEM)对在模拟原子氧(AO)环境中,空间材料及在其表面涂覆的有机防护涂层的表面所发生的侵蚀与防护作用进行了研究。结果表明：采用环氧树脂、聚胺脂、醇酸树脂作为防护涂层,经AO辐照后,它们的表面形貌均发生了较大变化,腐蚀严重;而用有机硅涂层的表面形貌变化却甚小,具有较明显的防护效果。光谱分析表明,这种防护作用缘于有机硅涂层表面经AO辐照后生成了致密的氧化硅膜层,对抑制AO的进一步侵蚀起到了抑制作用。     

keV质子辐照Kapton/Al的能量传输过程

采用TRIM和SRIM2003软件模拟计算了10—300keV能量区间质子辐照Kapton/Al的能量传输过程. 依据模拟结果选取了辐照能量参数, 在室温真空条件下, 采用空间综合辐照设备对Kapton/Al进行了质子辐照. 借助于表面红外光谱技术, 对Kapton的重要官能团特征峰做了定量分析, 通过特征峰处吸光度的变化得到了典型分子键的损伤截面. 平均损伤截面和电子能损的强烈依赖关系及TRIM计算结果一致说明keV质子辐照Kapton/Al的辐照损伤主要来自电子能损效应. 太阳吸收比的变化趋势和模拟结果都表明在入射能量80keV附近, 质子辐照Kapton/Al的辐照效应最大.     

原子氧与紫外综合辐照下Kapton/Al结构变化

在激光源原子氧地面模拟设备中对Kapton/Al薄膜二次表面镜进行了原子氧与紫外综合辐照实验,研究了Kapton/Al薄膜质量及太阳吸收比的变化,重点关注了实验前后Kapton/Al薄膜表面结构及成份的改变。结果表明:Kapton/Al薄膜二次表面镜的质量随辐照时间的增加逐渐减小,太阳吸收比的变化趋势与之相反,随辐照时间的增加逐渐增大;综合辐照后Kapton/Al薄膜表面主要官能团数量呈下降趋势;综合辐照过程中材料表面C-C键、C-N键的破坏及在原子氧和紫外环境中重新结合成新的化学结构是造成Kapton/Al薄膜性能退化的主要微观机制,气体小分子的挥发是造成Kapton/Al薄膜质量损失的主要原因。     

激光辐照下预加载CFRC层合板断裂行为实验研究

针对激光与机械载荷联合作用下碳纤维/环氧树脂增强复合材料（CFRC）层合板失效时间的预测需求,实验研究了不同激光功率密度（70～210 W/cm2）、不同预应力水平（拉伸强度的50%和70%）、不同光斑尺寸（拉伸试件宽度的70%和100%）下2 mm厚层合板的失效机理,获取了不同影响因素对断裂时间的影响规律。结果表明:预加载层合板失效机制为迎光面环氧树脂基底材料热解、纤维氧化断裂,背光面剩余结构偏脆性断裂;在预应力一定条件下,试件断裂时间与辐照激光功率密度成指数规律;预应力水平对断裂时间影响显著。     

电磁辐照金属铝膜材料释气效应研究

为研究空间环境中通用航天器表面覆盖的热控层电磁辐照效应,采用粒子模拟(PIC)和蒙特卡罗(MC)模拟相结合方法,建立了真空环境下电磁辐照航天器热控材料模型,模拟了场致电子发射、次级电子倍增、释气雪崩电离的全过程,并讨论了释气密度对热防护材料表面产生释气电离现象的影响。通过对比不同释气密度下该过程产生的电子和离子情况,获得热防护材料表面释气产生雪崩电离的阈值。模拟结果表明,当铝膜表面气体密度较小时,由于材料表面释气碰撞电离概率偏低而不会发生雪崩电离;只有当释气密度超过阈值时,材料表面释气碰撞电离过程加强,材料表面发生雪崩电离生成等离子体,等离子体吸收电磁波能量,其离子和电子总能量提升,可能对金属铝膜材料造成损伤。     

Chemical alteration of poly(vinyl fluoride) Tedlar induced by exposure to vacuum ultraviolet radiation

In this study the chemical alteration of poly(vinyl fluoride) Tedlar^® by vacuum ultraviolet radiation (VUV) (115-400 nm) has been examined using X-ray photoelectron spectroscopy (XPS). The initial F/C atom ratio of 0.34 decreases to 0.17 after a 2-h exposure. The F/C atom ratio is further reduced to a steady-state value of approximately 0.04 after a 24-h exposure. Similarly, the O/C atom ratio is reduced from 0.08 to 0.05 and then to 0.02 during these two exposures. As the F and O are removed by VUV exposure, the C concentration increases from 70.5 to 82.0 and then to 94.6 at.% thus forming a graphitic or amorphous carbon-like layer which erodes more slowly than the virgin Tedlar surface. Exposure of the VUV-damaged surface to O₂ results in chemisorption of O, indicating that reactive sites are formed during the chemical erosion by VUV. Further exposure to VUV removes this chemisorbed oxygen but a subsequent exposure to air at atmospheric conditions causes a three-fold increase in O chemisorbed at the surface. Comparison of XPS data indicates that the mechanisms of chemical alteration by VUV radiation and hyperthermal (∼5 eV) atomic oxygen (AO) are similar.     

Effect of 120 keV proton irradiation on mass loss and chemical structure of AG-80 epoxy resin

The AG-80 resin is a new type of thermosetting matrix for advanced carbon/epoxy composites. Mass loss effect and the related outgassing are major concerns for its application in space. The changes in mass loss, outgassing and chemical structure under 120 keV proton exposure were investigated for the AG-80 epoxy resin. The variation in chemistry was characterised by X-ray photoelectron spectroscopy. Experimental results show that by increasing the proton fluence, the surface colour of specimens becomes darker. Mass loss ratios ascend remarkably until the fluence of approximately 6.3×10¹⁵ cm^?2 and then tend to level off. The surface roughness of specimens exhibits an increasing trend followed by a decreasing trend as a function of proton fluence. Under the exposure, the C?C, C?H, C?N and C?O bonds are broken, a variety of molecule ions with smaller molecular weight are formed and carbon is enriched in the surface layer of the specimens. The changes in mass loss and surface roughness of the AG-80 epoxy resin could be attributed to the formation of the molecule ions and the enrichment of carbon content in the surface layer due to proton radiation.     

氯苯的同步辐射光电离研究

利用真空紫外同步辐射和反射式飞行时间质谱仪对氯苯进行了光电离研究,通过测量各离子的光电离效率(PIE)曲线,得到了氯苯的电离势为(9.11±0.05)eV及两种主要碎片离子C6H+5和C4H+3的出现势分别为(12.96±0.05)和(16.27±0.05)eV.结合有关文献的热力学数据,推导出C6H5Cl+、C6H+5及C4H+3的离子生成焓及一些键的解离能.实验获得了118.0nm同步辐射光电离下氯苯的质谱图.     

Vacuum ultraviolet smoothing of nanometer-scale asperities of Poly(methyl methacrylate) surface

Smoothing of the nanometer-scale asperities of a poly(methyl methacrylate) (PMMA) film using vacuum ultraviolet (VUV) with the wavelength λ = 123.6 nm was studied. The exposure time and the residual air pressure in an working chamber were varied during the process of VUV treatment. A nanostructured surface of PMMA film is used as a sample to be exposed. The nanostructured surface of the PMMA film was obtained by treating the initially smooth spin-coated film in oxygen radio-frequency plasma. The degree of VUV exposure is estimated using changes in the morphology and roughness of the nanostructured surface, which were determined by atomic-force microscopy (AFM). Recognition of morphological surface features on the AFM-images and determination of main geometrical characteristics of these features are performed by using virtual feature-oriented scanning method. It is discovered by morphology and Fourier spectra that the nanostructured surface of the PMMA film is partially ordered. The developed VUV smoothing procedure can be used to treat the electron-beam, UV, and X-ray sensitive PMMA resists, PMMA elements of microelectromechanical systems, biomedical PMMA implants, as well as to certify nanotechnological equipment incorporating UV radiation sources.     

Effect of processing temperature on the micro- and macro-interfacial properties of carbon fiber/epoxy composites

Three different temperature schemes were applied on carbon fiber/epoxy composite to elucidate the effect on interfacial shear strength (IFSS) and inter-laminar shear strength (ILSS). It showed that carbon fiber/epoxy IFSS was significantly influenced by the processing temperature, while ILSS was only slightly changed. Moreover, the mechanical properties revealed no necessary relationship between the micro- and macro-interfacial strengths with the properties of epoxy matrix. Among all the temperature schemes, Pro2 (the one-platform curing scheme with relatively rapid heating rate) produced highest IFSS and ILSS. Fourier transform infrared spectroscopy analysis demonstrated that the sizing agent can chemically react itself and also react with epoxy resin at temperature 180?°C. The resin rheological data showed that different temperature schemes can considerably impact diffusion behavior of the resin molecules. Hence, the highest interfacial strengths for Pro2 scheme were ascribed to large extent of chemical reactions and good inter-diffusion between components, at the interface region.     

真空紫外辐照对交联乙烯-四氟乙烯线缆的影响北大核心CSCD

以航天器舱外用交联乙烯-四氟乙烯共聚物(X-ETFE)线缆为试验对象,采用5倍加速因子对XETFE线缆累计进行了8000等效太阳小时(ESH)真空紫外(VUV)辐照,并通过极限耐电压、绝缘材料电阻测试分析X-ETFE线缆电性能,采用FTIR和SEM表征X-ETFE材料分子结构和微观形貌,以此研究不同VUV辐照时间对X-ETFE线缆的影响。试验结果表明,随着VUV辐照时间的增加,材料表面累积了碳而发生暗化,线缆外观颜色逐渐变为深棕色;X-ETFE线缆的极限耐压和绝缘电阻呈总体下降趋势,但整体电性能水平未发生本质变化;X-ETFE材料在1628 cm^(−1)处的吸收峰逐步增大,说明X-ETFE材料分子链中的−C=C−自由基团随辐照时间而增多,致使材料表面出现了微裂纹现象。     

Ultraviolet discharges from a radio-frequency system for potential biological/chemical applications

In this work, we describe a new electrode-less radio-frequency(RF) excitation technique for generating excimers in the vacuum ultraviolet(VUV) and ultraviolet(UV) spectral regions for potential biological/chemical applications. Spectra data of Xe~*_2, XeI~*, and KrI~* generated by this new technique are presented. Optical efficiency of the lamp system ranges from 3% to 6% for KrI~*, 7% to 13% for XeI~*, and 15% to 20% for Xe~*_2. Also, results of irradiating E-coli with XeI~*discharge from this lamp system is presented to show one of the promising applications of such electrode-less apparatus.This new RF lamp system offers an interesting addition to the already existing technologies for generating VUV and UV light for various biological, physical, and chemical processes especially those requiring large area for high productivity.