纳米电刷镀In层真空辐照环境下摩擦学性能研究

采用纳米电刷镀技术在(n-Al2O3/Ni)工作层上制备了In涂层,利用扫描电子显微镜和能谱仪观察和分析了In涂层在大气、真空、原子氧辐照、紫外线辐照后的表面、磨痕形貌及元素组成.利用真空摩擦磨损试验机分别完成了干摩擦条件下大气、真空、原子氧辐照及紫外线辐照四种环境下的摩擦磨损性能测试.结果表明:金属铟在常态下具有良好...     

真空-紫外线对空间材料降解的研究进展

综述了真空-紫外线的空间环境效应及真空-紫外线对空间材料的降解作用.真空-紫外线辐射使材料表面粗糙度增大,表面成分、结构发生变化,机械性能和光学性能下降,同时真空-紫外还可以与原子氧产生协同效应,加速材料的降解.     

紫外线对多孔聚四氟乙烯驻极体压电性能的影响

将恒压电晕充电的多孔聚四氟乙烯(polytetrafluoroethylene,PTFE)驻极体置于不同强度的紫外线下,研究紫外线对多孔PTFE驻极体压电活性的影响,探讨多孔PTFE医疗产品采用紫外消毒的可能性.研究结果指出(1)常温下,多孔PTFE驻极体的准静态压电系数d33随充电时间的延长而增加,并呈现出线性区、非线性区和饱和区三个区间,多孔PTFE驻极体的压电活性主要依赖于这类材料的电荷储存能力.(2)医用紫外线辐照对多孔PTFE的准静态压电系数d33的影响甚微.(3)多孔PTFE驻极体的d33随紫外辐照时环境湿度的提高而有下降,环境湿度越大,d33的下降越多.(4)紫外线辐照适合聚四氟乙烯医用驻极体产品的消毒.     

FeCrBSi/FeS层真空辐照环境下的组织结构与摩擦学性能研究

采用超音速等离子喷涂+低温离子渗硫技术在45#钢基体上制备了FeCrBSi/FeS复合涂层,考察了该复合涂层在大气、真空、原子氧辐照、紫外线辐照后的表面形貌、磨痕形貌及元素组成。利用真空摩擦磨损试验机分别完成了干摩擦条件下四种环境中的摩擦磨损性能测试。结果表明:复合FeCrBSi/FeS层经过原子氧及紫外线辐照后,有部分元素被氧化及化合物分解的现象,但并没有发生明显的材料性能改变以及润滑涂层的破坏。与45#钢相比,四种环境下该复合涂层均具有良好的润滑减摩效果。此研究表明,复合FeCrBSi/FeS层具有一定的抗原子氧和紫外线辐照的能力。     

TiO2改性M40/EP648复合材料的抗真空紫外辐照性能

利用射流式真空紫外辐照设备模拟空间的辐照条件，在温度为150K和压力为10^-4Pa的条件下，研究了波长为1-200nm的真空紫外线对纳米TiO2／EP648、纳米TiO2 M40／EP648、M40／EP648复合材料以及环氧树脂EP648的辐照损伤效应．结果表明，纳米TiO2具有明显的抗真空紫外辐照的作用．辐照后，与EP648和M40／EP648相比，纳米复合材料TiO2 EP648和M40／TiO2 EP648的质量损失率大幅度降低；纳米复合材料M40／TiO2 EP648的层间剪切强度随着辐照时间的延长呈上升趋势，M40／EP648呈下降趋势；辐照后，纳米复合材料M40／TiO2 EP648的表面形貌无明显变化，M40／EP648表面破损严重．     

紫外线辐照下BaFCl：Eu^2＋的电子转移过程

本文研究了BaF_xCl_(2-x):Eu~(2+)荧光材料在紫外线辐照下的光激励发光。在小于Eu~(2+)离化能而大于Eu~(2+)最低激发态的不同能量紫外线辐照后(Eex.相似文献   

蒸镀TiO2薄膜的面料

采用真空蒸镀法制备了负载纳米TiO2织物。利用扫描电镜（SEM）和X射线衍射仪（XRD）分别分析了其表面形貌和晶体结构,探讨了负载TiO2和热处理对棉织物的抗紫外线性能的影响。萁结果表明：在蒸镀条件相同的前提下,蒸镀时间为13s且经过热处理的负载纳米TiO2织物的抗紫外线性能较好。     

纳米TiO2对真空紫外辐照下MQ增强硅橡胶力学性能的影响

采用空间综合辐照模拟设备研究了纳米TiO2对真空紫外辐照下MQ(MQ硅树脂是由单官能硅氧单元(R3SiO0.5,简称M单元)和四官能硅氧单元(SiO2,简称Q单元)组成的有机硅树脂),增强硅橡胶力学性能的影响。试验结果表明,真空紫外辐照后,硅橡胶表面颜色加深,同时出现裂纹,裂纹数量随辐照剂量的增加而增加;在试验的辐照剂量范围内,硅橡胶的硬度和拉伸强度随辐照剂量的增加先增加而后降低,断裂伸长率则先降低而后增加。橡胶的模量和玻璃化转变温度也会发生不同变化。添加纳米TiO2的硅橡胶与未改性硅橡胶相比,经过相同剂量的辐照后,表面裂纹损伤程度减小,硬度和力学性能的损伤程度下降,表现出明显的抗真空紫外辐照性能。     

Co源辐照对聚乙烯电缆护套材料真空出气性能影响

材料真空出气性能是卫星设计选材时的一个重要依据,辐照是对材料出气性能影响较为严重的一种空间环境因素。本文对Co源辐照(1.2×10~9rad,Si)前后的材料样品,进行100及125℃条件下真空出气参数试验;结合红外光谱、扫描电镜、热重分析测试手段,研究辐照环境对聚乙烯电缆护套材料(SF-30-35)出气性能的影响。研究表明:经过辐照后的聚乙烯电缆护套材料样品的总质量损失及可凝挥发物量真空出气参数显著增加;Co源辐照使材料性质发生很大变化,辐照前材料表面为韧性网状结构,辐照后材料表面明显硬化,力学性能由柔韧变为干脆易断;辐照使材料发生氧化断链及交联反应,真空出气试验时断链产生的分子逸出。上述结果说明辐照环境改变了电缆护套材料特性,加速了材料真空环境下的出气性能。     

纳米TiO2和紫外线吸收剂对丙烯酸酯涂层抗光氧化性能的影响

讨论了锐钛矿型和金红石型纳米TiO2以及2．4-二羟基二苯甲酮和2-(2-二羟基-5-苯甲基)苯并三唑等有机紫外线吸收剂的光活性．并借助失重分析和SEM分析探讨它们对丙烯酸复合涂层抗光氧化性能的影响。UV分析表明：2，4-二羟基二苯甲酮、2-(2-二羟基-5-苯甲基)苯并三唑等有机紫外线吸收剂对400nm以下的紫外线有强烈的吸收作用；金红石和锐钛矿型纳米TiO2对紫外线也有较强烈的吸收和散射作用，紫外光透过率低。且有机紫外线吸收剂随着辐射时间的延长会分解失效，而纳米TiO2较稳定。失重分析和SEM分析结果显示：锐钛矿型纳米TiO2具有光催化性，加速丙烯酸酯聚合物的光降解，而金红石型纳米TiO2则是一种有效的遮光剂。同时添加金红石型纳米TiO2和有机紫外线吸收剂能更有效提高丙烯酸酯复合涂层的抗光氧化性能。     

Effects of VUV/UV radiation and oxygen radicals on low-temperature sterilization in surface-wave excited O2 plasma

Effects of VUV/UV radiation and oxygen radicals on low-temperature sterilization in surface-wave excited O₂ plasma were studied. To examine the effect of VUV/UV radiation on the inactivation of microorganisms, a small metal chamber covered with an optical filter at the top to block the radicals and allow the VUV/UV radiation was placed inside the plasma chamber. With a LiF and a glass filter, two different emission spectra above 120 nm (LiF filter) and above 300 nm (glass filter) were examined. The spores of Geobacillus stearothermophilus with a population of 2.5 × 10⁶ were put below the optical filter in the small chamber, which was filled with the oxygen gas at appropriate pressure or pumped down to 10^− 3 Pa. The survival curve showed that the vacuum condition inside a small chamber with a LiF filter was more efficient than the same O₂ gas pressure as that outside plasma chamber. From the SEM analysis of the spores, there was no obvious change in shape after plasma treatment with filter at vacuum condition. According to the present results, it is concluded that the etching effect by the oxygen radical is more efficient in inactivation process than the sterilizing effect by the VUV emission in the oxygen plasma.     

Luminescent properties of a novel green-emitting gallium borate phosphor under vacuum ultraviolet excitation

Vacuum ultraviolet (VUV) excitation and emission properties of a new Tb³⁺-activated green-emitting phosphor with huntite-type gallium borate, LnGa₃(BO₃)₄:Tb³⁺ (Ln = Y, Gd), are investigated. Overall absorption bands are in the range of 120-250 nm and can be tentatively interpreted in terms of the charge transfer transition from host to rare earth ions and the Tb³⁺ activator. Additionally, an appropriate atomic ratio of Y³⁺/Gd³⁺ in the host compound enhances both the excitation and emission efficiency under VUV excitation. Enhanced absorption efficiency for the VUV light makes these novel phosphors the prominent luminescent materials with plasma-discharge conditions, by converting the VUV radiation to the visible light.     

Degradation of natural organic matter in surface water using vacuum-UV irradiation

The use of vacuum-UV (VUV) radiation to degrade natural organic matter (NOM) and the main variables affecting the efficiency of this process were investigated using an annular photoreactor. After 180 min of irradiation with VUV, the total organic carbon (TOC) decreased from 4.95 ppm to 0.3 ppm. Also, decadic absorption coefficients of the water at 185 nm and 254 nm decreased from 3.2 cm(-1) to 2.85 cm(-1), and 0.225 cm(-1) to 0 cm(-1), respectively. The reactor operation was kinetically controlled for Reynolds numbers greater than 600, changes of pH between 5 and 9 had little effect, and increases in alkalinity decreased the process efficacy. Additionally, H(2)O(2)/VUV and VUV processes were compared to H(2)O(2)/UV and UV processes, where the formers showed greater effectiveness with complete mineralization of NOM as opposed to partial oxidation with H(2)O(2)/UV, and no mineralization with UV alone. Modeling and analysis of the photon flux and absorption in the reactor showed that 99% of the 185 nm radiation was absorbed by the water in the reactor. In comparison, only 48% of the 254 nm radiation was absorbed by the water. The overall quantum efficiency of the mineralization for VUV was 0.10 for 50% TOC reduction.     

真空紫外光激发下Tb~(3+)激活的稀土正硼酸盐的发光

报导了Tb3+、Ce3+激活的稀土正硼酸盐的真空紫外光谱。分析了Ce3+的4f75d能级随基质结构、基质阳离子的变化,讨论了温度、Tb3＋离子的浓度对发光的影响以及Ce3＋－Tb3＋间的能量传递.     

The electronic structure and luminescence properties of Ce3+ doped Sr10[(PO4)5.5(BO4)0.5]BO2 under UV/VUV and X-ray excitation

The apatite related compound Sr₁₀[(PO₄)_5.5(BO₄)_0.5]BO₂ (SrBPO) doped with Ce³⁺ was synthesized via solid state reaction method. Undoped SrBPO shows blue-green emission under ultraviolet (UV) and X-ray excitation due to the defects in the host. When excited by vacuum ultraviolet–ultraviolet (VUV–UV) light or X-ray, Ce³⁺ doped SrBPO shows a broad emission band peaking at 450 nm originating from 5d–4f transition of Ce³⁺ and defects in the host. The phosphor exhibits strong excitation bands in UV range and a weak broad excitation band in VUV region. The site occupation of Ce³⁺ was proposed based on fluorescence decay curves. Electronic structure shows the compound is an indirect semiconductor with a band gap of 3.04 eV. The extremely small density of states of [PO₄]³⁻ or [BO₄]⁵⁻ group near Fermi level or in the conduction band is a possible origin of the weak excitation band in the VUV range. A possible mechanism was proposed to explain the luminescence properties observed.     

Structural and optical properties of neodymium-doped lutetium fluoride thin films grown by pulsed laser deposition

Neodymium-doped lutetium fluoride (Nd³⁺:LuF₃) thin films were successfully grown on MgF₂ (0 0 1) substrates by pulsed laser deposition (PLD). It is void of cracks that are otherwise prevalent due to structural phase transitions in Nd³⁺:LuF₃ during thin film deposition and bulk crystal growth. Cathodoluminescence (CL) spectra revealed multiple emission peaks, with a dominant peak in the vacuum ultraviolet (VUV) region at 179 nm. This peak has a decay time of 6.7 ns. The ability to grow high quality Nd³⁺-doped fluoride thin films would enable fabrication of VUV light-emitting devices that will enhance applications requiring efficient VUV light sources.     

Increased efficiency of vacuum ultraviolet generation by stimulated anti-stokes Raman scattering with stokes seeding

Stimulated anti-Stokes Raman scattering in molecular hydrogen allows for the generation of continuously tunable narrow-bandwidth radiation down to the transmission limit of vacuum ultraviolet (VUV) window materials. Simultaneous irradiation of UV-pump radiation (in this application, dye laser radiation of wavelength lambda = 372 nm) and of radiation whose wavelength corresponds to the first Stokes component allows a considerable increase in efficiency-by nearly 2 orders of magnitude in the far VUV. The additional Stokes radiation is generated in a simple manner during the passage of the unfocused pump radiation through a high-pressure Raman cell that precedes the VUV Raman cell.     

Patterned hydrophobic-hydrophilic templates made from microwave-plasma enhanced chemical vapor deposited thin films

In the present research, nano-structured materials exhibiting super-hydrophobic behavior obtained by microwave-plasma enhanced chemical vapor deposition (MPECVD) had their surface chemical status altered through vacuum ultraviolet (VUV) light irradiation. Falling water droplets rolled and bounced without wetting or spreading over the initially super-hydrophobic surfaces. We demonstrate a surface preparation technique to create a patterned super-hydrophobic/super-hydrophilic substrate in which micropatterns with super-hydrophobic and super-hydrophilic regions were prepared through irradiation with VUV light. To confirm the method, growth of water droplets is observed in situ on such super-hydrophobic/super-hydrophilic micropatterns. We discuss the applicability of the super-hydrophobic/super-hydrophilic pattern to the bottom-up assembling of materials, like site-selective electroless Cu plating on patterned substrates made of paper and selective cell culture experiments.     

Monocyte adhesion and adhesion molecule expression on human endothelial cells on plasma-treated PET and PTFE in vitro

The aim of this study was to evaluate in vitro the inflammatory potential of endothelialized surfaces of polyethylene terephthalate (PET) and polytetrafluorethylene (PTFE) after ammonia gas plasma modification. HUVECs grown on polystyrene and HUVECs stimulated with tumor necrosis factor (TNF-alpha) were used as controls. At day 1 and day 7, surfaces were evaluated for U937 cells and HUVECs using flow cytometry and immunohistochemistry. Plasma-treated PET (T-PET) and treated PTFE (T-PTFE) increased U937 cell adhesion compared to the negative control but this was not statistically significant. Maximal adhesion of U937 cells to HUVEC was observed on TNF-alpha stimulated endothelium with significant differences between day 1 and day 7. There was a small increase in U937 cell adhesion to plasma-treated PET compared to PTFE on both day 1 and day 7, but this was not statistically significant. Immunohistochemical staining demonstrated two patterns of distribution for monocyte adhesion on materials. On T-PET the cells were positioned in clusters attached to HUVECs and on T-PTFE the cells were randomly distributed on HUVECs and material. The effects of plasma-treated PET and PTFE on HUVEC adhesion and proliferation were also studied. On day 1 there were slight increases in the growth of HUVECs on both of T-PET and T-PTFE but this was not statistically significant. On day 7, cell number increased significantly on all of surfaces compared to the negative control. The results demonstrate that the plasma treatment of PET and PTFE with ammonia improves the adhesion and growth of endothelial cells and these surfaces do not exhibit a direct inflammatory effect in terms of monocyte adhesion. Plasma-treated PTFE enhances HUVECs growth and was less adhesive for monocytes as compared with treated PET. The monocyte adhesion to endothelial cells on surfaces can be used as a tool for the evaluation of material surface modification and further to study the mechanisms of cell to cell interactions in response to surfaces.