聚氨酯基红外-激光兼容隐身涂层性能研究

以三氧化二铬包覆片状铝粉粒子(Al/Cr2O3)为填料,聚碳酸酯基水性聚氨酯为粘合剂,涂敷于玻璃片上,自然干燥制得涂层。研究了粘合剂、填料及它们的加入量对涂层红外发射率和激光反射性能的影响。采用红外发射率测量仪和可调谐CO2激光器测试涂层在8～14μm红外发射率和10.6μm激光反射性能。结果表明:使用的粘合剂较普通水性聚氨酯发射率低,固定粘合剂量,改变填料加入量,涂层在8～14μm波段发射率和10.6μm激光的反射性能都随着包覆粒子的增加而减小,当加入量达到30%时,涂层的红外发射率可以降低至0.688,激光反射能量降至初始入射能量的1%,且涂层综合物理性能良好,达到红外—激光兼容隐身的要求。     

高温含粒子自由流红外辐射特性的反向蒙特卡罗法模拟

高温含粒子自由流红外辐射特性的研究在目标探测、燃烧诊断、火焰温度测量等领域有着重要应用．利用反向蒙特卡罗法模拟计算高温含粒子自由流的红外辐射特性,考察了自由流中粒子散射和边界条件对定向辐射热流的影响,并与正向蒙特卡罗法进行比较,比较结果表明反向蒙特卡罗法在计算效率上明显优越．     

非均匀涂层的热辐射

考虑非均匀涂层自身辐射,以及对衬底辐射的透射和对外来辐射的反射,建立了热辐射传输方程;给出了涂层表观发射比和反射比的公式;并讨论了影响涂层辐射性能的诸因素。     

FeSiAl 粉末形貌对微波衰减涂层性能的影响

为了解粉末形貌对FeSiAl 微波衰减涂层性能的影响,本文采用四种粉碎方法制备出了不同形貌的FeSiAl 粉末,并对FeSiAl 烧结涂层的性能进行了研究。研究表明,当FeSiAl 颗粒呈片状或棱角状并伴有脆性解理面形貌时,烧结涂层具有良好的微波衰减性能。分析认为,FeSiAl 粉末具备片状或棱角状并伴有脆性解理面形貌特征,可使烧结涂层获得相对较高的磁导率损耗角正切值和较高的衰减常数。     

高抗热震性红外辐射节能涂层的制备与性能研究

以堇青石、SiC、Cr2O3、TiO2、SiO2为原料,与磷酸盐胶粘结剂配料混匀后,经机械搅拌制备红外辐射涂料,采用刷涂的方式在高铝砖基体表面制备红外辐射节能涂层。采用TG-DSC研究分析红外辐射粉末的热稳定性,利用涂-4杯和漆膜附着力测定仪对涂料的流动性能和涂层与基体的结合强度进行表征,采用空冷和水淬方式研究涂层的抗热震性能,并探讨了碳化硅的含量对涂层红外发射率的影响。研究结果表明:胶粉比为2:1时,获得的涂料均匀,流动性最好;以磷酸盐胶粘结剂制备的红外辐射涂料经1100℃以上高温瓷化后,红外辐射涂层与基体的结合力增强,涂层抗热震性能良好;碳化硅含量为40%时,制备的复合红外辐射涂层具有最优的红外辐射性能。此外,在炭砖焙烧窑上使用该红外辐射涂料后,炉内温度提高了128℃,降低能耗8%左右。     

深蓝色建筑节能涂层的制备及性能研究

为降低夏热冬冷地区建筑降耗,以片状钴蓝为颜料,改性纳米硅溶胶/苯丙复合乳液为基料,制备了深蓝色建筑节能涂层并探究片状钴蓝的掺量对涂层性能的影响。采用X射线衍射仪、紫外/可见光/近红外分光光度计、红外辐射率测量仪、精密色差仪和扫描电子显微镜对钴蓝和建筑节能涂层性能进行表征,自制隔热装置测量涂层隔热性能。结果表明:钴蓝的近红外平均反射率为49.64%;当钴蓝掺量为15%时,涂层近红外平均反射率最大,为21.47%,此时,涂层在8~14?m波段的法向发射率高达0.96,涂层试板背面平衡温度比空白石棉水泥板低7.5℃,隔热性能较好。     

红外隐身涂层的制备及其与雷达吸波涂料的兼容性研究

采用双层涂覆的方法制备了雷达.红外隐身兼容涂层,研究了红外隐身涂层的填料种类、含量以及涂层厚度对雷达隐身涂层吸波性能的影响,通过优化条件得到对雷达吸波性能影响最小的红外隐身涂层.实验结果表明,用双层涂覆的方法,以特殊形态片状微米级铝粉作为顶层红外隐身涂层的填料,填充量为40%,且涂层厚度达到20μm时,涂层的红外发射率可达0.15左右,其对底层雷达吸波层吸波性能的影响较小.     

镀Ni-Cu-La-B玻璃纤维对电磁屏蔽复合涂料性能的影响

以一种新型镀Ni-Cu-La-B玻璃纤维与片状镍粉为复合填料,以丙烯酸树脂作为粘结剂,研制出了一种新型镀Ni-Cu-La-B玻璃纤维/片状镍粉/丙烯酸树脂电磁波屏蔽复合涂料,并研究了其导电性能和电磁波屏蔽性能。结果表明,添加6 wt%的镀Ni-Cu-La-B玻璃纤维能显著改善涂层的电磁性能,膜厚300μm,涂层电阻率为0.68Ω·cm,涂层屏蔽效能在0.3～1 000 MHz频段内为47.78～64.28 dB。为研制低成本电磁波屏蔽涂料提供了一种新的思路和方法。     

激光熔覆镍包纳米氧化铝

进行了2Cr13不锈钢表面激光熔覆镍包纳米氧化铝的实验。使用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线能量色散谱仪(EDAX)、显微硬度仪等设备检测了涂层表面、横截面的显微组织和涂层的硬度、耐磨损等性能,分析了加入纳米氧化铝粒子后对涂层组织和性能的影响。研究结果表明,激光熔覆可获得致密的Fe-Ni(Cr)合金和Al2O3粒子复合涂层。其中,纳米氧化铝粒子弥散分布在微细合金晶粒之间,并与合金晶粒一起形成了胞状树枝晶结构。纳米氧化铝粒子的加入增加了基质金属的成核率,起到了细晶强化以及弥散强化的作用,使得复合涂层的机械性能大幅度提高。复合涂层的平均硬度为700HV0.2,比基体提高了1.5倍,耐磨损性能比淬火态基体提高了1.25倍。     

卫星光通信系统光电核心器件的伽马辐射实验研究

为了研究空间辐射导致的卫星光通信系统性能劣化,本文开展了光电核心器件的γ辐射实验。在辐照总剂量低于150krad的条件下,DFB激光器和LiNbO3光电调制器没有出现明显的性能变化,而EDFA器件表现出明显的增益衰减。实验结果表明,在卫星光通信系统的实际应用中应该更多的考虑高能粒子辐射所带来的影响。     

Power and ${rm Q}$ of a Horizontal Dipole Over a Metamaterial Coated Conducting Surface

The radiation properties of an electrically small antenna attached to an infinite conducting ground plane covered by a thin sheet of a metamaterial medium are considered. Using analytical field expressions, the radiation of an electric point dipole with arbitrary constitutive parameters of the material coating is studied. Attention is paid especially to permittivity values close to zero. Finite element simulations are employed to confirm the radiation enhancement and low quality factor Q characteristic of a zero-index coating as compared with regular ";air-filling."; The Q is evaluated partly through integration of the energy of the FEM-simulated fields within the antenna region and partly from the nonradiating component of the multipole fields outside the antenna region. Additionally, the influence of surface wave power is analyzed through simulations.     

Investigation on propagation properties of terahertz waveguide hollow plastic fiber

The propagation properties of terahertz (THz) waveguide plastic hollow fiber have been investigated in this paper. The effects of radiation frequency, bore diameters and dielectric coating layers on the waveguide property have been shown and discussed. The results show that the attenuation loss of TM mode increases and that of TE mode decreases as radiation frequency increases. The attenuation loss decreases with the increasing of fiber bore diameter. The attenuation loss decreases as the refractive index of dielectric coating layer and the ratio of the refractive index of outer dielectric layer to that of inner dielectric layer increase.     

Roll‐to‐roll gravure printing of organic photovoltaic modules—insulation of processing defects by an interfacial layer

Gravure printing as direct patterning roll‐to‐roll (R2R) production technology can revolutionize the design of thin‐film organic photovoltaic (OPV) devices by allowing feasible manufacturing of arbitrary‐shaped modules. This makes a distinction to coating methods, such as slot die coating, in which the pattern is limited to continuous stripes. Here, we analyze the thin‐film formation and its influence on OPV module performance as the gravure printing of hole transport and photoactive layers are transferred from laboratory to R2R pilot production environment. Insertion of a 0.8‐nm layer of lithium fluoride (LiF) as an interfacial layer between the active layer and the electron contact provided insulation against the detrimental pinholes formed in the R2R printing process. Using this device configuration, we produced well‐performing R2R‐printed monolithic modules with a mean efficiency of 1.7%. In comparison, reference modules with an efficiency of 2.2% were fabricated using laboratory‐scale bench top sheet‐level process. Surface energy and tension measurements together with optical microscopy were used to analyze the printability of the materials. The pinhole insulation was investigated in detail by processing R2R‐printed OPV modules with different interfacial layer materials and performing electrical measurements under dark and AM1.5 illumination conditions. Furthermore, we analyzed the LiF distribution using X‐ray photoelectron spectroscopy. The insulating nature of the LiF layer to improve module performance was confirmed by manufacturing lithographically artificial pinholes in device structures. The results show the possibility to loosen the production environment constraints and the feasibility of fabricating well‐performing thin‐film devices by R2R gravure printing. Copyright © 2014 John Wiley & Sons, Ltd.     

激光合金化制备WC颗粒增强复合层耐磨性研究

通过铸造WC和Co包WC与Ni45粉末的复合添加, 运用激光合金化技术在中碳钢表面制备以WC颗粒为增强相的Ni基复合层, 对复合层的微观组织、硬度及耐磨性进行了测试与分析。结果表明: 激光合金化技术可在中碳钢表面制备均匀的WC颗粒增强合金化层, 合金层的硬度及耐磨性得到显著提高。从表面磨损形貌可知, 合金层在室温干摩擦过程中, 均发生不同程度的磨料磨损和粘着磨损, 强化机理主要为第二相强化, WC＋Ni45制备的合金层耐磨性最佳。     

用于高功率激光放大器的单层宽谱增透膜

为了获得用于高功率激光放大器的单层宽带增透膜,采用有机聚合物聚乙烯吡咯烷酮掺杂调控二氧化硅胶体生长制备了粒度分布更宽广的稳定胶体体系,通过提拉镀膜工艺,制备了单层增透膜。采用粒度仪和粘度仪监测胶体的性质,用分光光度计测量了膜层透过率,并用X射线能谱分析了膜层结构。结果表明,聚乙烯吡咯烷酮引入胶体中使得胶体粒度分布更宽,所得膜层具有折射率渐变特性,因而膜层具有宽带增透的效果;膜层在550nm~950nm连续波段内透射率不低于99%。单层宽谱增透膜层不需后处理就可投入使用,膜层性能稳定,满足了激光装置片状放大器的运行要求。     

大面积等离子体片微波反射特性研究

分别通过实验测试与FDTD仿真得到了5.8 GHz标准抛物面天线发射出的微波经大面积等离子体片反射后的方向图;利用FDTD方法对不同入射角度的等离子体片反射特性进行了分析。研究表明:FDTD方法可以准确描述等离子体片的反射性能;等离子体的密度足够高时,它的反射性能与金属相似;微波入射角越大则对等离子体的密度要求越低。     

Radiation from a rectangular waveguide with a lossy flange

The radiation from a rectangular waveguide with a lossy flange coating is studied both analytically and experimentally. An analytic method using Fourier analysis and an impedance boundary condition is proposed. The experiment was performed using a flange covered with a rubber ferrite sheet at an X-band frequency. The numerical and measured results agree well and show that the lossy flange improves the E-plane radiation pattern and the crosspolar radiation. A boresight gain drop of about 2 db is predicted theoretically and measured experimentally     

基于非均匀特异媒质的赋形天线设计

在PCB板表面蚀刻不同尺寸的微带单元结构,构建非均匀特异媒质层,并将其放置在天线辐射单元前方,利用非均匀特异媒质层对电磁波不同的反射系数,实现对天线辐射波束的赋形。设计了由不同尺寸正方形贴片组成的非均匀特异媒质层,并放置于工作频率为5.8 GHz的矩形贴片天线前方。仿真和测试表明:该非均匀特异媒质层能够在基本保持贴片天线工作频点和回波损耗曲线不变条件下,通过调整与贴片天线距离,实现辐射波束由笔形波束向宽角波束和马鞍形波束的赋形转换。为赋形天线设计提供了一种有效的新方法。     

激光处理Ni-P-Al2O3纳米化学复合镀层的微观组织

为了获得性能优良的镀层,在Fe-C合金表面制备了均匀的化学镀层,然后通过高功率连续CO2激光处理镀层表面,利用透射电子显微镜(TEM)观察了沉积Al2O3粒子的微观形貌,采用光学显微镜(OM)和扫描电子显微镜(SEM)观察了镀层处理前后表面及截面形貌,用X射线能谱仪(EDS)对处理前后的镀层进行了元素分析,用X射线衍射仪(XRD)进行物相分析,测试了处理前后镀层物相的变化,用微观硬度仪测量了激光处理后截面的硬度分布.结果表明,激光处理后,强化层表面平整光滑,与基体形成冶金结合,成分均匀,组织细密;处理层物相明显栽从镀态的非晶态向晶态转变,出现了Ni3P和其他一些非平衡强化相.截面处理层由表及里可分为四层:激光作用层、过渡层、热影响区(HAZ)以及基体.纳米Al2O3颗粒均匀分布在过渡区,激光处理层显微硬度约提高3倍,这主要是由于Al2O3颗粒的弥散强化作用以及生成新的强化相磷化物所致.     

Anisotropic Optical Properties of Semitransparent Coatings of Gold Nanocaps

An ordered array of cap‐shaped gold nanoparticles has been prepared by vapor deposition onto polystyrene nanospheres supported on a glass substrate. The method of fabrication used imparts a significant anisotropy to the geometric and optical properties of the coating. The optical‐absorption properties of these deposits have been measured using UV‐vis spectrometry and simulated using a code based on the discrete dipole approximation. Because the nanocaps are not interconnected, they interact with incident light as individual particles with a plasmon resonance that depends upon wavelength and the polarization vector of the light. The resulting extinction peaks manifest in the upper visible and near‐infrared regions of the electromagnetic spectrum. Surprisingly, varying the angle of incidence of the light (for a fixed polarization) has no effect on the optical properties of individual nanocaps. Calculations show that these phenomena may be readily interpreted in terms of dipole resonances excited across the longitudinal, transverse, and short‐transverse directions of the nanocaps. Coatings comprised of arrays of these particles have the potential to serve as angularly and spectrally selective filters.