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红外探测系统的快速发展促进了对红外隐身材料的广泛研究。红外隐身材料主要是对目标的红外辐射能进行调控,主要措施是控制目标表面红外发射率和目标表面温度,使目标与背景环境的辐射能相融合,进而达到隐身的目的。概述了红外隐身的基本原理,综述了低发射率涂层材料、控温涂层材料和智能隐身材料等红外隐身材料近几年的国内外研究现状,并展望了红外隐身材料的未来。 相似文献
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红外隐身技术在军事应用中显得十分重要,而涂层材料则是隐身技术中的一个关键方面。首先从斯蒂芬一玻尔兹曼定律和基尔霍夫定律出发,分析了红外隐身的基本原理,介绍了红外隐身涂层的分类情况,说明了其组成中不同因素的影响作用并得出了低红外发射率涂层的理想结构。然后分类别地介绍了红外隐身材料的研究进展,并进一步预测了其发展趋势。未来的研究将主要包括两个方面:一是研制新的隐身材料;二是寻求各种隐身技术的兼容。 相似文献
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从基体树脂、填料和涂层综合性能三方面对8~14m波段水性红外隐身涂料进行了研究。用红外发射率测量仪测量了涂层在8~14m波段的红外发射率,用红外光谱仪测量了树脂红外吸收图谱,用扫描电镜观察了涂层表面形貌。结果表明,丙烯酸树脂在8~14m波段有较高的红外透明性,适合做涂料基体树脂;铝银浆能在涂层中形成致密的反射层,适合做红外隐身涂料的填料;填料的粒径、含量和形态都对涂层的发射率有较大的影响;选用钢板为基材,以丙烯酸树脂为基体树脂,粒径2000目、浮铝百分比为50%的铝银浆为填料,当涂层中填料含量为15%时,测得其发射率为0.34。 相似文献
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兼具表面低红外发射率和隔热性能的功能纺织材料在工业及军事领域有着广泛用途。从利用低表面发射率和控制物体表面温度两方面,研究制备具有低红外发射率且隔热性能良好的功能材料。选用聚丙烯酸酯(PA)作为成膜粘结物质,研究了铝粉的粒径及用量对涂层红外发射率的影响;以不同的空心微珠为隔热填充剂,并对其用于涂层织物的隔热效果进行探究。最后,将低发射率涂层与隔热涂层进行复合,制备出兼具低发射率与隔热性能的材料。结果表明,采用400目片状铝粉时的发射率比采用600目时更低,20%的400目片状铝粉的涂层胶所制备的涂层表面的红外发射率低至0.237。由于空心微珠是较好的隔热填料,以共混15%的玻璃微珠为隔热层,以共混20%的400目片状铝粉为低红外发射率涂层,所制备的纤维基复合涂层材料的发射率为0.507,热体试样与背景温差为3.75℃,具有较好的隔热性能和低红外发射率。 相似文献
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Aaron C. Jackson Jonathan A. Bartelt Paul V. Braun 《Advanced functional materials》2011,21(24):4705-4711
A self‐healing approach for optically transparent thermoplastic polymers, based on plasticizer‐induced solvent welding, is reported. For the specific system investigated, dibutylphthalate (DBP) filled urea‐formaldehyde capsules are dispersed in a polymethylmethacrylate (PMMA) matrix. Upon a damage event, DBP is released into the crack, and locally plasticizes and swells the polymer, enabling it to remend. Two challenges are addressed to maintain optical transparency: minimization of light scatter from the capsules in the polymer matrix and minimization of light scatter from the healed polymer. PMMA films containing DBP capsules have good transmissive properties as a result of the close index match between PMMA and DBP. The transmission properties are better than, for example, when DBP capsules are dispersed into a poorly index matched matrix, such as polystyrene. In the DBP PMMA system, the healed material is inherently index matched to the polymer matrix and thus the polymer's original optical properties are largely restored. Self‐healing using both small capsules, 1.5 μm in diameter, and large capsules, 75 μm in diameter is demonstrated. Smaller capsules are particularly important for thin polymer films which are not thick enough to hold the larger capsules. Polymer films with smaller capsules also have very good transmission properties due to a minimization of light scattering by the small size of the capsules. Large capsules enable healing of larger damage events, but do inherently result in some light scattering. This plasticizer‐based approach to self‐healing is shown to enable recovery of the protective properties and a portion of the mechanical properties of a polymeric film. 相似文献
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Nicholas R. Haase Samuel Shian Kenneth H. Sandhage Nils Kröger 《Advanced functional materials》2011,21(22):4243-4251
Recent insight into the molecular mechanisms of biological mineral formation (biomineralization) has enabled biomimetic approaches for the synthesis of functional organic‐inorganic hybrid materials under mild reaction conditions. Here we describe a novel method for enzyme immobilization in thin (nanoscale) conformal mineral coatings using biomimetic layer‐by‐layer (LbL) mineralization. The method utilizes a multifunctional molecule comprised of a naturally‐occurring peptide, protamine (PA), covalently bound to the redox enzyme Glucose oxidase (GOx). PA mimics the mineralizing properties of biomolecules involved in silica biomineralization in diatoms, and its covalent attachment to GOx does not interfere with the catalytic activity. Highly efficient and stable incorporation of this modified enzyme (GOx‐PA) into nanoscale layers (~5–7 nm thickness) of Ti‐O and Si‐O is accomplished during protamine‐enabled LbL mineralization on silica spheres. Depending on the layer location of the enzyme and the type of mineral (silica or titania) within which the enzyme is incorporated, the resulting multilayer biocatalytic hybrid materials exhibit between 20–100% of the activity of the free enzyme in solution. Analyses of kinetic properties (Vmax, KM) of the immobilized enzyme, coupled with characterization of physical properties of the mineral‐bearing layers (thickness, porosity, pore size distribution), indicates that the catalytic activities of the synthesized hybrid nanoscale coatings are largely determined by substrate diffusion rather than enzyme functionality. The GOx‐PA immobilized in these nanoscale layers is substantially stabilized against heat‐induced denaturation and largely protected from proteolytic attack. The method for enzyme immobilization described here enables, for the first time, the high yield immobilization and stabilization of enzymes within continuous, conformal, and nanoscale coatings through biomimetic LbL mineralization. This approach will likely be applicable to a wide variety of surfaces and functional biomolecules. The ability to synthesize thin (nanoscale) conformal enzyme‐loaded layers is of interest for numerous applications, including enzyme‐based biofuel cells and biosensors. 相似文献
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采用浇注法制备出了并联式2-2型PZT-环氧树脂复合压电材料,对其相关性能进行研究,结果表明,浇铸发生固化反应的最佳配比工艺为环氧树脂与聚酰胺650体积比为4∶1,室温下固化3~5天。复合材料的介电损耗随着测试频率的增大而下降并趋于稳定;随着锆钛酸铅(PZT)含量的增加,压电常数(d33)、介电常数(ε)、介电损耗(tanδ)数值均逐渐增大。在1kHz的测试频率下,复合材料的d33=146.5pC/N,ε=2 100,tanδ=0.090。弯曲强度(σf)=162.2 MPa。当复合材料的PZT的体积分数为63.5%时,σf=162.2 MPa,挠度为6%~10%。 相似文献
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Rupert Kargl Tamilselvan Mohan Stefan Köstler Stefan Spirk Aleš Doliška Karin Stana‐Kleinschek Volker Ribitsch 《Advanced functional materials》2013,23(3):308-315
Two different lithographic techniques for the patterning of thin biopolymer films are developed. The first method is based on using a microstructured elastomeric mold for the structuring of thin films of regenerated cellulose. The thin films are manufactured by spin‐coating of trimethylsilyl cellulose (TMSC) and subsequent regeneration. The microchannels formed by the mold and the cellulose film are filled with a cellulase solution by capillary action. In the areas exposed to the enzyme solution, the cellulose film is digested, whereas the area in contact with the mold is protected from the enzymatic activity. Optical thickness measurements, atomic force microscopy and fluorescent staining confirm a successful patterning of cellulose on several substrates by this method. The second method is based on the structured regeneration of thin TMSC films. TMSC surfaces are protected with metal masks and exposed to vapors of hydrochloric acid. These treatments result in hydrophilic cellulose structures surrounded by hydrophobic TMSC with differing physicochemical properties. Treatments of the obtained structures with cellulases allow the selective removal of pure cellulose, whereas a TMSC pattern remains on the surface. These TMSC can be regenerated back to pure cellulose by treatments with vapors of hydrochloric acid. The developed methods allow the effective fabrication of micropatterned biopolymer thin films suitable for further functionalization and application in, e.g., bioanalytical devices. This is shown by the immobilization and detection of single‐stranded DNA on structured cellulose surfaces. Owing to the versatility of both patterning approaches the methods can be further extended to other combinations of substrates and enzymes. 相似文献
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Highly Hydrophobic ZIF‐8/Carbon Nitride Foam with Hierarchical Porosity for Oil Capture and Chemical Fixation of CO2 下载免费PDF全文
Daeok Kim Dae Woo Kim Onur Buyukcakir Min‐Kyeong Kim Kyriaki Polychronopoulou Ali Coskun 《Advanced functional materials》2017,27(23)
The introduction of hierarchical porosity into metal‐organic frameworks (MOFs) has been of considerable interest in gas separation and heterogeneous catalysis due to the efficient mass transfer kinetics through meso/macropores. Here, a facile, scalable approach is reported for the preparation of carbon nitride (CN) foams as structural templates with micrometer‐sized pores and high nitrogen content of 25.6 wt% by the fast carbonization of low‐cost melamine foam. The nitrogen functionalities of CN foam facilitate chemical anchoring and growth of ZIF‐8 (zeolitic imidazolate frameworks) crystals, which leads to the development of hierarchical porosity. The growth of ZIF‐8 crystals also renders CN foam, which is hydrophilic in nature, highly hydrophobic exhibiting 135° of water contact angle due to the enhanced surface roughness, thus creating a natural shield for the MOF crystals against water. The introduction of ZIF‐8 crystals onto the CN foam enables selective absorption of oils up to 58 wt% from water/oil mixtures and also facilitates the highly efficient conversion of CO2 to chloropropene carbonate in a quantitative yield with excellent product selectivity. Importantly, this present approach could be extended to the vast number of MOF structures, including the ones suffering from water instability, for the preparation of highly functional materials for various applications. 相似文献
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激光熔覆镍基纳米WC/Co复合涂层的断裂韧性Kc的研究 总被引:4,自引:0,他引:4
对45钢表面激光熔覆Ni基纳米WC/Co复合涂层的断裂韧性Kc进行了研究。结果表明:激光熔覆Ni基纳米复合涂层的Kc≥18.0MN.m-3/2,而喷焊Ni基WC/Co复合涂层的Kc平均值为8.1 MN.m-3/2(最低值为4.4 MN.m-3/2)。分析认为:在本研究条件下,激光熔覆Ni基纳米WC/Co复合涂层中形成的呈三维网络结构分布的碳化物相及呈弥散分布的超细碳化物相的综合增强作用是该涂层断裂韧性Kc比常规喷焊同样材料(非纳米)涂层的Kc明显提高的主要原因。 相似文献
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Murat Tutus Stefan Kaufmann Ingrid M. Weiss Motomu Tanaka 《Advanced functional materials》2012,22(23):4873-4878
In biological cells, various transmembrane enzymes function as highly effective chemical reactors confined in space with characteristic length scales of tens of nanometers to micrometer. However, it is still challenging to quantitatively confine membranes in compact reactor platforms without losing their biochemical functions. Here, a simple and straightforward strategy towards the fabrication of a new flow‐through reactor by the functional coating of porous silica microparticles with sarcoplasmic reticulum membranes is described. After a short incubation, the membranes achieve the homogeneous, full coverage of the particle surface, spanning across pores with the diameter of about 100 nm. By using the underlying pores as cavity reservoirs, transmembrane enzyme (Ca2+‐ATPase) in the membrane retains their capability of ATP hydrolysis. This enables us to confine 1.1 m2 of native membranes containing a large amount of Ca2+‐ATPase (approx. 10 nmol) in a column‐packaged, flow‐through reactor with merely 1.8 mL volume, which cannot be achieved by the reconstitution of proteins in artificial lipid membranes or condensation of membranes in suspensions. The distinct functional levels corresponding to different reaction buffers can be reproduced even after many buffer exchanges over 14 days, confirming the stability and reproducibility of the membrane‐particle hybrid reactors. 相似文献
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激光熔覆制备SiC/Ni基复合涂层及其耐冲蚀性能 总被引:8,自引:3,他引:5
采用激光熔覆技术在45#钢表面分别制备了Ni60A涂层及SiC/Ni60A复合涂层。采用光学显微镜(OM)、扫描电镜(SEM)和X射线衍射(XRD)仪对涂层进行了显微组织和物相分析,并测试了熔覆层的显微硬度和耐冲蚀磨损性能。结果表明,在激光作用下,SiC由于具有较小的生成热容易溶解在合金涂层中。熔覆层的物相主要由γ(Ni-Cr-Fe)固溶体及Fe7C3,Fe0.79C0.12Si0.09等化合物组成。在固溶强化、第二相强化及细晶强化的共同作用下,SiC/Ni60A涂层的抗冲蚀性能显著提高,涂层的显微硬度也明显增加。 相似文献