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1.
Low infrared emissivity of polyurethane/Cu composite coatings 总被引:5,自引:0,他引:5
Huijuan Yu Guoyue Xu Xingmei Shen Xiaoxing Yan Chuangwei Cheng 《Applied Surface Science》2009,255(12):6077-6081
Polyurethane/Cu composite coatings with low infrared emissivity near to 0.10 at the wavelength of 8-14 μm were prepared by a simple and convenient process. The influences of the content of Cu powder, surface roughness, coating thickness and temperature on infrared emissivity of the coatings were systematically investigated. The results indicated that the emissivity decreases significantly with increasing content of Cu powder and coating thickness. The coatings with smooth surface exhibit lower emissivity values than those with rough coatings. Moreover, we found the relationship between the emissivity of coatings and temperature presents a “U” type, and the emissivity reaches to the minimum at about 380 K. The mechanisms of low emissivity were proposed by optical theories, which are found to be in a good agreement with the experimental results. 相似文献
2.
The main challenge of low infrared emissivity coatings based on aluminum flake lies in finding an efficient method to synthesize the composite pigment with low infrared emissivity and low lightness simultaneously. In this work, we overcome this constraint to some extent, synthesizing a novel Al/Co3O4 magnetic composite pigments with low infrared emissivity and low lightness by thermal cracking and hot flowing method. The results show that the covering area of Co3O4 on the aluminum flake can be tuned by the amount of CoCO3 adding in precursor and the reaction temperature of hot flowing, both of which pay a key factor on the VIS and IR spectral reflectance and magnetic properties. The magnetic Al/Co3O4 composite pigments with low lightness and low infrared emissivity can be obtained at 130 °C for 24 h in hot flowing liquid. The lightness L1 can be decreased to 69.2, however the infrared emissivity (8–14 μm) is also low to 0.45. Compared with the single Al flakes, Al/Co3O4 magnetic composite pigments present stronger magnetic properties. Therefore, the Al/Co3O4 magnetic composite pigments have offered new choice for the pigments of low infrared emissivity coatings. 相似文献
3.
Comparison of anti-corrosion properties of polyurethane based composite coatings with low infrared emissivity 总被引:1,自引:0,他引:1
Yajun Wang Guoyue XuHuijuan Yu Chen HuXiaoxing Yan Tengchao GuoJiufen Li 《Applied Surface Science》2011,257(10):4743-4748
Four polyurethane resins, pure polyurethane (PU), epoxy modified polyurethane (EPU), fluorinated polyurethane (FPU) and epoxy modified fluorinated polyurethane (EFPU), with similar polyurethane backbone structure but different grafting group were used as organic adhesive for preparing low infrared emissivity coatings with an extremely low emissivity near 0.10 at 8-14 μm, respectively. By using these four resins, the effect of different resin matrics on the corrosion protection of the low infrared emissivity coatings was investigated in detail by using neutral salt spray test, SEM and FTIR. It was found that the emissivity of the coatings with different resin matrics changes significantly in corrosion media. And the results indicated that the coating using EFPU as organic adhesive exhibited excellent corrosion resistance property which was mainly attributed to the presence of epoxy group and atomic fluorine in binder simultaneously. 相似文献
4.
Z.W. Wang Y.M. Wang Y. Liu J.L. Xu L.X. Guo Y. Zhou J.H. Ouyang J.M. Dai 《Current Applied Physics》2011,11(6):1405-1409
Ceramic coatings containing TiO2 were formed on Ti6Al2Zr1Mo1V alloy surface by microarc oxidation (MAO) method. The microstructure, phase and chemical composition of the coatings were analyzed by SEM, XRD and EDS techniques. The coating mainly consists of rutile TiO2 and a small amount of anatase TiO2. The infrared emissivity values of coated and uncoated titanium samples when exposed to 700 °C were tested. It was found that the coating exhibits a higher infrared emissivity value (about 0.9) in the wavelength range of 8–14 μm than that of the uncoated titanium alloy, although which shows a slight increase from 0.1 to 0.3 with increasing exposure time at 700 °C. The relatively high infrared emissivity value of the MAO coating is possibly attributed to the photon emission from the as formed TiO2 phase. 相似文献
5.
ZnO:Al(AZO) thin films with different Al-doped concentration were developed under different temperature. The effects of the temperature and Al-doped concentration on the infrared emissivity were investigated. Results show that the crystalline phase of the AZO films is hexagonal wurtzite which is the same as that of the un-doped ZnO film. The crystalline size become larger and the particle shapes become more regular with the increase of temperature, which lead to the increase of resistivity and the decreases of the infrared emissivity. 相似文献
6.
Collagen/SiO2 composites were prepared in aqueous suspensions. Adsorption behaviors of collagen onto the surfaces of SiO2 spheres were studied. Structure and thermal properties were measured with FTIR, SEM, TEM, and TGA-DTA. The results showed that the self-aggregation of collagen macromolecules was taken place during the adsorption of collagen on SiO2 sphere. The morphology of collagen evolved from line to microfibrils with the increase in the concentration of collagen along with the distortion of SiO2. Interfacial interactions of electrostatic forces and hydrogen bonding between the collagen macromolecule and SiO2 sphere had a vital effect on the adsorption of collagen. The amount of the collagen adsorption was increased with the increase of the collagen concentration, yet decreased in increased pH value of the solution. It was found that the composites exhibited lower infrared emissivity values in the wavelength ranged from 8 to 14 μm than not only pure collagen but also SiO2 sphere, and the value of infrared emissivity was related to the adsorption amount of collagen in the composites. 相似文献
7.
大气汽溶胶复合微粒子的光学截面及红外发射率光谱的计算 总被引:2,自引:1,他引:2
在文章[1]的基础上,根据M.L.Aden和A.Kerker的复合微粒子光散射理论计算了汽溶胶大气中复合微粒子模型的光学特性,得到了汽溶胶的散射截面、吸收截面和消光截面以及红外发射率光谱,为研究大气红外传输提供了计算方法. 相似文献
8.
As a focus of research on materials science, bionic structure has drawn a great deal of attention from researchers. In this paper, patterned antireflection microstructure used for space optical window was fabricated on the surface of sapphire single crystal based on “Biomimetic Motheye Structure”. Meanwhile, emissivity of patterned sapphire at high temperature was investigated. The results indicated that transmittance of sapphire increased with spectrum red shift effect because of surface microstructures; the emissivity of patterned sapphire increased with rising of temperature in 6∼11 μm band; microstructures on surface led the scattering and attenuation coefficient of light to increase, thus, the emissivity of patterned sapphire was greater than that of contrast specimen which was not patterned. At the end of the paper, an audacious conclusion was made that the effect of microstructure on emissivity would decrease or even disappear with the increase of temperature. 相似文献
9.
In this letter, we investigate the structural, optical, and electrical properties of Al-doped ZnO (AZO) thin film coating prepared by direct current (DC) facing-target sputtering method at room temperature, of which the average optical transmittance is 81% between 400 and 700 nm while the sheet resistance is about 10 Ω/□. Then, based on this AZO coating, in order to enhance the transmittance, interfacial adhesion strength and weathering resistance, two kinds of antireflective coatings are designed for different application purposes. For the two kinds, the highest transmittances in the visible region (400 700 nm) can reach 86.9% and 81.8%. resoectivelv. The design is performed using Macleod Optical Design software. 相似文献
10.
为研究航天领域特种材料高温区域的光谱辐射特性,建立了基于傅里叶光谱仪的超高温光谱发射率测量系统。系统线性度是发射率测量精度的保证,通过测量多温度点黑体辐射的光谱信号,采用多温度点线性拟合方法求得每个光谱点的光谱信号值与黑体光谱辐射亮度的函数关系式,并结合仪器线性度测量理论,建立了光谱发射率测量系统的线性度测量方法。实验测量了黑体温度范围1 000~2 000℃和光谱范围3~20μm的光谱辐射信号,求得波长λ=4μm的理论直线与测量光谱值的线性关系。实验表明,仪器在4~18μm光谱范围响应较好,除CO2强吸收光谱区域,仪器的光谱线性度均优于1%。当测量系统线性度一定时,温度越高,光谱误差对发射率的影响越小。评定光谱发射率测量系统的线性度有利于剔除个别温度点光谱扰动带来的误差。 相似文献
11.
6061 aluminum alloy was treated by MAO at various temperatures of the alkali silicate electrolyte using pulsed bipolar current mode for ten minutes. The surface microstructures and properties were studied using SEM, EDX, and XRD. The infrared emissivities of the MAO ceramic coatings were measured at the 70 °C using FTIR spectrometer. The electrolyte temperature strongly affected all the surface properties. The MAO alumina ceramics prepared in cold electrolytes have volcano-like and accumulated particles microstructures, while those prepared in hot electrolytes were: rougher, thinner and contained grainy spherical hollow bulgy microstructures with more pore density and more sillimanite and cristobalite phases which enhanced the IR emissivity. Also, the increment of sillimanite and cristobalite phases moved the apparent peaks toward longer wavelengths, and broadened the opaque region of the IR spectra. As a result, the increment of electrolyte temperature from 12.3 °C to 90.5 °C increased the average of LWIR emissivity from 80.4% to 94.4%, respectively, for the MAO ceramic coatings. 相似文献
12.
田贵才 《原子与分子物理学报》2002,19(1):91-93
根据Mie微粒子光散射理论计算了汽溶胶大气模型的光学特性,得到了汽溶胶的散射截面、吸收截面和消光截面以及红外波段散射强度分布,同时计算了汽溶胶大气的发射率光谱.为研究大气红外传输提供了计算方法. 相似文献
13.
Hui TangTiezhu Xin Qiu SunChuangui Yi Zhaohua JiangFuping Wang 《Applied Surface Science》2011,257(24):10839-10844
Ceramic coatings with high emission were fabricated on Ti6Al4V alloy by microarc oxidation (MAO) with additive FeSO4 into the electrolyte. The microstructure, chemical composition and chemical state of the coatings were determined by SEM, XRD, EDS and XPS, respectively. The bonding strength between the coating and substrate was studied by tensile strength test, together with the thermal shock resistance of the coating. The results showed that Fe content in the coating layer significantly affect its thermal emissivity. The relative content of Fe in the coatings surface increased at first and then decreased with increasing the concentration of FeSO4 in electrolytes, so does the emissivity of the coatings. The bonding strength became weaker with increasing the concentration of FeSO4. In addition, the coating remains stable over 40 cycles of thermal shocking. The coating formed at 3 g/L FeSO4 demonstrates the highest an average spectral emissivity value around of 0.87, and bonding strength higher than 33 MPa. 相似文献
14.
Janos Mink Judith Mihaly Csaba Nemeth Peter Nemeth Markus Drees Boris V. Lokshin 《应用光谱学评论》2018,53(6):439-485
New composite materials based on clay minerals had been prepared by reductive calcination. These materials exhibit very strong infrared (IR) emission at quite low temperatures. The structural properties and emission capabilities of the new materials have been studied by various theoretical and experimental methods. In addition, a brief overview of the medical and other practical applications of IR-emitting materials is presented. The basic principles of IR emission spectroscopy are discussed with special respect to low temperatures (close to human-body temperature). Furthermore, DFT calculations on a kaolinite structure of chemical composition of [Al4Si4 O8(OH)16]4? have been performed. The calculated bond distances and IR spectrum are in good agreement with experimental observations. Structural and compositional characterization of the new composite materials have been performed by various structural analytical methods. An interesting effect on the IR phosphorescence of composite samples has been established. After 2 hours of IR light exposure at room temperature from the FT-IR spectrometer, the composite materials exhibited enhanced emission of IR radiation with relaxation time about 40 min. Finally, two practical applications of the composites have been investigated, namely polyamide-based fabrics and rubber preservatives. 相似文献
15.
When heated by high-energy electron beam (EB), SiC can decompose into C and Si vapor. Subsequently, Si vapor reacts with metal oxide thin film on substrate surface and formats dense SiO2 thin film at high substrate temperature. By means of the two reactions, SiC/SiO2 composite thin film was prepared on the pre-oxidized 316 stainless steel (SS) substrate by electron beam-physical vapor deposition (EB-PVD) only using β-SiC target at 1000 °C. The thin film was examined by energy dispersive spectroscopy (EDS), grazing incidence X-ray asymmetry diffraction (GIAXD), scanning electron microscopy (SEM), atomic force microscopy (AFM), backscattered electron image (BSE), electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Fourier transformed infra-red (FT-IR) spectroscopy. The analysis results show that the thin film is mainly composed of imperfect nano-crystalline phases of 3C-SiC and SiO2, especially, SiO2 phase is nearly amorphous. Moreover, the smooth and dense thin film surface consists of nano-sized particles, and the interface between SiC/SiO2 composite thin film and SS substrate is perfect. At last, the emissivity of SS substrate is improved by the SiC/SiO2 composite thin film. 相似文献
16.
For the long-pulse high-confinement discharges in tokamaks, the equilibrium of plasma requires a contact with the first wall materials. The heat flux resulting from this interaction is of the order of 10 MW/m2 for steady state conditions and up to 20 MW/m2 for transient phases. The monitoring on surface temperatures of the plasma facing components (PFCs) is a major concern to ensure safe operation and to optimize performances of experimental operations on large fusion facilities. Furthermore, this measurement is also required to study the physics associated to the plasma material interactions and the heat flux deposition process. In tokamaks, infrared (IR) thermography systems are routinely used to monitor the surface temperature of the PFCs. This measurement requires an accurate knowledge of the surface emissivity. However, and particularly for metallic materials such as tungsten, this emissivity value can vary over a wide range with both the surface condition and the temperature itself, which makes instantaneous measurement challenging. In this context, the multi-spectral infrared method appears as a very promising alternative solution. Indeed, the system has the advantage to carry out a non-intrusive measurement on thermal radiation while evaluating surface temperature without requiring a mandatory surface emissivity measurement.In this paper, a conceptual design for the multi-spectral infrared thermography is proposed. The numerical study of the multi-channel system based on the Levenberg-Marquardt (LM) nonlinear curve fitting is applied. The numerical results presented in this paper demonstrate the design allows for measurements over a large temperature range with a relative error of less than 10%. Furthermore, laboratory experiments have been performed from 200 °C to 740 °C to confirm the feasibility for temperature measurements on stainless steel and tungsten. In these experiments, the unfolding results from the multi-channel detection provide good performance on temperature measurement, which supports our numerical evaluation and demonstrates the potential feasibility for metallic surface high temperature measurement with this method. 相似文献
17.
Nanocrystalline La0.6Sr0.4Co0.2Fe0.8O3 − δ (LSCF) and La0.25Ba0.25Sr0.5Co0.2Fe0.8O3 − δ (LBSCF) with a high specific surface area (~ 40 m²/g) were synthesized by spray pyrolysis. The as prepared powder was characterized by X-ray diffraction, nitrogen adsorption, and high-resolution electron microscopy. Water-based dispersions of pure LSCF, LBSCF and mixtures containing gadolinium doped ceria (GDC) with agglomerate sizes of approx. 50 nm were prepared by application of ultrasonic energy. Spin coating was employed to prepare porous thin films. The thickness of the films (≤1 μm) was more than 10–20 times lower than conventional cathode layers. The interfacial polarization resistances of LBSCF cathodes are 19, 38, and 101 mΩ cm2 at 650, 600, and 550 °C, respectively. The high performance is attributed to the nanometer-sized grain dimensions, the nanoporosity, and the large specific surface area within the cathode layer. The novel approach of preparing nanoparticulate thin film cathodes suggests strong benefit for Micro Solid Oxide Fuel Cells operating below 500 °C. 相似文献
18.
Francisco Javier Meca Meca Francisco Javier Rodríguez Sanchez Pedro Martín Sanchez 《Infrared Physics & Technology》2002,43(6):367-375
This paper develops a method that enables the most suitable range of wavelengths to be ascertained in which to take infrared temperature measurements of surfaces in the open air in conditions in which high uncertainty exists in the environmental radiation and emissivity values. The optimisation criterion adopted for the error is that of achieving the narrowest possible band of maximum uncertainty. The results demonstrate that it is possible to cancel out the solar radiation contribution to the maximum uncertainty present in the measurement whilst still working in short wavelengths where this radiation is very intense and, therefore, optimise the band of uncertainty produced by emissivity and environment radiation. 相似文献
19.
Indium tin oxide (ITO) films as the low emissivity coatings of Ni-based alloy at high temperature were studies. ITO films were deposited on the polished surface of alloy K424 by direct current magnetron sputtering. These ITO-coated samples were heat-treated in air at 600–900 °C for 150 h to explore the effect of high temperature environment on the emissivity. The samples were analyzed by X-ray diffraction (XRD), SEM and EDS. The results show that the surface of sample is integrity after heat processing at 700 °C and below it. A small amount of fine crack is observed on the surface of sample heated at 800 °C and Ti oxide appears. There are lots of fine cracks on the sample annealed at 900 °C and a large number of various oxides are detected. The average infrared emissivities at 3–5 μm and 8–14 μm wavebands were tested by an infrared emissivity measurement instrument. The results show the emissivity of the sample after annealed at 600 and 700 °C is still kept at a low value as the sample before annealed. The ITO film can be used as a low emissivity coating of super alloy K424 up to 700 °C. 相似文献
20.
The fabrication method and the pyroelectric response of a single element infrared sensor based lead zirconate titanate (PZT) particles and polyvinylidene fluoride P(VDF-TrFE) copolymer composite thick film is reported in this paper. A special thermal insulation structure, including polyimide (PI) thermal insulation layer and thermal insulation tanks, was used in this device. The thermal insulation tanks were fabricated by laser micro-etching technique. Voltage responsivity (RV), noise voltage (Vnoise), noise equivalent power (NEP), and detectivity (D*) of the PZT/P(VDF-TrFE) based infrared sensor are 1.2 × 103 V/W, 1.25 × 10−6 V Hz1/2, 1.1 × 10−9 W and 1.9 × 108 cm Hz1/2 W−1 at 137.3 Hz modulation frequency, respectively. The thermal time constant of the infrared sensor τT was about 15 ms. The results demonstrate that the composite infrared sensor show a high detectivity at high chopper frequency, which is an essential advantage in infrared detectors and some other devices. 相似文献