太阳吸收涂层与真空集热管的热性能

全玻璃真空集热管的热性能可用空晒温度，闷晒试验与平均热损系数表示。制备的五种多层铝－氮／铝吸收涂层，具有相近的高太阳吸收率，而法向发射率εｎ在０．１４－０．０５（８０℃）范围内。     

墨绿色太阳能选择性吸收涂层

报道了一种墨绿色太阳能选择性吸收涂层，其太阳吸收率α＝０．９４－０．９６，红外发射率ε＝０．３７￣０．３９。研究了吸光剂酞菁绿与Ｆｅ３ＣｕＯ５的光性互补效应及其配比对涂层光学性能和色相的影响。     

粉末火焰喷涂法制备黑铬太阳能选择性吸收涂层的实验研究

采用粉末火焰喷涂法制备的黑铬太阳能选择性吸收涂层,工艺简单,成本低,性能稳定,光谱选择性好。其可见光谱区的吸收率为０．９１,红外光谱区的发射率为０．１５。对黑铬涂层和黑板漆作集热板的太阳热水器性能进行了实验比较和讨论。     

Fe2O3—Cr2O3选择性吸收涂层的研究

研究了Ｆｅ２Ｏ３－Ｃｒ２Ｏ３有机硅改性丙烯酸选择性吸收涂层及其与ＴｉＯ２－ＳｉＯ２选择性透过膜复合涂层的性能，讨论了影响涂层光学性能的因素。当黑色颜料用量为４０－５０％、粒径０．０５－０．５μｍ、掺铝箔２０％左右、涂层厚度的２μｍ时，涂层光学性能较佳。该涂层还有较好的力学、耐腐蚀及耐老化等性能。涂敷ＴｉＯ２－ＳｉＯ２薄膜后其光学性能、硬度和耐蚀性等均得到改善。     

干涉型太阳选择性吸收涂层的光学性能设计

利用等效媒质理论对铝复合单层膜的光学性能进行了计算并以此为基础优化设计了具有干涉效应的铝复合选择性吸收涂层，该吸收层为两层时膜系谱曲线具有明显的干涉效应，与多层吸收层膜系相比其发射率低，吸收率二者相同，随温度的升高，发射率的变化前者较后者缓慢，实际制备了金属填充因子ｆａｌ为０．３８，０．２４的铝复合膜为吸收层，ＡｌＮ，Ａｌ２Ｏ３为减反射膜构成的膜系，其光谱线曲线与优化的理论曲线吻合较好。     

Al-AlN选择性吸收涂层性能分析及光学模拟

研究了双层Al-AlN吸收层加减反射层结构膜系,并对这种结构膜系涂层性能进行分析和模拟,在模拟得到单层Al-AlN层的膜厚和填充因子基础上,工艺优化制备得到的Al-AlN选择性吸收涂层吸收率达到0.942,100℃发射率为0.044,聚光比为1条件下,光热转换效率为0.89.     

Al-AlN选择性吸收涂层性能分析及光学模拟

研究了双层Al-AlN吸收层加减反射层结构膜系,并对这种结构膜系涂层性能进行分析和模拟,在模拟得到单层Al-AlN层的膜厚和填充因子基础上,工艺优化制备得到的Al-AlN选择性吸收涂层吸收率达到0.942,100℃发射率为0.044,聚光比为1条件下,光热转换效率为0.89。     

太阳光谱选择性吸收涂层制备工艺探讨

探讨粘结层、吸收层、减反射层的制备工艺及基底粗糙度状态对太阳选择性吸收涂层性能的影响。采用磁控溅射法,以SS/AlN涂层为例,制备太阳光谱选择性吸收涂层,并测试性能。结果表明：合适的制备工艺可以提高膜层的结合力和涂层的整体性能,胶带粘贴无脱落,吸收比96%,500℃发射比10.5%,并证实基底的粗糙度对涂层的发射率基本无影响。     

太阳能选择性吸收涂层

综述了国内外选择性涂层的研究进展与现状,介绍了涂层的制备方法和分类,分析了太阳能选择性吸收涂层的工作机理,对太阳能选择性吸收涂层的发展趋势做了展望。     

中温太阳光谱选择性PbS涂层制备

对现有的中温太阳光谱选择性PbS涂层制备方法加以改进,直接在预处理过的铜片上化学镀PbS。首先,考察了反应温度、反应物浓度、加碱量和反应时间等对PbS涂层太阳吸收率α的影响,得到了制备PbS涂层的优化条件;然后,在PbS涂层上涂敷TiO2作为保护层,以延缓PbS涂层的氧化,对两种涂层表面进行了XPS和SEM分析。实验结果证明,在不明显影响吸收率的情况下,TiO2/PbS涂层的耐热性能、耐腐蚀性和耐磨性能比单纯PbS涂层有明显提高,从而达到既降低发射率又延缓涂层寿命的目的。     

Measurement of Total Hemispherical Emittance of Spacecraft Thermal Control Coatings at Low Temperatures

Spacecraft payloads that operate at cryogenic temperatures often use passive thermal control systems that incorporate a variety of thermal control coatings to reject heat to space. The thermal performance of these systems depends significantly on the emittance of their thermal control coatings. This paper presents total hemispherical emittance measurements carried out at the ISRO Satellite Centre (ISAC) for thermal control coatings: Aeroglaze Z307 absorptive conductive polyurethane black coating (from 8 0K to 150 K) and PUC conductive black polyurethane coating (from 70 K to 200 K). The experiments were conducted in vacuum using a steady-state calorimetric method. This paper highlights the importance of obtaining a steady state for accurately estimating the emittance at cryogenic temperatures and the criterion for achieving this. The results indicate that the emittance in the cryogenic temperature range increases with temperature for the coatings considered in this paper. Determination of the uncertainty in the experimental results is also presented. Further, the sensitivity of emittance estimates to chamber wall emittance is discussed.     

Low emittance coatings and the thermal performance of vacuum glazing

The thermal performances of vacuum glazings employing coatings with emittance between 0.02 and 0.16 were simulated using a three-dimensional finite volume model. Physical samples of vacuum glazings with hard and soft coatings with emittance of 0.04, 0.12 and 0.16 were fabricated and their thermal performance characterised experimentally using a guarded hot box calorimeter. Good agreement was found between experimental and theoretical thermal performances for both a vacuum glazing with a soft coating (emittance 0.04) and those with hard coatings (emittance 0.12 and 0.16). Simulations showed that for a low value of emittance (e.g. 0.02), the use of two low-emittance coatings gives limited improvement in thermal performance of the glazing system. The use of a single high performance low-emittance coating in a vacuum glazing has been shown to provide excellent performance.     

Fabrication of hollow metal oxide–nickel composite spheres and their catalytic activity for hydrolytic dehydrogenation of ammonia borane

In this paper, we report an effective approach to the fabrication of hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres. In this approach, metal oxide–nickel composite shells were coated on polystyrene particles by the sol–gel method and the polystyrene templates were dissolved subsequently, or even synchronously, in the same medium to form hollow spheres. Neither additional dissolution nor a calcination process was needed to remove the polystyrene templates. The as-prepared hollow metal oxide–nickel composite spheres were characterized by transmission electron microscopy. The catalytic activities of hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres for hydrolytic dehydrogenation of aqueous NaBH₄/NH₃BH₃ solution were compared. The evolutions of 64, 58, and 18 mL hydrogen were finished in about 49, 69, and 162 min in the presence of the hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres from aqueous NaBH₄/NH₃BH₃ solution, respectively. The molar ratios of the hydrolytically generated hydrogen to the initial NH₃BH₃ both in the presence of hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres are 2.8, 2.4, and 0.1 (the theoretical value of 3.0), respectively, indicating that the hollow titania–nickel composite spheres and hollow zirconia–nickel composite spheres show much higher hydrogen evolution rates and the amount of hydrogen evolution via hydrolytic dehydrogenation of ammonia borane than the hollow silica–nickel composite spheres. From the results of ATR-IR spectra, a certain amount of residual PS templates exists in hollow silica–nickel composite spheres, and the amount of the residual PS templates were able to be reduced by increasing the amount of aqueous ammonia solution used for the preparation. The catalytic activity of hollow silica–nickel composite spheres increases when the amount of residual PS templates decreases.     

Reduction in emittance of thermal radiator coatings caused by the accumulation of a Martian dust simulant

Measurements were made of the effective emittance of three types of radiator coatings as a Martian dust simulant was added to the radiator surfaces. The apparatus consisted of multiple radiator coupons on which Carbondale Red Clay dust was deposited. The coupon design employed guard heating to achieve the accuracy required for acceptable emittance calculations. The apparatus was contained in a vacuum chamber that featured a liquid-nitrogen cooled shroud that simulated the Martian sky temperature. Three high-emittance radiator coatings were tested: two while silicate paints, Z-93P and NS-43G, and a silver Teflon film. Radiator temperatures ranged from 250 to 350 K with sky temperatures from 185 to 248 K.As dust was added to the radiator surfaces, the effective emittance of all three coatings decreased from initial values near 0.9 to a value near 0.4. A low-emittance control surface, polished aluminum, demonstrated a rise in effective emittance for thin dust layers, and then a decline as the dust layer thickened. This behavior is attributed to the conductive resistance caused by the dust layer.     

Fabrication of hollow silica–alumina composite spheres and their activity for hydrolytic dehydrogenation of ammonia borane

In this study, we investigated the influence of the preparation conditions of hollow silica–alumina composite spheres on their activity for the hydrolytic dehydrogenation of ammonia borane. Hollow silica–alumina composite spheres were prepared by polystyrene template method, and the polystyrene template particles were removed by calcination. The as-prepared hollow spheres were calcined at 523–873 K for 3 h. From the results of elemental analysis, polystyrene templates were completely removed by calcination at 873 K. small particles around the hollow spheres were observed from the images of transmission electron microscopy. To obtain homogeneous hollow spheres, the as-prepared hollow spheres were calcined at 873 K for 0–12 h. From the results of transmission electron microscopy, homogeneous hollow spheres were obtained by calcination for 0 h. The activity of the hollow spheres was the 2.6 times higher that of the hollow spheres calcined for 3 h. From the results of activity tests and ammonia temperature-programming desorption, the activity of the hollow spheres depends on amount of acid sites.     

Optimisation of metal sputtered and electroplated substrates for solar selective coatings

This study describes the performance of selective coatings to have maximum solar absorptance and minimum thermal emittance, in relation to substrate preparation. Aluminium and copper substrates, covered with sputtered or electroplated metal base layer, have been used to see the influence of different types of substrates for solar selective coatings. The effect of the base layer material, thickness, deposition process and deposition condition, on the optical performance of selective coatings has been analysed. Nickel was electroplated and nickel and vanadium were sputtered as a base layer on the Al and Cu substrates. A comparison of plated and sputtered nickel substrates for Ni:SiO₂ and V:Al₂O₃ composite solar selective coatings is presented. Theoretical results using computer simulation for solar selective composites on various substrates, and the effect of the base layer thickness on these substrates are compared with experimental results. The effects of the base layer thickness for cobalt and tungsten are also included. The sputtered base layers selective coatings produced higher absorptance along with higher emittance and electroplated base layer coatings resulted in comparatively lower absorptance and lower emittance. Hundred nanometre metal sputtered base layer is optimised for solar selective coatings.     

A review on recent advances in hollow spheres for hydrogen storage

Recent advancements in synthesizing materials potential for hydrogen storage have greatly forced the hydrogen storage technology ahead in recent years. Hollow spheres, with unparalleled characteristics like low density and high specific surface area, have emerged as one of the most promising alternatives for hydrogen storage applications. In the present review, the main synthesis approaches of hollow spheres including spray drying, Kirkendall, template-free and, template-assisted methods are surveyed and concisely described. In addition, different types of hollow spheres such as hollow carbons, hollow glasses and other less-common types like Boron nitrides and metal hollow spheres have been tackled with special focus on adsorption/desorption capacities as well as the kinetic of hydrogen storage/release. In addition to the recent progresses, some perspective and outlook on the advancement of hollow spheres and challenges in terms of synthesis methods and hydrogen storage performance were presented.     

Characterization of Ti1−xAlxN coatings with selective IR reflectivity

Ti_1−xAl_xN thin films were deposited by reactive magnetron sputtering. The obtained different stoichiometries give rise to different optical properties as the films change from metallic to dielectric. In this work the IR reflectivity of these coatings is investigated taking into account different application fields for IR selective Ti_1−xAl_xN thin films.Low Al content coatings present high reflectivity, high absorptance and low thermal emittance. High Al compositions give raise to coatings with high absorptance and high thermal emittance.The composition of the coatings was evaluated combining electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy. Scanning electron microscopy (SEM) revealed a columnar structure. Reflectance spectra for the visible and infrared spectral ranges were used to obtain the solar absorptance and thermal emittance values, used to calculate the equilibrium temperature of the coatings.The thermal stability in air from 300 to 600 °C was also evaluated.     

Enhanced electrochemical performance of nickel hydroxide electrode with monolayer hollow spheres composed of nanoflakes

Nickel hydroxide electrodes with hollow spheres were fabricated using a PS (polystyrene) sphere template and electrochemical deposition. The nickel hydroxide grew perpendicular to the electrode substrate during anodic deposition and around the PS spheres during cathodic deposition. After the removal of the PS template, hollow spheres or open hollow spheres were formed via cathodic deposition. The nickel hydroxide electrode with hollow spheres and nanoflakes showed greatly enhanced electrochemical performance in alkaline solution compared with the bare nickel hydroxide electrode. The opening of the hollow spheres facilitated easy electrolyte transport to the reaction sites and led to a further increase in the specific capacitance of the nickel hydroxide electrode. The specific capacitance of the electrode with the open hollow spheres reached 800 F g⁻¹, which was much higher than that of the bare electrode (224 F g⁻¹) and the hollow-sphere electrode (342 F g⁻¹) at a discharge current density of 10 A g⁻¹.     

Advanced procedure for the assessment of the lifetime of solar absorber coatings

New solar absorber coatings are developed and used in advanced collector designs with improved efficiency. The operation temperature and stagnation temperature as the main durability load for the absorbers were increasing during the past due to these innovations. Especially the highly selective new coatings have to suffer by these stronger loads. The service life estimation procedures developed in the framework of research activities of the IEA Solar Heating and Cooling Programme (Task 10 and Working Group Materials in Solar–Thermal Collectors) were based on load profiles for less-advanced absorbers and collectors and did not take into account the impact of the optical properties of the absorber coatings on the stagnation temperature of the collectors, which is the main reason for temperature degradation. A new procedure was developed, which allows testing depending on the optical properties (Solar absorptance and thermal emittance) of the absorbers.