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排序方式: 共有3612条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(36):16165-16178
This study deals with the manufacturing of catalyst-coated membranes (CCMs) for newcomers in the field of coating. Although there are many studies on electrode ink composition for improving the performance of proton-exchange membrane fuel cells (PEMFCs), there are few papers dealing with electrode coating itself. Usually, it is a know-how that often remains secret and constitutes the added value of scientific teams or the business of industrialists. In this paper, we identify and clarify the role of key parameters to improve coating quality and also to correlate coating quality with fuel cell performance via polarization curves and electrochemical active surface area measurements. We found that the coating configurations can affect the performance of lab-made CCMs in PEMFCs. After the repeatability of the performance obtained by our coating method has been proved, we show that: (i) edge effects, due to mask shadowing - cannot be neglected when the active surface area is low, (ii) a heterogeneous thickness electrode produces performance lower than a homogeneous thickness electrode, and (iii) the origin and storage of platinum on carbon powders are a very important source of variability in the obtained results. 相似文献
2.
AbstractDifferent drying methods (spray drying (SD), vacuum drying (VD), microwave vacuum drying (MVD), and infrared vacuum drying (IFVD)) were applied in order to compare the hygroscopicity behavior of chicken powders. The hygroscopicity curves and glass transition temperature were used to evaluate the influence of ambient humidity and temperature on moisture absorption of powders. The results showed that the chicken powder dried by MVD had the lowest moisture absorption, followed by IFVD, VD, and SD. The hygroscopicity of SD chicken powders was different from other three kinds of chicken powders due to the physical properties of particles and the changes of protein secondary structure as detected by the Fourier transform-infrared spectrometer. For the three vacuum drying methods, the difference of protein secondary structure was the main reason of differences in hygroscopicity. Although MVD chicken powders were slightly inferior to SD chicken powders in taste, MVD chicken powders were the best in terms of smell and color as suggested by instrumental sensory parameter evaluations. It was found that MVD had a positive effect on reducing moisture absorption and maintaining sensory quality of chicken powders. 相似文献
3.
《Ceramics International》2022,48(3):3652-3658
Digital light processing (DLP) is one of the most important additive manufacture technologies to fabricate ceramic parts with complex geometries. Compared with pure photosensitive resin, the cure performance of ceramic suspensions is obviously different due to the optical property change after the addition of ceramic powders. In this paper, a unique oxidation process was used to modify the optical properties of nitride powders including AlN and Si3N4. The properties of oxidized ceramics were investigated and the cure performance of ceramic suspensions was then characterized. The effect of oxidation time on cure performance was evaluated. The results showed that for AlN, oxidation process leads to the smaller cure depth and smaller excess cure width as compared with non-oxidized AlN and for Si3N4, oxidation process leads to the larger cure depth and larger excess cure width as compared with non-oxidized Si3N4, indicating that both refractive index and light absorbance of ceramic powders have obvious effects on cure behaviors. Additionally, the cure behavior of oxidized ceramic suspension in this study shows that the relationship of cure depth vs. incident energy agrees well with Beer- Lambert model, but the excess cure width vs. incident energy is not consistent with quasi Beer-Lambert model due to the nature of digital micromirror device (DMD). 相似文献
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介绍了细旦涤纶50/长绒棉30/丽赛20纤维的性能,及其混纺纱的生产加工工艺,针对生产中存在的问题,采取了有效的措施,生产的7.3 tex混纺纱线,满足了市场的要求。 相似文献
7.
Li Yonghua Wang Chunbo Chen Hongwei 《Frontiers of Energy and Power Engineering in China》2007,1(1):96-100
Power plants in China have to burn blended coal instead of one specific coal for a variety of reasons. So it is of great necessity
to investigate the combustion of blended coals. Using a test rig with a capacity of 640 MJ/h with an absolute milling system
and flue gas online analysis system, characteristics such as burnout, slag, and pollution of some blended coals were investigated.
The ratio of coke and slag as a method of distinguishing coal slagging characteristic was introduced. The results show that
the blending of coal has some effect on NO
x
but there is no obvious rule. SO
x
emission can be reduced by blending low sulfur coal.
Translated from Proceedings of the CSEE, 2005, 25(18): 97–103 [译自: 中国电机工程学报] 相似文献
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9.
Songping Wu 《Materials Letters》2007,61(16):3526-3530
In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion strength which is attributed to the rough interface from interfacial reaction between glass and chip, and a good densification. Diffusion of metal between copper thick film and nickel thick film is clear. Ni-Cu solid solution appears under high temperature firing. 相似文献
10.