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71.
《Sensors and actuators. B, Chemical》2006,113(1):265-271
Gas sensing characteristics of WO3 powder and its physical properties under different heat treatment conditions have been investigated. The WO3 powder was synthesized by wet process from ammonium tungstate parapentahydrate and nitric solution. The precipitated product was then calcined at 300–800 °C for 2–12 h. The physical properties of the products were characterized by using X-ray diffractometer (XRD), scanning electron microscope (SEM), and BET method. It was found that the crystallite size, particle size and surface area of the WO3 powders were in the range of 30–45 nm, 0.1–3.0 μm and 1.2–3.7 m2/g, respectively. Calcination at higher temperature and longer time led to the increase of particle size by more than 300%, and reduction in specific surface area by more than 60%. However, the crystallite size was found to increase only by ∼30% under identical heat treatment. These results inferred that such heat treatment had more profound effect on crystallite aggregation than on crystallite growth. Gas sensing measurement showed that the largest change of output voltage to both ethyl alcohol and ammonia was obtained from the sensor calcined at 600 °C for 2 h, which had the highest surface area. However, the highest sensitivity which is defined as the ratio of sensor's resistance in air to that in the sample gas, Rair/Rgas, was obtained from the sensor calcined at 600 °C for 6 h due to its highest background resistance in air. Moreover, it was also found that the sensors were less sensitive to the oxygen content in the carrier gas and did not sensitive at all to water vapor. 相似文献
72.
Polymer coating was widely used as a protective coating on Mg alloy stent due to its excellent deformability. However, the polymer coating with lots of macro- and micro-holes after solvent evaporation during forming process would make corrosion medium permeate easier and decrease the corrosion resistance of Mg alloy stent. In this study, a novel critical re-melting method was adopted to improve the polymer coating densification, which was evaluated by the surface morphology of coating. The corrosion resistance of Mg alloy stent after critical re-melting treatment was examined by the electrochemical and immersion tests. The results indicated that the corrosion resistance of Mg alloy stent with polymer coating was improved significantly by polymer critical re-melting treatment. 相似文献
73.
Waqas Ahmad Liang Pan Karim Khan Lingpu Jia Qiandong Zhuang Zhiming Wang 《Advanced functional materials》2023,33(19):2300686
Van der Waals (vdWs) heterostructures enable bandgap engineering of different 2D materials to realize the interlayer transition via type-II band alignment leading to broaden spectrum that is beyond the cut-off wavelength of individual 2D materials. Interlayer transition has a significant effect on the optoelectronic performance of vdWs heterostructure devices, and strong interlayer transition in 2D vdWs heterojunction is always demandable for sufficient charge transfer and rapid speed response. Herein, a state-of-the-art review is presented on recent progress on interlayer transition in vdWs heterostructures for near-infrared (NIR) photodetectors. First, the general synthesis techniques for vdWs heterostructures, band alignments in the vdWs heterostructures are provided. Then, the mechanism of interlayer transition in vdWs heterostructure and recent progress on interlayer transition in vdWs heterostructures for NIR photodetectors are summarized. Afterward, some worthy applications of NIR photodetectors are reviewed in related areas of this topic. At the last, an outlook, challenges, and future research directions of vdWs heterostructures for photodetectors at broaden response spectrum are presented. 相似文献
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通过对圆盘剪的工作原理和剪切机理的研究,利用ANSYS/LS-DYNA来对圆盘剪剪切铝带三维模型进行有限元分析,并采用显示动力学模块对剪切过程进行了有限元分析。分析了铝带剪切断裂的过程,得到了铝带剪切过程中的应力、应变随时间的变化,断裂区上特定单元的应力、应变变化。仿真研究了工艺参数如重叠量、侧向间隙、带料厚度、剪切速度等对铝带剪切品质的影响,进行分析和研究,提高了剪切品质。 相似文献
77.
《Journal of the European Ceramic Society》2006,26(1-2):73-80
The effect of SnO2 content on the sintering behavior of nanocrystalline indium tin oxide (ITO) ceramics was examined. Nanocrystalline ITO powders with different SnO2 content from 0 to 12 at.% were prepared by a coprecipitation method. The particle size of the ITO powders was in the range of 20–26 nm. The temperature that showed maximum densification increased as the content of SnO2 increased. Since the solubility limit of SnO2 in In2O3 is known to be about 6–8 at.%, the samples with 8 and 12 at.% Sn showed second phases after sintering. Various phase development processes of the second phases were observed, i.e., In2SnO5, which was observed at a low temperature, decomposed into In2O3 and SnO2 at over 1000 °C, then synthesized again into In4Sn3O12 at over 1300 °C. The densification behavior with respect to the SnO2 content was explained from a viewpoint of the second phase development at different sintering temperatures. 相似文献
78.
《Journal of power sources》2006,160(1):490-499
The objective of this review paper is to present a summary of the specific contributions in the field of fuel processing, particularly, outlines various developments involving catalytic reforming of a range of fuels for the development of an efficient fuel-processing unit for syngas production in fuel cell applications. Two major topics are discussed (i) the basic reactions involved in each of the processes and (ii) various catalyst systems that have been tested. A final short section offers some new possible routes for future research. 相似文献
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