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941.
用光学显微镜和扫描电镜观察了〔321〕和〔110〕位向的铌单晶在循环变形时的表面形貌变化.研究了圆形试样经过循环变形到饱和阶段表面出现的皱褶.本文用形变带这个词来表示材料经不均匀变形后产生的这种皱带,它不同于有特定位向的扭折带.根据表面形貌细节把形变带分成五类,并对形变带的形成过程进行了讨论.形变带所在平面和轴向夹角均在≈45°,说明宏观应力状态对形变带的形成起重要作用. 相似文献
942.
Electric Field and Gradient Microstructure for Cooperative Driving of Directional Motion of Underwater Oil Droplets 下载免费PDF全文
Dongliang Tian Linlin He Na Zhang Xi Zheng Yuhai Dou Xiaofang Zhang Zhenyan Guo Lei Jiang 《Advanced functional materials》2016,26(44):7986-7992
Driving a liquid droplet with control of directional motion on a solid surface, by introducing a surface wettability gradient or external stimuli, has attracted considerable research attention. There still remain challenges, however, due to the slow response rate and slow speed of continuous liquid droplet motion on the structured surface. Here, an approach to continuously drive the underwater oil droplet with control of directional motion by the cooperative effects of an electric field and the gradient of a porous polystyrene microstructure is demonstrated. The gradient microstructure induces the liquid droplet to take on an asymmetrical shape, causing unbalanced pressure on both ends to orient the droplet for motion in a particular direction. Meanwhile, the electric field decreases the contact area and the corresponding viscous drag between the droplet and the gradient‐structured surface. Then, the unbalanced pressure pushes the underwater oil droplet to move directionally and continuously at a certain voltage. This work provides a new strategy to control underwater oil droplets and realize unidirectional motion. It is also promising for the design of new smart interface materials for applications such as electrofluidic displays, biological cell and particle manipulation, and other types of microfluidic devices. 相似文献
943.
Zhonghua Bao Ke Li Shuo Wang Kai Gao Dongliang Zhang Mei Li 《Advanced Powder Technology》2021,32(5):1611-1618
Submicron-cerium oxide particles were synthesized by applying hypergravity using ammonium bicarbonate (precipitant) and cerium nitrate hexahydrate (precursor). The influence of the concentration, pH, dispersant loading, flow rate, rotation speed of the hypergravity rotating bed, calcination temperature, and time on the cerium oxide particle size were examined by zeta potential, solid–liquid contact angle, thermo-gravimetry–differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The cerium oxide particles were highly dispersed, with an average particle size of 200 nm. Calcining at 650 °C for 1.5 h afforded the smallest particles. The crystallite size and fraction crystallinity increased with prolonged calcination. Crystalline cerium dioxide grew along three crystal planes, forming a complete face-centered cube, affording high hardness and activity of the polishing powder. The optimal conditions were: cerium nitrate concentration: 0.7 mol/L, cerium nitrate/ammonium bicarbonate molar ratio: 1:3, dispersant mass fraction: 3%, cerium nitrate initial pH: 4–5; the precursor solution was adjusted to pH 9 with ammonia water. Hypergravity coprecipitation with 1.5 h calcination afforded submicron-sized cerium oxide with a uniform size distribution using ammonium bicarbonate in an industrially viable process. The simple and low-cost manufacturing process may enable the development of hypergravity-assisted chemical synthesis technology. 相似文献
944.
采用水热法先合成MnFe2O4(MFO), 然后通过与PH3反应制备了磷酸根离子掺杂的MnFe2O4(PMFO), 以提高它的电化学性能。研究结果表明, 磷酸根掺杂不仅增大了MnFe2O4的比表面积, 也增加了材料的电导性。在1 A/g电流密度下, PMFO比容量为750 F/g, 与MFO相比, 比电容提高了近70%, 同时循环稳定性也得到了极大改善。以PMFO为正极、活性碳为负极的非对称超级电容器(ASCs), 在功率密度为2.7 kW/kg时, 能量密度达到168.8 Wh/kg。因此, PMFO是有极大应用前景的超级电容器电极材料。 相似文献
945.
946.
Xinwen ZHU Dongliang JIANG Shouhong TANThe State Key Laboratory of High Performance Ceramics Superfine Structure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China Manuscript received February in revis 《材料科学技术学报》2002,18(1)
An innovative approach has been developed to fabricate reticulated porous ceramics (RPCs) with uniform macrostruc-ture by using the polymeric sponge as the templates. In this approach, the coating process comprises of two stages. In the first stage, the thicker slurry was used to coat: uniformly the sponge substrate. The green body was preheated to produce a reticulated preform with enough handling strength after the sponge was burned out. In the second stage, the thinner slurry was used to coat uniformly the preform. The population of the microscopic and macroscopic flaws in the structure is reduced significantly by recoating process. A few filled cells and cell faces occur in the fabrication and the struts were thickened. A statistical evaluation by means of Weibull statistics was carried out on the bend strength data of RPCs, which were prepared by the traditional approach and innovative approach, respectively. The result shows that the mechanical reliability of RPCs is improved by the innovative approach 相似文献
947.
948.
Kai Hui Zuo Yu-Ping Zeng Dongliang Jiang 《Materials science & engineering. C, Materials for biological applications》2010,30(2):283-287
Porous hydroxyapatite (HAP) ceramics with different morphologies were fabricated by the freeze casting method. The morphologies of HAP ceramics were modified by adjusting the concentration of polyvinyl alcohol (PVA) additive in the HAP slurries. HAP ceramics without PVA additive were composed of non-interconnected macroscopic lamellar pores and porous ceramic walls. With PVA additive, the HAP ceramics were made up of small lamellar pores or three-dimensional reticulate pores and porous ceramic walls. PVA additive had no effect on the phase composition of HAP ceramics. The open porosity and pore connectivity were improved because of the addition of PVA. 相似文献
949.
950.
Lin Yufang Zhao Dongliang Wang Xinlin 《中国稀土学报(英文版)》2006,24(5):532-532
Employing the first principles discrete variational method (DVM), the electronic structures of LaNi5 hydrogen storage alloys with Ni replaced by common element M (M = Al or Si) were investigated. The results show that the s electrons of H mainly interact with the s electrons of non-hydride-forming element Ni and M, though there is a larger affinity of La for hydrogen than that of Ni and M in pure metal hydrogen system. The effect on the electronic structure of Al is very similar to that of Si in the LaNi5 alloy because of their similar character. 相似文献