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61.
本文较详细地描述了多孔硅的电致发光(EL),以及发光的量子限制效应的机制,并且讨论了目前已经制备出的几种多孔硅发光二级管:Ps/电解液型,Schot-tky-Like,PN结等二极管。最后,讨论了多孔硅作为半导体光电材料所存在的一些问题。 相似文献
62.
铝质材料的摩擦学表面改性 总被引:1,自引:0,他引:1
铝质材料阳极氧化膜系均匀、规则的微观多孔质结构,利用物理、化学或电化学的方法在其中沉积或原位合成润滑性物质,在保持阳极氧化膜质硬、耐磨特性的基础上,使其具有一定的白润滑性,是近十多年来铝质材料表面改性研究的热点领域之一,本文对该研究的基本原理和国内外发展概况进行了概述,并重点介绍了我们在这一方面研究中的一些最新进展和结果,分别介绍了三种新型体系的自润滑改性阳极氧化铝材料. 相似文献
63.
In this work, the snail shell/hydroxyapatite/chitosan composite was prepared as adsorbent. The adsorption potential of the composite was studied for simultaneous sorption behavior of Zn(Ⅱ) and Cu(Ⅱ) ions in a batch system. Chitosan and hydroxyapatite(HAP) were extracted from shrimp shell and bone ash,respectively, so this is a low cost natural composite. To prepare the composite, chitosan was dissolved in acetic acid, then HAP and snail shell powders were added to the chitosan solution. The morphology and characterization of the composite was studied by SEM and EDX analysis. Atomic adsorption was used to measure the amount of the ions. Experimental parameters were optimized with Design Expert Software and five parameters such as the concentration of ions, p H, adsorbent amount and contact time were studied at room temperature. Optimized value for the parameters of Zn(Ⅱ) and Cu(Ⅱ) concentrations, p H, adsorbent dose, and contact time were 3.01 mg·L~(-1), 5.5, 0.02 g and 95 min, respectively. The adsorption isotherms for Zn(Ⅱ) and Cu(Ⅱ) showed Langmuir and Tempkin, respectively. Kinetic and equilibrium studies showed the experimental data of Zn(Ⅱ) and Cu(Ⅱ) ions were best described by the pseudo-second-order model. Studies on thermodynamic show the adsorption process were physical and spontaneous. 相似文献
64.
Eddy current measurements of electrical conductivity and magnetic permeability of porous metals 总被引:1,自引:0,他引:1
This paper presents a method, which simultaneously estimates the electrical conductivity and magnetic permeability of porous metals. Porous Cu and Fe manufactured by the lost carbonate sintering process have been tested. An air-cored solenoid coil was designed for the measurements of rod-shaped samples when inserted coaxially with the coil. It was theoretically found that the phase-frequency response of the normalised eddy current signal of the coil is virtually independent of the radius, electrical conductivity and magnetic permeability of the test samples. For non-magnetic, conductive porous Cu, the electrical conductivity was measured with a calibration curve of the coil relating the impedance change and the electrical conductivity of the sample. For magnetic porous Fe, the imaginary part of the signal at the lowest frequencies can be used to estimate the permeability. The measured conductivity values of the porous Cu are shown in the paper in comparison with that of bulk materials with known conductivity. The measured permeability values of the porous Fe are given and the sample-length effect on the measurements is also discussed. 相似文献
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67.
以钛酸四丁酯等为原料,采用简单工艺制得多孔TiO2陶瓷光催化剂;并研究了利用多孔TiO2陶瓷光催化降解糠醛废水。结果表明,在紫外灯下照射60min,糖醛废水的COD去除率可达59.8%,而通入空气有利于污染物的去除。 相似文献
68.
Mitra Dadvar 《Chemical engineering science》2007,62(5):1466-1476
The question of whether effective diffusivities in porous materials under reactive and nonreactive conditions are equal is addressed. Previous studies had considered the problem with first-order reactions. We study the issue with two nonlinear reactions—a second-order reaction and one governed by the Michaelis-Menten kinetics. Pore network and continuum models of porous media are utilized to estimate the effective diffusivities under reactive and nonreactive conditions. We show that the two effective diffusivities are significantly different. The difference is due to the heterogeneities of the porous material, and the fluctuations that they cause in the spatially varying local concentrations and diffusivities, and can be as large as a few orders of magnitude. Theoretical analysis of diffusion and reactions in porous media is also presented that supports the results of the simulations. In particular, it is shown that the results of pore network simulations cannot be fitted to the classical continuum equation of diffusion and reaction, and that a more complex continuum equation should be used for this purpose. 相似文献
69.
研究了开孔剂对a-Al2O3多孔道氧化铝支撑体的影响,发现开孔剂的种类及质量分数对支撑体的性能有重要影响,选择合适的开孔剂种类及质量分数可使氧化铝支撑体的纯水通量提高2~3倍。 相似文献
70.