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介绍了几种计算纳米金属颗粒镶嵌于陶瓷基体中而形成的复合纳米金属陶瓷薄膜渗透阈的理论方法,分析了理论方法中所运用模型的特点及其精度.并将Landauer有效介质理论和Priou渗透阈理论应用于Ag-MgF2复合纳米金属陶瓷薄膜的渗透阈计算,所得值分别为0.08和0.14(Ag的体积分数),按Priou渗透阈理论计算的结果与实验结果相符.最后讨论了影响复合金属陶瓷薄膜体系渗透阈的主要因素.
关键词:
2复合纳米金属陶瓷薄膜')" href="#">Ag-MgF2复合纳米金属陶瓷薄膜
渗透阈理论
渗透阈 相似文献
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以渗透理论的方法研究一价离子通过荷电膜的传质机理,用计算机编程模拟一价带电离子通过荷电膜的过程以研究荷电膜中导电性能和荷电组分含量的关系.模拟结果表明,对于二维格栅体系在荷电组分含量为0.4~0.6时,膜导电性能存在渗透突跃现象;而对于三维格栅体系则在0.1~0.2时存在渗透突跃现象,此结果和MontoCarlo的二维、三维随机模拟结果比较接近.由于实际的荷电膜也可看作为三维格栅体系,因此,可用三维格栅体系程序对不同荷电分率膜的电导数据进行拟合,结果表明,对于实际的磺化聚苯硫醚(SPPS)/聚醚砜(PES)共混膜,当荷电组分SPPS的分率达到0.144时,共混膜即会从不良导体变为良导体,显然该值落在理论值0.1~0.2,因此,理论模拟结果与实际荷电膜传质的实验数据相吻合. 相似文献
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壁面渗透燃烧微燃烧器结构参数优化实验研究 总被引:1,自引:0,他引:1
针对一种圆柱多孔壁面组织渗透燃烧微尺度燃烧器,本文在甲烷/空气不同燃料当量比和混合气流量下,对比实验了关键参数燃烧室内径(d)和燃烧室高度(h)变化对燃烧器性能的影响.结果表明随燃烧室内径减小,吹熄极限速度显著下降,烟气平均温度升高,同时壁面温度下降;燃烧室高度减小,可燃烧极限当量比和淬熄极限速度均增大;在高径比h/d接近1时,烟气平均温度最高,壁面最高温度不变,大流量下壁面温度降低更快.因此,当缩小壁面渗透微燃烧器时,为防止燃烧效率降低和热损失增加,应优先缩小内径并保持高径比接近1.0. 相似文献
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构建采用阴/阳极通流的穿透电极型热再生氨电池(Thermally Regenerative Ammonia-based Battery,TRAB),并研究了电解液/氨流量比、氨浓度、电极孔隙和支持电解质浓度对电池性能的影响.结果 表明,电解液/氨流量比过低会导致氨渗透,恶化阴极性能,进而降低电池性能;通过增大流量比,可加强传质提升电池功率.一定流量比下,随氨浓度增加,电池性能逐渐提升,但过高浓度会引起氨渗透,恶化电池性能.电极孔隙密度越大,电极反应表面积越大,电池性能提升.随硫酸铵浓度增大,电解质电导率不断增大,电池性能逐渐提升,在高浓度(>2 mol.L-1)下,浓度增大对电池性能提升不明显. 相似文献
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陶瓷—金属复合体系氢同位素渗透模型 总被引:2,自引:0,他引:2
在陶瓷(玻璃或氧化物)材料中氢同位素分子扩散的1次方定律和金属材料中原子扩散的1/2次方定律的基础上建立了双层介质扩散模型,推导出氢浓度分布函数,镀膜复合体的氢渗透速率以及渗透速率对驱动氢压的幂指数表达式,讨论了稳态氢渗透速率随膜厚,测量温度,驱动氢压变化的规律,根据实验测量的镀膜复合体的渗透速率,稳态渗透速率对驱动氢压依赖关系的幂指数大小,得以了膜材本身的渗透,扩散,溶解等热力学参数,同时估算了 相似文献
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An analysis of the phenomenon of osmosis within the lattice gas model is presented. The model considered is a two-species version of the Frisch-Hasslacher-Pomeau model with rest particles and a semipermeable membrane which is implemented as a boundary that blocks one species, but lets the other pass freely. In this way the equilibrium between a pure and a mixed subsystem can be studied. Analytic expressions for both the pressure difference and the fluctuations of this quantity are obtained from the entropy function for the lattice gas, and we find that these results are in good agreement with those obtained from simulation. The osmotic flow across the membrane is also studied. We characterize the concentration boundary layer, and an analytic expression for the osmotic permeability as a function of porosity is compared with results from simulations. 相似文献
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We investigate single-file osmosis of water through a semipermeable membrane with an uncharged, a positively and a negatively charged nanopore. Molecular dynamics simulations indicate that the osmotic flux through a negatively charged pore (J_) is higher compared to the osmotic flux in a positively charged pore (J+) followed by the osmotic flux in the uncharged pore (J(0)), i.e., J_ > J+ > J(0). The molecular mechanisms governing osmosis, steady state osmosis, and the observed osmotic flux dependence on the nanopore charge are explained by computing all the molecular interactions involved and identifying the molecular interactions that play an important role during and after osmosis. This study helps in a fundamental understanding of osmosis and in the design of advanced nanoporous membranes for various applications of osmosis. 相似文献
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Unsteady compressible flow fields past a wedge and a cone, evolved by propagation and interaction of shock waves, slip lines, and vortices, are studied by shadowgraphs and holographic interferograms taken during the shock tube experiment. The supplementary numerical calculation also presented time-accurate solution of the shock wave physics which was essential to recognize the similarity and dissimilarity between the wedge and the conical flows. The decelerated shock detained by the vortex interacts with the small vortexlets along the slip layer, producing diverging acoustics: this phenomenon is more distinct in the case of wedge flow for a given shock Mach number. The decelerated shock penetrated through the vortex core constitutes a transmitted shock, which eventually merges with the diaphragm shock that bridges the vortex pair/vortex ring. This phenomenon became remarkably salient in the case of conical flow. 相似文献
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对小孔泄漏振荡演示实验的研究 总被引:5,自引:4,他引:1
对小孔泄漏演示实验给出了物理解释,分析了引起小孔泄漏振荡的原因:液体系统由于浓度差产生的自由能的降低是不同浓度液体之间相互渗透的动力,由于液体黏性的存在使得液体通过小孔的渗流只能单向发生,以及在小孔附近两侧的压力差控制着渗流的流向. 相似文献
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单层石墨烯凭借超薄的厚度和优异的力学化学防污性能,成为新一代纳滤膜材料的最佳选择之一.本文采用经典分子动力学方法,研究了氢化多孔石墨烯反渗透膜对盐水的反渗透特性.结果表明,水渗透量会随着驱动力、孔径和温度的增加而增加;而孔径大于水合半径的条件下,盐离子截留率会随驱动力和温度的增加而降低.当反渗透膜和盐水存在切向运动时,随着切向速度的增加可以有效提高盐离子截留率和减弱浓差极化现象,但也在一定程度上牺牲了水通量.通过分析水流沿渗透方向的能障分布、水分子的氢键分布和离子水合状态,解释了各参数变化对盐水在氢化多孔石墨烯中反渗透特性的影响机理.研究结果将提供基于单层多孔石墨烯反渗透特性的理论认识,并将为纳米级反渗透膜的设计提供帮助. 相似文献
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Unlike reverse osmosis (RO) that is dominated by the hydraulic pressure differential, forward osmosis (FO) uses the osmotic pressure gradient as the driving force between a dilute feed solution and a concentrated draw solution across a membrane. High pressure is not required in FO, which means that FO can be used as an alternative to RO as an energy-saving separation process in desalination technology. However, a major limiting factor of the FO process is the internal concentration polarization (ICP). Because of the stagnant environment inside the porous supporting layer of a FO membrane, it is difficult to mitigate the ICP by simply increasing the shear stress or promoting turbulence. In this study, the ICP is reduced by ultrasound. The effect of the ultrasound frequency and output power on the ICP coefficient is investigated in a flat-sheet FO membrane module with counter-current flow. The ultrasound frequency and output power are varied between 25, 45, and 72 kHz and over the range of 10–70 W, respectively. NaCl solution is used as both the feed and draw solution. The results illustrate that moderate ultrasonic irradiation is effective for reducing the ICP in a FO process. A modified solution–diffusion model based on film theory is used to assess the effect of ultrasound on the ICP in a FO process. The ICP coefficient is estimated using this model. 相似文献