Nguyen Van PHUONG
,
Manoj GUPTA
,
Sungmo MOON
中国有色金属学报(英文版)
doi:10.1016/S1003-6326(17)60127-4
通过在含Mg2+和34PO?离子的溶液中进行浸泡,在AZ31镁合金上制备磷酸镁转化膜以增强其抗腐蚀性能.经磷化处理20 min后,AZ31镁合金上的磷酸镁转化膜呈微裂纹状结构,厚度均匀(约为2.5μm).X射线能谱分析和X射线光电子谱分析表明,磷酸镁转化膜由磷酸镁和氢氧化镁或氧化镁组成.磷酸镁转化膜对AZ31镁合金可起到强烈的保护作用.磷酸镁转化膜的腐蚀电流大幅降低,约为未覆膜表面腐蚀电流的3%.在0.5 mol/L NaCl溶液中的腐蚀恶化时间由10 min延长至24 h.
关键词:
镁合金
,
AZ31合金
,
磷酸镁
,
转化膜
,
腐蚀保护
Physical Review B
The van der Waals (vdW) interactions between carbon nanotubes (CNTs) were studied based on the continuum Lennard-Jones model. It was found that all the vdW potentials between two arbitrary CNTs fall on the same curve when plotted in terms of certain reduced parameters, the well depth, and the equilibrium vdW gap. Based on this observation, an approximate approach is developed to obtain the vdW potential between two CNTs without time-consuming computations. The vdW potential estimated by this approach is close to that obtained from complex integrations. Therefore, the developed approach can greatly simplify the calculation of vdW interactions between CNTs.
关键词:
molecules;clusters;bundles;growth;phase;c-60
Chemical Physics Letters
The potential energies of van der Waals (VDW) interactions between two parallel, infinitely long and perfect SWNTs with identical, and different sizes were studied based on the continuum Lennard-Jones model. The conclusion of Girifalco's work on (n, n) SWNTs that the potentials of SWNT-SWNT fell on a single curve, is also applicable to SWNTs with different sizes. We further obtained the corresponding constants of the well depth \phi(0)\ and equilibrium VDW gap g(0) for SWNTs with a radius from 2 to 25 Angstrom. (C) 2005 Elsevier B.V. All rights reserved.
关键词:
carbon nanotubes;graphite;bundles;c-60;moduli;ropes
Journal of Physical Chemistry B
The potential energies of van der Waals interactions between two multiwalled carbon nanotubes (MWNTs) as well as two carbon nanoparticles (CNPs) were calculated and compared on the basis of the continuum Lennard-Jones model. The well depth of the potential is 1 order of magnitude higher for MWNTs than for CNPs, indicating that MWNTs and CNPs can be separated from each other through polymer-induced steric stabilization. On the basis of this prediction, a novel method for the purification of MWNTs was proposed. The method involves a high-temperature annealing ( 2600 degrees C, 1 h) followed by an extraction treatment with a selected dispersing agent. While the annealing process evaporates the metal particles, the extraction treatment removes CNPs. The quality of the nanotubes obtained after purification was examined by laser Raman, thermogravimetric analysis, and electron microscopy observations.
关键词:
decomposition;hydrocarbons;temperature;nanofibers;pyrolysis;monoxide;bundles;purity;gas
张霞
,
苏希玉
,
侯芹英
,
侯艳丽
低温物理学报
doi:10.3969/j.issn.1000-3258.2008.03.011
考虑态密度的Van Hove奇异性和非电声作用,我们在BCS理论框架内研究了HgBa2Cun-1CunO2n+2+δ(n=1,2,3)系统的超导转变温度和同位素效应.结果表明,当同时考虑Van Hove奇异性和非电声作用时,可以更好地解释HgBa2Cun-1CunO2n+2+δ(n=1,2,3)系统的超导性质.
关键词:
Van Hove奇异性
,
非电声作用
,
超导转变温度
,
同位素效应
钱晨
,
杨斌
,
章于川
,
夏茹
,
钱家盛
高分子材料科学与工程
通过动态流变学方法研究了不同配比下聚丙烯/乙烯-丙烯-二烯三元共聚物(PP/EPDM)共混体系相分离行为.结果表明,EPDM与PP相容性不佳,当EPDM质量分数达到20％即已发生相分离,在质量分数为50％时形成双连续相结构,在质量分数50％～60％时发生相反转.采用Cole-Cole曲线、Han曲线、van Gurp曲线等方法表征了PP/EPDM体系相分离行为,其中van Gurp曲线最为敏感.
关键词:
聚乙烯
,
三元乙丙橡胶
,
共混
,
动态流变行为
,
相分离
Science in China Series B-Chemistry
The equation of the state of the hydrogen bonding fluid system of A(a)D(d) type is studied by the principle of statistical mechanics. The influences of hydrogen bonds on the equation of state of the system are obtained based on the change in volume due to hydrogen bonds. Moreover, the number density fluctuations of both molecules and hydrogen bonds as well as their spatial correlation property are investigated. Furthermore, an equation describing relation between the number density correlation function of "molecules-hydrogen bonds" and that of molecules and hydrogen bonds is derived. As application, taking the van der Waals hydrogen bonding fluid as an example, we considered the effect of hydrogen bonds on its relevant statistical properties.
关键词:
hydrogen bonding fluid;equation of state;fluctuation;correlation;effect;liquid methanol;temperature;water;dependence
Transactions of Nonferrous Metals Society of China
The method for preparing a new solid lubrication system of nano S-W-S was presented. The microstructure of the S-W-S nano cluster was investigated using TEM and XRD. The system is a mixture clusters of both monocrystal and polycrystal of layered hexagonal structure with one tungsten atom linking with two sulphur atoms, and the week Van der Waals' force bonding together the different layers. The changes of electronic structure were studied with XPS. The hybridization of different electronic shelf orbitals of the sulphur atom in the nano cluster is regarded as the quantum size effect. The clusters are found to be of a closed spherical,structure without any dangling bond.
关键词:
solid lubrication system;nanometer cluster;quantum size effect;powders
