Effect of RE-B-Al on Composition of Permeation Layer

It is indicated that theinitial layer of RE-B-Al permeation is mainly composed of Fe2Bby means of TEM and EDAX, and(RE0.65 Feo0.35) 23B6 is found afterRE permeation for 4 h. (Fe0.8,RE0.2)6B is found in the layer ofRE-B-Al permeation and the distance of crystal face of α-Fe is enlarged. The mechanism of formation of boride was analyzed. Prevention of compounds, such asAl, C etc., on dislocation movement, strengthening of grainboundary, dislocation and solutionare responsible for th…     

A model for multicomponent diffusion in oxide melts

A general flux equation for multicomponent diffusion in oxide melts is presented. An explicit method was developed to calculate the gradients of single-ion activities from those of oxides with the constraints of local equilibrium and electroneutrality. This resolves ambiguity in quantifying the thermochemical driving force for ionic diffusion. A model equation for multicomponent ionic diffusion was derived within the framework of non-equilibrium thermodynamics by de Groot and Mazur. The proposed model takes empirically measurable quantities as input variables, so the diffusion calculations are consistent with thermochemical data, as furnished by the CALPHAD (CALculation of PHAse Diagrams) method, as well as ionic mobility measurements. Although the model is derived for oxides, it can be applied to diffusion in other concentrated liquid electrolytes, such as chloride and fluoride melts. Formulas for multicomponent ionic diffusion in various reference frames are presented with respect to mole fraction.     

On problems of multicomponent system maintenance modelling

We present an overview of some recent developments in the area of mathematical modeling of maintenance decisions for multi-unit systems. The emphasis is on three main groups of multicomponent maintenance optimization models： the block replacement models, group maintenance models, and opportunistic maintenance models. Moreover, an example of a two-unit system maintenance process is provided in order to compare various maintenance policies.     

计算机控制氢渗透测量电化学测试系统

研制的计算机控制氢渗透测量电化学测试系统由微机,单板机接口和电化学传感器组成,测量软件设计为下拉菜单和弹出式输入／输出窗口,具有友好的用户操作界面。用系统测定的氢在２．２５Ｃｒ１Ｍｏ合金钢中的扩散系统与文献值一致。     

An understanding of high entropy alloys from phase diagram calculations

The concept of High Entropy Alloy (HEA) is understood from the point of view of phase diagram calculation. The role of entropy of mixing on the phase stability is discussed for both ideal and non-ideal solid solution phases. The relative stability of a solid solution phase and line compounds is illustrated using hypothetical systems. Calculated binary and multicomponent phase diagrams are used to explain the phenomena observed experimentally for HEAs. The potential of using the CALPHAD (CALculation of PHAse Diagrams) approach in aiding the design of alloys with multiple key components is also discussed.     

一种水清洁阳极的基于甲醇渗透的浓度传感器

提出一种基于膜电极(MEA)结构的驱动模式甲醇浓度传感器。甲醇溶液从MEA阴极流过,通过MEA渗透到阳极,Nafion膜既是电解质膜又是甲醇渗透膜。由于引入水清洁阳极,有效避免了甲醇的累积,提高了该传感器稳定性和重现性。该传感器测量范围最大可以达到5 mol/L,适合于直接甲醇燃烧电池(DMFC)系统中甲醇的监测。     

聚酰亚胺／磺化聚芳醚砜共混中空纤维膜用于醇／醚气相分离的研究

甲醇／ 甲基叔丁基醚的分离是目前具有实用意义的重要研究课题之一．文中采用气流吹扫式操作,研究了不同共混比的磺化聚芳醚砜／ 聚酰亚胺中空纤维膜对甲醇／ 甲基叔丁基醚气相混合体系的分离性能,以及不同操作条件对分离性能的影响．结果表明,共混改性聚酰亚胺膜具有非常高的醇／ 醚分离系数,有很好的应用前景．     

A relatively simple method for calculating Mark‐Houwink parameters using basic definitions

A method for calculating Mark‐Houwink parameters from intrinsic viscosity, size exclusion, and number‐ or weight‐average molecular weight data using basic definitions was presented. Polydispersity is not an issue and no calibration curve is required as long as all of the aforementioned data are available. Results for polystyrene, cellulose acetate, and polymethylhydrosiloxane are discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Temperature influence on transport parameters characteristic of Knudsen and Poiseuille flows

Single gas permeation experiments results using neon, argon, nitrogen and methane are reported. From gas permeation experiments the characteristic parameters of the Knudsen and Poiseuille transport mechanisms were determined by means of an equation derived from the “Dusty-Gas” model. The experiments were performed at different temperatures from 303.15 to 323.15 K, in order to study the temperature influence on those parameters. For PVDF and PCTE membranes the influence of the temperature on K_o and B_o parameters was not significant. Gas influence was also investigated for both types of membrane, a slight tendency of K_o to decrease with increase in molar mass and a very slight tendency of B_o to increase with increase in molar mass, although these trends were not fulfilled by neon gas.     

Hydrogen permeation in Fe-40 at.% Al alloy at different temperatures

The electrochemical permeation technique for studying transport and trapping of hydrogen in Fe-40 at.% Al alloy at temperatures of 5, 25, 45 and 65 °C was used in the paper. The influence of temperature on the effective hydrogen diffusion coefficient, hydrogen permeation rate and hydrogen solubility was determined. The activation energy of hydrogen diffusion in iron aluminide in the studied temperature range was also determined.