Hydrogen permeability of nonsymmetric metallic membranes

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 27, No. 6, pp. 76–79, November–December, 1991.     

氢化锆表面电镀铬制备氢渗透阻挡层的研究

研究了在氢化锆(H/Zr原子比为l.801)表面通过电镀铬制备氢渗透阻挡层的工艺。结果显示,基体表面经过适当氧化处理后电镀所得铬镀层与基体的结合强度和阻氢性能都有一定的提高;随着电流密度的升高,氢渗透阻挡层孔隙、显微裂纹明显增多;反之,氢渗透阻挡层连续致密。     

Fabrication of defect-free Pd/α-Al2O3 composite membranes for hydrogen separation

Hydrogen production and separation are two important chemical processes. The development of membrane technology has opened up a new possibility for in situ separation of hydrogen from a reaction mixture at elevated temperature in an energy effective way. The availability of a membrane with adequate hydrogen permselectivity and good thermal and mechanical stability is the key for the successful application of membrane technology in hydrogen production and separation. In this paper, a thin-film, defect-free Pd/α-Al₂O₃ composite membrane was fabricated by the electroless plating technique combined with osmosis. The hydrogen permeation performance of the fabricated Pd/α-Al₂O₃ composite membrane was investigated using pure hydrogen at various temperatures from 320–577°C. The hydrogen separation performance was studied using a hydrogen/nitrogen mixture at 467°C. The influence of sweep gas was also investigated.     

Hydrogen permeation through deformed and heat-treated Armco pure iron

ABSTRACT

The goal of this study is to obtain a deeper insight in the relation between hydrogen diffusion and hydrogen traps present in Armco pure iron. Cold deformation was applied to this material, which initially contained a limited amount of traps. The cold deformation was applied to increase the dislocation density and modify grain boundary characteristics. In this way, the hydrogen diffusivity decreased as the hydrogen trapping ability of the microstructure increased. A subsequent heat treatment allowed changing the density of microstructural defects again and consequently increased the hydrogen diffusion coefficient. In addition, studying blister formation showed that a higher degree of deformation caused more surface blisters, while recovery lowered the number of blisters. Electron backscatter diffraction characterisation provided the necessary input on the microstructural features and their evolution. Analysis of these samples allowed evaluating the correlation between hydrogen diffusion, blister formation and microstructural defects.

This paper is part of a thematic issue on Hydrogen in Metallic Alloys     

Hydrogen transport through thin palladium-copper alloy composite membranes at low temperatures

Hydrogen permeation performance of three thin palladium-copper composite membranes with different thicknesses had been studied between 398 K and 753 K. Hydrogen permeance was obtained up to 2.7 × 10^− 6 mol/(m² s Pa) with an ideal selectivity over 1000 at 753 K. The hydrogen permeation exhibited two different activation energies over the temperature range: lower activation energy of about 9.8 kJ/mol above 548 K, while higher activation energy of about 26.4 kJ/mol below 548 K. After permeation tests, the alloy membranes were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis and in situ X-ray diffraction. Palladium segregation on the surface of these palladium-copper alloys may induce changes of hydrogen permeation performance and thus influence the activation energies.     

The fabrication and characterization of a metallic glass coating

This paper presents t~e results o.fa study on the use ofplasma spraying for the fabrication of metallzc glass coatmgs on mzld steel. A commercial, nickel-based alloy powder, Amdry 915, was found to produce sound, amorphous coatings.

The hardness, strength and wear coefficient of the coating are related to the crystallzmty of the alloy. It is shown that the properties of the plasma-sprayed coating compare favourably wzth those of a metallic glass ribbon made of the same commercial alloy.     

Hydrogen permeability of reactor steels

The hydrogen permeability of 12Kh18N10T, 316SS, and 10Kh9VFA reactor steels and EP-838 and Kh12G20V alloyed chrome-manganese steels is studied in the intact state, after thermal treatment, alloying, application of protective coatings, oxidation, irradiation with H⁺ ions, and in the presence of welded joints. We compute the permeation of hydrogen P _c corresponding to the ecologically safe level of losses of tritium through the reactor equipment into the environment and show how the changes in the structure and modification of the surface agree with this value. The permeability and solubility of hydrogen in welded joints of the investigated steels are determined.     

Performance of Amperometric and Potentiometric Hydrogen Sensors

The principle, design, construction and performance of the amperometric and potentiometric sensors for measuring the permeation rate of hydrogen through the wall of metal equipment were investigated in order to develop a new type of hydrogen sensor with high accuracy. The transient curves of hydrogen permeation under a given charging condition were employed to evaluate the performance of two types of hydrogen sensors. The relative deviation of the hydrogen concentration detected with two types of sensors under the same condition varied from 3.0% to 13%. The accuracy, response time, reproducibility, and installation were discussed and compared. Response time of the potentiometric sensor （E-sensor） was shorter than that of the amperometric sensor （I-sensor）. Both types of sensors exhibited good reproducibility. Development of I-sensor composed of a kind of proton conductor adhesives or non-fluid electrolytes which contain two functions of high electrical conductivity and a strong adhesion will be a promising prospect in order to measure hydrogen permeation at high temperature.     

Pd-Ni-P metallic glass film fabricated by electroless alloy plating

In the present study a Pd-Ni-P film has been fabricated by electroless alloy plating. The fabricated Pd-Ni-P film was found to be a metallic glass on the basis of two features, namely, an amorphous structure and a glass transition followed by crystallization during heating. The thermal stability of the supercooled liquid region, however, was lower than that of bulk Pd-Ni-P metallic glass. And unlike the conventional metallic glasses, the fabricated Pd-Ni-P film did not have a uniform microstructure. The non-uniform microstructure of this film resulted from the inhomogeneous distribution of the free volume accompanying the electroless alloy plating reaction.     

A transient method of measuring the water vapour permeability of packaging films. II. Iterative determination of permeability

Principles of the conversion of a measured electrical signal to the relative humidity units have been worked out according to a theory of the method and the measuring system for water vapour permeability through packaging films measurement. The method and the system were based on sorptive sensor reaction inertia analysis. The constants of the measuring vessel were determined by means of the dish method for fixed measurement conditions. Using the developed theory, water vapour permeability was determined for the chosen films. The results obtained were in close agreement with values determined by the dish method and additionally for PET-50 film also in close agreement with the literature data. The uncertainty of the results obtained by this method was estimated. The relative mean uncertainty (α = 0.05) was B_p ≃ 1.1% and the relative maximum uncertainty of a single result B_pmax = 3.1%.     

氢对钛合金的影响

介绍了钛合金的基本性质,分析了钛合金氢脆机理及表现,概括了氢对钛合金裂纹扩展速率和疲劳寿命的影响,总结了氢致裂纹的影响因素。     

不锈钢及其镀膜复合材料气相氢渗透研究

叙述了全金属超高真空气相氢渗透装置和HR－1超低碳不锈钢镀膜复合材料的研制，以及氢通过不锈钢基体及其镀膜复合材料的气相氢渗透实验．实验表明，镀膜复合材料的氢渗透率比基体材料降低二个量级以上。     

Ultrasound-velocity measurement of strain in metallic polycrystals

During extension tests of metallic polycrystals, in situ measurement of ultrasound velocity (USV, V _US ) was carried out for the plastically deforming metallic polycrystalline specimens. USV has been found to depend on the plastic strain or acting stress of plastic flow. The complicated form of these dependencies is discussed in the context of the concept of evolution of lattice defects. V _US is shown to be associated with the multistage nature of the plastic flow curve. This allows plastic flow stages to be recognised with a higher degree of certainty. Thus the linear stage of work hardening has been separated for Al polycrystals by the procedure of USV measurement and certain peculiarities of plastic strains localisation as associated with USV variation have been investigated. Received: 2 April 2001 / Accepted: 24 May 2001     

氢在钢中晶格间隙和氢陷阱之间的扩散模式

氢在晶格间隙和陷阱点的扩散包括：氢在晶格间隙之间的扩散,氢从晶格间隙扩散到陷阱点,氢从陷阱点逃逸到晶格间隙的过程。本文运用气体在金属中的扩散理论,分析了氢在钢中晶格间隙和氢陷阱之间的扩散模式,以及通过扩散在两者之间建立的平衡状态。氢陷阱中氢浓度随时间的变化率等于晶格间隙的氢扩散到陷阱点引起的氢浓度变化率减去陷阱点中氢逃逸到晶格间隙引起的氢浓度变化率,其数学关系式符合McNabb和Foster建立的氢陷阱模型。氢在晶格间隙和陷阱点之间的平衡,实质是氢在晶格间隙的化学势μL和氢在陷阱点的化学势μT之间达到局部平衡,氢在陷阱中的占据分数很低的情况下（θT《1）,氢的有效扩散系数Deff的表达式是与陷阱结合能EB有关的温度函数。     

Opportunity of metallic interconnects for solid oxide fuel cells: a status on contact resistance

The status and opportunity of metallic interconnects for an anode-supported solid oxide fuel cell stack is reviewed with special emphasis on the variation of contact resistance of currently developed interconnects at operating temperatures, as well as the prevailing approaches to reduce contact resistance. It appears that without a coating, current metallic interconnects are not suitable for practical applications at 800 °C since they may cause drastic performance degradation of the stack within its expected service lifetime. Some guidelines in designing new metallic interconnects with both excellent oxidation resistance and reasonably low contact resistance in SOFC environments are set forth.     

氟硅橡胶复合膜透气性的研究

通过把氟硅橡胶填充进多孔微滤支撑体来制备聚偏氟乙烯(PVDF)和氟硅橡胶(FVMQ)的复合膜.并研究了支撑层孔径和白炭黑填料对FVMQ复合膜透气性能的影响.自制气室,测试了FVMQ复合膜对H2、Ar和N2的渗透特性.结果表明,PVDF膜孔径越大FVMQ复合膜的渗透速率就越快,在FVMQ溶液中加入白炭黑填料却降低了膜的渗透速率.支撑层孔径对膜渗透性能的影响比填料的影响显著.对FVMQ复合膜透气性的研究为其在气体分离方面应用奠定基础.     

贮氢合金的开发与应用

本文对贮氢合金的分类、基本性能、发展过程、研究现状、应用情况以及发展趋势进行了综合论述。