Problems of Hydrogen Degradation of Metals

We present a new scientific trend concerned with the behavior of materials interacting with hydrogen, namely, hydrogen-containing materials science. Most of the attention is concentrated on hydrogen degradation of structural materials, which is a major aspect of this trend, and the types of hydrogen degradation are considered. The most important factors predetermining the processes observed are the tendency of hydrogen to localization in the metal and a decrease in the binding forces between atoms of metal. Tasks aimed at solving the problems of hydrogen degradation of metals are formulated.     

A New Analysis of Hydrogen Diffusion in Metals with Trapping

A new model of hydrogen diffusion in metalshas been developed,it is more efficient todescribe the hydrogen diffusion with trappingin metals.In the model newly developed an impli-cit dependence on time of hydrogen diffusioncoefficient in metals with trapping was firstlybuilt and it is shown that hydrogen diffusioncoefficient will be different at different posi-tions in a dynamic process of hydrogen diffusionin a metal.Numerical solutions of the present modelwere obtained by finite difference method.Bychanging the parameters in the model the diffusionof hydrogen in a metal and the effect of trappingwere described and discussed.And the comparisonbetween the well known McNabb and Foster's modeland the present model was also made.     

离子微探针研究氢在材料中行为的新进展

本文阐述了我们近年来利用离子微探针对氢在材料中的基本行为研究取得的若干新进展:(1) 在裂纹尖端氢分布研究方面有突破性进展,首次实验发现在受载裂纹尖端存在着氢富集的双峰,对氢双峰的变化规律和形成原因进行了系统研究,并提出了相应的模型;(2) 实验确证了氢在六角密堆结构(hcp)和高位错密度(10~(12)/cm~2)材料塑性形变过程中的可动位错输运行为,并揭示了氢在位错芯部的“隧道扩散效应”;(3) 定量测定了工程厚度材料微区氢浓度分布,通过Fourier变换和Laplace变换,建立了新的微区氢扩散方程解析式,具有重要的实用价值。     

Analysis of Hydrogen Diffusion in Metals with Trapping under Local Equilibrium Assumption

The assumption of the local equilibrium ofhydrogen distribution in metals[1]was used in themodel formerly developed[2]to describe the diffu-sion of hydrogen in metals.From the assumption adirect relationship between the hydrogen diffusivityand the hydrogen concentration in metals is estab-lished asD=D_o/{1+N_x(k/p)/[1+C(k/p)]}The comparison between the two results drawnfrom the assumption of equilibrium and the dynam-ics of hydrogen trapping[3]was also presented.Thecomputation results well explained the scatteringphenomenon existed in hydrogen diffusion data andsuggested that the experimental conditions shouldbe identical for the study of hydrogen permeation inmetals.     

从原子结构探讨贵金属在提取冶金过程中的行为

从原子结构特征分析了第Ⅷ族和IB族中Fe、Co、Ni、Cu 3d贱金属元素与其余8个贵金属元素化学性质的差异,以及Ru、Rh、Pd、Ag 4d贵金属与Os、Ir、Pt、Au 5d贵金属化学性质的差异。指出横向比较时,它们的化学稳定性都是从左到右增大;纵向比较时,化学稳定性是3d<4d<5d。以从硫化铜镍矿中提取富集贵金属为例,讨论了焙烧-还原熔炼-氧化吹炼等火法过程及电解富集、阳极泥硫酸化处理、湿法氯化、加压氧化、选择性还原等湿法过程中贵金属的行为。     

Carbon-based Electrocatalysts for Hydrogen Evolution Reaction Modulated by Embedded Metals

正Development of effective technologies for clean and sustainable hydrogen energy has been attracting great attention lately,as hydrogen is hailed as a promising energy source to reduce our dependence on fossil fuels and benefit the environment by reducing the emissions of greenhouse and other toxic gases.Toward this end,an effective and promising approach is based on the electrolysis of water for     

Effect of Strain Rate on Hydrogen Embrittlement Behaviour of Amorphous NiCrFeSiB Alloy

The effect of strain rate on hydrogen embrittlement behaviour of amorphous Ni-6.6Cr-2.6Fe-7.8Si-14.5B (at pct) alloy in 0.1 mol/L H2SO4 solution was studied by the methods of slow Strain rate testond electrochemical charging. The results show that fracture Stress of the alloy decreases with the decrease of Strain rate within a certain range. As a tentative explanation, the effect of strain rate on hydrogen embrittlement fracture stress was attributed to the interaction between hydrogen and the excess volume in amorphous alloys     

Propagation of Cracks in Metals under the Action of Hydrogen and Long-Term Static Loading

We propose a computational model of crack growth caused by the action of hydrogen and long-term static loads. The model is based on the energy criterion of fracture of materials. As a result, we deduce the expression for the crack growth rate as a function of the load, size of the initial crack, and physicochemical and strength characteristics of the material. The theoretical curve reveals satisfactory agreement with the experimental data. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 3, pp. 29–33, May–June, 2005.     

A100钢低氢脆刷镀镉镀层海洋环境腐蚀行为研究

通过海洋环境下的户外暴露实验研究了A100钢表面低氢脆刷镀镉的腐蚀行为及腐蚀对力学性能的影响.通过腐蚀动力学曲线反映了镀层腐蚀失重的变化,并利用交流阻抗技术表征了镀层在不同腐蚀阶段的特征.结果表明:镀层具有很好的耐腐蚀性能,但随着实验的进行腐蚀速率逐渐加快;腐蚀对镀层力学试样的力学性能影响很大,导致抗拉强度降低,断口呈氢脆断裂.     

The Effect of Hydrogen on Fatigue Properties of Metals used for Fuel Cell System

The effect of hydrogen on the fatigue properties of alloys which are used in fuel cell (FC) systems has been investigated. In a typical FC system, various alloys are used in hydrogen environments and are subjected to cyclic loading due to pressurization, mechanical vibrations, etc. The materials investigated were three austenitic stainless steels (SUS304, SUS316 and SUS316L), one ferritic stainless steel (SUS405), one martensitic stainless steel (0.7C-13Cr), a Cr-Mo martensitic steel (SCM435) and two annealed medium-carbon steels (0.47 and 0.45%C). In order to simulate the pick-up of hydrogen in service, the specimens were charged with hydrogen. The fatigue crack growth behaviour of charged specimens of SUS304, SUS316, SUS316L and SUS405 was compared with that of specimens which had not been hydrogen-charged. The comparison showed that there was a degradation in fatigue crack growth resistance due to hydrogen in the case of SUS304 and SUS316 austenitic stainless steels. However, SUS316L and SUS405 showed little degradation due to hydrogen. A marked increase in the amount of martensitic transformation occurred in the hydrogen-charged SUS304 specimens compared to specimens without hydrogen charge. In case of SUS316L, little martensitic transformation occurred in either specimens with and without hydrogen charge. The results of S-N testing showed that in the case of the 0.7C–13Cr stainless steel and the Cr–Mo steel a marked decrease in fatigue resistance due to hydrogen occurred. In the case of the medium carbon steels hydrogen did not cause a reduction in fatigue behaviour. Examination of the slip band characteristics of a number of the alloys showed that slip was more localized in the case of hydrogen-charged specimens. Thus, it is presumed that a synergetic effect of hydrogen and martensitic structure enhances degradation of fatigue crack resistance.     

Effects of Hydrogen on Behaviour of Low Cycle Fatigue of 2.25Cr-1Mo Steel

The effects of hydrogen atoms on behaviour of low cycle fatigue of 2.25Cr-1Mo steel have been investigated in present work. The results indicate that the cyclic softening rate and low cycle fatigue life are respectively increased and reduced remarkably by hydrogen atoms. In addition, hydrogen atoms make the original stress amplitude of low cycle fatigue increase, which is because of the drag effect of hydrogen atoms on the moving dislocations. Analyses using electron microscopy show that hydrogen atoms accelerate crack initiation of low cycle fatigue from inclusion and transfer the source of low cycle fatigue crack from the surface of specimen to the inclusion, which results in the marked decrease of low cycle fatigue life. The increase of cyclic softening rate for hydrogen charged specimen is due to hydrogen atoms accelerating the initiating and growing of microvoids from the secondary phase particles in the steel. The reducing of the drag effect of hydrogen atoms on moving dislocations is also helpful to the increase of the cyclic softening rate.     

金属板材屈服行为与塑性失稳力学模型在微尺度下的应用

板材屈服准则与塑性失稳模型是精准描述高性能构件成形或服役过程的基础与前提。在板材塑性成形过程中,试样几何尺寸、材料晶粒大小、自由表面粗化和织构分布等都会对材料的塑性变形行为产生不可忽略的影响,导致单一尺度下的本构模型和断裂准则不能有效预测微观尺度下的材料变形行为和各种缺陷,大大限制了合金板材在航空、航天、汽车、医疗等工业上的应用。对现有屈服准则的研究进展进行了较为全面的回顾,从Hill、Hershey-Hosford和Drucker这3个系列出发,分别进行了对比分析,并总结了目前国内外用于验证屈服准则的金属板材双向拉伸实验机发展状况。基于不同的破裂失稳机理,将失稳模型分为宏观失稳准则、韧性断裂准则和耦合材料损伤演化的韧性断裂准则,并分别进行了归纳和阐述。此外,随着微成形技术的逐步推广,也对宏观塑性成形理论在微尺度下的应用进展进行了说明,指出了宏观屈服准则和失稳模型在微尺度下的不足和缺陷。最后讨论了宏观屈服准则和失稳模型今后的发展趋势以及宏观塑性成形理论在微尺度下的应用前景。     

双元活性金属Ni/Al/石墨烯储氢复合材料的研究

通过还原氧化石墨烯法制得了片状石墨烯,并以片状石墨烯为载体,采用原位生成和自组装法结合高温还原工艺负载得到双元活性金属Ni/Al/石墨烯复合材料,分别表征了石墨烯的分子结构、微观形貌和比表面积,并系统研究了Ni/Al/石墨烯复合材料的物相组成、微观结构和储氢性能。结果表明,片状石墨烯具有石墨烯的典型特征,并可以清晰地观察到透明的片层石墨烯,其Brunauer-Emmett-Teller(BET)比表面积达到600m2/g以上。Ni/Al/石墨烯复合材料主要包含Ni、Al和C三相,其中石墨烯对Ni和Al颗粒形成了有效负载,使得Ni/Al/石墨烯复合材料具有较好的储氢性能和吸放氢稳定性,473K时,其最大储氢容量接近5.7%(质量分数)。该材料的释氢效率高达96%~97%(质量分数),且释氢温度低至380K,表现出良好的应用前景。     

飞机表面水基清洗剂对金属材料腐蚀及氢脆性能影响研究

研究了AHC-1及AHC-5两种飞机表面水基清洗剂对飞机表面典型金属材料的腐蚀性能及高强度钢氢脆性能的影响,探讨了应用缓蚀剂控制高强度钢氢脆的有效性以及用电化学极化法预测高强度钢在清洗剂中的氢脆倾向性.     

Application of Hydrogen in the Production of Sintered Anisotropic Nanostructured Magnets from Alloys of Rare-Earth and Transition Metals

Materials Science - The main stages of the procedure of hydrogen treatment of ferromagnetic materials based on Nd2Fe14B, SmCo5, and Sm2Co17 compounds of rare-earth and transition metals aimed at...     

非贵金属Co5.47N/N-rGO助催化剂增强TiO2光催化制氢性能

高效稳定的光催化剂或助催化剂研究一直是光催化领域的重要课题之一。本研究以氧化石墨烯、氯化钴和2-甲基咪唑为前驱体, 结合液相法和氨气氮化法制备了负载Co_5.47N的氮掺杂还原氧化石墨烯(Co_5.47N/N-rGO), 其中Co_5.47N高度分散、晶粒尺寸为10~20 nm。Co_5.47N/N-rGO可以作为助催化剂有效地改善商业二氧化钛(P25)的光催化分解水制氢性能, 当其质量分数为25%时, 催化剂的制氢性能可以达到11.71 mmol·h ^-1·g ^-1, 相比于纯P25提升了90倍, 与负载贵金属Pt的性能相当(11.88 mmol·h ^-1·g ^-1), 并且具有良好的稳定性。本研究为高效非贵金属助催化剂的研制提供了新思路。