检索结果-南通市图书馆

Influence of aluminium and lead on activation of magnesium as anode

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2010年第8期20卷 1403-1411页

作者：王乃光王日初彭超群冯艳张翔宇 School of Materials Science and Engineering Central South University Changsha Research institute of mining and metallurgy

Mg-6%Al, Mg-5%Pb and Mg-6%Al-5%Pb （mass fraction） alloys were prepared by induction melting with the protection of argon atmosphere. Their electrochemical activations in different electrolyte solutions were investigated by galvanostatic test. The microstructures of these alloys and their corroded surfaces were studied by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. The results show that the activation of magnesium is not prominent when only aluminum or lead exists in the magnesium matrix, but the coexistence of the two elements can increase the activation. The activation mechanism of Mg-Al-Pb alloy is dissolving-reprecipitating and there is a synergistic effect between aluminium and lead： the precipitated lead oxides on the surface of the alloy can facilitate the precipitation of Al（OH）3, which can peel the Mg（OH）2 film in the form of 2Mg（OH）2AI（OH）3 and activate the magnesium matrix.

关键词： Mg alloy anode AP65 Mg alloy alloying activation mechanism electrochemistry

Directional migration behavior of cerium during sintering process of mischmetal doped cemented carbide

在线全文

学校读者我要写书评

暂无评论

Journal of central south University of Technology 2008年第1期15卷 6-10页

作者：张立陈述熊湘君余贤旺王元杰 State Key Laboratory of Powder metallurgy Central South University Changsha mining and metallurgy Research institute

Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal （RE, with lanthanum and cerium） doped WC-8%Co-0.048%RE（mass fraction） alloy with low carbon-containing level by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDXS）, considering the fact that the addition amount of rare earth in the alloy is very minute. The directional migration process and mechanism of cerium were discussed. First, the sinter skin （surface） is observed. oxide on the sinter skin, and lanthanum in these cerium observed, and lanthanum containing phase/micro-zone in It is shown that there exists a dispersedly distributed cerium containing enrichment positions is very minute. Secondly, the polished section is the alloy is identified. Finally, based on the fact that the fracture of cemented carbide is resulted from the heterogeneous phase or other defects within the microstructure, the fracture surface is observed and cerium containing phase/micro-zone in the fracture source approximately 260 μm from the surface is identified. These combined observations reveal adequately the fact that lanthanum and cerium get separated and cerium predominantly migrates towards the surface during the sintering process.

关键词： cemented carbide rare earth surface segregation directional migration liquid phase sintering

Synergetic migration behavior of La and Ce and related microstructure character of Cr-V-RE co-doped WC-Co alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2012年第5期30卷 480-485页

作者：张立唐炜陈述南晴解明伟 State Key Laboratory of Powder metallurgy Central South University Changsha mining and metallurgy Research institute Co. Ltd.

The as-sintered sinter skin and the polished section of WC-11Co-0.4Cr 3 C 2-0.3VC-0.2RE（RE=mischmetal with La/Ce ratio of 0.65） alloy were *** was shown that the microstructures on the skin and in the inner part of the alloy were all characterized with a WC＋β＋M structure,where β was a cobalt-based binder phase and M represented a RE-containing *** existed an inward diffusion of S atoms,which caught and fixed the Ce atoms in the alloy and an outward diffusion of La atoms during the sintering ***,the M phase was characterized with the decreased La/Ce ratio（0.59） in the inner part and the increased La/Ce ratio（1.01） on the *** M phase on the skin was characterized with a γ-Ce 2 S 3 type *** suppress the long range migration of rare earth to the skin,S in the sintering atmosphere had to be eliminated.

关键词： cemented carbide sintering rare earth diffusion La and Ce synergetic migration Ln 2 S 3 dispersed phase sulfur

Performances of lithium manganese oxide prepared by hydrothermal process

在线全文

学校读者我要写书评

暂无评论

Journal of central south University 2014年第4期21卷 1279-1284页

作者：孔龙李运姣张鹏黄海花叶万奇李春霞 School of metallurgy and Environment Central South University Citic Dameng mining Industries Limited Changsha Research institute of mining and metallurgy Corporation Limited

A simple hydrothermal process followed by heat treatment was applied to the preparation of spinel Li1.05Mn1.95O4. In this process, electrolytic manganese dioxide(EMD) and LiOH·H2O were used as starting materials. The physiochemical properties of the synthesized samples were investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), X-ray diffractometry(XRD), and scanning electronic microscopy(SEM). The results show that the hydrothermally synthesized precursor is an essential amorphous. The precursor can be easily transferred to spinel powders with a homogeneous structure and a regularly-shaped morphology by heat treatment. Li1.05Mn1.95O4 powder obtained by heat treating the precursor at 430 °C for 12 h and then calcining at 800 °C for 12 h shows an excellent cycling performance with an initial charge capacity of 118.2 mA·h·g-1 obtained at 0.5C rate and 93.8% of its original value retained after 100 cycles.

关键词： lithium ion batteries LiMn2O4 hydrothermal method heat treatment

A NEW APPROXIMATE SOLUTION OF NONLINEAR DIFFUSION EQUATION

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 1985年第7期6卷 701-706页

作者：袁镒吾 central-south institute of mining and metallurgy Changsha

In this paper,the same problem in ref.[1] is *** author’s solutionapproximately satisfies the whole fundamental equations (1.1)and(1.2)and the wholebound values conditions (1.3-1.5).But the Liu’s solution does not s... 详细信息

关键词： In A NEW APPROXIMATE SOLUTION OF NONLINEAR DIFFUSION EQUATION exp

AN ACCURATE SOLUTION FOR THE SURFACE OF ELASTIC LAYER UNDER NORMAL CONCENTRATED LOAD ACTING ON A RIGID HORIZONTAL BASE

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 1986年第5期7卷 505-513页

作者：文丕华 Changsha central-south institute of mining and metallurgy

On the basis of ref.,this paper deduces an accurate solution for the surface ofelastic layer under normal concentrated load acting on a rigidhorizontal base,andgives numerical results, which suit civil engineers for r... 详细信息

关键词： exp AN ACCURATE SOLUTION FOR THE SURFACE OF ELASTIC LAYER UNDER NORMAL CONCENTRATED LOAD ACTING ON A RIGID HORIZONTAL BASE

PERFECTLY PLASTIC STRESS FIELD AT A STATIONARY CRACK TIP

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 1985年第5期6卷 431-438页

作者：林拜松 central-south institute of mining and metallurgy Changsha

Under the hypothesis that all the perfectly plastic stress components at a cruck tip arethe functions of θ only,making use of yield conditions and equilibrium *** the generally analytical expressions of the perfectly plastic stress field at a crack *** these generally analytical expressions to the concrete *** analyticalexpressions of perfectly plastic stress fields at the tips of Mode I,Mode II,Mode III andMixed Mode I-II cracks are obtained.

关键词： mode line In PERFECTLY PLASTIC STRESS FIELD AT A STATIONARY CRACK TIP

Phase composition, transition and structure stability of functionally graded cemented carbide with dual phase structure

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of central south University of Technology 2007年第2期14卷 149-152页

作者：张立陈述熊湘君贺跃辉黄伯云张传福 State Key Laboratory of Powder metallurgy Central South University Changsha mining and metallurgy Research institute School of Metallurgical Science and Engineering Central South University

The phase composition, phase transition and phase structure transformation of the wire-cut section of functionally graded WC-Co cemented carbide with dual phase structure were investigated by XRD phase analysis. It is shown that the composition of η phase in the core zone is Co_3W_3C (M_6 C type). The structure of cobalt based solid solution binder phase is fcc type. At the cooling stage of the sintering process, the phase transition of η phase, i.e. M_6C→M_12C and the martensitic phase transition of the cobalt based solid solution binder phase, i.e. fcc→hcp are suppressed, which facilitates the strengthening of the alloy. Because the instantaneous temperature of the discharge channel is as high as 10 000 ℃ during the wire cutting process, the processed surface is oxidized. Nevertheless, the oxide layer thickness is in micro grade. In the oxide film, η phase is decomposed into W_2C and CoO, and cobalt based solid solution binder is selectively oxidized, while WC remains stable due to the existence of carbon containing liquid organic cutting medium.

关键词： cemented carbide dual phase structure functionally graded material phase identification fracture toughness testing

Microstructure and mechanical properties of 3D fine-woven punctured C/C composites with P_yC/SiC/TaC interphases

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2009年第6期19卷 1428-1435页

作者：曾凡浩熊翔李国栋黄伯云罗健 State Key Laboratory of Powder metallurgy Central South University Powder metallurgy Research institute Central South University

The 3D fine-woven punctured C/C-(PyC/SiC/TaC)composites,composed of PyC/SiC/TaC interphases and pyrocarbon (PyC)matrix,were synthesized by isothermal chemical vapor infiltration(ICVI)*** alternating layers and the structure of these composites were examined by polarized light microscopy(PLM),X-ray diffractometry(XRD)and scanning electron microscopy(SEM).It is found that the PyC matrix has rough laminar(RL)structure,the TaC layer has NaCl-type cubic structure,and the SiC layer has few wurtzite type 10H-SiC besidesβ-SiC *** effects of fiber coating and the bulk density on the tensile and flexural properties of composites along X or Y and Z direction were *** is shown that fiber coated 3D woven punctured C/C composites have good tensile and flexural strength,and the maximum of flexural strength is 375 MPa in X or Y direction at density of 1.89 g/cm 3 ,which is about three times higher than that of samples without TaC/SiC fiber *** flexural strength and bending strength increase with increasing the density of the *** analysis of fracture surfaces reveals that fibers and fiber bundles are pulled out in composites,indicating that the composite exhibits a non-linear failure behavior through propagation and deflection of the cracks.

关键词：复合材料结构碳/碳化硅三维微结构热解碳碳化钽力学性能无纺布扫描电子显微镜