材料期刊网

Semiconducting properties of passive film formed on stainless steel by using A. V. passivation

Acta Chimica Sinica

Passive film formed on 304 stainless steel in 2.5 mol/L H2SO4 solution by using alternating voltage (A. V.) passivation have been investigated by measuring capacitance and photoelectrochemical parameters. The investigation of the effect of measure frequency on the slope of Mott-Schottky curve has been carried out. The photoelectrochemical measurements were consistent with the capacitance measurement. Analysis of the experimental results showed that the passive film formed 304 stainless steel by using A. V. passivation exhibits semiconducting properties. Using the simple model of semiconductor rather than the multi-donor level model can explain satisfactorily the semiconducting behavior of the film formed on 304 stainless steel by using A.V. passivation.

关键词: A. V. passivation;passive film;semiconducting properties;stainless;steel;model;electrodes

缓蚀剂阳极脱附现象的研究──V.缓蚀剂脱附与金属阳极过程

王佳 , 曹楚南

中国腐蚀与防护学报

根据缓蚀剂阳极脱附与金属阳极溶解相互作用的分析，建立了描述缓蚀剂体系中金属阳极过程动力学规律的物理模型。依据该模型讨论了缓蚀剂覆盖度随电位与浓度的变化、脱附电位与半覆盖电位、电位扰动与浓度扰动的电流响应及稳态阳极极化曲线。

关键词: 缓蚀剂 , Desorption , Kinetics

New Dental Alloys with Special Consumer Properties

TYKOCHINSKIY D. S. , VASEKIN V. V.

贵金属

关键词:

Phase Equilibria in System Pd-Au-Sn and Pd-Cu-Sn at 800℃ and 500℃

KABANOVA E. G. , KAREVA M. A. , KUZNETSOV V. N. , VASEKIN V. V.

贵金属

关键词:

Design and Range of Application of Slot Bushings with Volumetric Orifice Fields

ULYBYSHEV V. V. , VASEKIN V. V. , PERELMAN S. L.

贵金属

关键词:

Manufacture of Precious Metal Products:Advancement and Prospect

MOROZOVA L. E. , YASTREBOV V. A. , VASEKIN V. V.

贵金属

关键词:

First-principles study of transport of V doped boron nitride nanotube

Physics Letters A

We perform first-principles calculations of spin-dependent quantum transport in V doped boron nitride nanotube: the junction of pristine (6, 0) boron nitride nanotube in contact with V doped (6, 0) boron nitride nanotube electrodes. Large tunnel magnetoresistance and perfect spin filtration effect are obtained. The zero bias tunnel magnetoresistance is found to be several thousand percent, it reduces monotonically to zero with a voltage scale of about 0.65 V, and eventually goes to negative values after the bias of 0.65 V. The ratio of spin injection is above 95% till the bias of 0.85 V and is even as large as 99% for the bias from 0.25 eV to 0.55 eV when the magnetic configurations of two electrodes are parallel. The understanding of the spin-dependent nonequilibrium transport is presented by investigating microscopic details of the transmission coefficients. (C) 2008 Elsevier B.V. All rights reserved.

关键词: first-principles;one-dimensional;tunnel magnetoresistance;spin filter;large magnetoresistance;ferromagnetic-films;sic nanowires;bn;nanotubes;systems;conductance;junctions

Electronic effects of alloying elements Nb and V on body-centred-cubic Fe grain boundary cohesion

Journal of Physics-Condensed Matter

The segregation effects of Nb and V on bcc FeSigma3[110](111) grain boundary cohesion are studied by the first-principles DMol method within the framework of density functional theory. The calculated segregation energy difference between the grain boundary and the corresponding free surface is -0.51 eV (-0.58 eV) for solute Nb (V), which indicates that both Nb and V could enhance the grain boundary cohesion in body-centred-cubic Fe. We found that the chemical effect and the geometry effect of Nb (V) play crucial but opposite roles in determining whether a material is brittle or ductile. The chemical effect is dominant and advantageous for grain boundary cohesion. Also, Nb and V show very different behaviours: in chemical effect, Nb is more conducive to ductility than V; while in the geometry effect, Nb is less conducive to ductility and more conducive to embrittlement than V.

关键词: first-principles determination;local-density;embrittlement;iron;phosphorus;hydrogen

Apatite formation on anodized Ti-6Al-4V alloy in simulated body fluid

Metals and Materials International

Titania layers were successfully prepared on the surfaces of Ti-6Al-4V alloy via anodic oxidation in H(2)SO(4) or Na(2)SO(4) solutions at room temperature. The titania layers consisted of pure rutile or a mixture of anatase and rutile structures after the Ti-6Al-4V alloy had been anodized in 1.0 M H(2)SO(4) solution at 150 V or 0.5M Na(2)SO(4) solution at 100 or 130 V. Good apatite-forming ability was demonstrated in simulated body fluid. However, surface layers with mainly titanium metallic phase or a pure anatase structure did not possess the ability to induce apatite formation. Anodic oxidation is an effective method to prepare bioactive Ti-6Al-4V alloy that can be used as an artificial bone substitute under load-bearing applications.

关键词: alloys;anodization;surface;x-ray diffraction;apatite;bioactive titanium metal;chemical surface-treatment;heat-treatments;oxide-films;oxidation;coatings;ability;bone;ca

Ti-6Al-4V合金熔体中各组元挥发趋势

刘贵仲 , 苏彦庆 , 郭景杰 , 丁宏升 , 贾均 , 傅恒志

材料科学与工艺 doi:10.3969/j.issn.1005-0299.2001.02.015

在基于本课题组建立的熔体组元活度系数计算模型的基础上,计算了Ti-6Al-4V熔体中各组元的活度系数及其蒸气压,推导了判断熔体组元挥发趋势的相对挥发系数β.研究结果表明:在熔体温度低于2 000 K时,铝钛相对挥发系数β(Al:Ti)＞17,铝钒相对挥发系数β(Al:V)＞96,钛钒相对挥发系数β(Ti:V)＞5,即熔炼过程中组元挥发趋势从大到小依次为Al,Ti,V.这说明熔体成分变化主要是由于Al元素的挥发所致.

关键词: Ti-6Al-4v合金 , 活度系数 , 饱和蒸气压 , 挥发趋势