材料期刊网，材料期刊，材料类期刊，材料期刊投稿

本文研究了带有阻挡型阳极氧化膜或空气中生成的氧化膜的纯铝浸泡在中性1MNa_2CrO_4/Na_2Cr_2O_7溶液中时的交流阻抗行为。高频下的阻抗数据主要跟膜的介电性质有关,而1Hz以下低频的数据反映了膜上进行的电化学过程。对于空气氧化膜,电化学反应速度逐步变慢,直至达到相应于稳定钝态的恒定值,同时电位向正移动,表明膜中的微裂纹不断得到修补。阳极氧化膜的情况较为复杂。开始时氧化膜比较厚,电化学反应主要局限在微裂纹内,由于阴极反应受抑止,电位变负;随着氧化膜减薄,电位变正,电化学反应速度加快,最后进入稳定钝态。

关键词:

Energy spectra, g factors and their pressure-induced and/or thermal shifts of SrTiO3 : Cr3+ and SrTiO3 : Mn4+ II: Pressure effects on ground-state g factor and splittings of t(2)(3) E-2 and t(2)(3) (4)A(2) of SrTiO3 : Cr3+

Communications in Theoretical Physics

By using the wavefunctions obtained from diagonalizing the complete d(3) energy matrix at normal and various pressures, the g factor of the ground state of SrTiO3:Cr3+ and its pressure-induced shift have been microscopically calculated. Only by taking the local strains around Cr3+ in SrTiO3:Cr3+ (which are about twice the bulk ones) and corresponding P-chi dependence, can we obtain a good agreement between the calculated result of pressure-induced shift of ground-state g factor and the experimental one. The physical origins of this pressure-induced shift have been explained. It is found that the change of Dq(-1) with pressure makes main contribution to the pressure-induced shift of ground-state g factor of SrTiO3:Cr3+. By using the wavefunctions obtained from diagonalizing the complete d3 energy matrix at normal pressure, the relevant matrix elements and accordingly strain-induced splittings of t(2)(3) E-2 and t(2)(3) (4)A(2) of SrTiO3:Cr3+ have been calculated. The important results of Y-c, Z(c), P-c and Q(c) have also been evaluated. It is the admixtures of basic wavefunctions resulted from the spin-orbit interaction and/or Coulomb interaction and/or Kramers degeneracy that make the strain-induced splittings of the levels nonzero. It is found that there are nonvanishing matrix elements of operators T2 xi, T2 eta and T2 zeta between wavefunctions with positive M-s and those with negative M-s', which have important effects on the strain-induced splittings of the levels.

关键词: crystal fields;energy spectrum;g factors;high-pressure effect;strain-induced splitting;theoretical calculations;ruby;crystal

E型环氧树脂的NMR研究

冀克俭 , 刘元俊 , 张银生

高分子材料科学与工程

利用1H-NMR测定了E型环氧树脂的数均分子量,并利用13C-NMR表征了E型环氧树脂的微观结构.

关键词: 环氧树脂 , 核磁共振谱 , 微结构

低能电子碰撞Ar(e, 3e)双电离实验

贾昌春 , A.Lahmam-Bennani , A.Duguet , L.Avaldi , M.Lecas , Dal Cappello

原子核物理评论 doi:10.3969/j.issn.1007-4627.2002.z1.007

通过Ar(e, 3e)五重微分截面3维图的理论与实验比较发现, 在低能电子入射的情况下, 理论与实验存在较大的偏差.

关键词: (e,3e) , 双电离 , 五重微分截面

屏栅电离室+△E-E望远镜探测器系统

王涛峰 , 朱丽萍 , 孟庆华 , 王黎明 , 韩洪银 , 夏海鸿 , 黎光武 , 屈从会 , 顾先宝

原子核物理评论 doi:10.3969/j.issn.1007-4627.2007.03.008

研制了屏栅电离室+△E-E望远镜探测器系统,系统的屏栅电离室用来测定252Cf自发裂变碎片的能量和相对于探测器系统轴线的发射角,与屏栅电离室耦合安装的△E-E望远镜探测器由一个薄的屏栅电离室(气体△E)和一个金硅面垒探测器(E)组成,用来确定互补碎片的电荷.用本系统对252Cf自发裂变碎片电荷分布进行了4个参数的关联测量,结果表明,这个探测器系统的电荷分辨能力Z/△Z好于40:1.

关键词: 屏栅电离室 , △E-E望远镜 , 电荷分辨能力

R7E拖车轮E级热处理工艺的研究及应用

张振国 , 刘英 , 邹东红

机械工程材料 doi:10.3969/j.issn.1000-3738.2004.09.010

根据英国BS5892-1992标准中的R7E拖车轮E级热处理要求和力学性能要求,研究了温度、冷却介质、车轮形状等对拖车轮整体力学性能的影响,确定了R7E拖车轮E级热处理工艺为(830士10)℃×(3.5～4)h+(530±10)℃×(3.5～4)h,该工艺可以满足BS5892-1992的要求,按此工艺规程生产的车轮达到了标准中规定的力学性能要求.

关键词: 车轮 , E级热处理 , 力学性能

A study of the temperature dependence of g factor for MgO:V2+ crystal

Physica B-Condensed Matter

The temperature dependence of EPR g factor for MgO:V2+ crystal has been studied theoretically by considering both the static contribution due to the thermal expansion of crystal and the vibrational contributions due to the electron-phonon interaction of the acoustic and optical branches. The static contribution is calculated from the high-order perturbation formula of g factor and the thermal expansion coefficients alpha(T) at various temperatures. The vibrational contribution of acoustic phonons is obtained by using a Debye model for the lattice vibrations and that of optical phonons is calculated by use of a single frequency model. The calculated results show that for the g factor at various temperatures, the static contribution is dominant, but for the temperature dependence of g factor, i.e., (dg/dT)(p) or Delta g(T) = g(T) - g(0), the vibrational contributions from the acoustic and optical phonons are comparable with the static contribution due to thermal expansion. It appears that a reasonable theoretical explanation for the temperature dependence of g factor should take all of these contributions into account.

关键词: impurities

PP/PP-g-MAH/Talc/EP复合材料的性能

罗筑 , 陈梅红 , 涂兴文 , 孙华伟

高分子材料科学与工程

通过熔融共混制备聚丙烯（PP）/马来酸酐接枝聚丙烯（PP-g-MAH）/滑石粉（Talc）/环氧树脂（EP）复合材料,研究了E-51/504/554（55.6/42.4/2,E1）、E-51/EDA/554（92.2/7.8/0.01,E2）、E-20/2E4MZ（100/4,E3）三种EP体系及其含量对复合材料力学性能的影响,结果表明,E-1对复合材料的弯曲模量改善最显著,当加入4%的E1时,复合材料的弯曲模量达到最大值,提高了29.1%。傅里叶红外光谱（FT-IR）分析表明,EP与PP-g-MAH发生了酯化反应。观察复合材料的微观结构,发现EP阻止Talc的凝聚,加强了两相界面作用力。