材料期刊网

STUDY ON THE PREDICTIVE METHOD OF BUCKLING DEFORMATIONS OF THIN-PLATE WELDED STRUCTURES

X. Q. Yang , L. X. Huo , Y. F. Zhang and J. X. Yan (School of Material Science and Engineering , Tianjin University , Tianjin 300072 , China)

金属学报(英文版)

The buckling formation and influence factors during welding thin - plated structures were investigated based on finite element methods, An engineering treatment method for prdicating the buckling distor- tion was proposed in here. It was used the equivalent applied thermal - load to simulate the welding residual stress,therefore the calculation of complex welding distoriton can be transformed into 3D elas- tic structural applied- load analyses, which can reduce the quantities of calculating works effectively. The validation of the method was verified by comparison of the numerical simulation and experimental results. The simulation of buckling distorition for side - walled structrues of paseenger train was per- formed and the calculation was in agreement with measuring results in general. It was shown that the main factors for producing the buckling were the intermittent fillet and ping the during welding the stiffened beams and columns to the panel.The existence of the free edge of panels would reduce the crit- ical buckling stress and enlarge the deflection obviously,but the continuous weld in closed frames didn' t degrade the buckling situation.

关键词: welding buckling distortion , null , null

低速Ar~(q+)(q＝7-14)离子入射Au表面激发的X射线谱

原子核物理评论

研究了高电荷态离子~(40)Ar~(q+)(q＝7-14)轰击金属Au表面产生的特征X射线谱.实验结果表明,在弱束流(nA量级)的情况下,对于动能相同的入射离子,当电荷态比较高(q＝11)时,便能有效地激发靶原子的特征X射线,单离子的X射线产额高达10~(-8)量级.分析结果显示,入射离子的势能、动能和这种相互作用特有的镜像相互作用势能沉积在靶表面,使靶原子内壳层电子激发和电离,形成空穴和产生外壳层电子填充空穴辐射特征X射线,特征X射线的产额随入射离子的势能(电荷态)的增加而增加.

关键词: 高电荷态离子 , X射线 , 产额

Q235钢与X70钢在新加坡土壤环境中1年腐蚀行为研究

杜翠薇 , 王胜荣 , 刘智勇 , 李晓刚 , 朱敏 , 李琼 , 黄一中 , 刘明

腐蚀学报（英文） doi:10.11903.1002.6495.2014.210

通过土壤理化性质分析、现场埋样的腐蚀形貌观察、腐蚀产物的扫描电镜观察和X射线衍射分析以及腐蚀失重实验等分析手段,研究了国产X70钢和Q235钢在新加坡土壤中现场埋样1a后的短期腐蚀行为特征.结果表明,新加坡土壤属于酸性土壤;埋样1a后Q235钢平均腐蚀速率略大于X70钢,两种钢以局部腐蚀为主,Q235钢的局部腐蚀较严重;两种钢的腐蚀产物组成相似,均为Fe2O3,Fe3O4,FeOOH和FeOCl,腐蚀产物表面粗糙,存在裂纹与空隙,从而加速局部腐蚀的进行.

关键词: X70钢 , Q235钢 , 酸性土壤 , 土壤腐蚀

涂层破损时杂散电流对Q235、16Mn、X70钢腐蚀的影响

王燕 , 闫永贵 , 董超芳 , 钱建华 , 李晓刚

腐蚀学报（英文）

通过腐蚀速率测定、腐蚀形貌观察、腐蚀坑深度测量及分形维数计算等方法,研究了杂散电流作用下涂层破损率对Q235、16Mn和X70钢腐蚀的影响.结果表明,杂散电流作用下,Q235钢腐蚀程度最严重,16Mn次之,X70最小;随杂散电流增大和涂层破损率减小,腐蚀速率和腐蚀坑深度均相应增大,腐蚀程度加剧;根据"盒子"维法测定杂散电流腐蚀形貌的分形维数,反映的腐蚀规律与实测腐蚀速率吻合,分形维数可定量表征杂散电流腐蚀形貌.

关键词: 杂散电流腐蚀 , 涂层破损率 , 腐蚀速率 , 分形维数 , 腐蚀坑深

X-波段混合集成平衡I-Q矢量调制器

田为中 , 钱蓉 , 喻筱静 , 齐鸣

功能材料与器件学报 doi:10.3969/j.issn.1007-4252.2007.06.019

在介电常数为2.20±0.02,厚度为254μm的Rogers5880衬底上用混合集成技术制作了9.5～10.5GHz平衡,I-Q矢量调制器.测试结果表明:各状态插入损耗为(7.5±1)dB,回波损耗大于16dB,均方根(RMS)相位误差小于5.,各状态之间的幅度不平衡小于0.5dB,可实现对9.5～10.5GHz载波信号的直接QPSK调制.文中还提出电路性能优化的一些方法.

关键词: Rogers5880 , I-Q矢量调制器 , BPSK调制器

Theoretical calculations of spin-Hamiltonian parameters for CsCdX(3):Ni(2+) (X = Cl, Br) crystals from the two-mechanism model

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

The high-order perturbation formulas of spin-Hamiltonian (SH) parameters (g factors g(||),g(perpendicular to) and zero-field splitting D) for 3d(x) ions in trigonal octahedral sites of crystals are derived considering not only the crystal-field (CF) mechanism, but also the charge-transfer (CT) mechanism (which is neglected in the extensively used CF theory). From these formulas and by considering the suitable impurity-induced local lattice relaxation. the SH parameters of CsCdX(3):Ni(2+) (X = Cl, Br) crystals are calculated. The results are in reasonable agreement with the experimental values. The sign of Q(CT) (Q = Delta g(||). Delta g(perpendicular to) or D. where the g-shift Delta g(i) = g(i) - g(c). g(c) approximate to 2.0023 is the free-electron value) due to CT mechanism is the same as that of the corresponding Q(CF) due to CIF mechanism. The relative importance of CT mechanism (characterized by Q(CT)/Q(CF)) increases with the, increasing atomic number of ligand X. So. for 3d(n) ion clusters in crystals with heavy element ligand ion (e.g., Br(-)), the reasonable explanations of SH parameters should contain the contributions from both CF and CT mechanisms. (C) 2008 Elsevier B.V. All rights reserved.

关键词: Electron paramagnetic resonance (EPR);Crystal- and ligand-field theory;Charge-transfer mechanism;Ni(2+);CsCdX(3) (X = Cl;Br);atomic screening constants;excited-state;resonance-spectra;epr;parameters;scf functions;ions;spectroscopy;vanadium(ii);nickel(ii);absorption

Theoretical studies of spin-Hamiltonian parameters for Ni2+ ions in CsMgX3 (X = Cl, Br, I) crystals from the two-mechanism model

Physica B-Condensed Matter

In this paper, the high-order perturbation formulas of spin-Hamiltonian (SH) parameters (g factors g(parallel to), g(perpendicular to) and zero-field splitting D), including both the crystal-field (CF) and for the first tune charge-transfer (CT) mechanisms, are established for 3d(8) ions in trigonal octahedral clusters. By using these formulas, the SH parameters of Ni2+ ions in CSMgX3 (X = Cl, Br, 1) crystals are calculated. The results are consistent with the experimental values. The calculations suggest that the sign of Q(CT) (Q = Delta g(parallel to), Delta g(perpendicular to) or D, where the g-shift Delta g(i) = g(i)-g(e), g(e)approximate to 2.0023 is the value of free-electron) due to CT mechanism is the same as that of the corresponding Q(CF) due to CF mechanism, and the relative importance of CT mechanism (characterized by Q(CT)/Q(CF)) increases with the increasing atomic number of ligand X. So, for the 3d(n) MLm clusters with ligand having large atomic number, the reasonable theoretical explanations of all SH parameters should take both CF and CT tnechanisms into account. The defect structure of (NiX6)(4-) impurity centers in CSMgX3:Ni2+ crystals is also considered in our model. (c) 2007 Elsevier B.V. All rights reserved.

关键词: spin-Hamiltonian (SH) parameters;electron paramagnetic resonance (EPR);crystal- and ligand-field theory;charge-transfer mechanism;Ni2+;CSMgX3 (X =Cl;Br;I);linear-chain lattices;spectroscopic properties;g-values;field;csmgbr3;cscdbr3;spectra;epr

高Q值(1-x)(Sr0.2Nd0.208Ca0.488)TiO3-xNd(Ti0.5Mg0.5)O3微波陶瓷的微结构及介电性能研究

屈婧婧 , 魏星 , 经本钦 , 刘飞 , 袁昌来

无机材料学报 doi:10.15541/jim20150155

采用固相法制备了(1-x)(Sr0.2Nd0.208Ca0.488) TiO3-xNd(Ti0.5Mg0.5)O3(0.3≤x≤0.4,SNCT-NTMx)系微波介质陶瓷材料,并研究了该体系的相组成、显微结构、烧结性能和微波介电性能之间的关系.结果表明:在x=0.3～0.35范围内,SNCT-NTMx陶瓷形成了正交钙钛矿固溶体,并伴随有少量未知第二相;当x增至0.4时,第二相含量有所增加.介电性能研究结果显示:随着x的增加,体系介电常数(εr)减小,但品质因子(Q×f)得到改善;此外,体系谐振频率温度系数(τf)随NTM含量的增加逐渐向负值方向移动.当x=0.35,陶瓷样品在1520℃烧结4h得到的微波介电性能较优:εr=50.1,Q×f=44910 GHz,τf=-1.7× 10-6/℃.

关键词: (Sr0.2Nd0.208Ca0.488)TiO3 , Nd(Ti0.5Mg0.5)O3 , 钙钛矿 , 微波介电性能

Investigations of the electron paramagnetic resonance parameters and defect structures for Ni(2+) ions in CdX(2) (X = Cl, Br) crystals

Journal of Magnetism and Magnetic Materials

The high-order perturbation formulas of electron paramagnetic resonance (EPR) parameters (g factors g(parallel to), g(perpendicular to) and zero-field splitting D) for 3d(8) ions in trigonal octahedral clusters are established. These formulas contain the contributions not only from the crystal-field (CF) mechanism, but also from the charge-transfer (CT) mechanism (which is not considered in the widely used CF theory). From these formulas, the EPR parameters and the impurity-induced defect structures for Ni(2+) ions in CdX(2) (X = Cl, Br) crystals are studied. The calculated EPR parameters are coincident with the experimental values, and the defect structure of Ni(2+) impurity center obtained from the calculation is different from the corresponding structure in the host crystal. The sign of Q(CT) (Q = Delta g(parallel to), Delta g(perpendicular to), or D) due to CT mechanism agrees with that of the corresponding Q(CF) due to CF mechanism and the relative importance of CT mechanism (characterized by Q(CT)/Q(CF)) increases with increasing covalence of 3d(8) clusters and hence with raising atomic number of ligand X. So, in the explanations of the EPR parameters of 3d(8) (or other 3d(n)) ions in crystals with the heavy-element ligand ion (e. g., Br(-)), the calculated formulas based on the two-mechanism (CF and CT mechanisms) model are preferable to those based on only the CF mechanism in the CF theory. (C) 2008 Elsevier B. V. All rights reserved.

关键词: electron paramagnetic resonance (EPR);crystal- and ligand-field theory;charge-transfer mechanism;defect structure;Ni(2+);CdCl(2);CdBr(2);atomic screening constants;single-crystals;local-structure;scf;functions;spectra;transition;cadmium;cdcl2;epr

Microstructure, magnetic properties, and spontaneous magnetostriction of Tb0.2Pr0.8(Fe0.4Co0.6)(x)

Ieee Transactions on Magnetics

The microstructure, magnetic properties and magnetostriction of Tb0.2Pr0.8(Fe0.4Co0.6)(infinity) (1.65 less than or equal to x less than or equal to 1.90) alloys has been studied. The Curie temperatures for the 1:2 and 1:3 phases decrease with increasing x, whereas the saturation magnetization increases with increasing cc. The remanent magnetization remains almost constant for all the samples and the coercivity decreases with increasing x. The spontaneous magnetostriction (lambda (111)) estimated from the splitting of the (440) lines is found to decrease with increasing x. The largest lambda (111) recorded for Tb0.2Pr0.8(Fe0.4Co0.6)(1.65) is 2900 ppm at room temperature.

关键词: Laves phase;microstructure;spontaneous magnetostriction;alloys