Industrial & Engineering Chemistry Research
The densities, viscosities, and conductivities were measured for the ternary solution NaCl + urea + H(2)O, the quintuple solution NaC1 Na(2)SO(4) KCl K(2)SO(4) + H(2)O, and their binary subsystems at 298.15 K. The results together with the densities, viscosities, and conductivities of multicomponent solutions reported in the literature were used to study the predictability of the Young's rule for density and conductivity, the rule of Patwardhan and Kumar for density, Flu's equation for the viscosity of mixed electrolyte solutions based on the Eyring's absolute rate theory and the rule of Patwardhan and Kumar, and the semiideal solution theory for thermodynamic and transport properties. The results show that all the tested equations can provide comparable and accurate predictions for the densities of multicomponent electrolyte solutions. The semiideal solution theory is applicable to the aqueous solutions of electrolytes and nonelectrolytes, and its predictions for the densities of the examined solutions are in nice agreement with the experimental results. The simple equation based on Eyring's absolute rate theory and the rule of Patwardhan and Kumar and the semiideal solution theory can provide nice predictions for the viscosity of the tested electrolyte solutions. The predictions for the viscosity of the ternary solution NaCl + urea + H(2)O by the semiideal solution theory are also in accordance with the measured viscosities. The semiideal solution theory can provide better predictions for the conductivities of the tested electrolyte solutions than the extended Young's rule, and their predictions are both in good agreement with the experimental results. The advantages of the semiideal solution theory are briefly discussed and reviewed.
关键词:
mixed-electrolyte-solutions;linear isopiestic relation;absolute rate;theory;aqueous-solutions;298.15 k;activity-coefficients;sodium-chloride;potassium-chloride;ternary subsystems;unified;approach
LU Lu
,
WANG Fu-zhong
,
WANG Zhao-xu
,
ZHU Guang-ya4
,
ZHANG Xing-xiang5
钢铁研究学报(英文版)
Based on test data from the hot forge experiments on Gleeble 1500, a Kumar type constitutive equation for 33Mn2V steel is established. Applying this constitutive equation in commercial FEM software of MSC/SuperForm 2005, the piercing process of 33Mn2V steel in Mannesmann mill is then simulated. The modeling results visualized the dynamic evolution of equivalent stress, especially inside the workpiece. It is shown that the non-uniform distribution of stress on the internal and external surface of the workpiece is a distinct characteristic of processing tube piercing. The numerical model was verified by comparing the values of calculated force parameters of the piercing process with those measured in laboratory conditions. And it shows that the Kumar-type constitutive relationship meets the practical needs.
关键词:
33Mn2V
,
constitutive equation
,
tube piercing process
,
thermo-mechanical coupling simulation
,
FEM analysis
张辉
,
郑桂丽
,
田毅
,
张志东
液晶与显示
doi:10.3788/YJYXS20163108.0740
基于 Pramoda Kumar 等人文章中关于向列相液晶反转壁中＋1缺陷处挠曲电效应的实验现象，我们利用 Landau-de Gennes 理论给出相应的理论分析。当对弱锚定的平行排列向列相液晶盒施加垂直基板的直流电压，在反转壁中的±1缺陷会发生旋转。对于其中的＋1缺陷，我们给出了外加电场作用下液晶分子的自由能表达式并通过模拟描述指向矢的方位角和极角的变化情况给出相应的缺陷处电场驱动的结构变化。模拟结果给出的挠曲电效应引起的方位角的变化角度与 Pramoda Kumar 等人的实验得到的在＋1缺陷处消光刷的变化情况是一致的。
关键词:
液晶
,
挠曲电效应
,
+1 缺陷
,
Landau-de Gennes 理论
王民庆
,
王凯
,
邓群
,
徐庭栋
钢铁研究学报
结合偏聚理论的最新进展，对R.D.K.Misra等认为Ni和Sn的晶界偏聚动力学曲线相互平行，而且2种元素可同时达到一个晶界浓度极大值的实验结果重新进行了分析。分析结果证实，Ni和Sn在恒温过程中发生的是一非平衡晶界共偏聚现象，Ni的非平衡偏聚是由Sn的非平衡偏聚引起的。
关键词:
晶界偏聚;共偏聚;时效
徐庭栋
,
焦兰英
钢铁研究学报
以文献[1]建立的张应力引起的非平衡晶界偏聚动力学方程模拟了Shinoda T等的磷在钢中的应力时效实验结果和Misra R D K的硫在钢中的应力时效实验结果,模拟结果与实验结果互相吻合.通过模拟发现,张应力使磷-空位复合体以及硫-空位复合体在钢中的扩散系数均增加3个数量级,且磷原子和硫原子的扩散系数分别降低3个和5个数量级.
关键词:
晶界
,
空位
,
偏聚
,
动力学
,
扩散系数
王民庆
,
王凯
,
邓群
,
徐庭栋
钢铁研究学报
结合偏聚理论的最新进展,对R.D.K.Misra等认为Ni和Sn的晶界偏聚动力学曲线相互平行,而且2种元素可同时达到一个晶界浓度极大值的实验结果重新进行了分析.分析结果证实,Ni和sn在恒温过程中发生的是一非平衡晶界共偏聚现象,Ni的非平衡偏聚是由Sn的非平衡偏聚引起的.
关键词:
晶界偏聚
,
共偏聚
,
时效
Journal of Physics-Condensed Matter
Nb(2)AsC showed superior mechanical properties to those of other layered ternary carbides (Kumar et al 2005 Appl. Phys. Lett. 86 111904). In the present density functional calculation, the underlying mechanism is interpreted by astonishing bonding features of Nb(2)AsC. The Nb d-As (p(x) + p(y)) and Nb d-As p(z) bonding states locate in the same energy range as those of Nb d-C p bonding, which indicates that the Nb-As bond has similar bonding strength as the Nb-C bond does; and thereafter, Nb(2)AsC has improved mechanical properties compared to the others. The present reported bonding features are interestingly different from those experienced by T(2)AlC (T=Ti, V, Cr, and Nb), wherein the weak T-Al coupling was separated from T-C bonding states in the higher energy level by a pseudogap. This work proposes an effective method to strengthen the relative weaker T-A (A is the A-group element) bonding in layered ternary carbides.
关键词:
ti3sic2;solids;gpa
袁清华
,
张文明
,
黄重国
,
任学平
稀有金属
doi:10.3969/j.issn.0258-7076.2009.04.005
采用普通工业TC4板料,在MTS高温拉伸试验系统上进行了不同变形条件的恒速拉伸试验,研究材料的高温变形行为.分析了5类通用高温本构关系对该材料真实应力应变曲线的拟合情况.最终,采用经典的Kumar模型建立了TC4的高温本构关系.利用MARC分析TC4机身盒形零件的气压成形过程,依据正交试验原理确定FEA仿真方案,并对成形模具进行了设计.以壁厚标准差为评价指标,采用极差分析法确定各因素对指标的影响程度和最佳工艺参数,并通过气压成形试验获得满足质量要求的零件.
关键词:
TC4(Ti-6Al-4V)
,
本构关系
,
气压成形
,
有限元分析
Weiyan LÜ
,
Lin LI
,
Li WANG
,
Yanlin HE
,
Shuigen HUANG
材料科学技术（英文）
Phase diagram information of the Fe-C, Fe-Al and Al-C systems are reviewed and the Fe-Al-C system is assessed. A FeAlC database is created by combining a set of thermodynamic parameters established by Kumar and SSOL database in Thermo-Calc software package. Ternary phase diagrams are calculated with FeAlC and the newly developed Thermo-Calc databases SSOL2 and SSOL4. The FeAlC database is the best one to describe the Fe-Al-C system. A1 and A3 values on the vertical section containing 1.5 wt pct Al are calculated with the FeAlC database in this work. To validate the thermodynamic calculation, critical temperatures Ac1 and Ac3 are determined by using dilatometer analysis. There exist some errors between the calculated values and the experimental results. So further optimization of the Fe-Al-C system regarding bcc and fcc phases is necessary. The experimental data in this work could be of some value in further optimization.
关键词:
Fe-Al-C
,
null
,
null
