材料期刊网

NUMERICAL SIMULATION OF ULTRASONIC NON-DESTRUCTIVE TESTING FOR WELDS

H.D. Chen , Y.W. Wang , J. Xue

金属学报(英文版)

A computer simulation technique for ultrasonic propagation is utilized for the simulation of ultrasonic nondestructive testing (NDT). In this paper, one goal of the simulation is to compute ultrasoniceld radiated by arbitrary transducers into pieces under examination. The other simulates a testing experiment. The simulation approach is based on the model for the computation of the ultrasoniceld in isotropic media radiated from actual NDT transducers. After the eld is known, remaining to be modeled is the interaction between this eld and the scatters (defect) and the echo structure. The model of beam-defect interaction is based on the Kirchho's diffraction approximations theory applied to elastodynamics. We assumed that the incident wave fronts on the defect are plane in the case of a focused immersed transducer and material is isotropic and homogeneous. The simulating results demonstrate that the model in ultrasonic NDT of welds is practical in further research and useful in optimizing testing congurations.

关键词: ultrasonic testing , null , null , null

SPE水电解进行H/D同位素分离

孟建波 , 桑革 , 薛炎 , 曹伟 , 叶小球

应用化学 doi:10.3969/j.issn.1000-0518.2007.12.017

将固体聚合物电解质(SPE)水电解技术应用于H/D同位素分离,考察了电极材料、电流密度和温度对分离系数(α)的影响.在40 ℃、90×10-3 A/cm2条件下,得到IrRu/Nafion117/PbAg、IrRu/Nafion117/TiNi3、IrRu/Nafion117/Ni和C/Nafion112/Pt-TiO2三合一电极(MEA)的H/D分离系数α分别为4.49、3.48、3.14和4.53.对IrRu/Nafion117/PbAg电极研究结果为:电流密度分别为90×10-3、150×10-3和300×10-3 A/cm2,40 ℃时分离系数α分别为4.49、4.65、5.46,60 ℃时分别为3.76、4.11、4.38;温度分别为40、60和70℃,电流密度为90×10-3 A/cm2条件下,分离系数α分别为4.49、3.76、3.53,ln α～103/T的拟合直线为ln α=0.816×(103/T)-1.112.在40～70 ℃范围内反应的活化能-△Ha约为6 778 J/mol.结果表明,分离系数α随电流密度增加而增大,随温度升高而减小.此外,分析了Nafion膜中在H/D传输的同位素效应.

关键词: 固体聚合物电解质 , 水电解 , 电催化剂 , 氢同位素 , 分离

Chen系统的状态变量周期性反馈控制

李开明 , 李亚洲 , 冯维贵 , 林长

量子电子学报 doi:10.3969/j.issn.1007-5461.2007.05.014

采用非线性反馈控制,用附加了带参数的正弦项对Chen系统进行了有效的控制.随着参数k的逐渐增大,系统的动力学行为呈现出一系列的变化.数值研究结果表明:随控制参数的增大,驱动信号的强度渐大,混沌系统由混沌运动到周期轨道,最终到一相点.

关键词: 混沌 , Chen系统 , 不动点 , Lyapunov指数 , 反馈控制

钯与氢(H2,D2)反应的热力学性质研究

唐涛 , 郭淑兰 , 陆光达 , 陈虎翅 , 朱新亮

稀有金属 doi:10.3969/j.issn.0258-7076.2004.02.005

采用PVT方法精确测定了40～60目的海绵钯(Pd)粉末在5～50 ℃范围内吸放H2, D2的P-C-T 曲线.结果表明:25 ℃, 0.1 Mpa时H2, D2在Pd中的溶解度分别为75.8和70.4 ml(STP)·g-1 Pd;Pd与H2, D2反应的坪台热力学函数分别为:Δha=-18.7 kJ·mol-1 H, -17.6 kJ·mol-1 D, Δsa=-46.4 J·K-1·mol-1H, -49.6 J·K-1·mol-1D;ΔHd=21.3 kJ·mol-1H, 18.7 kJ·mol-1D, ΔSd=50.8 J·K-1·mol-1H, 49.1 J·K-1·mol-1D.H, D在α相的溶解热力学函数为:ΔHr→0=-6.5 kJ·mol-1H, -5.6 kJ·mol-1D;ΔSr→0=-53.5 J·K-1·mol-1H, -53.7 J·K-1·mol-1D.Pd-Q(Q=H, D)体系存在明显的迟滞效应, 升高温度可改善吸放氢循环的压力迟滞效应, 但不能消除.伴随迟滞效应的吉布斯自由能损失(Δgloss)在低于50 ℃时保持不变, 对Pd-H和Pd-D体系分别为1.28和1.25 kJ·mol-1H(D);当高于50 ℃时Δgloss分别减小约4%和11%.

关键词: 钯 , 氢同位素 , 热力学 , 迟滞效应

A Novel near Net-Shape Technique for P/M Parts with Large H/D Ratio

Yong LIU , Baiyun HUANG , Kechao ZHOU , Hongwu OUYANG , Yuehui HE

材料科学技术（英）

In order to overcome the shortcomings of conventional hot pressing, a novel near net-shape technique, called radial hot pressing, for P/M parts with large height-to-diameter (H/D) ratio was introduced. Effects of processing parameters on the microstructures and density of P/M TiAl base alloy valves were studied. Results show that the radial hot pressing is an effective technique for manufacturing valves with a H/D ratio of about 10:1, and the perfect joint interface between the Mo sheet and the parts is helpful for subsequent HIPing.

关键词: Near net-shape technique , null , null

含铌Q275D热轧H型钢的研制

郭秀辉

钢铁研究

为保证莱钢Q275D热轧H型钢极限规格的-20℃冲击功值满足GB/T 700-2006要求,采用Nb微合金化结合再结晶控轧工艺试制了极限规格H400 mm× 200 mm×8 mm×13 mm的Q275D热轧H型钢.结果表明:试制产品的上屈服强度为360～368 MPa,抗拉强度为480～500 MPa,伸长率为32.5 ％～33.0％,平均冲击功为154～233 J,各项性能指标满足标准要求.

关键词: 热轧H型钢 , 再结晶控制轧制 , Nb微合金化

Pt-Ir/C/PTFE疏水催化剂及催化H-D交换研究

梁宏伟 , 桑革 , 王清 , 李嵘 , 沈崇雨

稀有金属 doi:10.3969/j.issn.0258-7076.2003.02.010

制备了8种金属含量不同的Pt-Ir/C/PTFE疏水性催化剂,采用这些催化剂进行了H-D同位素气液对流、气汽并流交换实验,初步考察了温度、压力、氢气流速对催化活性的影响. 实验表明,Ir的加入能够提高疏水催化剂的催化活性,当Ir在二元金属中的含量为25%时,催化剂的催化活性得到提高.

关键词: 催化化学 , 疏水催化剂 , 氢同位素交换 , 氘

提高特厚规格Q275D热轧H型钢冲击性能的研究

郭秀辉 , 杜传治 , 李超

钢铁研究

针对莱钢特厚规格Q275D热轧H型钢纵向低温冲击性能不合格的问题,采用金相显微镜和扫描电镜对其显微组织进行了分析,结果表明:混晶组织是造成低温冲击性能不合格的主要原因.根据莱钢现有设备,通过优化成分设计和控制轧制工艺参数,使得此规格H型钢晶粒尺寸细小均匀,-20 ℃纵向V型冲击功平均值大于160 J,满足相应标准要求.

关键词: Q275D , V-Ti微合金化 , 再结晶控制轧制 , 特厚规格H型钢

First-principles investigations of isotope effects in thermodynamic properties of TiX2 (X = H, D, and T) system

Journal of Alloys and Compounds

As hydrogen, deuterium and tritium storage materials, a series of investigations of mechanical and thermal properties of titanium hydrides, deuterides and tritides have been performed, however, very limited theoretical studies of thermodynamic properties for them can be found. Based on density-functional theory (DFT) and density-functional perturbation theory (DFPT) we have discussed systematically the hydrogen isotope effects on the thermodynamic properties of TiX2 (X = H, D, and T) system. Our calculations indicate that for evaluating accurately their physical properties at absolute zero temperature, such as the equilibrium lattice constants, bulk modulus, and heat of formation, the zero-point energy correction must be taken into account. By performing the phonon calculation within quasiharmonic approximation (QHA), we obtain their vibrational free energies, vibrational entropies, and temperature dependence of specific heat, thermal expansion, and bulk modulus. Those results demonstrate that comparing with TiH2, TiT2 and TiD2 are more stable and the zero-point effects play an important role in their thermal expansion. The increase in the force constant between Ti and H causes the higher value of specific heat of TiH2 during the phase transition from FCC to FCT. In addition, comparing with available experimental values, we can conclude that QHA is feasible for describing the thermal properties of TiX2. (C) 2006 Elsevier B.V. All rights reserved.

关键词: isotope effects;thermodynamic properties;density-functional;perturbation theory;quasiharmonic approximation;functional perturbation-theory;neutron spectroscopy;thermal-properties;titanium;hydrogen;dependence;expansion;constants;palladium;hydrides

稀土固体超强酸催化D4和D4H开环共聚合制备二甲基含氢硅油

刘佳 , 邵倩 , 杨雄发 , 曹诚 , 陈忠红 , 来国桥

高分子材料科学与工程

二甲基含氢硅油是制备二甲基硅橡胶不可缺少的原料,其性能对硅橡胶性能有较大影响.针对二甲基含氢硅油传统制备方法存在的缺点,本文中采用高活性、便于处理、能重复利用、低腐蚀性的稀土固体超强酸SO42-/TiO2/Ln3+催化八甲基环四硅氧烷(D4)与1,3,5,7-四氢-1,3,5,7-四甲基环四硅氧烷(D4H)开环共聚合,制备了二甲基含氢硅油.系统考察了共聚合反应的规律,并探索了所得产物在加成型硅橡胶制备中的应用.结果表明,用SO42-/TiO2/Nd3+做催化剂,[SO42-]=1.85 mol/L,[Nd3+]=0.05 mol/L时,在80℃聚合60 min,获得的二甲基含氢硅油收率为87.9％,相对分子质量为4.23×104,相对分子质量分布指数为3.07.当单体按照D4H/(D4H+ D4)=30％,共聚单体与封端剂摩尔比为178.5∶1时,所得硅橡胶性能最佳.

关键词: 稀土固体超强酸 , 二甲基含氢硅油 , 开环聚合 , 硅橡胶