磁性液体的研究进展

本文综述了国内外磁性液体的研究现状与进展，系统地介绍了磁性液体的理论、现有种类、制备方法，并在此基础上对磁性液体的性能特点和应用进行了论述，其中着重介绍了磁性液体在制备方法上的优缺点及在密封和医学上的应用。     

纳米磁性液体的制备方法

纳米磁性液体具有很多特殊的物化性质,在工业上具有广泛的应用。本文介绍了纳米磁性液体的组成,着重描述了几种常见的纳米磁性液体制备方法,介绍了纳米磁性液体的发展现状,并对今后的发展方向进行了展望。     

高饱和磁化强度氮化铁磁性液体的研制

叙述了制造氮化铁（Fe3N）磁性液体的方法和装置,探讨了影响磁性兴体饱和磁化强度Ms值的工艺因素。试验了提高磁性液体Ns值的浓缩方法。磁性液体最高Ms值达到了0．1346T（1346Gs）。     

传递矩阵法在管系液体振动研究中的应用

在对气柱振动研究的基础上,将传递矩阵法引入管系液体振动研究。这种方法可以方便地获得各种管系内液体振动的固有频率和压力振型。与传统的方法比较,它对于研究管系液体动特性以及避免管系的振动具有较强的实用性。     

氮化铁磁性液体及其制备

介绍了较铁氧体系列、金属系列磁性液体性能优越的氮化铁磁性液体。并简要介绍了它的两种制备方法、特点及性能。指出该磁性液体作为一种新型功能材料具有广阔的应用前景和巨大的潜在市场。     

仿生无动力液体输送机理及结构研究进展∗

液体输送在化工过程中起着至关重要的作用,目前的液体输送是主动的,需要消耗大量的能量,而自然界中部分生物可以实现无动力的液体输送。 在能源匮乏的今天,模仿这些生物体无动力液体输送原理、结构,制得具有同样或超越其性能的仿生液体输送系统成为近年来的研究热点。 通过列举自然界的特殊生物实例,分析这些生物所特有的结构、液体输送现象, 阐述无动力液体输送机理。 在此基础上对比分析相应的仿生液体输送系统的结构、制备材料、方法、特点等,指出随着各种新材料加工技术的出现,无动力液体输送系统从模仿单一的生物结构,向基于无动力液体输送原理设计新型结构的方向发展。 最后提出该领域研究存在的挑战和未来研究方向,以促进该领域进一步的研究及工程应用。     

恒流开式液体静压支承动力学建模及参数辨识方法

针对现有恒流开式液体静压支承线性动力学模型计算偏差较大问题,建立了液体静压支承的非线性动力学模型。基于液体静压支承振动响应,提出应用Fourier级数方法和最小二乘联合方法,识别该非线性动力学模型中的刚度与阻尼。同时,设计了多种阶跃激励作用下的实验工况,应用研制的实验平台,获取了各种工况条件的振动响应。结合液体静压支承的非线性动力学模型和提出的参数辨识方法,得到了液体静压支承的刚度、阻尼参数。在此基础上,对比识别的动力学参数计算的位移响应与实验值,发现理论值与实验值的决定系数都在0.97以上,从而验证了建立的非线性动力学和参数辨识方法的有效性。     

���淨����͸��Һ�����������¶ȵı仯��ϵ��

 文章提出了一种利用迈克尔逊干涉仪研究透明液体折射率受温度影响变化的实验方法。利用这种方法得到透明液体水从18 ℃~50 ℃的折射率变化曲线。该方法具有操作简单，测量精度高，测试温度范围宽等特点，并可用于多种透明液体折射率的研究，尤其是通过干涉环的吞吐可以形象地反映折射率随温度变化的动态过程。     

圆柱形储液罐声发射检测的液体声速现场测量

提出了一种现场测量圆柱形储液罐液体声速的方法,并通过试验分析了影响测量精度的有关因素。液体声速测量采用常规的声发射检测布置方案,激发模拟声源产生振动,然后获取液体直达波的传播时间从而计算出声速。对比了断铅、30kHz和60kHz的三种模拟信号,结果表明高频成分为主的声源更有利于定位液体直达波。对阈值法、相关法和包络切线法三种波达时差计算方法进行了比较,结果表明包络切线法更有效。试验数据表明,提出的现场测速方法具有较高的精度。     

基于SPH方法的罐式贮箱动力响应及稳定性研究

应用光滑粒子动力学(SPH)方法建立罐式贮箱模型,模拟在横摇激励下贮箱内的液体晃动。分析贮箱拓扑结构、防波板数目及防波板高度对贮箱壁面冲击压力及结构稳定性的影响。模拟结果表明:SPH方法可以很好地模拟液体晃荡强非线性特征,改进的梯形截面的罐式贮箱可以有效抑制液体晃动;在椭圆形贮箱中合理布置防波板可有效降低液体质心,减小倾覆力矩,更有利于罐式贮箱保持稳定。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。