双曲壳结构复合材料的热临界屈曲温度研究

以双曲壳结构复合材料为研究对象,利用Block-Lanczos研究分析法对复合材料层合双曲壳结构在温度场下热屈曲行为进行研究,并研究了复合材料层合双曲壳铺层厚度、边界条件、纤维方向等对临界屈曲温度的影响。结果表明:在均匀温度场下复合材料层合双曲壳临界屈曲温度与边界条件、铺层厚度、纤维方向有密切关系并成一定规律分布。通过对复合材料双曲壳结构的热屈曲性能分析,为复合材料结构设计和实际工程应用提供了一种有效的分析及建模方法。     

石墨-FeNi核-壳结构复合微球的制备

以硫酸亚铁、硫酸镍、碳酸钠和石墨微球为主要原料，利用非均相成核工艺制备出水合氧化铁和碱式碳酸镍均匀包覆石墨的前驱体微球：通过对前驱体进行热还原处理得到了晶粒约为50nm的γ-FeNi合金颗粒层包覆石墨的产物微球。利用SEM，EDS，XRD对前驱体和产物的形貌、成分、物相分别进行了表征，并利用TG／DSC对前驱体热分解过程进行了分析。通过研究，得出了制备这种核．壳结构复合微球的优化工艺参数。     

双曲壳结构复合材料的热临界屈曲温度研究（英文）

以双曲壳结构复合材料为研究对象,利用Block-Lanczos研究分析法对复合材料层合双曲壳结构在温度场下热屈曲行为进行研究,并研究了复合材料层合双曲壳铺层厚度、边界条件、纤维方向等对临界屈曲温度的影响。结果表明:在均匀温度场下复合材料层合双曲壳临界屈曲温度与边界条件、铺层厚度、纤维方向有密切关系并成一定规律分布。通过对复合材料双曲壳结构的热屈曲性能分析,为复合材料结构设计和实际工程应用提供了一种有效的分析及建模方法。     

一种制备核-壳纳米Ni／Al复合粉末的新方法

在含氟离子的水溶液中，采用Al粉直接置换还原Ni盐的方法，实现了纳米Ni在Al粉表面上的快速化学沉积，制备出核-壳结构的Ni／Al复合粉末。探讨了反应的过程，利用粒度分析，SEM，XRD，BET，XPS等测试手段对复合粉末进行了微观测试和表征。结果表明：平均粒度为7．13μm的铝颗粒表面包覆着一层纳米Ni（其晶粒度为20．4nm），形成了壳层。     

聚氨酯泡沫表面化学镀镍及其热处理研究

以聚氨酯泡沫为基体,采用化学镀工艺在其表面得到金属镍镀层。在不同温度下对化学镀镍后的聚氨酯泡沫进行热处理,通过扫描电子显微镜（SEM）、X射线衍射仪（XRD）和热重分析仪（TG）对镍镀层的组成、结构、形貌和热分解行为进行表征。结果表明：聚氨酯泡沫的热分解分为300-400℃和500-650℃两个热失重阶段;随着热处理温度的升高,化学镀镍层的镍晶粒逐渐长大;当热处理温度达到500℃,聚氨酯骨架基本完全消失而金属镍镀层依然存在,这为制备泡沫镍提供了可能。     

镁合金在金属置换镍膜上的化学镀镍

在镁合金表面上通过置换反应制备了一层均匀的镍金属膜,它可以使镁合金基体免于被化学镀液过度腐蚀,同时为化学镀提供了具有反应活性的表面,然后在其上进行化学镀镍.镍金属膜的制备工艺对环境无害,减少了化学镀过程对镁合金基体的浸蚀损耗,提高了其镀膜精度,可延长化学镀液寿命,并简化了工艺过程.通过扫描电镜、辉光放电光谱仪、电化学动电位极化测试,表明所得到的镍金属膜和化学镀层性能良好,化学镀层耐蚀性有明显提高.     

化学镀法制备镍包覆铝粉

用化学镀法在活性铝粉表面包覆纯镍层制备ＮｉＡｌ复合粉末。结果表明，控制温度为８６～８９℃、ｐＨ＝１２５～１３２、硫酸镍加入量为３５０～４５０ｇ／Ｌ、还原剂加入量为７５～９５ｍＬ／Ｌ时可获得镀覆质量良好的粉末，且镍呈结晶态析出。此外还讨论了这些工艺参数对镀覆质量的影响     

ZnO-TiO_2核壳纳米线结构及其热稳定性研究

采用热还原法和原子层沉积技术制备了ZnO-TiO_2核壳纳米线,研究沉积厚度、沉积温度及退火对于ZnO-TiO_2核壳纳米线晶化和结构的影响。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨率透射电镜(HRTEM)等手段对退火前后核壳纳米线进行表征。结果表明:沉积厚度和温度的增加有利于TiO_2壳层发生非晶向晶化的转变;500℃退火提高了TiO_2的结晶性,但可能会使细核壳纳米线(ZnO纳米线直径80 nm)产生波浪形变形,使150℃沉积的非晶TiO_2壳层形成凸出晶粒,并导致其界面处ZnO缺失。     

压铸镁合金化学镀Ni-P的沉积过程

通过扫描电镜和GDA辉光放电光谱分析仪等手段，研究了压铸镁合金化学镀Ni-P的沉积过程，结果表明镁合金化学镀的前处理使基材表面呈现孔洞结构，活化形成比较平整的疏松网孔状MgF2和AIF3层：镁合金化学镀Ni-P的初始沉积过程，首先是Ni的还原析出，并不含P；随着Ni形核数量的增多和长大，有自催化能力的Ni层产生，镍磷共沉积开始：镀层中存在铬化物、氟化物与镀液成分以及Ni的混杂层。     

氮化硅晶须表面化学镀镍及应用研究

采用化学镀方法在α-Si3N4晶须表面镀覆了一层均匀的镍镀层,以保护氮化硅晶须在增强增韧复合材料时不被破坏.考察了温度、时间和pH值等对镀层增重和微观结构的影响;采用差热-热重分析(DTA),XRD,SEM及EDS对化学镀后的α-Si3N4晶须进行了结构、形貌以及成分分析,结果表明:α-Si3N4晶须表面镀覆了一层均匀...     

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。