Effect of barium on the refinement of primary aluminum and eutectics in a hypoeutectic Al-Si alloy

The effect of barium on the refinement of primary aluminum and on themodification of eutectics in a hypoeutectic aluminum-silicon alloy was investigated. The resultsindicate that barium not only modifies the eutectic silicon but also refines the primary aluminumand there is a relationship between the retained barium and the second spacing of primary aluminum.Experiments of barium-treated commercial Al-Si hypoeutectic alloy show that barium is a bettermodifier than sodium when there is a longer holding time.

Electrochemical behavior and electrolytic preparation of lead in eutectic NaCl−KCl melts

A novel molten salt extraction process consisting of chlorination roasting and molten salt electrolysis was proposed to develop a more efficient and environmental friendly technology for recovering lead from spent lead acid batteries(LABs).The feasibility of this process was firstly assessed based on thermodynamics fundamentals.The electrochemical behavior of Pb(II)on a tungsten electrode in the eutectic NaCl−KCl melts at 700℃ was then investigated in detail by transient electrochemical techniques.The results indicated that the reduction reaction of Pb(II)in NaCl−KCl melts was a one-step process exchanging two electrons,and it was determined to be a quasi-reversible diffusion-controlled process.Finally,potentiostatic electrolysis was carried out at−0.6 V(vs Ag/AgCl)in the NaCl−KCl−PbCl2 melts,and the obtained cathodic product was identified as pure Pb by X-ray diffraction analysis.This investigation demonstrated that it is practically feasible to produce pure Pb metal by electrochemical reduction of PbCl2 in eutectic NaCl−KCl melts,and has provided important fundamental for the further study on lead recovery from spent LABs via molten salt extraction process.

NON-DESTRUCTIVE MEASUREMENTS OF LEAD AND BARIUM IN ARCHAEOLOGICAL BONE SAMPLES USING XRF

The lead and barium contents in sixteen archaeological bone samples from 10 persons buried in Dalsby, Sweden, were determined by means of X- ray fluorescence analysis using two "Co sources for excitation and a planar Ge detector for registration of the X- rays. The lead concentrations were found to be less than 168μ g/g, and the barium concentrations were in the range of 15- 97μg/g.

Flow characteristics of natural circulation in a lead–bismuth eutectic loop

Lead and lead-alloys are proposed in future advanced nuclear system as coolant and spallation target.To test the natural circulation and gas-lift and obtain thermal-hydraulics data for computational fluid dynamics(CFD) and system code validation, a lead–bismuth eutectic rectangular loop, the KYLIN-Ⅱ Thermal Hydraulic natural circulation test loop, has been designed and constructed by the FDS team. In this paper, theoretical analysis on natural circulation thermal-hydraulic performance is described and the steady-state natural circulation experiment is performed. The results indicated that the natural circulation capability depends on the loop resistance and the temperature and center height differences between the hot and cold legs. The theoretical analysis results agree well with,while the CFD deviate from, the experimental results.

Effects of cooling rates on microstructure and microhardness of lead-free Sn-3.5%Ag solders

The microstructure and microhardness of Sn-3.5%Ag solders were explored in the cooling rate ranging from 0.08 to 104 K/s. Under rapid cooling condition, the strong kinetic undercooling effect leads to the actual solidification process starting at the temperature lower than the equilibrium eutectic point, and the actual metastable eutectic point shifts to the higher Ag concentration. Hence, the higher the applied cooling rate is, the more the volume fraction of primary β-Sn crystal forms. At the same time, the separation of primary β-Sn crystal favors restraining the formation of bulk Ag3Sn intermetallic compounds (IMCs) in solder due to the mismatch crystalline orientation relationship, those Ag3Sn phase separating through the eutectic reaction could hardly cling to the primary β-Sn crystal and grow up. Additionally, the Vickers hardness test shows that fine β-Sn and spherical Ag3Sn phase in the rapidly solidified alloy strongly improves the microhardness of the Sn-3.5%Ag solder.

The performance of Pt/air oxygen sensors in stagnant Pb-Bi eutectic at high temperatures

Oxygen control technology is a critical issue for compatibility of candidate structural materials with liquid lead-bismuth eutectic(LBE) in accelerator driven systems. Performances of a self-developed Pt/air sensor and another one from Karlsruher Institute of Technology(KIT) were tested in stagnant oxygen-saturated liquid LBE.Calibrations showed that the trend and values of corrected electromotive force(EMF) of the self-developed sensor, with a bias voltage of 20 mV, were consistent with theoretical results above 425℃, and similar results were obtained in cross-calibration test with EMF value of KIT sensor as reference. In stability test at 450℃ for 100 hours, the KIT sensor performed better than the self-developed one, which showed signal fluctuations.Both sensors exhibited quick response to temperature variations in the responsiveness test.

Studies on Progressive Reactions Leading Formations of Different Types of Barium Ferrites

The present investigation is concerned with the reaction of barium and iron nitrates mixtures using three different molar ratios, 1:1 (Ⅰ), 1:2 (Ⅱ) and 2:1 (Ⅲ) at different temperatures as pointed out from the DTA data. The reaction products exhibit 12 compounds namely, Ba(NO3)2, αFe2O3, Fe3O4, BaFeO3, BaFeO2.9, hexagonal BaFeO3-x, tetragonal BaFeO3-x, BaFe2O4, αBaFe2O4, Ba2Fe6O11, Ba5Fe14O26 and BaFe12O19. The formation of these products depend on the molar ratio between the reactants and the reaction temperature. The reaction products were studied by DTA and TG techniques and characterized by X-ray diffraction patterns, magnetic susceptibility data and scanning electron microscopy, SEM.

Structural and Dielectric Properties of Sn Doped Barium Magnesuim Zirconium Titanate Perovskite Ceramics

Perovskite type ceramics (Ba0.9Mg0.1)(SnxZr0.4-xTi0.6)O3 (with x = 0.01, 0.02, 0.03 and 0.04) relaxor composition prepared through solid state reaction route and calcinated at temperature is 1150°C for 5 hrs with intermediate mixing. The room temperature XRD study suggests that all the samples have the single phase cubic symmetry with space group pm 3 m. The pellets were sintered at 1500°C for 4 hrs. Scanning Electron Microscope (SEM) observations revealed enhanced micro structural uniformity and retarded grain growth with decreasing Sn content. The dielectric measurements at constant frequency show that dielectric constant increases with Sn content. Loss factor and dielectric constant decreased with increasing frequency but at very high frequencies it was independent.

Thermal and Electrical Properties of Sn-Zn-Bi Ternary Soldering Alloys

Sn-Zn based solder is a possible replacement of Pb solder because of its better mechanical properties. The alloys need to be studied and explored to get a usable solder alloy having better properties. In this work, eutectic Sn-9Zn and three Tin-Zinc-Bismuth ternary alloys were prepared and investigated their thermal and electrical properties. Thermo-mechanical Analysis and Differential Thermal Analysis were used to investigate thermal properties. Microstructural study is carried out with Scanning Electron Microscope. The alloys have single melting point. The co-efficient of thermal expansion and co-efficient of thermal contraction varies with alloy composition and temperature range. Electrical conductivity changes with Bi addition.

Effect of Bismuth Addition on Structure and Mechanical Properties of Tin-9Zinc Soldering Alloy

Sn-Zn based solder is a possible replacement of Pb solder because of its better mechanical properties. The alloys need to be studied and explored to get a usable solder alloy having better properties. In this work eutectic Sn-9Zn and three Tin-Zinc-Bismuth ternary alloys were prepared and investigated their microhardness and mechanical properties. Microhardness, tensile strength and elastic modulus increase with Bi addition while ductility decreases with Bi addition.

Influence of Composition on Properties of BNT-BT Lead-Free Piezoceramics

Lead-free piezoelectric ceramics of (Bi1/2Na1/2)TiO3-BaTiO3(BNT-BT) were prepared by the conventional piezoelectric ceramic preparation technique (free air atmosphere sintering). The influence of BaTiO3 additive amount and La2O3 additive amount on the properties of BNT-BT lead-free piezoceramics were investigated. The results show that the dielectric constant(ε) and piezoelectric strain constant(d33) of materials start increasing and then decreasing while BaTiO3 additive amount increasing, the e and d33 of materials have maximum value (ε= 1650, d33 = 120 PC·N -1 ) while x (BaTiO3) =0.06 mol. Theεand d33 of materials start increasing and then decreasing while La2O3 additive amount increasing, the e and d33 of materials have maximum value (ε= 1684, d33 = 153 PC·N-1) while w(La2O3) =0.3% . The influence of La2O3 additive amount on the microstructure of BNT-BT piezoelectric ceramics was analysed by SEM( scanning electron microscope). The influence mechanism of La2O3 additive amount on the properties of BNT-BT piezoelectric ceramics was discussed. The BNT-BT ceramics with optimum comprehensive properties were obtained.

First-Eutectic Features of Polar Metals in Double Systems

It is known that the dense part of any liquid metal consists of ramified clusters of almost regular tetrahedrons (triangular pyramids with atoms in their vertexes) that are connected into chains by faces. Any metal additive as a second component of liquid alloy can be both beyond these clusters as separated atoms and into them as inherent clusters. The liquid-metal alloy transfers into the second state, at the first eutectic of the solvent. This polymorphic transition of liquid matrix is discovered in the systems, Pb-K and Na-Pb, by molecular-dynamic simulating their microstructure and in experiments on scattering slow neutrons by these alloys of different compositions. In the first system, the obtained results identify both the homogeneous alloy at low concentrations of potassium in liquid lead and the alloy clustering, (Pb4K)n, at potassium concentrations following the eutectic, Pb0.91K0.09. In the second one at the concentrations of lead more than 2%, just the second state is discovered with the clusters, (Na4Pb)n. One can expect the same polymorphic transition in the eutectic, Na0.93Tl0.07, with the micro-inhomogeneity, (Na6Tl)n, and with the melting point of 64 C. This eutectic maintained by the oxygen-free technology and enriched by the isotope, 205Tl, can become the best coolant for fast nuclear reactors due to the depressed chemical activity of sodium and composition stability.

Optical Properties Of Mn²⁺Doped Lead Phosphate (Lp) Glasses

Doping of MnO (less than One mole %) in LP glass system promotes the transparency and the general quality of the LP glass.- Mn2+ occupying an Oh site in the LP glass network - The influence of the LP glass network on Mn2+ energy levels and its electronic structure seems to be different when the concentration of MnO is extremely small (0.2 mole%) - The observation of single band of Mn2+ in this case probably correlates well with the observation of forbidden hyperfine EPR transitions in the same glass.

Embrittlement effects on ferritic/martensitic steels by liquid lead-bismuth eutectic

Studies of synergetic irradiation effects and liquid lead-bismuth eutectic(LBE) corrosion/embrittlement effects on ferritic/martensitic(F/M) steels are of great importance for developing high power spallation neutron targets(>1 M W) such as the European Spallation Source(ESS) and Accelerator Driven System(ADS) facilities that can be used for transmuting long-lifetime radioactive wastes. Liquid LBE(45Pb-55Bi,in terms of mass fraction) has been selected as the candidate target material in high power spallation neutron targets due to its favourable thermal,physical & chemical properties,and to its high spallation neutron yield. 9Cr F/M steels such as T91(9Cr1M oVNb,in terms of mass fraction) have been chosen as the structural material for the targets due to their good mechanical properties and good resistance to irradiation induced swelling in fission neutron irradiation environments. For developing high power spallation neutron targets,behaviors of F/M steels in spallation neutron target irradiation environments and LBE corrosion/embrittlement effects have been extensively studied. However,many open questions have not been answered. The aim of this paper is to describe the present research situation on this topic. The obtained experimental data about LBE embrittlement effects on F/M steels is summarized and the influence of different parameters involved is analyzed to understand the influence effect on LBE embrittlement effect of F/M s.

Data acquisition and control system for lead-bismuth loop KYLIN-Ⅱ-M

Among different heavy liquid metals(HLMs), lead-bismuth eutectic(LBE) is considered at present as a potential candidate for the coolant of new generation fast reactors(critical and subcritical) and for liquid spallation neutron sources and accelerator driven systems(ADS). A high temperature liquid LBE loop, KYLIN-II-M,has been built to study the characteristics of corrosion and fluidity of LBE at the Institute of Nuclear Energy Safety Technology. However, due to the sensors and execution components of the loop work at high temperatures and in severely corrosive environments, the reliability and security of the data acquisition and control system(DACS) of KYLIN-II-M face challenges during the loop operation. In order to meet the urgent needs for KYLIN-II-M's long-term stable operation, a virtualization and redundancy control system has been developed.The onsite operation result shows that the DACS is stable and reliable. In this paper, the experimental results are described in detail.

10Cr9Si1Mo1VNb钢在450℃静态铅铋中的腐蚀行为

液态铅铋腐蚀问题是制约铅冷快堆发展的主要问题,商用9%~12%Cr铁素体/马氏体钢被认为是铅冷快堆首选结构材料。本文研究了10Cr9Si1Mo1VNb钢在450℃静态饱和氧铅铋共晶(LBE)中的腐蚀行为。结果表明:10Cr9Si1Mo1VNb钢暴露在LBE后,表面氧化膜主要由外氧化层Fe3O4、次外层(Fe,Cr)3O4和SiO2、内氧化区组成;Si与Cr在氧化过程中表现出协同作用,促进次外层形成,阻碍元素扩散,提高了基体抗氧化性;腐蚀1500 h后基体表面形成连续致密的氧化层,表现出良好的耐铅铋腐蚀性能。本文提出了10Cr9Si1Mo1VNb钢在450℃静态饱和氧LBE环境下的氧化扩散过程模型,为9%Cr耐热钢在铅冷快堆系统的应用提供了一定的理论依据。

基于Modelica的铅铋合金自然循环回路特性仿真分析

为更好地研究铅铋反应堆自然循环特性,采用Modelica语言建立了铅铋合金(lead-bismuth eutectic,LBE)自然循环回路实验装置的热工水力仿真模型。模拟了铅铋合金自然循环回路的稳态工况、变功率工况以及失流工况,将加热段出入口LBE的温度及入口处LBE的质量流量与3种工况下的实验结果进行对比。结果表明,仿真结果与实验结果的温度最大相对偏差为9.96%,质量流量最大相对偏差为10.4%,程序计算的结果与实验较吻合。该模型可为铅铋反应堆设计开发过程中,铅铋合金的热工水力分析提供支持。

含铝强化奥氏体钢在550℃液态铅铋中的腐蚀行为

先进铅冷快堆和加速器驱动次临界系统商业化的关键材料问题是结构材料与铅基冷却剂之间的相容性问题,结构钢材料需要在高温液态铅铋共晶中具有优异的抗腐蚀能力.含铝强化奥氏体钢(alumina-forming austenite steel,AFA钢)因其表面可以形成Al_(2)O_(3)膜而在极端环境中具有良好的耐蚀性能.本文研究了降低Ni元素成分和高温预氧化对AFA钢耐铅铋腐蚀性能的影响,利用扫描电子显微镜、能量色散X射线光谱仪、X射线衍射技术,对AFA钢在550℃液态铅铋饱和溶氧条件下腐蚀600 h的氧化层形貌及结构进行表征.结果表明:降低合金中Ni含量和高温预氧化处理都会促进样品表面形成保护性Al_(2)O_(3)氧化膜,进而降低腐蚀层厚度,提升材料耐铅铋腐蚀性能.

战国时期铅钡硅酸盐制品相互关系的新思考

铅钡硅酸盐是中国古代费昂斯和玻璃制品的典型成分类型。本文首先明确了铅钡硅酸盐制品包含铅钡釉陶、铅钡釉砂、铅钡玻璃以及硅酸铜钡颜料四大类,并重点讨论前三者,强调不宜用“铅钡玻璃”指代铅钡硅酸盐制品。其后,文章整体梳理了战国时期铅钡硅酸盐制品的出土范围和存续时间。在此基础上,重新讨论了铅钡釉陶、铅钡釉砂、铅钡玻璃的关系问题,提出铅钡釉陶和铅钡釉砂都不是铅钡玻璃的先驱,三者在战国早期的出现更像是铅钡这种全新助熔剂在不同材质上的应用。

不同温度LBE对主容器振动特性的影响分析

采用流固耦合的方法,利用ANSYS软件对铅基快堆主容器在空气中和不同温度铅铋共晶(Lead-BismuthEutectic,LBE)介质中的振动特性进行了研究。主容器采用实体建模,铅铋共晶介质流体采用FLUID30单元进行模拟,考虑铅铋共晶介质附加质量对主容器振动特性的影响。计算结果表明,主容器在空气中的两种模型前六阶模态均为一阶梁式振型以及低阶壳式振型。由于两种模型约束条件的差异,振型出现的顺序有所不同。铅铋共晶环境中的前六阶振型与空气中相比,没有出现更高阶的振型,但由于附加质量的影响,其各阶频率计算值大幅下降,下降幅度在80%左右,同时伴随着振型互换的现象出现;随着温度的升高,主容器的各阶振型频率均呈现降低的趋势,当温度从150℃上升至390℃时,频率降低大约27.3%。