Thermal and radiative characteristics of oxyfluoride glass singly doped with lanthanide ions

Rare earths-doped oxyfluoride glasses based on germanium oxide and lead fluoride were prepared from commercial raw materials. The glasses with general composition of 50GeO2-(50-x-y)PbO-yPbF2-xLnF3 (Ln=Pr3+-Yb3+), contained different concentrations of optically active dopants (x=0.2 mol.% and 2 mol.%) and PbF2 (y≤15 mol.%). The differential thermal analysis (DTA) was used to determine both thermal characteristic and thermal stability properties of the glasses in the function of the kind of dopant, its concentration, and a glass composition. Characteristic glass temperatures such as glass transition temperature (Tg), glass crystallization temperature (Tc) and temperature corresponding to the maximum of the crystallization rate (Tpc) were evaluated. On the basis of obtained results, the thermal stabilities of glasses under study were evaluated using various thermal stability criteria (Dietzel factor ?T, Saad-Poulain factors H' and S). It was found that the increase in rare earth fluoride contents influenced thermal characteristics when the characteristic temperatures of the individual glass was shifted towards higher values. The effect of the PbF2 content and the kind of rare earth impurity on the glass stability was observed. Absorption spectra of lanthanide-doped glasses were measured at room temperature and used to determine the phenomenological intensity parameters Ωt and next, to estimate radiative properties of lanthanide ions in this matrix. Radiative transition probabilities of luminescent states of Ln3+, branching ratios and radiative lifetimes were determined. The variation of the Ωt along the lanthanide series was presented and discussed.     

Process optimization of electroless copper plating and its influence on electrochemical properties of AB5-type hydrogen storage alloy

The amount of Cu coating by chemical plating was investigated based on quadratic regression orthogonal experimental design being adapted to the variation law of temperature,pH value and Ni2+concentration,and the relevant regression equation was expressed as y=2.1609+0.5295×10-3T2-0.0342P2-0.0265N2+0.0023TP+0.0020TH+0.0199PN-0.0959T+0.3814P-0.2073N.The results showed that the deposition rate augmented with the increasing in temperature,pH value and Ni2+concentration.The experimental parameters of the optimal coating were temperature 75 ℃,pH value 8.5 and Ni2+concentration 1.2 g/L.The electrochemical tests indicated that the cycle stability increased from 60.66% to 75.58%,indicating that the treated alloy exhibited better corrosion resistance.     

天铁热力风机升级改造方案设计

通过对天铁集团高炉现状、风机现状的分析,提出了对热力厂风机升级改造的规划,确定了实施方案.该方案实施后将彻底改变风机渐进式改造的现象,使新高炉的备用机组发挥更大的作用,可增加现有高炉的风压、风量,使现有高炉的产量、冶炼强度进一步提高.     

Recent progress report on DNA B-Z transition modulated by rare earth-amino acid complex and Alzheimer's disease amyloid beta

Rare earth dements have unique physical, magnetic, luminescent and catalytic properties. They have been successfully used as medicine and probes in luminescent resonance energy transfer (LRET) for bioassays, as well as reagents for diagnosis in magnetic resonance imaging (MRI). In this progress report, we will focus on recent progress on how rare earth amino complexes bind to DNA and change DNA structure, especially on DNA B-Z transition induced by rare earth amino acid complex and its potential impact on Alzheimer's disease (AD).     

Numerical Simulation on Inclusion and Bubble Entrapment in Solidified Shell in Model Experiment and in Mold of Continuous Caster With DC Magnetic Field

A model experiment investigating entrapment of inclusions and bubbles on the solidified shell was performed using molten steel,and the conditions for inclusion and bubble entrapment and mechanism of entrapment were studied.The results were applied to the flow behavior in the casting mold of a continuous caster.At the solid-liquid interface,entrapment of inclusions is greatly reduced by the existence of a low velocity flow,e.g.,0.05m/s.The above-mentioned interfacial flow velocity dependency of inclusion entrapment is considered to be largely influenced by changes in the thickness of the concentration boundary layer,which depend on the interfacial flow velocity.Specifically,bubbles and inclusions which enter the concentration boundary layer are drawn to the solid-liquid interface by a suction force which is several orders larger than the Saffman’s force.In addition to the above-mentioned suction force,the so-called cleaning effect is determined by fluid-dynamic forces such as drag force,etc.which act on particles,and furthermore,by resident time of particles at the solid-liquid interface,which depends on the solidification rate.In a FC mold with a 2-stage electromagnetic brake,flotation of bubbles entrained in the jet flow from the nozzle is accelerated with the large DC magnetic field.This is attributed to the braking effect of the DC field on the nozzle jet and the upward flow by the buoyancy of the bubbles.As a result,the interfacial flow velocity can be normalized by increasing the strength of the magnetic field,and entrapment of large bubbles and inclusions can be reduced.     

Influence of Controlled Rolling and Cooling Process on the Mechanical Properties of Low Carbon Cold Forging Steel

In the present paper,controlled rolling and cooling processing was conducted by using a laboratory hot rolling mill.The influence of different processing parameters on the mechanical properties of low carbon cold forging steel was investigated.The results show that the faster cooling after the deformation (especially in low temperature rolling conditions) leads to the refinement of the ferrite grain.The specimen exhibits very good mechanical properties owing to the finer ferrite grains.The pearlite morphologies can also affect the mechanical properties of low carbon cold forging steel.The mechanical properties increase with decreasing final cooling temperature within the range from 650℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony.The mechanical properties of the specimens with fast cooling after the conventional rolling are not only better than those of the specimens with slow cooling after low temperature rolling,but also almost similar to those of the specimens with fast cooling after low temperature rolling.It is suggested that fast cooling after high temperature rolling (the conventional rolling) process would be of important industrial value.     

The LIMMCAST Program at HZDR:Modelling of Fluid Flow and Transport Phenomena in the Continuous Casting Process

Model experiments with low melting point liquid metals are an important tool to investigate the flow structure and related transport processes in melt flows relevant for metallurgical applications.We present the new experimental facility LIMMCAST for modelling the continuous casting process of steel using the alloy SnBi at temperatures of200-400℃.The parameters of the facility and the dimensions of the test sections will be given,and the possibilities for flow investigations in tundish,submerged entry nozzle and mould will be discussed.In addition,the smaller set-up Mini-LIMMCAST will be presented,which works with the room-temperature liquid alloy GaInSn.The main value of cold metal laboratory experiments consists in the capabilities to obtain quantitative flow measurements with a reasonable spatial and temporal resolution.New ultrasonic and electromagnetic techniques for measuring the velocity in liquid metal flows came up during the last decade allowing for a satisfying characterisation of flow quantities in the considered temperature range up to 400℃.First results from LIMMCAST and Mini-LIMMCAST will be presented covering the following phenomena:fully contacfless electromagnetic tomography of the flow in the mould,flow monitoring by a multitude of ultrasonic sensors,and analysis of the flow in the mould under the influence of an electromagnetic brake:intensification of the flow turbulence contrary to the expected flow damping,injection of argon bubbles through the stopper rod:occurrence of pressure oscillations.     

汽车零件强度、寿命与可靠性分析与模型

The elasto-plastic stress/strain behavior of an automobile rear axle was analyzed by three-dimension finite element method.Based on the stress in critical area where fatigue crack appears,the fatigue life of the welded structure was predicted using the critical shear stress plane criterion.To improve the fatigue property of the rear-axle,the welding-seam was strengthened by both pellet spraying and plasma melting,and evident improvement was experimentally illustrated.Based on the viewpoint that a complex component is also a system in the respect of reliability assessment and statistical dependence among component failures(i.e.the so call"common cause failure")is inherent for system under stochastic load environment,a system-level load-strength interference model was presented and the reliability of the rear axle was estimated as a system,instead of a component.     

铝土矿、氧化铝和电解铝产业链市场及利润流向

本文主要介绍近几年铝土矿、氧化铝和电解铝产业链的市场和利润流向演变以及未来发展形势.     

提高轧制重轨BS75A成材率的措施

介绍了武钢大型厂生产重轨BS75A时,利用现有设备,通过不断研究,找到了一条提高重轨(BS75A)生产成材率的方法,并取得了较好的经济效益.     

模具的合金堆焊研究

用合金堆焊模具，是在普通碳结构钢的基体上堆焊合金钢或硬质合金作为模具工作部分，以提高模具寿命及耐用度，降低模具成本.介绍了模具合金堆焊的工艺、焊接设备、堆焊材料的选用以及堆焊产生的同题及其防止措施．     

大型箱梁主梁焊接变形控制措施探讨

在大吨位箱形梁架桥机主梁的制作中，遇到大型箱梁，既要保证高精度的外形尺寸，又要保证主梁四条主焊缝要求一级焊缝的问题。针对不同形式的外形结构的主梁，依据其特点，采用不同的防变形方法。     

Cr5Mo管焊接工艺

焦油管式炉辐射管材质为Cr5Mo，其体积庞大，形状特殊，焊接质量要求较高，作业环境差，施工难度大。根据现场实际，通过焊接试验，得出较合理的焊接参数，制定出切实可行的焊接工艺，以保证辐射管的焊接质量。     

激光焊接技术研究

介绍了激光焊接技术的研究概况,包括焊接用激光发生器、激光焊接工艺参数、激光焊接工艺特点等,重点介绍了激光焊接在汽车工业中的应用情况.     

焊接质量热态控制系统及其应用设备

攀钢冷轧薄板厂2释热镀铝锌生产线，采用法国克莱西姆（CLECIM）公司的窄搭接电阻滚压焊机。该焊机是为了实现连续生产对前、后卷带钢进行焊接。本文重点阐述了该焊机的焊接质量热态控制系统的原理及特点。通过该项技术的应用，避免了焊缝因温度而导致的未焊透或烧穿等焊接缺陷，保证了焊接质量，有效地提高了产品的成品率，减少了断带次数。     

新型焊割气应用在黑色金属焊接工艺上的探索

只有掌握新型焊割气的特性和焊接操作工艺，可代替乙炔对低中碳钢，低合金结构钢进行焊接。     

螺旋埋弧焊管焊接事故分析

着重分析送丝机构对焊接的影响 ,电弧爆裂声变化 ,焊缝宽度不均匀等螺旋埋弧焊管在生产过程中一些常见焊接事故产生的原因 ,并针对这些事故提出了防治措施和处理方法 .要求在焊接生产过程中 ,要认真做好设备运转记录 ,为预防和处理事故提供科学依据 ;对每一次发生的焊接事故要搞清现象 ,联系原理 ,区别情况 ,周密分析 ;从简到繁 ,由表及里 ,总结经验 ,及时整理 ;不断提高观察、判断、处理事故的能力 .     

喷涂、喷焊和堆焊材料

简要介绍了喷涂、喷焊和堆焊材料的发展、应用和对于国民经济的重要意义。     

高频焊管生产中操作对焊接质量的影响

高频焊管生产中 ,操作对焊管质量的影响因素包括输入热量、焊接压力、焊接速度、开口角、感应器和阻抗器的放置位置、管坯的几何尺寸及形状等几方面。在生产中掌握操作是提高焊管质量的重要途径之一。     

CO_2焊在大型高炉钢结构厚板焊接中的应用及推广

采用ＣＯ２焊代替手工电弧焊及埋弧自动焊，经过工艺性能试验及实际操作后，认为ＣＯ２焊是可行的。