Effects of rare earth on inclusions and corrosion resistance of 10PCuRE weathering steel

The types,morphologies and distributions of nonmetallic inclusions in Cu-P weathering steels with and without rare earth were analyzed through a quantitative image analyzer,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)attached to SEM.Solid-soluble content of rare earth in the steels was analyzed by non-aqua electroanalysis and ICP.The results showed that rare earth modified the types and the morphologies of inclusions in the weathering steels.The small spherical rare earth oxysulfides and rare earth sulphides replaced the elongated MnS inclusions in the RE weathering steels.The rare earth inclusions dispersedly distributed and most inclusions were smaller than 2 μm in size.The optimum content of RE was 0.0065%-0.016% for 10PCuRE weathering steels containing about0.002% oxygen and 0.004% sulfur.Solid-soluble content of rare earth in steels was(14-20)x 10-6,which can act as a micro-alloying element.The corrosion resistance of 10PCuRE weathering steels and Q235 were studied by dry-wet cyclic immersion test.Their corrosion rates were obtained respectively.The polarization curves and pitting corrosion behaviors of weathering steels with and without rare earth were measured by electrochemical methods.The corrosion resistance of Cu-P weathering steels was improved by adding an appropriate amount of rare earth.Less and fewer rare earth inclusions largely decreased pitting susceptibility and rate of pit propagation.The pitting potential and the resistance against pitting corrosion of the RE weathering steel were significantly improved due to the modification of rare earth to inclusions.     

Lanthanide NIR luminescence for telecommunications, bioanalyses and solar energy conversion

Present-day advanced technologies heavily rely on the exciting magnetic and spectroscopic properties of lanthanide ions. In particular, their ability to generate well-characterized and intense near-infrared (NIR) luminescence is exploited in any modern fiber-optic telecommunication network. In this feature article, we first summarize the whereabouts underlying the design of highly luminescent NIR molecular edifices and materials. We then focus on describing the main trends in three applications related to this spectral range: telecommunications, biosciences, and solar energy conversion. In telecommunications, efforts concentrate presently on getting easily processable polymer-based waveguide amplifiers. Upconversion nanophosphors emitting in the visible after NIR excitation are now ubiquitous in many bioanalyses while their application to bio-imaging is still in its early stages; however, highly sensitive NIR-NIR systems start to be at hand for both in vitro and in vivo imaging, as well as dual probes combining magnetic resonance and optical imaging. Finally, both silicon-based and dye-sensitized solar cells benefit from the downconversion and upconversion capabilities of lanthanide ions to harvest UV and NIR solar light and to boost the overall quantum efficiency of these next-generation devices.     

Evaluation of D113 cation exchange resin for the removal of Eu(Ⅲ) from aqueous solution

Batch adsorption experiments were conducted for the adsorption of Eu(Ⅲ) ions from aqueous solution by D113 resin. The results indicated that D113 resin could adsorb Eu(Ⅲ) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH turned from 3.50 to 7.00 and the optimal adsorption condition was in HAc-NaAc medium with pH value of 6.50. The maximum uptake capacity of Eu(Ⅲ) ions was 290.9 mg/g D113 at 298 K, at an initial pH value of 6.50. The overall adsorption process was best described by Lagergren-first-order kinetics. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. The thermodynamic parameters such as free energy (G) which were all negative, indicated that the adsorption of Eu(Ⅲ) ions onto D113 resin was spontaneous and the positive value of enthalpy (H) showed that the adsorption was endothermic in nature. Thomas model was applied to experimental column data to determine the characteristic parameters of column useful for process design. Furthermore, Eu(Ⅲ) could be eluted by using 3.0 mol/L HCl solution and the D113 resin could be regenerated and reused.     

Phase structure and temperature dependent luminescence properties of Sr2LiSiO4F: Eu2+ and Sr2MgSi2O7: Eu2+ phosphors

Green-emitting Sr2LiSiO4F:Eu2+ and blue-emitting Sr2MgSi2O7:Eu2+ phosphors were synthesized by the conventional high temperature solid-state route,respectively.Their structures and photoluminescenee properties were comparatively investigated.It was found that the mixture phases of Sr2MgSi2O7 and SrF2 were obtained when a part of Sr2+ in Sr2LiSiO4F was replaced by some amount of Mg2+ in order to design the possible SrMgLiSiO4F:Eu2+ phosphor.Based on the photoluminescence analysis,Sr2LiSiO4F:Eu2+ phosphor exhibited a green broad emission band of main peak at 513 nm under the excitation of 365 nm,while the Sr2MgSi2O7:Eu2+ and SrMgLiSiO4F:Eu2+ phosphor showed blue emission centered at 467 nm.The temperature dependent photoluminescence properties and room temperature decay time for the three kinds of phosphors were also discussed in this paper.     

Er3+-substituted W-type barium ferrite: preparation and electromagnetic properties

Er3+-substituted W-type barium ferrites Ba1-xErx(Zn0.3Co0.7)2Fe16O27(x=0.00,0.05,0.10,0.15,0.20)were synthesized by polymer adsorbent combustion method.Samples were characterized by X-ray diffraction analysis(XRD),X-ray fluorescence(XRF),scanning electron microscopy(SEM)and network analyzer to investigate the relationships among Er3+concentration,crystal structure,surface mcrphology and electromagnetic properties.All the XRD patterns showed pure phase of W-type barium ferrite when x≤0.15,while the impurity phase of ErFeO3 appeared when x=0.20.The pure W-type barium ferrite showed a hexagonal flake shape.In addition,the microwave electromagnetic properties of samples were analyzed in the frequency range of 2-18 GHz.It was indicated that the electromagnetic properties were significantly improved when Er3+doping content was 0.10.The reasons were also discussed using electromagnetic theory.The optimized ferrite exhibited excellent microwave absoption performance.The maximum of reflection loss(RL)reached about-27.4 dB and RL was below-10dB at the frequency range from 8.4 GHz to 18 GHz,when the thickness was 2.6 mm.     

EXAFS investigation and luminescent properties of nanosized Tb: Lu2O3 phosphors

Nanosized terbium doped Lu2O3 phosphors were synthesized via a modified co-precipitation processing.The as-prepared Tb:Lu2O3 phosphors was consisted of well crystallized nanosized sphere particles with a diameter of about 30 nnx Local structure of Tb ions in Lu2O3 lattice was investigated by an analytical approach based on Fourier transformation of the extended X-ray absorption fine structure(EXAFS) data.X-ray near edge structure (XANES) spectra suggested that all Tb ions doped were tervalonce.EXAFS results indicated that Tb ions have entered the Lu2O3 cubic lattice by means of solid solution.The coordination number and first shell Tb-O distance dropped with the increasing of Tb concentration.Emission spectra of the phosphors was shown to be typical for Tb3+ with main components at 542,550 and 490 nm,derived from irradiative relaxation of 5D4 level.The emission intensity decreased severely with the increasing of Tb concentration from 1 mol.% to 15 tool.%,suggesting a significant concentration quenching above 1 mol.% Tb.The reduction of emission intensity was interpreted by higher distortion derived relaxation among the surface state resident Tb3+ ions.     

Multi-Pass Simulation of Heavy Plate Rolling Including Intermediate Forced Cooling

Thermomechanical Controlled Processing (TMCP) including accelerated cooling after the final hot rolling pass is a well-established technology,widely applied in HSLA steel plate production.However,there are still certain limitations,especially for thicker plate.The rolling schedule includes a long holding period (HP) after the roughing stage to allow the temperature to fall sufficiently for optimised TMCP during finishing.Intermediate Forced Cooling (IFC) applied during the HP can increase productivity by decreasing the required hold time,can restrict austenite grain growth,and can also improve the subsequent strain penetration in thick plate with further metallurgical benefits.Multi-pass plane strain compression (PSC) tests have been performed on the thermomechanical compression (TMC) machine at Sheffield University including different severities of IFC.Clearly it is impossible to simulate all aspects of the temperature and strain gradients present in thick plates in laboratory specimens,and most of the tests were conducted at temperatures and strains calculated by Finite Element modelling as relevant to specific positions through the plate thickness.However,some aspects of the gradients were addressed with tests using cold platens.The results have indeed shown that IFC can shorten the HP and reduce austenite grain growth and its variation across thick plate.     

Overview of Particles and Bubbles in Continuously Cast Steel

This paper gives an overview of phenomena associated with particles and bubbles in continuously cast steel. During steel processing from deoxidation to solidification the inclusion population undergoes changes with opportunities of removal. Flotation is an important separation mechanism. Inclusion particles may accumulate in the solidifying strand, thus forming enriched bands, which depend on the type of casting machine. Bubbles are created during inert gas injection. They also change in size, can float out, but also form accumulation bands. The interaction of bubbles and particles is discussed. Internal structure that recently has been observed on the inner surface of bubbles will be reviewed.     

烦恼 快乐 艺术——池莉“人生三部曲”解读

池莉的"人生三部曲"--<烦恼人生>、<不谈爱情>、<太阳出世>诉尽了普普通通的市民烦恼,小说中主人公被柴米油盐、吃喝拉撒、老婆孩子等琐事所烦着,从而构成他们的"烦恼人生".然而池莉通过自己的艺术创作,以积极的人生态度,又让读者体会到生活本身的快乐,"烦恼人生"中包含着"快乐人生".     

属性块在工程图形中的研究与应用

介绍了在工程图形中用属性块标注表面粗糙度的方法.采用属性块不仅能避免大量重复性的工作,还能节省大量的存储空间,具有提高绘图速度、质量,便于修改,资源共享等应用价值.     

两翼工作面采动影响下采区大巷围岩变形破坏特征

与单翼采区相比,两翼工作面开采能提高煤炭资源开采效率和巷道利用率,然而两翼工作面先后回采对采区大巷具有多次采动影响,易导致采区大巷围岩变形加剧,甚至破裂。本文通过数值模拟、理论分析和现场实测等方法,研究了内蒙古利民煤矿I0309采区大巷在两翼工作面顺序采动影响下的应力分布及变化特征,分析了采区大巷围岩大变形机理,确定了I030901工作面停采线合理位置,研究结果对两翼工作面开采采区大巷的稳定维护具有重要的参考价值。     

深部软岩巷道支护方案数值模拟研究

为确定某煤矿安全生产的巷道支护方案,以其601综采工作面顺槽开挖为背景,利用FLAC2D数值软件模拟,并对比分析了有无预应力桁架两种支护方案下巷道围岩的位移.应力和塑性区分布状态. 结果表明:采用原支护方案时,巷道顶板.两肩角及两帮等多处出现应力集中,塑性区域较大,并且巷道的变形量大,两帮的变形位移高达1 m;采用预应力桁架支护时,巷道顶板应力分布状况良好,只有两肩角及两帮深处岩体出现了应力集中,但塑性区域明显减小,巷道变形有较大改善,两帮变形位移降至0.0106 m,深部软岩巷道的损伤变形降低显著,在实际应用中取得了良好的效果,为煤巷支护设计提供了一种可行的方法.      

金川二矿区地应力特征及其对巷道变形破坏的影响研究

随着地下工程建设不断向地球更深处发展,高地应力已成为影响深部巷道围岩稳定性的关键因素.针对金川二矿区高地应力问题,总结研究区地应力分布特征,采用离散元数值方法计算了3种不同地应力条件下巷道围岩的变形破坏过程.所得主要结论包括:(1)研究区地应力分布离散性较强,已测最大主应力多数为水平方向,但随着埋深的增加,竖直主应力逐...     

滥泥坪铜矿三维地应力测量及巷道布置优化研究

随着矿山开采深度的持续增加,深部高地应力作用下矿区的地压灾害发生率逐渐增长。为使矿区能够安全合理地开展生产工作,准确测量区域内的地应力分布情况,并在此基础上进行巷道布置优化研究很有必要。采用套孔应力解除法对滥泥坪深部3个中段进行三维地应力测试,并对三维应力场分布特征进行分析。测量结果表明：滥泥坪矿区应力随深度基本呈线性增长,实测的各中段最大主应力值在28.62~43.10 MPa之间,原岩应力场以水平构造应力为主,总体表现为NNW-SSE向,根据测量结果调整巷道布置方向并建立三维地质模型对巷道稳定性进行分析,研究结果对巷道布置和矿山安全生产具有重要的指导意义。     

高地应力破碎围岩巷道变形破坏特征及支护方式研究

巷道支护一直是阻碍矿山安全、高效开采的难题,特别是在深部高地应力区,如何通过合适的支护手段控制巷道的变形,已成为国内外学者们特别关注的工程问题。针对金川二矿区高地应力破碎围岩这一特殊的地质条件,采用现场调查与数值模拟计算相结合的方法,对研究区巷道变形破坏特征和8种不同支护方式效果进行了研究。结果表明:(1)研究区巷道的变形破坏模式可划分为6种,分别为偏压变形、顶板下沉、顶板开裂、底鼓、边墙开裂和片帮,其中片帮是最常见的一种破坏模式;(2)研究区巷道的变形破坏具有3个特征,分别为最大主应力主导性、大变形和显著的时间效应;(3)在支护方式中增加U钢支架、补充底部支护、增大锚杆长度及减小锚杆间排距几种方法均能不同程度地改善支护效果。其中,增加U钢支架和底部喷锚网支护效果最显著,可以减小约70%的巷道变形量和塑性区;增大锚杆长度能更好地控制巷道的变形和整体稳定性,但优化效果不显著;减小锚杆间排距有利于巷道各部位变形和塑性区的控制,密集的锚杆布置能够有效改善围岩的完整性,且降低锚杆排距的支护效果更好。该项研究成果为金川矿区以及具有相似地质条件的地下工程支护问题提供了借鉴。     

大断面六角形进路采矿法结构参数优化研究

针对龙首矿普通六角形进路采矿法在西一贫矿区回采过程中进尺率低、断面轮廓不规整、机械化程度低和炸药单耗高等回采问题,通过数值模拟和现场试验,对大断面六角形进路采矿法在龙首矿西一贫矿开采区的可行性进行研究。结果表明:与普通六角形进路采矿法相比,采用大断面六角形进路采矿法回采西一贫矿资源时,采场顶底板及边帮矿岩受力条件更好,顶底板变形量小,2条相邻进路之间未出现贯通;平均进尺由2.4 m提高至3.2 m,提高了33.3%;炸药单耗由0.20 kg/t降低至0.15 kg/t,降低了25%;轮廓完整性更好,最大超挖量降低了97 cm,最大欠挖量降低了10 cm;凿岩效率由1.25 m/min提高至2.10 m/min。研究结果证明了大断面六角形进路采矿法在龙首矿西一贫矿开采区回采过程中的可行性,符合回采过程中对安全性和高效的要求。     

平煤十矿地应力测量及其应用

平煤十矿采用三维套孔应力解除地应力测量技术和具有温度补偿功能的空心包体应变计,完成了矿区6个水平、11个测点的现场地应力实测,最大测点深度达到1123 m.这是我国煤矿首次采用应力解除法进行系统的矿区地应力测量并且测量深度超1100 m.通过测量获得了矿区11个测点的三维地应力状态,揭示了矿区地应力场的分布规律,建立了矿区地应力场模型.针对平煤十矿是我国典型的高瓦斯矿井、深部采矿存在引发煤(岩)爆和瓦斯爆炸的高危险性,本文提出:根据实测地应力数据,采用数值模拟技术,定量计算开挖扰动引起的开采煤层和围岩中能量聚集状况及其随采矿过程的变化规律,借助地震学的知识,根据能量聚集状态对未来开采可能引发煤(岩)爆的时间、地点和震级进行预测.     

基于上覆巷道保护的下伏煤层安全回采

针对千米深井下伏煤层回采需保证上覆巷道稳定性的问题,通过理论分析、数值模拟和现场实测的方法,研究了下伏煤层开采过程中上覆岩层巷道变形破坏类型、破坏机理和防治办法。通过对开采条件和开采形成的覆岩空间结构的研究,得到了走向和倾向方向上的巷道变形破坏规律;通过研究下伏工作面不同开采阶段、不同充填率条件对上覆巷道的采动影响,得到了巷道变形破坏的应力演化规律。结果表明:千米深井下伏煤层开采,上覆巷道潜在的变形破坏类型主要有两种,一是巷道断面缩减型破坏,二是巷道走向阶梯下沉型破坏。上覆巷道变形破坏的根本原因是大埋深、强采动应力,特别是下伏煤层距上覆巷道较近且距离不均等的影响,直接原因是采动造成的巷道围岩应力突增及关键岩层的破断下沉。开采过程中,工作面走向开采范围超过400 m时,巷道断面缩减型破坏和走向阶梯下沉型破坏会相互叠加,诱发更大的巷道破坏。为控制这两种巷道的潜在破坏类型,设计了沿工作面下部巷道动态部分充填和巷道补强支护方案,通过现场实测发现上述方案能够满足上覆巷道稳定性和下伏工作面高效高产的要求,研究结果和控制方案可为千米深井巷道下压煤的安全回采提供一定的借鉴。      

巷道腰线的标定

由于矿山测量工作涉及地面和井下,不但要为矿山生产建设服务,也要为安全生产提供信息。矿山测量的任何疏忽或粗率都会影响生产或有可能导致严重事故发生。因此,巷道的定向与测量,掘进时中、腰线的给定,井下巷道贯通,弯道设置、竖并联测、斜洞布设,井下场地开拓,回采定水平,矿量计算,井上下对照等等,处处都离不开测绘。而巷道的坡度和倾角是用腰线来控制的,所以腰线的标定是井下巷道施工测量的主要任务之一。     

动力扰动下深部出矿巷道围岩的变形特征

以冬瓜山铜矿井下900 m深处的出矿巷道作为研究对象,基于“隔一采一充一”阶段凿岩、分段崩落的回采方案,利用FLAC^3D数值模拟软件研究了静动态开挖过程中出矿巷道围岩的变形特征。模拟相关岩体力学参数由三轴压缩及频繁冲击扰动试验数据折减获得,采用Mohr-Coulomb模型进行静态开挖分析,结合Strain-Softening模型进行动态扰动影响模拟分析。研究结果表明：爆破产生的扰动促使围岩变形加剧,但不会改变静态开挖时围岩变形演化的规律;开挖时巷道周边产生应力卸荷现象,且顶板出现拉应力,靠近采场巷道两帮应力离散性大,造成顶板易产生拉伸破坏,靠近采场巷道两帮易发生片帮;结合深部出矿巷道实际稳定情况,推测巷道顶板及靠近采场部位易产生破坏,需加强支护,其余部位稳定性相对较好。