Two Isostructural Multi-metal Borates: Syntheses, Crystal Structures and Characterizations of M_3LiNa_4Be_4B_(10)O_(24)F(M = Sr, Cd)

Two new isostructural multi-metal beryllium borates, m^3 Li Na4Be4B10O24F（M = Sr（1）, Cd（2））, have been synthesized by spontaneous crystallization. The structures were verified by single-crystal X-ray crystallography. The compounds crystallize in the trigonal space group R 3, with a = b = 9.4645（1） A, c = 38.842（8） A, V = 3013.2（6） A3, Z = 6, F（000） = 2568, Dc = 3.005 g/cm^3, Mr = 908.9, R = 0.0327, w R = 0.0678, μ = 8.160 mm-1 for Sr3 Li Na4Be4B10O24F and a = b = 9.3019（8） A, c = 37.782（7） A, V = 2831.12（9） A3, Z = 6, F（000） = 2748, Dc = 3.459 g/cm^3, Mr = 983.24, R = 0.0158, w R = 0.0455, μ = 3.586 mm-1 for Cd3 Li Na4Be4B10O24F. The structures are characterized by an infinite two-dimensional [Be8B16O40F2]∞ double layer bridged by [B12O24] groups like a sandwich structure, while the cations reside in tunnels along different directions. UV-vis-IR diffuse reflectance spectroscopy demonstrates that their cut-off edges are below 200 nm. Thermal analysis shows that they melt incongruently and their melting points are around 740-770 ℃.

Performance tests of multi-metal zincate solutions with zinc sulfate and zinc oxide

Morphology of zinc alloy layer,from zincate solution with zinc sulfate and zinc oxide respectively,together with the consequent deposit was observed with SEM and back scattering electron image.EDS was applied to analyze the components of zinc alloy layer and the interface of high-Si aluminum alloy substrate-zinc alloy-deposit.Besides,the surface morphology of the zincated aluminum alloy after immersing in 3.5% NaCl solution for 7 d,is observed and the corrosion rate was calculate.Finally,tension test is conducted to quantify the adhesion between high-Si aluminum cast substrate and the deposit.The results show that,the zinc oxide contained zincating solution with sodium potassium tartrate and sodium citrate is a better one in multi-metal zincating solutions.The zinc alloy layer from this one gets stable performance,perfect adhesion with deposit,and good corrosion resistance.

Zincate mechanism on cast Al-Si alloy in non-cyanide multi-metal zincate solutions

Arrhenius formula was applied to calculate the apparent activation energy of zincate reaction. The standard electrode potential of all the metal coordinating ions and the order of galvanic couple of different metals in zincate solution were also calculated. Electrochemical behavior of zincate process was studied by Tafel polarization curves, E—t curves, and electrochemical impedance spectroscopy(EIS). The results show that the apparent activation energy of zincate reaction in non-cyanide multi-metal zincate solution is smaller than that in simple zincate solution, and precipitation sequence of all the metals in zincate solution is Cu, Ni, Fe and Zn. Relationship between the potential at 30 s before zincate and coverage was attained according to the change of potential of zincate. EIS shows that inductive reactance is produced during zincate.

Dissolution kinetics of copper from multi-metal copper alloy roasted in oxygen

A kinetic study on the sulfuric acid leaching of multi-metal oxide, which is the product of multi-metal copper alloy with iron trioxide roasted in oxygen, was carried out. The effects of leaching time, stirring speed, sulfuric acid concentration, reaction temperature, and particle size of the multi-metal oxide on the kinetics and mechanism of copper extraction were studied. It was found that the reaction kinetic model about the copper extraction from multi-metal oxide follows the mixed kinetic shrinking core mode: 1/3ln(1–X)+(1–X)^(–1/3)–1=680.5C(H_2SO_4)^(0.4297)d_P^(–0.75115)exp(–E_a/RT)t.

Highly efficient multi-metal catalysts for carbon dioxide reduction prepared from atomically sequenced metal organic frameworks

The precise control on the combination of multiple metal atoms in the structure of metal-organic frameworks(MOFs)endowed by reticular chemistry,allows the obtaining of materials with compositions that are programmed for achieving enhanced reactivity.The present work illustrates how through the transformation of MOFs with desired arrangements of metal cations,multi-metal spinel oxides with precise compositions can be obtained,and used as catalyst precursor for the reverse water-gas shift reaction.The differences in the spinel initial composition and structure,determined by neutron powder diffraction,influence the overall catalytic activity with changes in the process of in s itu formation of active,metal-oxide supported metal nanoparticles,which have been monitored and characterized with in situ X-ray diffraction and photoelectron spectroscopy studies.

Interfacial Features of Stainless Steel/Titanium Alloy Multi-metal Fabricated by Laser Additive Manufacturing

Laser additive manufacturing(LAM)is promising for fabricating multi-metallic component,but the mechanism of microstructural evolution at the interface of two metals is still needed to research further.In this study,a 316L stainless steel/Ti6Al4V alloy multi-metal was fabricated by LAM,and the mechanism of intermetallic phase transformation was deeply investigated.Results show that a strong reaction zone(SRZ)can be induced at the interface of the multi-metal.The phase constituents at the SRZ vary fromχ(Ti_(5)Fe_(17)Cr_(5))+Fe_(2)Ti+α′-Ti+β-Ti or FeTi to Fe_(2)Ti+χwhen the laser power is increased.When the scanning speed is further decreased,the thickness of the SRZ is significantly increased,andα′-Ti phase is also formed at this region besides Fe_(2)Ti andχphases.Moreover,the micro-hardness at the SRZ is increased,caused by the intermetallic phase transformation and elemental interdiffusion at the interface.

Bioinspired Multi-Metal Structures Produced via Direct Ink Writing

Bioinspired Multi-Metal Structures(MMSs)combine distinct properties of multiple materials,benefiting from improved properties and providing superior designs.Additive Manufacturing(AM)exhibits enormous advantages in applying different materials and geometries according to the desired functions at specific locations of the structure,having great potential in fabricating multi-materials structures.However,current AM techniques have difficulty manufacturing 3D MMSs without material cross-contamination flexibly and reliably.This study demonstrates a reliable,fast,and flexible direct ink writing method to fabricate 3D MMSs.The in-situ material-switching system enables the deposition of multiple metallic materials across different layers and within the same layer.3D Fe-Cu MMSs with complex geometries and fine details are fabricated as proof of concept.The microstructures,chemical and phase compositions,and tensile fracture surfaces of the Fe-Cu interfaces indicate a well-bonded interface without cracks,delamination,or material cross-contamination.We envision this novel method making other metallic combinations and even metal-ceramic components.It paves the way for manufacturing 3D MMSs using AM and establishes the possibilities of numerous MMSs applications in engineering fields.

Effects of anions on the biosorption of microelement cations by macroalga Enteromorpha prolifera in single-and multi-metal systems

The results of research on the effects of anions on the biosorption of microelement cations by the edible marine macroalga Enteromorpha prolifera in singleand multi-metal systems are discussed in this paper. It was shown that the maximum biosorption capacity (qmax) in a single-metal system of Co(II) ions decreased in the following sequence: Cl- (46.0 mg g-1) > SO42- (42.8 mg g-1) > NO3- (41.9 mg g-1). In multi-metal systems, in which the ratios of Cl-, NO3-, and SO42- were 0:0:4, 1:1:2, 3:0:1, and 4:0:0, there were clear differences among the biosorption capacities. In all the examined systems (other than the 0:0:4 system), inhibition of the binding of microelement cations by the macroalga was observed. In all the systems, the highest value of qmax was obtained for Cu(II) cations; the value ranged from 31.9 mg g-1 in 0:0:4 (SO42- only) to 18.2 mg g-1 in 4:0:0 (Cl-only).

金属疲劳损伤全寿命过程及工程应用综述

金属疲劳损伤过程复杂,不同载荷类型与服役环境下金属疲劳损伤机理、变形特性和破坏模式存在较大差异。将疲劳损伤全寿命过程按照循环寿命周次划分为超高周、高周、低周和裂纹扩展4个类别,根据变形响应特性和变形机理特征阐述了各类别疲劳损伤的研究现状及发展趋势,涉及宏观尺度、微细观尺度和宏细微观多尺度理论体系。同时结合工程实际案例,以轧辊和燕尾榫作为代表性构件,分析其疲劳损伤行为与影响因素,探讨了目前疲劳理论在工程实践中的应用及挑战,旨在为金属疲劳损伤全寿命理论体系的完善和关键部件健康质量管控提供理论依据和技术指导。

Cu/V复合中间层对TC4/IN718激光焊接接头组织及性能的影响

为了实现TC4钬合金与GH4169镍基高温合金的有效连接.采用Cu/V复合中间层对TC4和IN718合金进行连续激光焊接,并分析添加中间层对接头裂纹、组织及力学性能的影响机制.结果表明,常规激光焊接时,TC4/IN718接头焊缝区产生大量Ti-Ni脆性金属间化合物,导致接头形成大量纵向裂纹,焊缝组织为Ti(s,s)+Ti_(2)Ni+Ti-Cr+NiTi+Ni_(3)Ti+Cr(s,s).当采用Cu/V复合中间层后,实现了TC4与IN718合金的有效连接,接头抗拉强度达到271MPa,焊缝组织转变为Ti(s,s)+V(s,s)+NiV_(3)+Cr(s,s)+Cu(s,s)+未熔铜。

基于波谱响应特征的雄安新区农田土壤重金属含量反演

分析并监测雄安新区农田土壤污染状况,对于保障粮食安全、建设绿色雄安具有重要意义。该研究以雄安新区为研究区,基于多源遥感数据珠海一号(Zhuhai-1)OHS数据、哨兵二号(Sentinel-2)L2A级数据的波谱响应特征及实地测得的农田土壤重金属含量数据,在对土壤重金属含量单因子与多因子污染评价的基础上,筛选出3种超标的农田重金属元素铅(Pb)、铜(Cu)、锌(Zn),采用偏最小二乘回归方法(partial least squares regression,PLSR)建立农田土壤重金属含量反演模型。利用Zhuhai-1提取土壤样本点的原始光谱反射率以及4种变换后的光谱反射率,Sentinel-2提取7种对重金属胁迫敏感的植被指数,将其与3种土壤重金属含量作相关性分析,筛选出敏感波段与植被指数,即波谱响应特征,构建土壤重金属含量反演模型。结果表明,3种模型整体反演精度较为优良,Pb含量反演模型决定系数(determination coefficient,R^(2))为0.490,均方根误差(root mean squared error,RMSE)为4.66 mg/kg,平均绝对值误差(mean absolute error,MAE)为1.92 mg/kg;Cu含量反演模型R^(2)为0.491,RMSE为16.85 mg/kg,MAE为3.69 mg/kg;Zn含量反演模型R^(2)为0.664,RMSE为20.63 mg/kg,MAE为9.36 mg/kg。将该模型应用于雄安新区农田区域,得到大部分农田土壤中Pb含量均未超过风险筛选标准,在研究区西南部、西部部分区域Cu含量超过土壤污染风险筛选值,同时在研究区西部、西南部Zn污染较严重,雄安新区东南部部分农田有Zn零星分布,其他区域Cu和Zn含量未超过国家土壤污染风险管控值。因此,利用多源遥感数据波谱响应特征反演土壤重金属Pb、Cu和Zn含量,能够快速准确地实现对雄安新区土壤重金属污染情况的调查,同时为大面积土壤重金属含量监测提供解决方案。

多离子印迹膜的制备及其吸附性能研究

以Zn^(2+)、Co^(2+)、Cr^(3+)和Pb^(2+)为混合模板,双硫腙为螯合剂,APTES为功能单体,TEOS为交联剂,PVDF为基膜,采用凝胶溶胶法成功合成了对模板离子有高吸附量和良好特异性识别能力的多离子印迹膜(MIIM)。采用SEM对材料的形貌进行了表征,并以多离子印迹聚合物(MIIP)为对比评价了MIIM的吸附性能。结果表明,MIIM对Zn^(2+)、Co^(2+)、Cr^(3+)和Pb^(2+)的吸附量分别是MIIP的1.71、1.43、1.60和9.03倍,最大吸附量分别为21.32、11.21、12.72和25.97 mg·g^(-1)。在竞争离子(Cu^(2+)、Ni^(2+)、Fe^(2+))存在的情况下具有良好的吸附选择性,MIIM的4种模板离子对Ni^(2+)和Fe^(2+)的特异性因子(SP)值在4.86~8.34之间,对Cu^(2+)的SP值在3.58~3.92之间。同时,MIIM可以多次再生,而不会明显降低吸附能力,在废水处理和样品前处理领域具有很好的应用前景。

生物炭-硅酸钙联合修复铅镉污染土壤的持续性效应

为探究棕榈生物炭与硅酸钙联合施用对Pb-Cd复合重金属污染土壤的钝化效果及其稳定性,本研究采用蔬菜种植盆栽实验,测定土壤溶液pH和Pb、Cd浓度以及蔬菜可食部分Pb、Cd含量。结果表明:与不添加钝化剂的对照组相比,添加钝化剂能够有效提高土壤溶液pH,使土壤溶液中Pb、Cd浓度显著降低,种植小白菜可食部分Pb含量下降62.20%~96.77%、Cd含量下降92.76%以上,多数处理符合国家食品安全标准。土壤种植适宜性研究结果表明,五种供试蔬菜可食部分重金属含量与富集系数规律一致,小白菜对Pb的富集能力最强,苋菜对Cd的富集能力最强。当土壤Pb<500 mg·kg^(-1)时,韭菜、苋菜、甘蓝和大白菜四种蔬菜均可种植;当土壤Cd>0.6 mg·kg^(-1)、Pb>500 mg·kg^(-1)时,不适宜种植上述五种蔬菜。本研究探明了钝化剂的持续修复效果,研究结果可为土壤修复提及中低污染风险地区的适宜蔬菜种植提供技术和数据支撑。

多金属MOF衍生多孔碳微波吸收性能研究进展

在对单金属MOF衍生多孔碳微波吸收性能研究进展的基础上进行了拓展,继续研究了多金属MOF衍生多孔碳材料做微波吸收材料的吸波原理和相较于单金属MOF衍生多孔碳的优势。分别从双磁性金属MOF多孔碳、单磁性金属MOF多孔碳和三金属MOF多孔碳3个方面论述了其研究进展。综合上述进展分析了多金属MOF衍生多孔碳做吸波材料存在的问题并对其未来发展方向做出了展望和预测。

球黏土对单及多组分重金属离子的吸附效果

重金属污染水的防范和治理一直是国际上的难点和热点研究课题。吸附法具有经济可行和环境友好等优点,被认为是去除水中重金属离子的最佳技术。球黏土具有潜在的高吸附性能,为进一步探索利用球黏土治理重金属污染水的可行性,该研究通过单组分与多组分重金属离子的批式吸附试验,重点考察球黏土对Pb^(2+)、Cu^(2+)、Zn^(2+)、Cd^(2+)、Cr^(6+)的吸附效果和竞争吸附关系。单组分离子吸附试验表明,球黏土对重金属离子的吸附量遵循先快速增加后缓慢增长,随pH值的增大而增大,随初始浓度增加而增加,直至吸附饱和的规律。最佳吸附平衡时间为90 min;最佳溶液pH值为5。pH值对球黏土吸附5种重金属离子的影响程度由大到小依次为Zn^(2+)、Cd^(2+)、Cr6+、Cu^(2+)、Pb^(2+),当pH值从2增到5时,Zn^(2+)吸附量提高了184%。球黏土对5种离子Pb^(2+)、Cr^(6+)、Zn^(2+)、Cd^(2+)、Cu^(2+)的饱和吸附量分别为311.847、301.437、263.213、195.435和179.635 mg/g。通过动力学模型和等温线模型拟合,吸附数据更加符合准二阶动力学模型和Langmuir等温吸附模型,说明吸附过程为单层吸附,吸附方式为化学吸附,最大吸附量依次为Pb^(2+)(497.593 mg/g)>Cr6+(442.868 mg/g)>Zn^(2+)(339.376 mg/g)>Cd^(2+)(290.039 mg/g)>Cu^(2+)(194.941 mg/g)。多组分离子吸附试验表明,球黏土对4种离子的吸附量同样呈先快速后缓慢增长,直至平稳的趋势。各离子在球黏土的活性位点上表现出的竞争能力由强到弱依次为Cr^(6+)、Zn^(2+)、Cd^(2+)、Cu^(2+)。通过等温线模型拟合,发现多组分重金属离子吸附数据更加符合Langmuir等温吸附模型,吸附方式和吸附过程与单组分一致,各组分的最大吸附量与单组分相比有所下降,但吸附总量却大大增加,说明球黏土对多组分重金属离子具有良好的吸附能力。与其他原生矿物材料相比,球黏土对重金属离子具有更大的吸附量,该研究成果可为球黏土作为吸附剂的利用和推广提供理论依据和数据支持,具有较大的现实意义。

高效多丝熔化极气体保护焊(GMAW)工艺的研究现状及进展

随着全球制造业竞争的日益激烈,我国提出了“中国制造2025”制造强国战略,其重点发展的十大领域中,与焊接技术密切相关的就高达八个,不仅极大地推动了焊接技术的革新发展,而且对焊接效率和质量均提出了更高的要求。由于熔化极气体保护焊(Gas metal arc welding,GMAW)易于实现自动化焊接,具有生产效率高、焊接质量好及位置适应性好等优点,所以广泛应用于机械制造业中。实现高效GMAW的主要途径有提高焊接速度以及焊接熔敷率。针对以上两种途径,国内外焊接工作者在双丝GMAW的基础上,引入了第三根甚至多根焊丝,研发了各种多丝GMAW工艺。本文针对国内外研发的各类多丝GMAW工艺进行了分析,重点介绍了多丝GMAW工艺的焊接原理、工艺特点及其应用,通过上述分析对各类多丝GMAW工艺进行归纳总结,并进一步展望了多丝焊接的发展方向,即多丝GMAW工艺亟需在电弧物理理论、设备开发和新焊材研发等方面展开深入的研究工作。

基于多层融合振动数据分析的GIS设备机械缺陷诊断方法研究

气体绝缘金属封闭开关设备(gas insulated metal enclosed switchgear,GIS)机械缺陷是导致设备故障的重要因素,针对单测点、单证据机械缺陷诊断模型信息缺失和精度不足问题,该文提出一种多层融合振动数据分析的GIS设备机械缺陷诊断方法。首先,基于真型GIS设备振动模拟平台试验研究测点位置与缺陷类型对振动行为的影响特性;然后,联合统计分析、模态分解、尺度变换方法提出机械振动信号整体与局部信息关注的复合参数分析方法,引入主成分分析开展多测点振动信息的特征层融合降维;最后,提出改进放缩权重的Dempster-Shafer(DS)证据理论和Bagging投票机制的强/弱基学习器决策层融合机制,联合构建多层融合振动数据分析的GIS设备机械缺陷诊断模型。结果表明:不同类型机械缺陷信号的响应幅值、特征频点和畸变程度存在显著差异,复合特征参量大小及分散程度各不相同;同时,测点位置对缺陷信号的复合振动特征参量的表现形式及分布区间也具有一定影响;基于多层融合数据分析的诊断模型实现缺陷有效识别,辨识准确率为98.66%,相比单一分类器诊断效果提升5.83%。该文可为GIS设备机械缺陷诊断方法提供有价值的参考。

某铅锌冶炼污染场地基于多源信息的重金属稳定化修复及其评价

冶炼污染场地土壤中多重金属复合污染的特征增大了对土壤的修复和最终利用的难度。本研究深入调查了某铅锌冶炼场地土壤重金属污染特征,针对性地制定多种联合稳定化修复方案,采用高精度混合装备添加药剂,实施稳定化修复工程。结果表明,Cd、Pb、Zn和As是场地土壤中最主要的重金属污染物,其中Cd、Pb、As的超标率分别为75.80%、76.43%、88.54%。重金属的分布模式与土壤理化性质、污染物迁移路径、水文地质条件、地层岩性、冶炼工艺、厂区功能布局等密切相关。土壤重金属污染主要来源于冶炼粉尘、废渣和废水排放等冶炼活动。稳定化工程效果显示,在药剂与土壤混匀程度不低于90%时,采用无机混合药剂与TJ400螯合剂的组合方案,对土壤稳定化处理7 d后,土壤中Cd、Pb和As同步稳定化效果最好。本研究结果可对多金属重污染场地土壤的稳定化修复提供实践指导。

凹凸模具对多层金属板弯曲成型损伤的影响

凹凸模具在对金属板料的弯曲加工成型工艺中占有重要的地位,其中凹凸模具的圆角半径也一直是弯曲件工艺设计的关键参数。多层金属板在弯曲加工中会出现单层金属板不存在的分层损伤现象,因此主要研究凹凸模具对多层金属板在弯曲加工中损伤的影响情况,通过改变相应模具参数来进行试验并使用有限元仿真来验证。结果表明,多层金属板在弯曲加工过程中会出现分层损伤的现象,而在不改变凸模的情况下,分层损伤的程度会随着凹模圆角半径的增大逐渐减小,多层金属板的弯曲成型效果越好。同时发现,当凹模圆角半径的数值等于凸模圆角半径与金属板材的厚度之和时,该多层金属板的弯曲成型性能最好,基本不会出现分层损伤的现象。

新型电力系统电磁暂态加速仿真技术

为解决新型电力系统电磁暂态仿真时由于系统拓扑结构复杂、电力电子开关器件较多以及仿真机单核计算能力不足导致的仿真效率低下、仿真难度大等问题,文中采用理想变压器模型分割算法将大规模新型电力系统模型分割成若干子系统,实现了大系统的解耦和降阶,有效减少了仿真时整个系统作为一个状态空间系统矩阵的运算量。为进一步减轻单个处理器的计算负担,利用CPU(Central Processing Unit)多核并行技术设计一款在裸机环境下高效并行运算的加速仿真平台UREP300。将分割后的模型载入UREP300进行加速仿真实验,同时与基于MATLAB/Simulink的原模型离线仿真进行对比。实验结果表明,融合理想变压器模型分割与多核并行运行的加速仿真技术能够在保障仿真精度的同时将仿真速度提升至原来的586倍,可显著提高仿真效率,适用于大规模新型电力系统的仿真工作。