Electrical conductivity optimization of the Na3AlF6-Al2O3-Sm2O3 molten salts system for Al-Sm intermediate binary alloy production

Metal Sm has been widely used in making Al-Sm magnet alloy materials. Conventional distillation technology to produce Sm has the disadvantages of low productivity, high costs, and pollution generation. The objective of this study was to develop a molten salt electrolyte system to produce Al-Sm alloy directly, with focus on the electrical conductivity and optimal operating conditions to minimize the energy consumption. The continuously varying cell constant (CVCC) technique was used to measure the conductivity for the Na₃AlF₆-AlF₃-LiF-MgF₂-Al₂O₃-Sm₂O₃ electrolysis medium in the temperature range from 905 to 1055℃. The temperature (t) and the addition of Al₂O₃ (W(Al₂O₃)), Sm₂O₃ (W(Sm₂O₃)), and a combination of Al₂O₃ and Sm₂O₃ into the basic fluoride system were examined with respect to their effects on the conductivity (κ) and activation energy. The experimental results showed that the molten electrolyte conductivity increases with increasing temperature (t) and decreases with the addition of Al₂O₃ or Sm₂O₃ or both. We concluded that the optimal operation conditions for Al-Sm intermediate alloy production in the Na₃AlF₆-AlF₃-LiF-MgF₂-Al₂O₃-Sm₂O₃ system are W(Al₂O₃) + W(Sm₂O₃)=3wt%, W(Al₂O₃):W(Sm₂O₃)=7:3, and a temperature of 965 to 995℃, which results in satisfactory conductivity, low fluoride evaporation losses, and low energy consumption.     

Phosphate enrichment mechanism in CaO–SiO2–FeO–Fe2O3–P2O5 steelmaking slags with lower binary basicity

The addition of silica to steelmaking slags to decrease the binary basicity can promote phosphate enrichment in quenched slag samples. In this study, we experimentally investigated phosphate enrichment behavior in CaO–SiO₂–FeO–Fe₂O₃–P₂O₅ slags with a P₂O₅ content of 5.00% and the binary basicity B ranging from 1.0 to 2.0, where the (%Fe_tO)/(%CaO) mass percentage ratio was maintained at 0.955. The experimental results are explained by the defined enrichment degree R_C2S-C3P of solid solution 2CaO·SiO₂–3CaO·P₂O₅ (C₂S–C₃P), where R_C2S-C3P is a component of the developed ion and molecule coexistence theory (IMCT)–N_i model for calculating the mass action concentrations N_i of structural units in the slags on the basis of the IMCT. The asymmetrically inverse V-shaped relation between phosphate enrichment and binary basicity B was observed to be correlated in the slags under applied two-stage cooling conditions. The maximum content of P₂O₅ in the C₂S–C₃P solid solution reached approximately 30.0% when the binary basicity B was controlled at 1.3.     

1623 K时SiO2饱和的MnO–SiO2渣和Al2O3饱和的MnO–SiO2–Al2O3渣中NiO的活度系数

MnO–SiO₂二元系作为废旧锂离子电池、海洋锰结核还原熔炼过程中的基础渣型,测定有价金属（如镍）在渣中的溶解度、活度及活度系数热力学数据十分必要。为此,本文测定了温度1623 K、氧分压10?7,10?6,和10?5 Pa时SiO₂饱和的MnO–SiO₂渣和Al₂O₃饱和的MnO–SiO₂–Al₂O₃渣中NiO的溶解度和活度系数。结果表明:在试验条件下,镍在MnO–SiO₂渣和MnO–SiO₂–Al₂O₃渣中主要以NiO形式存在,且渣中NiO的溶解度随着氧分压增加而增加;向MnO–SiO₂渣中加入Al₂O₃可以降低渣中镍的溶解度,增加NiO的活度系数。此外,SiO₂饱和的MnO–SiO₂渣和Al₂O₃饱和的MnO–SiO₂–Al₂O₃渣中NiO的活度系数（γ_NiO,以纯固体NiO为参考态）可分别按如下公式计算:γ_NiO = 8.58w(NiO) + 3.18; γ_NiO=11.06w(NiO) + 4.07, 其中,w(NiO)为渣中NiO的质量分数。     

钐对SmxMn0.3?xTi催化剂NH3选择性催化还原NOx过程中N2选择性的影响

本文研究了Sm对Mn基催化剂NH₃选择性催化还原NO的改善作用。采用共沉淀法制备了一系列Sm_xMn_0.3?xTi催化剂(x = 0, 0.1, 0.15, 0.2和0.3)。活性测试表明,Sm_0.15Mn_0.15Ti催化剂在180?300°C条件下,NO转化率达100%,N₂选择性达87%以上。表征结果表明,Mn基催化剂中添加Sm,抑制了TiO₂和Mn₂O₃相的结晶,提高了比表面积和酸性,其中Sm改性催化剂的比表面积从152.2增加至241.7 m2·g?1。这些作用有利于提高催化活性。X射线光电子能谱(XPS)结果表明,Sm_0.15Mn_0.15Ti的Sm3+/Sm和O_β/O的相对原子比分别为76.77at%和44.11at%,添加Sm增加了表面吸附氧(O_β),降低了Mn4+的表面浓度;程序升温还原H₂(H₂-TPR)结果表明,Sm_0.15Mn_0.15Ti催化剂还原温度提高,H₂消耗量降低至0.3 mmol?g?1。Sm的引入降低了催化剂Mn4+表面浓度,使得该催化剂氧化还原性能降低,进一步抑制NH₃氧化和非选择性催化还原反应生成N₂O,从而提高了催化剂的N₂选择性。原位漫反射红外傅立叶变换光谱(DRIFTs)表明,Sm_0.15Mn_0.15Ti催化剂的NH₃-SCR反应主要遵循Eley?Rideal机制。Sm掺杂增加了Sm_0.15Mn_0.15Ti催化剂的表面吸附氧(O_β),降低了氧化还原性能,提高了Sm_0.15Mn_0.15Ti催化剂的NO转化率和N₂选择性。     

第一性原理研究Ba2O2S的结构、电子和热传输性质

运用第一性原理和机器学习算法预测2种Ba₂O₂S结构,其具有P-3m1和P63/mmc空间群.通过弹性和声子特性计算发现2种结构都满足动力学和弹性稳定性要求.分析电子结构发现2种结构均为直接带隙半导体,带隙分别为4.6和4.5 eV,Ba—S和Ba—O键都是离子键型.B1-Ba₂O₂S和B2-Ba₂O₂S的晶格热导率表现出各向异性,[100]和[010]方向的热导率比[001]方向的晶格热导高约1.6倍.预测的2种结构的多晶热导率约为1.86和1.40 W·m^-1·K^-1,因而Ba₂O₂S可以作为潜在的隔热材料.由于B1-Ba₂O₂S的群速度外积分值要高于B2-Ba₂O₂S,因此导致B1-Ba₂O₂S的热导率略高于B2-Ba₂     

络合沉淀法合成纳米二氧化铈及其表征

由于其独特的物理化学性质,纳米二氧化铈是一种良好的无机紫外线屏蔽剂。纳米二氧化铈的制备方法有水热法、溶胶–凝胶法、均相沉淀法、电化学方法等,这些方法通常有操作流程复杂、周期较长等缺点。本文旨在探索一种操作简单,周期短的纳米二氧化铈制备方法。本文以氯化铈为铈源、柠檬酸为沉淀剂,采用络合沉淀法成功合成了纳米二氧化铈。通过元素分析计算了前驱体的组成,并采用比表面积测试、显微组织观察、紫外-可见光透过率曲线研究了纳米二氧化铈的物理性能、微观组织与紫外屏蔽性能的关系。研究结果表明,随着pH的升高,前驱体中Ce(H₂Cit)₃的比例下降,而Ce(OH)₃的比例上升,当pH = 6.5时,前驱体由CeCit和Ce(OH)₃组成;随着柠檬酸与Ce3+的摩尔比(n)的增加,前驱体中Ce(H₂Cit)₃的比例升高,而Ce(OH)₃的比例下降。当柠檬酸与Ce3+的摩尔比(n)为0.25、pH为5.5时,纳米二氧化铈在长波紫外线波段的平均透过率为4.42%,在中波紫外线波段的平均透过率为1.56%。良好的紫外屏蔽性能离不开纳米二氧化铈的物理性能和微观组织:比表面积的增大可以提高纳米二氧化铈的紫外屏蔽性能,当柠檬酸与Ce3+的摩尔比(n)为0.25、pH为5.5时,纳米二氧化铈的比表面积最大,为83.17 m2/g。纳米二氧化铈低指数晶面的晶面间距也影响着纳米二氧化铈的紫外屏蔽性能,在合理变化区间内,晶面间距越大,原子排列越密集,紫外屏蔽性能越好。由此得出这样的结论:络合沉淀法制备出的纳米二氧化铈具有优异的紫外屏蔽性能,但是,柠檬酸与Ce3+的摩尔比(n)不宜过大,pH不宜超过5.5。     

全水解制氢用自支撑多孔NixFe–S/NiFe2O4异质结构双功能电催化剂

稳定的非贵金属双功能电催化剂是可再生能源驱动的波动全水电解面临的难题之一。本文在三维碳纤维布上电沉积制备了多孔Ni–Fe金属阵列,并在此基础上进行原位氧化和化学硫化,构建了一种新型的自支撑分级多孔Ni_xFe–S/NiFe₂O₄异质结构双功能电催化剂。研究结果表明,Ni_xFe–S/NiFe₂O₄异质结构催化剂对析氢反应(HER)和析氧反应(OER)都表现出良好的催化活性和稳定性,优异的催化性质与其大比表面积提供丰富的活性位点、异质结构的协同效应、超亲水表面和稳定的自支撑结构密不可分。分析结果证析氧过程异质结构中的Ni_xFe–S转化为金属氧化物/氢氧化物和Ni₃S₂。与商用20wt% Pt/C||IrO₂-Ta₂O₅相比,自支撑Ni_1/5Fe–S/NiFe₂O₄||Ni_1/2Fe–S/NiFe₂O₄在10-500mA/cm2的波动电流密度范围内表现出更好的稳定性和更低的槽电压。在500 mA/cm2的工业电流密度下,Ni_1/5Fe–S/NiFe₂O₄||Ni_1/2Fe–S/NiFe₂O₄的槽电压仅为约3.91 V,比Pt/C||IrO₂–Ta₂O₅ (约4.79 V)降低了约20%。     

w(CaO)/w(Al2O3)对钙铝基保护渣结晶性能的影响

利用热丝法测试技术,结合扫描电镜和能谱分析,研究了不同w(CaO)/w(Al₂O₃)条件下钙铝基保护渣的结晶性能.结果表明,较低w(CaO)/w(Al₂O₃)下,保护渣结晶物相为LiAlO₂和CaO·Al₂O₃.其析出由渣中的Li⁺离子和Ca²⁺离子分别对高聚合度铝氧四面体结构的电荷补偿所致.而且,Li⁺离子优先参与,LiAlO₂优先析出.较高w(CaO)/w(Al₂O₃)下,结晶物相转变为LiAlO₂和3CaO·Al₂O₃.其变化原因为,CaO相对质量分数提高,保护渣聚合度降低,Ca²⁺离子和低聚合度铝氧四面体结构单元Q²结合而形成3CaO·Al₂O₃并析出.随着w(CaO)/w(Al₂O₃)由1.13提高至1.82,钙铝基保护渣析晶能力先减弱然后增强.在w(CaO)/w(Al₂O₃)为1.50和1.82时分别具有最弱和最强的析晶能力.     

Activity coefficient of NiO in SiO2-saturated MnO–SiO2slag and Al2O3-saturated MnO–SiO2–Al2O3slag at 1623 K

As a part of the fundamental study related to the reduction smelting of spent lithium-ion batteries and ocean polymetallic nodules based on MnO–SiO₂slags,this work investigated the activity coefficient of NiO in SiO₂-saturated Mn O–Si O₂slag and Al₂O₃-saturated Mn O–SiO₂–Al₂O₃slag at 1623 K with controlled oxygen partial pressure levels of 10^-7,10^-6,and 10^-5Pa.Results showed that the solubility of nickel oxide in the slags increased with increasing oxygen partial pressure.The nickel in the Mn O–Si O₂slag and Mn O–Si O₂–Al₂O₃slag existed as Ni O under experimental conditions.The addition of Al₂O₃in the Mn O–Si O₂slag decreased the dissolution of nickel in the slag and increased the activity coefficient of Ni O.Furthermore,the activity coefficient of Ni O(γN_(i O)),which is solid Ni O,in the Si O₂saturated Mn O–Si O₂slag and Al₂O₃saturated Mn O–Si O₂–Al₂O₃slag at 1623 K can be respectively calculated asγN_(i O)=8.58w(Ni O)+3.18 andγN_(i O)=11.06w(Ni O)+4.07,respectively,where w(Ni O)is the Ni O mass fraction in the slag.     

Co离子掺杂La2Ti2-xCoxO7的室温多铁性

通过向传统铁电材料La₂Ti₂O₇中引入磁性Co离子,成功制备出了新型室温多铁材料La₂Ti_2-xCo_xO₇(x=0、0.03、0.05、0.07)。测试结果表明,所有样品均为单相晶体结构,在x射线探测范围内无第二相杂质出现。适当浓度的磁性Co离子掺杂不仅可有效提高材料的饱和铁磁磁化强度,还可有效降低体系漏电流,提高La₂Ti₂O₇绝缘性,进而改善La₂Ti_2-xCo_xO₇铁电性和多铁性。对La₂Ti_2-xCo_xO₇等样品的顺磁、反铁磁和铁磁等复杂磁相互作用的微观机理进行了探讨。铁磁性的产生被认为与氧空位和过渡金属离子3d电子自旋之间的交换耦合作用有关。而对未掺杂的La₂Ti...     

Na2S改性CoSO4催化氨硼烷水解放氢

以Na₂S和CoSO₄为原料,采用水热法和烧结制备了一种CoSO₄和Co₃O₄两相共存的Co基催化剂(命名为Co₃O₄-CS(NS))用于催化氨硼烷水解.研究表明,由于CoSO₄和Co₃O₄的协同效应使得该催化剂对氨硼烷水解表现出良好的催化性能.在催化剂直接添加量为10 wt.%、水料比为25 mL/g和反应温度为40℃的反应条件下,每0.2 g AB/Co₃O₄-CS(NS)复合物在2.5 min内放氢量达到440.06 mL,对应的放氢速率为8 801.2 mL/(min·g_cat),氢转化率为92.6%,反应活化能为50.4 kJ/mol.     

金属有机框架衍生的Co3O4/SnO2复合材料制备及其光催化性能

金属有机框架(metal-organic framework,MOF)材料ZIF-67衍生Co₃O₄十二面体纳米块在室温下与SnO₂复合,制备出立方体Co₃O₄/SnO₂复合光催化剂.煅烧后形成的Co₃O₄/SnO₂材料禁带宽度明显降低,荧光淬灭明显,说明Co₃O₄的加入拓展了SnO₂的光响应范围至可见光甚至红外光区域,同时促进了光催化反应过程中光生载流子的分离.以罗丹明B(Rhodamine B,Rh B)为目标反应物,在可见光下考察了MOF衍生的Co₃O₄/SnO₂的光催化降解活性,发现Co₃O₄/SnO₂在60 min内可以降解89.6%的Rh B,分别是纯SnO₂和纯...     

CaO-SiO2-MgO-Al2O3四元渣系Al2O3活度预测模型

高炉渣系各组元活度对高炉冶炼和产品质量具有重要的影响作用. 基于分子-离子共存理论,建立CaO-SiO₂-MgO-Al₂O₃四元渣系Al₂O₃活度预测模型;结合试验测定值对其进行验证与修正,最终建立了修正的CaO-SiO₂-MgO-Al₂O₃四元渣系Al₂O₃活度预测模型;同时,依据模型计算结果探究R(w(CaO)/w(SiO₂)),w(MgO)/w(Al₂O₃)和w(Al₂O₃)对Al₂O₃活度的影响. 研究结果表明:修正后的CaO-SiO₂-MgO-Al₂O₃四元渣系Al₂O₃活度预测模型具有较高的预测精度,能够很好地预测熔渣Al₂O₃活度;当w(MgO)/w(Al₂O₃)=0.40,w(Al₂O₃)=20%时,随着R增加,Al₂O₃活度逐渐减小;当R=1.25,w(Al₂O₃)=20%时,随着w(MgO)/w(Al₂O₃)增加,Al₂O₃活度逐渐减小;当w(MgO)/w(Al₂O₃)=0.40,R=1.25时,随着w(Al₂O₃)增加,Al₂O₃活度逐渐增大.     

稠油硫酸盐热化学还原生成H2S实验研究

为了研究稠油注汽热采过程中生成H₂S机理，以Na₂SO₄，CaSO₄，MgSO₄，Fe₂（SO₄）₃，Al₂（SO₄）₃与稠油硫酸盐热化学还原（TSR）实验为基础，探究稠油TSR生成H₂S机理。实验表明，不同硫酸盐与稠油反应生成H₂S不尽相同，硫酸盐的阳离子所带电荷数决定TSR反应程度的难易，电荷数越多越容易进行反应，且H₂S生成量顺序为Al₂（SO₄）₃>Fe₂（SO₄）₃ > MgSO₄ > CaSO₄ > Na₂SO₄，但生成的烃量顺序为Fe₂（SO₄）₃ > Al₂（SO₄）₃ > MgSO₄ > CaSO₄ > Na₂SO₄。与其他硫酸盐不同的是，由于Fe₂（SO₄）₃的氧化性，Fe³⁺可能与生成的H₂S进一步反应。通过傅里叶红外变换光谱（FT-IR）对固相检测发现，不仅存在金属氧化物（CaO，MgO，Fe₂O₃，Al₂O₃）还存在FeS₂。最后，通过对MgSO₄油相硫含量的检测发现，反应后硫含量高于原油硫含量，证明了无机硫向有机硫的转化。     

Eu3+掺杂Ca2ZrSi4O12的红色荧光粉性能分析

采用高温固相法制备Ca₍2(1-x))ZrSi₄O₁₂:2x Eu³⁺系列红色荧光粉,并对样品的物相结构、荧光特性、热稳定性和色坐标进行实验分析。分析结果表明：红色荧光粉Ca₂ZrSi₄O₁₂:Eu³⁺可以被紫外光或蓝光激发,并在612 nm处表现出较强的红光发射;Eu³⁺的最佳掺杂浓度为60%,浓度淬灭机理归因于电四级-电四极相互作用;样品在室温到453 K这一温度范围内有较为良好的热稳定性;所有样品色坐标均位于红色发光区域。表明Eu³⁺掺杂Ca₂ZrSi₄O₁₂荧光粉在白光LED领域具有潜在的应用前景。     

Fabrication of Fe–TiC–Al2O3 composites on the surface of steel using a TiO2–Al–C–Fe combustion reaction induced by gas tungsten arc cladding

The aim of the present study was to fabricate Fe–TiC–Al₂O₃ composites on the surface of medium carbon steel. For this purpose, TiO₂–3C and 3TiO₂–4Al–3C–xFe (0 ≤ x ≤ 4.6 by mole) mixtures were pre-placed on the surface of a medium carbon steel plate. The mixtures and substrate were then melted using a gas tungsten arc cladding process. The results show that the martensite forms in the layer produced by the TiO₂–3C mixture. However, ferrite–Fe₃C–TiC phases are the main phases in the microstructure of the clad layer produced by the 3TiO₂–4Al–3C mixture. The addition of Fe to the TiO₂–4Al–3C reactants with the content from 0 to 20wt% increases the volume fraction of particles, and a composite containing approximately 9vol% TiC and Al₂O₃ particles forms. This composite substantially improves the substrate hardness. The mechanism by which Fe particles enhance the TiC + Al₂O₃ volume fraction in the composite is determined.     

V2O5/ZrO2-Al2O3催化甲醇选择性氧化合成二甲氧基甲烷

采用浸渍法制备了V₂O₅质量分数不同的V₂O₅/Al₂O₃催化剂,采用Zr对Al₂O₃载体进行改性并应用于催化甲醇选择性氧化制备二甲氧基甲烷(DMM)的反应中。经X-射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见分光光谱(UV-Vis)、傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman)、N₂吸附-脱附(BET)、H₂程序升温还原(H₂-TPR)和NH₃程序升温脱附(NH₃-TPD)表征分析,结果表明:与单一Al₂O₃负载的钒基催化剂相比,Zr改性提高了钒氧化物的分散性与稳定性,加强了催化剂中各组分间的相互作用,有效调变了催化剂的酸性和氧化性,进而提高了DMM的选择性。考察了反应条件对甲醇选择性氧化制备DMM的影响,最佳反应温度为175 ℃,经20%V₂O₅/12%ZrO₂-Al₂O₃催化氧化,甲醇转化率为27.9%,DMM选择性为99.9%。     

18wt%Cr–8wt%Ni不锈钢中增塑性MnO–Al2O3–SiO2基非金属夹杂物的演变及其浸泡性能

The properties of MnO–Al₂O₃–SiO₂-based plasticized inclusion are likely to change during soaking  process due to its low melting point. In this study, the evolution of the MnO–Al₂O₃–SiO₂-based inclusion of 18wt%Cr?8wt%Ni stainless steel under isothermal soaking process at 1250°C for different times was investigated by laboratory-scale experiments and thermodynamic analysis. The results showed that the inclusion population density increased at the first stage and then decreased while their average size first decreased and then increased. In addition, almost no Cr₂O₃-concentrated regions existed within the inclusion before soaking, but more and more Cr₂O₃ precipitates were formed during soaking. Furthermore, the plasticity of the inclusion deteriorated due to a decrease in the amount of liquid phase and an increase in the high-melting-point-phase MnO–Cr₂O₃ spinel after the soaking process. In-situ observations by high-temperature confocal laser scanning microscopy (CLSM) confirmed that liquid phases were produced in the inclusions and the inclusions grew rather quickly during the soaking process. Both the experimental results and thermodynamic analysis conclude that there are three routes for inclusion evolution during the soaking process. In particular, Ostwald ripening plays an important role in the inclusion evolution, i.e., MnO–Al₂O₃–SiO₂-based inclusions grow by absorbing the newly precipitated smaller-size MnO–Cr₂O₃ inclusions.     

锂离子电池电极材料Li4Ti5O12@TiO2的制备及性能

用水热法制备Li₄Ti₅O₁₂@TiO₂复合材料与同样方法制备的尖晶石型Li₄Ti₅O₁₂进行对比.对2种材料采用扫描电子显微镜、X射线衍射仪、光电子能谱仪(XPS)进行表征;N₂吸附-脱附曲线进行比表面积分析;恒电流充放电测试和电化学交流阻抗(EIS)技术进行电化学性能分析.结果表明Li₄Ti₅O₁₂@TiO₂和Li₄Ti₅O₁₂均呈颗粒状,粒径分别约为50和70 nm.XPS分析显示Li₄Ti₅O₁₂@TiO₂中的Ti为+4价态.电化学测试结果显示Li₄Ti₅O₁₂复合了锐钛型TiO₂...     

SmCo5型中熵、高熵金属间化合物的结构与磁性

以SmCo₅为原型,设计了3种中熵金属间化合物(Sm_1/3Ce_1/3Pr_1/3)Co₅、(Sm_1/3Ce_1/3Nd_1/3)Co₅、(Sm_1/3Pr_1/3Nd_1/3)Co₅和1种高熵金属间化合物(Sm_1/4Ce_1/4Pr_1/4Nd_1/4)Co₅,并采用原子半径差和混合焓预测了形成单相结构的可能性. 应用真空电弧熔炼技术成功制备了4种金属间化合物. 采用X射线衍射仪(XRD)、能谱仪(EDS) 和振动样品磁强计(VSM) 表征了样品的物相、成分和磁学性能. 结果表明:4种化合物均为单相,具有六方CaCu₅结构,空间群为P6/mmm,稀土原子占据1a位置;稀土位置上的原子浓度为等原子比;化合物的室温磁化行为遵循Langevin模型,磁化强度依赖于化合物的成分;磁价模型计算证实了化合物(Sm_1/3Ce_1/3Pr_1/3)Co₅、(Sm_1/3Ce_1/3Nd_1/3)Co₅和(Sm_1/4Ce_1/4Pr_1/4Nd_1/4)Co₅中的Ce为+4价,对磁矩没有贡献.