具有良好可再生性的新型二氧化硅磁性氧化石墨烯纳米复合材料

Graphene oxide (GO) wrapped Fe₃O₄ nanoparticles (NPs) were prepared by coating the Fe₃O₄ NPs with a SiO₂ layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO₂ coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. The effect of the amount of SiO₂ on the morphology, structure, adsorption, and regenerability of the composites was studied in detail. An appropriate SiO₂ layer can effectively induce the GO nanosheets to completely wrap the Fe₃O₄ NPs, forming a core-shell Fe₃O₄@SiO₂@GO composite where Fe₃O₄@SiO₂ NPs are firmly encapsulated by GO nanosheets. The optimized Fe₃O₄@SiO₂@GO sample exhibits a high saturated adsorption capacity of 253 mg·g?1 Pb(II) cations from wastewater, and the adsorption process is well fitted by Langmuir adsorption model. Notably, the composite displays excellent regeneration, maintaining a ~90% adsorption capacity for five cycles, while other samples decrease their adsorption capacity rapidly. This work provides a theoretical guidance to improve the regeneration of the GO-based adsorbents.     

微波预处理对复杂铜矿磨矿及浮选动力学的影响

The effect of CaCO₃, Na₂CO₃, and CaF₂ on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe₃PO₇ and apatite was investigated. The results revealed that Na₂CO₃ had the most significant effect on iron recovery and dephosphorization, followed by CaCO₃, the effect of CaF₂ was negligible. The mechanisms of CaCO₃, Na₂CO₃, and CaF₂ were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe₃PO₇ was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO₃ reacted with Fe₃PO₇ to generate an enormous amount of Ca₃(PO₄)₂ and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na₂CO₃, the phosphorus in Fe₃PO₇ migrated to nepheline and Na₂CO₃ improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF₂ reacted with Fe₃PO₇ to form fine Ca₃(PO₄)₂ particles scattered around the iron particles, making the separation of iron and phosphorus difficult.     

不同硅饱和系数水榴石的碳酸化分解动力学

Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method, which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method. In this study, the effect of the silica saturation coefficient (x) on the carbonation of hydrogarnet was investigated from the kinetic perspective. The results indicated that the carbonation of hydrogarnets with different x values (x = 0.27, 0.36, 0.70, and 0.73) underwent two stages with significantly different rates, and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3. The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol, respectively. Moreover, the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.     

一种超重力燃烧合成制备高性能高熵合金的新方法

A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr_0.9FeNi_2.5V_0.2Al_0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.     

利用皮秒激光烧蚀制备非球形铝纳米颗粒

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl₃) with ~2 ps laser pulses at an input energy of ~350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ~340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ~280 nm. Additionally, coarse structures with a period of ~700 nm were observed.     

窄板坯结晶器内连铸工艺参数对钢液流场的影响

Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting (CC) molds with narrow widths for the production of automobile exposed panels. Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process. The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold. Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone. The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min?1 and casting speed of 1.7 m·min?1. Under the present experimental conditions, the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.     

电渣重熔脱硫技术研究进展

Electroslag remelting (ESR) gives a combination of liquid metal refining and solidification structure control. One of the typical aspects of liquid metal refining during ESR for the advanced steel and alloy production is desulfurization. It involves two patterns, i.e., slag–metal reaction and gas–slag reaction (gasifying desulfurization). In this paper, the advances in desulfurization practices of ESR are reviewed. The effects of processing parameters, including the initial sulfur level of consumable electrode, remelting atmosphere, deoxidation schemes of ESR, slag composition, melting rate, and electrical parameters on the desulfurization in ESR are assessed. The interrelation between desulfurization and sulfide inclusion evolution during ESR is discussed, and advancements in the production of sulfur-bearing steel at a high-sulfur level during ESR are described. The remaining challenges for future work are also proposed.     

Mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al2O3?Na2O system during high-temperature sintering

The mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al₂O₃?Na₂O system during the high-temperature sintering process were systematically investigated using DSC?TG, XRD, SEM?EDS, FTIR, and Raman spectra, and the crystal structure of Na₄Ca₃(AlO₂)₁₀ was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na₄Ca₃(AlO₂)₁₀, CaO·Al₂O₃, and 12CaO·7Al₂O₃, and the content of Na₄Ca₃(AlO₂)₁₀ could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na₄Ca₃(AlO₂)₁₀ occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na₄Ca₃(AlO₂)₁₀ was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na₄Ca₃(AlO₂)₁₀ was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.     

含细夹层的分矿充填层中流动特性的可视化

Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography (CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers (24.21%) was significantly lower than that of the heap packed by coarse ores (37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity (1.8 × 10?5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10?5 m/s appeared in flow paths with a large diameter.     

具有负载识别功能的数字电能表设计

针对现有电能表精度差、可靠性低的问题,设计了一种基于SST89E564RD单片机和ADE7753电能计量芯片的智能数字电能表,该数字电能表具有能量累积、费用计算、恶性负载识别、过流过载保护、定时关断、电力线载波通信等功能.给出了硬件原理和软件流程,采用C语言模块化编程,便于理解和维护.市场应用表明该数字电能表精度能够达到1.0级,运行可靠,具有广泛的应用前景.     

基于87C51单片机的复费率电能表的设计

讨论了一种以87c51单片机为核心处理器的多功能复费率电能表,该表具有电量采集、分段计费、电子显示、远红外无线操表等功能,适合我国目前电力供应紧张和用电负荷不平衡的需求,同时也可减轻人工抄表的劳动强度.该表以87C51为核心控制单元,以ADE7755作为电量采集芯片,以高清晰的 LCD 作为显示屏来显示系统中谷、峰、平等各时段的电能值,具有结构简单,可靠性高和成本低等特点.     

基于USB主机技术的三相多功能电能表设计

提出一种基于USB主机技术的新型三相多功能电能表结构,设计基于USB1.1协议的三相多功能电能表,给出USB接口单元的硬件电路与电磁兼容设计技术,重点论述电能表USB接口单元的软件设计方法,以及在FAT16和FAT32为文件系统的U盘中的文件查找、新建和电能表数据抄读、电能表参数设置等功能的实现方法.该三相多功能电能表利用USB主机技术可自动识别U盘,方便现场抄表,避免了人为差错.     

浅谈如何搞好变电所电度表的接线工作

指出了电度表计接线的准确是影响电量计量的关键,介绍了几种有功电能计量的接线形式,分析了高压三相两元件有功电度表的错误接线方式。     

智能电能表及其应用研究

21世纪是信息网络化、高新科技成果被广泛应用的时代,数字化、智能化、标准化、系统化和网络化是现代电能计量装置发展的必然趋势,智能电能表应运而生。介绍了智能电能表及其工作原理,分析了智能电能表的常见故障及处理方法,探讨了智能电能表的自查方法、节电措施及发展趋势。     

专变采集终端故障分析及处理

随着用电信息采集的不断发展,提高电力部门电费实时结算水平,建立一种新型的抄表方式已成为所有电力部门的共识。介绍了电能用电信息采集系统的构成和特点,从抄表故障和通信故障两方面对专变采集终端故障原因及处理进行了分析。     

基于AD7755的掌上型电能表现场校验仪的设计与实现

分析了现场校验仪的测量原理,给出了被校电度表的电压、电流、功率、电能表误差等参数的计算公式,并以CPU89C2051为控制计算核心,AD7755为测量核心,配以高精度钳型电流互感器和液晶显示模块,设计和实现了掌上型电能表现场校验仪系统.该系统可在不拆表、不断电的情况下,快速准确地测出被校电度表的电压、电流、功率、电能表误差等参数.     

单片机89C52在多功能电度表中的应用研究

讨了一种以89C52单片机为核心构成的多功能电度表，它可以同时具有电能表、自动补偿、分时段测电能等多种功能，并以先进的LCD显示屏显示当前的功率因数、总电能值、所消耗的峰、谷、平电能值。     

基于DLMS的电能表负荷监测技术

为实现计算机与多种电能表的通信和数据采集,构建了一种基于设备语言报文规范（DLMS）的电表负荷监测软件设计方法,介绍了DLMS/COSEM通信协议,给出了程序设计流程与软件设计方法,介绍了建立对象模型、通信参数配置、建立连接和数据采集等模块设计.软件采用面向对象的编程思想,遵循国际电工委员会DLMS/COSEM通信协议,根据采集的数据自动绘制负荷曲线,数据归档入库,利于维护和查询,克服了现有电能表通信控制软件兼容性差、互联性差等缺点,并在多功能电表监测系统中得到了应用.     

关口电能表通信配置检测与管理系统的设计

为建立发电公司与电网公司各自准确可靠及时的电能量计量计费系统，本文选择了功能强大的Microsoft VC＋＋6．0作为软件开发平台，以Microsoft SQL Server 2000作为数据库管理平台，开发了一套专门、科学有效的检测与管理系统软件．对全局（公司）或运行现场电能表的通信配置和通信功能进行批量检测，实现关口电能表通信系统准确可靠的运行．