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.     

单跨无吊车门式刚架结构的用钢量分析

门式刚架结构体系作为轻型钢结构的一种结构型式,近10年来在我国大量涌现.随着门式刚架结构的广泛使用,其用钢量问题就显得日益重要.针对无吊车单跨轻型门式刚架结构,分析了影响门架用钢量的各种参数,结果表明：门式刚架结构的用钢量主要与刚架的高度、跨度、柱距、竖向荷载、水平荷载等因素有关,且基本上呈线性影响关系.     

从钢构到钢材表现

针对20世纪以来建筑技术翻天覆地的变革情况,从传统的哲学观念和建筑美学出发,分析了钢结构建筑在当代的发展趋向,以促进钢材料在我国更加广泛的应用.     

钢结构中工字钢梁腹板厚度的确定

在钢结构中为节省用钢量常采用高而薄的腹板 ,因此腹板厚度的确定至关重要。本文主要从剪应力、弯曲应力、弯曲剪切共同作用以及腹板屈服后强度利用等方面分析了腹板高厚比的限值。所得数据供设计工作者参考使用。     

无内胎钢制车轮高强度钢等代设计

利用SolidWorks和Ansys软件建立22.5 in×9.0 in无内胎钢制车轮的有限元分析模型,采用高强钢代换低强钢的方法,在保证强度和疲劳寿命的前提下,对车轮进行了轻量化设计,减薄了轮辋和轮辐厚度。弯曲和径向试验的仿真结果表明:虽然改进后的各自最大等效应力都有所增加,但都没有超过材料的屈服极限;采用名义应力法并根据经验公式建立的590CL材料的S-N曲线方程,计算得出的疲劳寿命符合GB/T 5909—2005标准要求。     

吨钢钢液面积对钢质量的影响

本文利用示踪法对高T[O]条件下钢中夹杂物的来源及特点进行研究。结果表明:正常浇注条件下,钢水一次脱氧不彻底,钢中T[O]高,造成钢中氧化物夹杂含量高,铸坯内大型非金属夹杂物主要来源于脱氧产物。吨钢钢液面积大对钢质量不利,宜减小吨钢的钢液面积。显微夹杂总体积率为0.15%,各类夹杂占显微夹杂总量的比例为:硅钙酸盐夹杂55.4%,硅铝酸盐夹杂34.4%,硫化物夹杂10.2%。     

IF钢与ELC钢织构及性能的对比

研究了经铁素体区热轧、冷轧和退火生产的ELC钢和IF钢的组织、织构及性能.结果表明,铁素体区热轧后,ELC钢中的大部分组织是变形带;而IF钢中已经形成了等轴晶粒.ELC钢的热轧织构中形成了较强的α织构和很弱的γ织构,织构主要组分集中在{001}〈110〉~{223}〈110〉;而IF钢中形成了强的γ织构和很弱的α织构.ELC钢的退火织构中主要是γ织构,但仍有较弱的α织构存在;IF钢的退火织构中只有很强并且均匀的γ织构,强度明显高于ELC钢的退火织构.与ELC钢相比,IF钢的平均塑性应变比(r值)高出0.6,延伸率高出5%,同时,抗拉强度升高,而屈服强度降低.     

宝钢IF钢大生产产品性能预测

以ＢＰ算法为基础开发了ＡＮＮ学习预测系统,用于宝钢ＩＦ钢大生产产品性能预测．同时,应用在宝钢ＩＦ钢大生产数据对该系统进行了测试和分析,并与多元线性回归结果进行预测精度比较．结果表明,ＡＮＮ学习预测系统,除σ_(０.２)误差较高（９．０％）外,σ_ｂ,δ,ｒ和ｎ值均＜５．０％,且比多线性回归方法精度高．     

钢厂废钢生成量与需求量的计算

通过对钢厂历年有关数据的统计分析,使用二元回归方法建立废钢生成量预测模型。预测废钢生成量和需求量,可为钢铁企业制定生产经营计划提供重要依据。     

型钢悬挑扣件式钢管脚手架设计与安装

高层建筑施工用脚手架工程中往往离不开悬挑结构用来分担荷载。或者因建筑物设计需要而必须采用悬挑脚手架。本文结合工程实例介绍型钢悬挑扣件式钢管脚手架设计与安装，为施工生产提供符合安全使用要求的脚手架。     

热成形钢与低碳钢电阻凸焊的数值模拟

摘要： 利用专用有限元分析软件SORPAS模拟了热成形钢与低碳钢电阻凸焊熔核形成的过程,定性及定量地分析了2种材料在电阻凸焊过程中温度场、应力场的参数变化规律以及最终凸焊接头的熔核直径,并将模拟结果与实验结果进行对比.结果表明：模拟过程中出现了熔核偏移的现象;凸焊接头熔核直径的变化趋势均与其实验结果较吻合.