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.     

高灵敏度光纤MZI折射率传感器

首次在实芯光子晶体光纤中制备了横向大偏置结构光纤马赫-曾德尔干涉仪折射率传感器,并理论分析了此种干涉仪的干涉机制和折射率传感特性,以及影响折射率传感特性的各种因素;搭建实验系统,测试了折射率传感特性。结果表明,腔长330 μm传感器的干涉谱对外部环境折射率变化的响应成线性,透射谱随环境介质折射率增大而向短波方向移动,灵敏度超过-15 100 nm/RIU,灵敏度与腔长长度无关,光子晶体光纤的气孔对折射率传感特性影响很小。此种高灵敏度的光纤微腔折射率传感器适用于液体或气体的快速检测领域。     

全反射比较法测量液体折射率色散的研究

基于全反射原理,提出一种用比较法测量液体折射率色散的方法.分析了棱镜全反射比较法测量液体折射率色散的基本原理,推导得到折射率色散的计算公式.结果表明:待测液体折射率色散与标准液体折射率色散、全反射极限出射角有关,与棱镜折射率色散无关;搭建相应的实验光路及系统,通过与阿贝折射仪及双棱镜法测量折射率色散对比证明了该方法的准确性.实验测量了葡萄糖水、印度墨水、聚苯乙烯溶液、品红溶液、唾液、汗液及不同浓度蜜糖溶液样品的折射率色散曲线,同一样品的折射率随着波长的增加而降低,并通过柯西色散公式得到相关样品色散曲线的拟合方程.实验表明:测量液体折射率的精度约0.000 2;分离餐后汗液、唾液的折射率明显高于餐前,这一实验结论给糖尿病的无创检测血糖提供一种可能的思路.文中提出的方法不需要棱镜折射率及其色散数据,具有实验系统简单、样品量少、测量过程方便、测量精度高等特点,不仅适合于透明及弱吸收散射的液体,而且可被用于固体折射率色散的测量,具有实际推广应用意义.     

电荷耦合器件型折射率测定仪的研制

基于折射定律设计光路，利用线阵电荷耦合器件（CCD）对光斑位移进行检测，研制成功小型的能够测量透明介质折射率的仪器，设计的测量折射率的范围显著增加．介绍了该仪器设计的基本原理、使用方法，并通过对一些材料折射率的测量，证明其具有较高的测量准确性．     

倾斜光纤光栅透射光谱对外界介质折射率的响应规律研究

倾斜光纤光栅因其独特的结构在传感和通信领域应用前景广阔。基于模式耦合理论,仿真研究介质折射率对倾斜光纤光栅透射功率谱的影响及其变化规律。研究结果表明,当介质折射率在1.35至1.4之间变化时,本文设计的倾斜光纤光栅透射功率谱包层谐振峰位置随外界介质折射率的增大而逐渐向长波长方向移动,波长偏移量与外界介质折射率之间呈良好的线性关系,利用这个结论可进行介质折射率的测量。     

Sensitivity dependence of surface plasmon resonance based sensors on prism refractive index

We theoretically and experimentally demonstrate that refractive index of the prism used to load metal film has significant influence on sensitivity of surface plasmon resonance based sensors. The prism with lower refractive index gives the sensors a higher sensitivity in detecting refractive index variations of a sample. We attribute this effect to the fact that a prism with low refractive index will increase coupling distance between surface plasmons and the medium under investigation. Foundation item: Supported by Wuhan University and National Education Ministry of China Biography: Wang Guo-ping (1964-), male, Professor, research direction: bolographic materials, diffractive optical elements, optical properties of metallic nanopracticles and metal-dielectric nanostructures     

酯肪醛折光指数与分子结构间定量关系的探讨

用图论方法探讨了脂肪酸折光指数与分子结构的关系，提出一个既能表征脂肪酸结构性能关系又能预测折光指数的定量关系式。结果表明，脂肪酸折光指数计算值与实验值的一致性令人满意，平均误差０．１０２％．     

常压下低折射率纳米多孔二氧化硅薄膜的制备

以正硅酸乙酯(TEOS)为有机醇盐前驱体,采用溶胶-凝胶技术,通过酸/碱二步法控制实验条件,结合低表面张力溶剂替换以及甲基非活性基团置换修饰、超声振荡等,在常压下成功地制备出折射率在1.11～1.27范围内的二氧化硅纳米多孔光学薄膜。制备过程中充分注意到稀释、老化、有机修饰表面、热处理和提拉条件对薄膜都有很大的影响,利用这些因素可以对该纳米薄膜的孔洞率、折射率进行控制,尤其是能制备低折射率薄膜,从而为该薄膜的应用开发奠定基础。采用椭偏仪测量薄膜的厚度和折射率,薄膜中高的孔洞率、低的折射率归结于最终干燥阶段中的弹性回跳。扫描电镜(SEM)观察发现修饰薄膜的表面形貌具有明显的多孔结构。耐磨实验表明所制备的薄膜有良好的机械性能。     

基于单模光纤偏芯结构的光纤折射率传感器研究

基于迈克尔逊(Michelson)干涉仪(MI)原理,结合光纤传感器的特性,设计和实现了一种单模光纤(SMF)偏芯干涉仪结构光纤折射率传感器,并针对蔗糖溶液进行了折射率的测量。实验结果表明:这种传感器的传感范围在1.33～1.39时,特征波长与外界折射率有单调的递减变化关系,蔗糖折射率每变化0.01时,特征波长平均变化约为0.12nm。这种传感器结构简单,灵敏度较高,能够实现液体折射率与浓度变化的在线检测。     

基于棱镜耦合的双循环法测量液体复折射率

提出一种棱镜耦合布儒斯特角双循环算法,实现了液体复折射率的精确测量.使用p线偏振光入射到等腰棱镜底面与待测液体样品的分界面上,逐步旋转棱镜,得到样品总光强反射率随入射角变化关系的实验曲线;基于菲涅尔公式及布儒斯特定律,分析了棱镜测量液体复折射率的基本原理,采取双循环拟合算法,求得样品折射率及消光系数;搭建了相应的实验系统,测量了印度墨水、脂肪乳溶液和二碘甲烷匹配液等样品的复折射率,也得到了印度墨水和脂肪乳溶液的折射率、消光系数随浓度变化的实验曲线.实验表明:测量液体折射率及消光系数的精度分别约为0.000 2和0.000 1,有较高的测量准确度及稳定性,测量液体折射率范围不受棱镜折射率限制.     

几种折射率标定方法的比较

讨论了几种光学玻璃折射率绝对测量方法的特点。指出传统的最小偏向角法的不足之处。提出了一种所谓任意偏折法的绝对测量方法。在对四种方法互相比较的基础上,指出用任意偏折法对基准传递样块进行折射率标定是较好方法。文中还给出了任意偏折法的测量步骤和测量实例。