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.     

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.     

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.     

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.     

桥梁全寿命设计总体框架研究

提出把桥梁全寿命设计概括为使用寿命设计、美学设计、性能设计、环境生态设计、监测养护与维修设计及成本分析等六大过程的设计,提出一种包括三大设计阶段、六大设计过程的桥梁全寿命设计总体框架.     

浅析概念设计

概念设计是利用设计概念并以其为主线贯穿全部设计过程的设计方法。概念设计是完整而全面的设计过程，它通过设计概念将设计者繁复的感性和瞬间思维上升到统一的理性思维从而完成整个设计。概念设计围绕设计概念而展开，设计概念则联系着概念设计的方方面面。     

机械零件的可靠性优化设计

在分析传统设计方法与可靠性设计方法在设计思想、设计原理上的区别的基础上,将可靠性设计与优化设计结合起来,对机械零件的可靠性优化设计方法进行研究。在满足可靠度约束及结构几何约束的条件下,以机械零件具体情况最小作为优化目标函数进行可靠性优化设计,得到了比常规设计更为合理的设计结果。     

车身NVH性能设计策略

汽车噪声、振动、平顺性(noise vibration harshness, NVH)性能是影响汽车质量和品质的关键因素,是汽车研发人员重点关注的性能指标。为此,提出了汽车产品开发过程的车身NVH性能设计策略。通过车身结构设计、阻尼设计、密封设计、阻隔设计、补强设计、吸声设计、隔声设计、低风噪设计方法实现NVH性能提升。结果表明,所提出的车身系统设计策略有效提高了车身NVH性能,该策略为汽车的NVH设计提供参考方案。     

西坟地块的规划设计

从设计依据、规划理念、设计理念、总平面布置、平面设计、立面设计、景观设计、建筑设计的生态理念等方面,阐述了西坟地块的规划设计。     

基于广义装配的液压集成块设计过程建模

提出一种能提高液压集成块设计效率和质量的设计过程建模方法．在分析液压集成块设计过程中的主要设计活动和设计过程功能模型基础上,引入广义装配的概念,借助于计算机辅助设计软件的装配技术及装配部件间的关联关系,在装配模型中以部件或零件的形式描述产品的设计过程,包括设计活动、中间设计结果及最终设计结果,并构造了液压集成块设计的广义装配平台．在液压集成块快速设计原型软件系统上完成的设计实例表明,基于广义装配的液压集成块设计过程模型可完整记录设计过程信息,保证设计关联性,提高设计效率和设计变更的便捷性．     

产品级参数化设计方法研究

参数化设计已成为产品设计的重要方法，参数化设计主要分为零件级参数化设计和产品级参数化设计。零件级参数化设计已经在设计中广泛使用了，但是产品级参数化还在探索过程中，本文主要是把杂交思想应用到产品级参数化建模过程中，更够更好的加快产品的设计和更新周期。     

2021年创新设计热点回眸

 面向知识网络时代的创新设计呈现绿色低碳、网络智能、开放融合、共创分享的新特征。2021年，创新设计研究在理论方法、技术手段及应用拓展等方面取得了重要进展。从生物启发创新设计、数据驱动创新设计、可持续创新设计、基于人工智能的创新设计以及面向疫情的创新设计等视角回顾了创新设计年度研究热点和代表性成果，并展望了创新设计未来的研究热点。     

概念设计中机器学习技术的运用

设计中开发计算理论的一个挑战是必须能支持计算机的有效运用，这一机制允许从设计专家那儿或设计样例中取得产生，累加和转换的设计知识。而其中的一个方法是把机器学习机制综合成基于知识的支持系统，以模拟设计过程初级阶段，使设计成为一个增加和诱导学习的过程。模拟的需要产生于在不同的提取阶段获取，提炼和转移设计知识的需求，从而使得能轻而易举的熟练操作。在设计中，现有的知识产生于过去的设计解决方案，而过去的解决方案提供的反馈信息能更新和提高设计理论知识基础。但是，没有学习接受能力，设计系统不能反映设计家们在这一领域的成长经历，也不能反映设计家们从以往设计案例中提取知识的能力。在此提出了方案设计和效力评价中的三种方法。     

抽油机减速器轴和轴承的计算机辅助设计

在设计抽油机减速器的轴和轴承时,设计人员一直采用手工设计方法。用这种传统的方法设计出的结构缺乏一定的协调性和灵活性,设计计算繁冗,并难以获得最佳设计方案。本文用计算机辅助设计(CAD)技术,编制出了软件系统,使轴和轴承的设计计算整体化,克服了传统设计方法的缺点,提高了设计质量,并由于简化设计过程而大大节省了工作量。