烧结铁矿中FeO含量对其在富氢高炉中还原行为的影响

Japan started the national project “COURSE 50” for CO₂ reduction in the 2000s. This project aimed to establish novel technologies to reduce CO₂ emissions with partially utilization of hydrogen in blast furnace-based ironmaking by 30% by around 2030 and use it for practical applications by 2050. The idea is that instead of coke, hydrogen is used as the reducing agent, leading to lower fossil fuel consumption in the process. It has been reported that the reduction behavior of hematite, magnetite, calcium ferrite, and slag in the sinter is different, and it is also considerably influenced by the sinter morphology. This study aimed to investigate the reduction behavior of sinters in hydrogen enriched blast furnace with different mineral morphologies in CO–CO₂–H₂ mixed gas. As an experimental sample, two sinter samples with significantly different hematite and magnetite ratios were prepared to compare their reduction behaviors. The reduction of wustite to iron was carried out at 1000, 900, and 800°C in a CO–CO₂–H₂ atmosphere for the mineral morphology-controlled sinter, and the following findings were obtained. The reduction rate of smaller amount of FeO led to faster increase of the reduction rate curve at the initial stage of reduction. Macro-observations of reduced samples showed that the reaction proceeded from the outer periphery of the sample toward the inside, and a reaction interface was observed where reduced iron and wustite coexisted. Micro-observations revealed three layers, namely, wustite single phase in the center zone of the sample, iron single phase in the outer periphery zone of the sample, and iron oxide-derived wustite FeO and iron, or calcium ferrite-derived wustite 'FeO' and iron in the reaction interface zone. A two-interface unreacted core model was successfully applied for the kinetic analysis of the reduction reaction, and obtained temperature dependent expressions of the chemical reaction coefficients from each mineral phases.     

Mg和La对Ca–Ti 处理钢中夹杂物演变和组织的影响

The evolution of inclusions and the formation of acicular ferrite (AF) in Ca–Ti treated steel was systematically investigated after Mg and La addition. The inclusions in the molten steel were Ca–Al–O, Ca–Al–Mg–O, and La–Mg–Ca–Al–O after Ca, Mg, and La addition, respectively. The type of oxide inclusion in the final quenched samples was the same as that in the molten steel. However, unlike those in molten steel, the inclusions were Ca–Al–Ti–O + MnS, Ca–Mg–Al–Ti–O + MnS, and La–Ca–Mg–Al–Ti–O + MnS in Mg-free, Mg-containing, and La-containing samples, respectively. The inclusions distributed dispersedly in the La-containing sample. In addition, the average size of the inclusions in the La-containing sample was the smallest, while the number density of inclusions was the highest. The size of effective inclusions (nucleus of AF formation) was mainly in the range of 1–3 μm. In addition, the content of ferrite side plates (FSP) decreased, while the percentage of AF increased by 16.2% due to the increase in the number of effective inclusions in the La-containing sample in this study.     

摩擦焊接碳钢（EN24）和镍基高温合金（IN718）的显微组织和力学性能

Continuous-drive rotary friction welding was performed to join cylindrical specimens of carbon steel (EN24) and nickel-based superalloy (IN718), and the microstructures of three distinct weld zones—the weld interface (WI)/thermo-mechanically affected zone (TMAZ), the heat-affected zone (HAZ), and the base metal—were examined. The joint was observed to be free of defects but featured uneven flash formation. Electron backscatter diffraction (EBSD) analysis showed substantial changes in high-angle grain boundaries, low-angle grain boundaries, and twin boundaries in the TMAZ and HAZ. Moreover, significant refinement in grain size (2–5 μm) was observed at the WI/TMAZ with reference to the base metal. The possible causes of these are discussed. The microhardness profile across the welded joint shows variation in hardness. The changes in hardness are ascribed to grain refinement, phase transformation, and the dissolution of strengthening precipitates. The tensile test results reveal that a joint efficiency of 100% can be achieved using this method.     

采用超声组装与滚压工艺制备铝–碳纳米管复合材料

This study introduced a novel fabrication of aluminum–carbon nanotube (CNT) composites by employing bulk acoustic waves and accumulative roll bonding (ARB). In this method, CNT particles were aligned using ultrasonic standing wave in an aqueous media, and the arrayed particles were precipitated on the aluminum plate substrate. Then, the plates rolled on each other through the ARB process with four passes. Optical and scanning electron micrographs demonstrated the effective aligning of CNTs on the aluminum substrate with a negligible deviation of arrayed CNTs through the ARB process. The X-ray diffraction pattern of the developed composites showed no peaks for carbon and aluminum carbide. In addition, tensile tests showed that the longitudinal strength of the specimens processed with aligned CNTs was significantly greater than that of the specimens with common randomly dispersed particles. The proposed technique is beneficial for the fabrication of Al–CNT composites with directional mechanical strength.     

活化天然矿石选择性还原二氧化碳为无定形碳

Natural magnetite formed by the isomorphism substitutions of transition metals, including Fe, Ti, Co, etc., was activated by mechanical grinding followed by H₂ reduction. The temperature-programmed reduction of hydrogen (H₂-TPR) and temperature-programmed surface reaction of carbon dioxide (CO₂-TPSR) were carried out to investigate the processes of oxygen loss and CO₂ reduction. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS). The results showed that the stability of spinel phases and oxygen-deficient degree significantly increased after natural magnetite was mechanically milled and reduced in H₂ atmosphere. Meanwhile, the activity and selectivity of CO₂ reduction into carbon were enhanced. The deposited carbon on the activated natural magnetite was confirmed as amorphous. The amount of carbon after CO₂ reduction at 300°C for 90 min over the activated natural magnetite was 2.87wt% higher than that over the natural magnetite.     

含钛高炉炉渣微波合成碳化钛及其介电性能测定

The preparation of functional material titanium carbide by the carbothermal reduction of Ti-bearing blast furnace slag with microwave heating is an effective method for valuable metals recovery; it can alleviate the environmental pressure caused by slag stocking. The dynamic dielectric parameters of Ti-bearing blast furnace slag/pulverized coal mixture under high-temperature heating are measured by the cylindrical resonant cavity perturbation method. Combining the transient dipole and large π bond delocalization polarization phenomena, the interaction mechanism of the microwave macroscopic non-thermal effect on the titanium carbide synthesis reaction was revealed. The material thickness range during microwave heating was optimized by the joint analysis of penetration depth and reflection loss, which is of great significance to the design of the microwave reactor for the carbothermal reduction of Ti-bearing blast furnace slag.     

汽车暴露面板带有表面条状缺陷的夹杂物分布特征分析:一种定量电解方法

The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface. A quantitative electrolysis method was used to compare and evaluate the three-dimensional morphology, size, composition, quantity, and distribution of inclusions in the defect and non-defect zone of automobile exposed panel. The Al₂O₃ inclusions were observed to be aggregated or chain-like shape along with the sliver defect of about 3–10 μm. The aggregation sections of the Al₂O₃ inclusions are distributed discretely along the rolling direction, with a spacing of 3–7 mm, a length of 6–7 mm, and a width of about 3 mm. The inclusion area part is 0.04%–0.16% with an average value of 0.08%, the inclusion number density is 40 mm?2 and the inclusion average spacing is 25.13 μm. The inclusion spacing is approximately 40–160 μm, with an average value of 68.76 μm in chain-like inclusion parts. The average area fraction and number density of inclusions in the non-defect region were reduced to about 0.002% and 1–2 mm?2, respectively, with the inclusion spacing of 400 μm and the size of Al₂O₃ being 1–3 μm.     

在酸性溶液中加压氧化三价砷离子和二价铁离子

The co-oxidation of As(III) and Fe(II) in acidic solutions by pressured oxygen was studied under an oxygen pressure between 0.5 and 2.0 MPa at a temperature of 150°C. It was confirmed that without Fe(II) ions, As(III) ions in the solutions are virtually non-oxidizable by pressured oxygen even at a temperature as high as 200°C and an oxygen pressure up to 2.0 MPa. Fe(II) ions in the solutions did have a catalysis effect on the oxidation of As(III), possibly attributable to the production of such strong oxidants as hydroxyl free radicals (OH·) and Fe(IV) in the oxidation process of Fe(II). The effects of such factors as the initial molar ratio of Fe(II)/As(III), initial pH value of the solution, oxygen pressure, and the addition of radical scavengers on the oxidation efficiencies of As(III) and Fe(II) were studied. It was found that the oxidation of As(III) was limited in the co-oxidation process due to the accumulation of the As(III) oxidation product, As(V), in the solutions.     

谈直观教学在植物学教学中的应用

文章探讨了直观教学在植物学教学中的应用,从四个方面提高植物学教学效果:一是充分展示大量的图像资料,提高学生的理解能力;二是依靠校园植物资源,加强直观教学;三是充分发挥我区丰富的高原植物资源优势,加强特色教学的建设;四是通过多媒体教学的应用提高教学质量。     

高师数学分析教学模式研究

结合专业特点 ,阐述了高师数学分析课程教学目标的双重特征 ,据此提出了“双重教学目标并重”的教学模式 ,并主要就教学中应把握的几项具体教学要求作了举例分析     

控制系统仿真课的双语教学

双语教学是逐步实现"使用英语等外语进行公共课和专业课教学"的有效过渡手段,也是使学生的外语学习学以致用的关键一步。针对高校实施双语教学存在的主要问题进行了分析,提出了解决问题的途径和方法。结合《控制系统仿真》课程双语教学的实践,提出了自编英文教材、采用CAI教学、开通网上学习平台、讲课与自动演示结合等各种具体做法。通过对学生调查数据的分析,发现学生大部分都能认可该课程教学,取得了较好的教学效果。     

论大学英语分级教学改革

探讨阶段性分级教学改革措施及其必备的实施条件。即通过实施大学英语的深化教改,实行按等级分班教学和精读、听说一体化教学,将培养学生自我提高的能力纳入分级教学目标中,将文化品位渗透到教学过程中,将完善教学体制、完善考核手段和提高师资素质列入教改实施的基本条件中,为进一步构筑具有建设性和趋势化意义的双语教学平台奠定基础。     

夸美纽斯教学艺术的类型、特点与功能

夸美纽斯的教学艺术思想十分丰富。其教学艺术主要分为教学过程的艺术和教学组织与管理的艺术两大方面；其教学艺术可以归纳为直观性、便易性、彻底性三大特点；再教学艺术具有优化教学、提高教学效率和实现整体培养人的功能。     

OBE理念下的高职线上线下混合式教学模式研究与实践-以计算机应用基础课程为例

在互联网高速发展的背景下,线上教学方式为高职教育注入了新活力,线上线下混合式教学成为教学改革的一项重要内容。基于成果导向的OBE教学理念,以线上教学为切入点,借助问卷调查,对课程教学目标,教学内容、教学方法和考核评价等方面进行改进,构建了成果导向、任务驱动、“教学分析—实践验证─成果反馈─诊断改进"的闭环混合式教学体系。实践应用表明,该教学体系能够激发学生学习热情,有效提升学习效果。     

反思教学:教师提高教学水平的必由之路

反思教学(reflective teaching)即对教学的反思,是教师探索思考课堂教学经验、不断提高自身业务素质和教学质量的一种重要手段.教师通过观察、日志、录音和录像、问卷、行动过程研究等步骤,不断深化对教学实践的理性思考,完善教学环节,提高教学水平.     

体育教学论与体育教学实践

长期以来,体育教学论与教育实践的脱节一直是制约我国体育教学改革的重要因素之一,而体育教学的选择缺乏充分的理论根据则是产生上述因素的主要原因.21世纪之初,随着体育教学改革逐步深入,传统的以传授书本知识作为课堂教学唯一目标的教学论,在当代教学论思想发展中受到了强烈的冲击,教学目标的扩大成为世界各国教学改革的共同趋势.面对多元化的体育教学目标,如何以教学论为工具使体育教学走出目标选择的困境,在具体的体育教学中来体现现代体育教学论,就成为摆在我们面前的重要课题.     

非计算机专业计算机教学探讨

文章对我校非计算机专业计算机基础教学改革进行了探讨。认为学校根据现代教育思想和教学理论,改进教学方法,正确选择教学内容,改革课程体系和教学模式,更新教学手段,强化实验教学,改进考核方式,加强师资队伍建设,以提高计算机基础教学的效果和教学质量。     

大学英语"课堂面授+网络教学"模式整合的探讨

通过对某所地方院校的部分学生进行问卷调查,发现学生在肯定网络教学模式的优势时并没有否定传统教学有利的一面。他们希望能将“网络教学和课堂面授”相结合,大多数学生认为网络教学能大大提高他们的学习兴趣和主动性、自我调控学习方法、增强自信心,同时,有利于他们分享最优化的学习资源。另一方面,课堂面授能弥补网络教学的不足,增加师生间的亲和力,避免“机灌”代替“人灌”。此外,调查也发现地方院校的网络教学基础设施存在的问题。网络自主学习室的建立、多媒体教室和语音室的修缮和改进、教学资源的丰富和教学形式的多样化等方面亟待解决。由此,进一步提出将课堂面授和网络教学进行有机整合,实现教学手段和教学模式的多样化。要实现教学模式的整合,教师必须转变教学理念、学院要改进教学设备、增强师资力量。