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.     

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.     

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.     

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.     

布料方式对竖冷炉内烧结矿偏析及气流分布的影响

为优化梅钢竖冷炉的布料方式，采用离散单元法和多孔介质模型研究中间布料和边缘-中心布料对炉内烧结矿的偏析、空隙率分布、气流分布以及气体压力的影响.结果表明，对比中间布料，采用边缘-中心布料时，大颗粒偏析区域由中心区和上部边壁区变为中间区，且烧结矿偏析得到改善.床层空隙率虽有下降，但沿宽度方向分布更均匀.中间布料条件下，气体流速主要呈沿边壁区向中心区逐渐增大的分布，且气体压力较小.边缘-中心布料时，气体流速呈中间区较大、中心区和边壁区较小的“Λ”型分布，但上述区域间的流速差值减小.气体压力增幅较大，但能够沿高度方向同步下降.综合上述因素，推荐使用边缘-中心布料.     

遥测中频带宽选取方法

针对现代空空导弹,随着遥测参数需求的增加,遥测信号的码速率在不断提高。只有合理选取遥测系统的中频带宽,才能保证遥测系统的通信质量。本文对标准PCM-FM遥测信号的频谱特性进行了分析和仿真,给出了理论上最小中频带宽和工程应用中的选取方法。     

形状记忆合金弹簧变形速度的研究

形状记忆合金 (SMA)弹簧具有形状记忆功能 ,电热驱动时的相变过程中有回复力输出。这种弹簧的回复变形速度先随回复位移的增加而逐渐增加 ,当回复位移接近中间位置时速度达到最大值 ,并在一段位移内保持最大速度不变。此后 ,随回复位移的增加而减小 ,达到记忆长度时速度为零。通过控制电流可控制SMA弹簧的回复变形速度 ,但不能选择过高或过低的电流 ,否则会破坏其记忆功能。在使用SMA弹簧时应选择合适的载荷和拉伸变形长度 ,过大的载荷不仅使其回复变形速度变得很慢 ,而且还会使弹簧产生不完全回复变形 ,从而降低SMA弹簧的循环工作寿命。过大的拉伸变形长度 ,同样也会降低其循环工作寿命。     

位错和溶质原子交互作用的蒙特卡罗模拟

文章运用动态蒙特卡罗方法,模拟了二维条件下单个刃型位错和置换溶质原子间的相互作用.在假设位错始终静止的情况下,模拟得到位错中心形成密集的溶质气团,远离中心处形成弥散的溶质云层;动态结果反映,在低外加应力下位错受到溶质原子的有效钉扎,运动速度很小;高外加应力下位错运动几乎不受溶质原子的影响,速度较大;而在中间应力范围内,位错的运动状态具有歧义性,速度处于高低跳跃的状态.     

闭链机构机器人的运动分析和动力分析

本文作了单闭链结构机器人的运动分析和动力分析。作运动分析时,将单闭链分为左右两路,建立某一中间杆的位姿。速度和加速度恒等式,求出了从动关节的位移、速度和加速度关系式。在此基础上,导出了各杆速度和加速度计算公式。然后,应用Kane方程导出了单闭链结构机器人的动力学逆问题计算模型。     

Comparative power curves in bird flight

The relationship between mechanical power output and forward velocity in bird flight is controversial, bearing on the comparative physiology and ecology of locomotion. Applied to flying birds, aerodynamic theory predicts that mechanical power should vary as a function of forward velocity in a U-shaped curve. The only empirical test of this theory, using the black-billed magpie (Pica pica), suggests that the mechanical power curve is relatively flat over intermediate velocities. Here, by integrating in vivo measurements of pectoralis force and length change with quasi-steady aerodynamic models developed using data on wing and body movement, we present mechanical power curves for cockatiels (Nymphicus hollandicus) and ringed turtle-doves (Streptopelia risoria). In contrast to the curve reported for magpies, the power curve for cockatiels is acutely concave, whereas that for doves is intermediate in shape and shows higher mass-specific power output at most speeds. We also find that wing-beat frequency and mechanical power output do not necessarily share minima in flying birds. Thus, aspects of morphology, wing kinematics and overall style of flight can greatly affect the magnitude and shape of a species' power curve.     

卷取后冷却速度对高强度热轧带钢组织的影响

采用拉伸实验、电镜观察、能谱分析和硬度测试等方法,研究了700MPa级高强度钢热轧钢卷组织性能分布不均的特点,对造成其组织性能不均的原因进行了分析. 结果表明,钢卷纵向力学性能分布不均,分布规律为成卷后钢卷的中部>内部>外部,内部和外部相差不大. 沿钢卷纵向,中部试样和外部试样的金相组织、碳氮化物析出状态均存在着明显差异,这是造成钢卷力学性能不均的主要原因. 卷取后的冷却速度对金相组织、碳氮化物析出状态有着重要影响.     

基于虚拟仪器的超声Doppler管道低流速测量

传统的超声Doppler流量计在管道流量测量中会遇到无法判断流速方向和低流速测量困难等问题。该文基于虚拟仪器平台,将Doppler信号解调到15kHz的中心频率,并运用Zoom-FFT算法对其进行高精度选带频谱分析,然后进行加权平均频率估计,得到被测流体的平均流速及方向,实现了一个新的超声Doppler流量测量系统。超声波探头外夹安装在充满流体介质的不锈钢管道上进行流量测量,实验结果表明该系统不仅可以正确分辨流速方向,还能测量低达0.02m/s的流速,在判断流速方向和低流速测量上比传统超声Doppler流量计更为有效。     

光电子成像方法研究N2多光子电离过程

利用速度映像成像技术实验探测了N2在70 fs,410 nm,场强(1-3)×1014W/cm2范围内的光电子成像,获得了光电子的动能分布和角分布.研究表明分子强场电离有一些和原子相似的性质.电子产生于两步过程,中间态有真实布居.在低场强非共振布居转移起主要作用,在较高场强共振布居转移起主要作用.光电子角分布体现中间态的角量子数特征.     

Upper mantle SH velocity structure beneath Qiangtang Terrane by modeling triplicated phases

We constrain SH wave velocity structure for the upper mantle beneath western Qiangtang Terrane by comparing regional distance seismic triplicated waveforms with synthetic seismograms, based on an intermediate event （-220 km） recorded by the INDEPTH-Ⅲ seismic array. The ATIP model reveals a low-velocity anomaly with up to -4% variation at the depth of 190-270 km and a relatively small velocity gradient above the depth of 410 km in the upper mantle, which is in agreement with previous results. In combination with other geological studies, we suggest that the depth of top asthenosphere is 190 km and no large-scale lithosphere thinning occurs in western Qiangtang Terrane, besides, Qiangtang Terrane has the same kind of upper mantle structure as the stable Eurasia.