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.     

高速切削刀具材料及其合理选用

刀具是实现高速切削加工的关键,本文阐述了高速切削刀具材料的要求、高速切削加工刀具材料的种类,以及高速切削不同材料时刀具材料的合理选用。     

高压水射流切割装置和切割试验研究

高压水射流切割是一项正在发展中的新技术,由于它具有许多其它切割技术所不能比拟的优点,因此日益受到人们的注意和重视。本文介绍了高压水射流切割的装置和对非金属板材切割试验的情况,得到了射流压力、喷嘴口径、靶距、进给速度与切割深度之间的关系,探讨了高分子聚合物对射流性能的影响。此外,还介绍了对板材进行复杂形状的切割等。     

基于综合截割性能优化的采煤机变速截割控制

针对目前滚筒采煤机在生产过程中采用单一牵引调速影响截割性能的问题,对采煤机的变速截割进行了探索研究.考虑变速截割的可行性及可靠性,按截割阻抗的大小对煤层硬度进行了平均划分;综合考虑不同截割性能指标的要求,对其进行加权平均作为优化目标,对截割运动参数进行了优化;在此基础上,对由截割阻抗变化引起的不同工况的调速策略进行了比较分析,得到了截割性能最优的变速截割调速控制策略.研究结果可为采煤机高效变速截割奠定理论基础.     

一种新型的表面高速钢的形成方法

本文介绍了一种新的等离子表面冶金高速钢的形成方法，并对由这种工艺方法形成的高速钢中的碳化物大小、分布及结构进行了分析研究。     

圆弧插补的一种算法

常用的时间分割圆弧插补算法 ,麻烦、误差大、执行速度慢。本文提出一种新的时间分割圆弧插补算法 ,作了证明 ,并通过实例进行验证 ,该算法简单、插补精度高、执行速度快 ,可以方便地应用于两坐标两联动CNC系统。     

AlCrN涂层硬质合金切削高温合金耐用度对比实验

采用新型涂层AlCrN硬质合金,并同时采用无涂层YW1和TiAlN涂层硬质合金作为对比实验的刀具材料,对变形镍基高温合金GH4169进行车削刀具磨损的系列实验研究.借助光学显微镜、电子扫描显微镜与能谱探针等工具,建立刀具寿命T-v公式,以刀具耐用度为评价指标,对刀具的磨损形态、磨损机理以及此类新型涂层(AlCrN)刀具对应于镍基高温合金的切削性能进行了分析.研究表明,干切削镍基高温合金,AlCrN涂层硬质合金的性能优于当前主流应用的刀具涂层(TiAlN)刀具.其失效形式主要表现为:后刀面磨损和主切削刃微崩刃.前刀面的磨损程度相对较低.其磨损机理为:高温高应力条件下的扩散、氧化磨损与黏接的综合作用.     

刀具温度分布与组织结构的关系

本文研究了ASP30粉末冶金高速钢车刀重加热后的显微组织和显微硬度的变化规律。用来评定高速钢刀的温度分布。实验证明,具有直观、精密方便等特点,在相同切削条件下,粉末高速钢刀与普通高速钢刀有相似的温度-组织效应。     

数控机床多方案切削试验宏程序构建研究

在数控切削加工试验中需依据试验要求经常修改数控程序,费时费力且容易出错。本文通过对典型切削实验方案的分析,对切削实验进行参数化处理。根据数控系统变量的特性,将多方案切削加工参数转换为变量表格,基于宏程序变量间接寻址方法实现对表格数据查询、调用,进而设计宏程序实现数控程序的参数化,简化了试验过程的数控程序的重新编制及修改调试。文中通过多方案正交切削实验对宏程序方法的有效性进行检验,实验结果表明宏程序法在多方案切削加工中具有良好的适用性,且能降低误操作,提升试验效率,具有较高的应用价值。     

单板旋切厚度调节机构的改进

简化单板旋切厚度的调节过程，是实现单板旋切加工自动化的关键。利用气动、液动多点控制可实现自动调节，但机构复杂，造价高。笔提出一种曲线轨道式单点控制调节方案，进而实现厚度自动调节，该调节机构结构简单，造价低，易实现设备改造。     

两种不同截齿排列截割头性能的比较

为了评价利用等螺旋升角进行截齿排列设计的截割头的截割性能,选用了一个实际的截割头进行比较,通过计算机仿真获得两个截割头截割过程的切屑图和载荷曲线,经比较分析表明,用等螺旋升角排列截齿的截割头截槽合理,各段切屑图均匀,载荷大小及其波动较小,截割性能良好,所以用等螺旋升角排列截齿是一种高效、实用的截齿排列方法。