微细钴粉的研制

微细钴粉由于其特殊的物理、化学性能,在硬质合金、电池、催化剂、磁性材料、吸波材料、陶瓷等领域的应用中表现出许多优异的性能。本试验采用硫酸钴为原料、水合肼和SBH的混合溶液作为还原剂,探讨了在弱碱性条件下微细钴粉的制备,并对其反应机理进行了分析。     

用活性氧化钨制取中细W和WC工艺研究

利用活性氧化钨粉末细、表面能发达、活性高、相成分单一等特点，经过工艺试验和优化，生产出粒度分布较用蓝色氧化钨生产的中细钨、碳化钨粉末均匀，同时也减少了中细钨、碳化钨粉末中的粗大晶粒和聚集颗粒，从而提高了中细钨、碳化钨粉末的质量，并且利用此碳化钨粉末还可以生产出高质量的合金产品。     

无汞碱锰电池用锌粉综述

无汞锌粉是无汞碱锰电池的关键材料之一。文章分析了汞在电池中的功能作用;提出了实现碱锰电池无汞化的重要性;综述了无汞锌粉的制备方法;介绍了锌粉中合金元素含量、杂质和氧化锌含量、以及锌粉颗粒大小和形状对碱锰电池性能的影响。     

Graphite–Aluminium Composite Anode for Li-Ion Battery by High Energy Ball Milling

Graphite–30% aluminium composite powder is prepared by high energy ball milling for different time intervals to improve the capacity over the conventionally used natural graphite powder as anode in Li-ion battery. Optimum milling time of 10 h results in higher capacity than either lower or higher milling duration. Initial increase in capacity with milling time is attributed to the reduction in crystallite size and alloying of Al and C. The formation of surface oxide layer on Al particles reduces the conductivity and capacity of the powder milled beyond 10 h. Formation of cracks during charge–discharge cycling of the anode causes fading in the capacity.     

高能球磨法制备吸气材料用超细锆粉

采用高能球磨的方法制备出超细锆粉，并采用XRD，TEM，动态光散射粒度测试仪等多种测试手段研究了粉末的组成，形貌和粒度分布，结果表明，经20h高能球磨后粉末晶粒达到纳米级，粉末颗粒形状不规则，在球磨过程中有少量铁杂质带入，对试验结果进行了进一步的分析和讨论。     

A Novel Method for Direct Synthesis of WC-Co Nanocomposite Powder

In this study, a novel method, termed dielectric-barrier-discharge-plasma (DBDP) assisted ball milling and low-temperature carburization, was used to synthesize WC-Co nanocomposite powder. X-ray diffraction, scanning/transmission electron microscopy, and differential scanning calorimetry were used to characterize the microstructure of powders. Starting from W, Co, and graphite powder mixtures, the DBDP-milled W-C-10Co powder exhibited a flakelike morphology with very fine lamellar structure. The WC-Co composite powder was synthesized at 1273 K (1000 °C), which is much lower than the requisite temperature for the conventional carburizing method. The obtained WC-Co composite powder had a nanocomposite microstructure in which fine WC particles were bounded by homogenously distributed Co phase, and the WC crystals had a slablike morphology with a planar size of about 200 nm and <100-nm thickness. The combinational effect of the milling and the plasma in the DBDP milling caused a unique fine flakelike morphology and high-density interfaces in the W-C-10Co powder mixture, which is responsible for the reduced carburization temperature and the nanocomposite structure of WC-Co powder.     

固相扩散法制造Ag-CdO触头材料

本文介绍用合金内氧化法和粉末冶金法结合的固相扩散法新工艺制造Ag-CdO触头材料。用金相显微镜、扫描电子显微镜、电子衍射X光衍射等方法,研究了固相扩散法预制的Ag-Cd合金粉末和内氧化制得的Ag-CdO复合粉末的组织结构和内氧化特点。并对触头的物理机械性能和电气性能进行了试验。结果表明,固相扩散法制得的Ag-CdO触头性能优良,可缩小尺寸(CJ10-40A交流接触器可缩小触头尺寸50%左右),实现节银目的。固相扩散法制得的细小合金粉末是在较低的温度下进行内氧化,且内氧化时间比传统的合金内氧化法显著缩短。因此该工艺也是一项好的节能技术。     

Investigation of the process of grinding reduced sponge iron and development of the technology of producing iron powders of different bulk density

Summary The following grinding technology is recommended for the purpose of increasing the fine-fraction yield of powder: a) grinding of reduced briquets in a hammer mill and the sifting of powder into coarse and fine fractions; b) grinding of the coarse fraction in a ball mill over a period of 16 h and the sifting of powder by means of a vibrating screen; c) mixing of the fine fractions obtained in the first and the second screenings.In order to increase the bulk density of the powder, it is recommended to perform triple grinding of the powder in a hammer mill or to grind it in a ball mill.     

掺杂异物铁精粉的鉴别

烧结球团矿作为炼铁生产过程中的主要原料广泛使用经磁选的铁精粉,由于资源、价格、成本等原因,原料市场出现了掺入铁屑、磨床屑、氧化铁皮等异物提高铁精粉中全铁含量的假铁精粉,烧结过程中一旦使用这些假铁精粉,严重影响生产。针对外购进厂铁精粉是否为掺杂异物的铁精粉,通过检查外观特征是否有白色石灰颗粒,通过检查气味是否有臭皮蛋、氨气味道,再通过测定水化后pH值是否呈碱性以及检测铁精粉中的磁性铁和金属铁含量,可以快速简单鉴定该铁精粉是否由铁屑、硫酸渣、氧化铁皮等外来含铁物质配矿而成。     

Very fine strontium powder for magnetic ceramics

The possibility of preparing very fine strontium ferrite powder with application of preliminary mechanical treatment in a rolling mill is studied. It is established that powder preparation time is shortened by a factor of 2.5–3 and the amount of coarse particles is reduced. The method used for preparing very fine powder makes it possible to control the size of particles and their specific surface. The powder may be used for preparing permanent magnets with a high specific magnetizability (above 32 kJ/m³). __________ Translated from Poroshkovaya Metallurgiya, Nos. 3-4(448), pp. 3–6, March–April, 2006.     

锂离子电池安全性研究进展

综述了近年来电解液的热稳定性影响因素、热失控过程及产物成分、单体及电池组燃爆安全性、灭火措施的研究进展.指出电解液的热稳定性受锂盐和有机溶剂的共同影响,当电池内部温度达到120℃左右时放热反应开始出现,在热量持续积累的情况下热失控将自发进行,同时产生氢气和烷烃类具有燃烧爆炸危险的气体产物.与二氧化碳和干粉类灭火剂相比,七氟丙烷和水的灭火效果较好.最后对锂离子电池的应用前景做了展望,提出了不同滥用条件下的热失控过程、热失控产物生成机理,指出开发新型电解液和寻求高效灭火介质是今后研究的方向.      

锂离子电池负极材料研究概述

锂离子电池已经在新能源动力电池、便携式电子设备及储能领域广泛使用。商业化锂电池大多采用锂过渡金属氧化物/石墨体系作为正负极,由于电池材料本身的理论储锂容量较低,限制了锂电池向高比能量、长使用寿命方向的发展。对于当前成熟的石墨类碳负极材料,其嵌锂能力基本已被充分发挥,难以实现这一目标。本文介绍了应用于锂离子电池负极的相关材料和研究进展,并就作为下一代锂离子电池理想负极材料-硅负极进行了展望。     

宝钢钢渣微粉及其胶凝材安定性和相容性研究

在研究宝钢钢渣微粉的化学成分及其矿物相组成X射线分析的基础上,通过压汞法测定了矿渣微粉与钢渣微粉的孔结构数据,分析了钢渣微粉孔结构特性和分布情况,比较了矿渣与钢渣微粉显微的照片形貌;对掺30%钢渣微粉的钢渣水泥进行了压蒸法安定性试验;以不同厂家水泥为基准,并采用四种不同类别的外加剂,对掺加30%钢渣粉进行了凝结时间和强度、塑性扩张度等水泥及外加剂相容性对比试验,提出了宝钢钢渣微粉可以作为水泥混凝土掺合料利用的技术可行性。     

In-situ VN reinforced powder metallurgy M30 steels prepared from water atomized powers via pressureless sintering

ABSTRACT

In this paper, in-situ VN reinforced powder metallurgy high-speed steel was fabricated from water atomised powder via pressureless sintering. During sintering, N would replace C to react with V, resulting in the formation of in-situ VN phase. According to the first-principles calculations, the formation energy of VN was – 9.45 eV while that of VC was – 9.08 eV. The relative density of as-sintered samples reached up to 99%. Homogeneous microstructure and fine reinforced phases were obtained. Ultrafine VN phase (0.5 μm) was uniformly distributed in the matrix. As a result, the mechanical properties were improved. The optimal mechanical performance was obtained in the sample with 1.0 wt.% C addition. The hardness, bend strength and impact energy were 65 HRC, 3011 MPa and 18–22 J, respectively. Besides, the sintering window significantly increased from ～10 to 30～50°C.     

Mechanical properties and fracture behavior of an ultrafine-grained Al-20 wt pct Si alloy

The effect of powder particle size on the microstructure, mechanical properties, and fracture behavior of Al-20 wt pct Si alloy powders was studied in both the gas-atomized and extruded conditions. The microstructure of the as-atomized powders consisted of fine Si particles and that of the extruded bars showed a homogeneous distribution of fine eutectic Si and primary Si particles embedded in the Al matrix. The grain size of fcc-Al varied from 150 to 600 nm and the size of the eutectic Si and primary Si was about 100 to 200 nm in the extruded bars. The room-temperature tensile strength of the alloy with a powder size <26 μm was 322 MPa, while for the coarser powder (45 to 106 μm), it was 230 MPa. The tensile strength of the extruded bar from the fine powder (<26 μm) was also higher than that of the Al-20 wt pct Si-3 wt pet Fe (powder size: 60 to 120 μm) alloys. With decreasing powder size from 45 to 106 μm to <26 μm, the specific wear of all the alloys decreased significantly at all sliding speeds due to the higher strength achieved by ultrafine-grained constituent phases. The thickness of the deformed layer of the alloy from the coarse powder (10 μm at 3.5 m/s) was larger on the worm surface in comparison to the bars from the fine powders (5 μm at 3.5 m/s), attributed to the lower strength of the bars with coarse powders.     

鱼雷罐喷补料的研制开发与应用

以致密高铝矾土、碳化硅、白刚玉细粉、SiO2微粉、Al2O3微粉和纯铝酸钙水泥等为原料,开发了鱼雷罐喷补料,研究了微粉加入量对喷补料性能的影响,比较了氯化钙、聚合氯化铝、三乙醇胺、铝酸钠的促凝效果.结果表明,加入7％的SiO2微粉和3％的Al2O3微粉,对提高施工性能和使用性能有利;以三乙醇胺为促凝剂有较好的促凝效果.开发的喷补料在鱼雷罐大修时一次喷补,可提高鱼雷罐使用寿命200次以上,喷补工艺简单、施工性能好,吨铁降成本约0.3元.     

Enhanced low-temperature sintering of tungsten

The effects of various transition metal additions on the sintering of a well-characterized, fine tungsten powder were analyzed using both isothermal and constant heating rate experiments in the temperature range 900 to 1400°C. Approximately four atomic mono-layers of palladium on the tungsten powder surface were found to be the optimal enhancer, followed by nickel, cobalt, platinum, and iron. The addition of Cu to the tungsten had no appreciable effect on the sintering kinetics. Sintering enhancement by these transition metals is related to their periodic chart position (i.e., electron structure). An overall non-Arrhenius shrinkage temperature dependence is attributed to grain growth in the activator-treated specimens. The activation energy for tungsten densification was determined to be 430 to 450 kJ/mol, which is in general agreement with a grain boundary diffusion process.     

Enhanced low-temperature sintering of tungsten

The effects of various transition metal additions on the sintering of a well-characterized, fine tungsten powder were analyzed using both isothermal and constant heating rate experiments in the temperature range 900 to 1400‡ C. Approximately four atomic monolayers of palladium on the tungsten powder surface were found to be the optimal enhancer, followed by nickel, cobalt, platinum, and iron. The addition of Cu to the tungsten had no appreciable effect on the sintering kinetics. Sintering enhancement by these transition metals is related to their periodic chart position(i.e., electron structure). An overall non-Arrhenius shrinkage temperature dependence is attributed to grain growth in the activator-treated specimens. The activation energy for tungsten densification was determined to be 430 to 450 kJ/mol, which is in general agreement with a grain boundary diffusion process.     

The role of particle size on the laser sintering of iron powder

The effects of powder particle size on the densification and microstructure of iron powder in the direct laser sintering process were investigated. Iron powders with particle sizes ranging from 10 to 200 μm were used. It was found that the sintered density increases as the laser energy input is increased. There is, however, a saturation level at which higher density cannot be obtained even at very intensive energy input. This saturation density increases as the size of the iron particles decreases. Meanwhile fine powders with narrow particle size distributions have a tendency toward agglomeration, and coarse powders with broad particle size distributions have a tendency toward segregation, both of them resulting in lower attainable density. In order to investigate the role of particle size, a “densification coefficient (K)” was defined and used. This coefficient depends on the particle size and the oxygen content of iron powder. The results of this investigation demonstrate that the presence of oxygen significantly influences the densification and pore morphology of laser-sintered iron. At higher oxygen concentrations, the iron melt pool is solidified to agglomerates, and formation of pores with orientation toward the building direction is more likely to occur. When the oxygen concentration is kept constant, the densification coefficient decreases with decreasing the particle size, meaning the densification kinetics enhances. This article presents the role of powder characteristics and the processing parameters in the laser sintering of iron powder as a model material. The mechanism of particle bonding and microstructural features of laser-sintered parts are addressed.     

锌/空气电池无汞锌粉制备技术现状

文章叙述了锌空气电池用无汞锌粉制备技术的现状，详细介绍了无汞锌粉制造的喷射雾化和电解沉积工艺。