高密度铁基粉末冶金零部件制造原料的研究

温压粉末原料是采用温压成形技术制造高密度粉末冶金零件的基础和温压工艺的技术核心。高价格的进口温压粉末制约了我国高密度铁基粉末冶金零件的开发与应用,因此,必须开发出符合我国国情的温压粉末原料体系。作者根据我国资源特点,采用鞍钢产水雾化铁粉、水雾化低合金钢粉和攀枝花钢铁公司产转炉烟尘铁粉为原料,进行了制备相应体系的温压粉末原料和温压工艺参数优化的研究。以水雾化铁粉为原料设计制造的Fe-1.5Ni-0.5Mo-0.5Cu-0.6C粉末经637MPa压制,温压密度为7.46g/cm~3;压坯的回弹率为0.03％.在1150℃烧结40 min后,收缩率为0.025％。而以转炉烟尘铁粉设计制造的Fe-1.5Ni-0.5Mo-0.5Cu-0.6C粉末经686 MPa压制,压坯密度达7.35g/cm~3;以Fe-1.5Ni-0.5Mo水雾化合金钢粉为原料制造的Fe-1.5Ni-0.5Mo-1.5Cu-0.8C粉末在686 MPa时压制密度为7.35g/cm~3。这些粉末原料的设计为我国高强度铁基粉末冶金零部件的制造创造了条件。     

改善还原铁粉流动性能的试验

流动性是粉末冶金重要的工艺参数之一,其优劣直接影响生产效率,同时对于形状复杂件、细长件、大高度件等,流动性差将导致装粉时模具充填不佳甚至出现搭桥从而影响制件的成形。实际生产中还原粉的流动性能控制相对较难,本文提供了几个改善流动性的试验,主要包括:调整粉末粒度组成、配入雾化粉、调整原料松装密度并延长合批时间、调整还原温度。以上方法均可以改善还原铁粉的流动性,其中第三个最可行。     

Reduction Annealing for Cast Iron Powder and Its Effect on Sintered Antifriction Material Properties

The effect of reduction annealing for powder obtained from cast iron shavings on powder specimen properties is studied. An approximate mechanism is suggested for the oxidation-reduction process during annealing of cast iron powder. An increase in annealing temperature leads to an increase in carbon gasification rate and change in absolute powder weight. Prior reduction annealing for cast iron powder improves its compactability, and increases the mechanical properties of sintered material. The best mechanical properties were obtained for specimen made from cast iron powder reduced at 1000°C. Alloying an iron-cast iron charge with 3 mass% of nickel-chromium alloy leads to a marked improvement in the mechanical properties of a sintered composite.     

Using Small Particles with High Moisture Content in Iron Production by Liquid-Phase Reduction

Drying of small wet particles by mixing with lime powder to permit safe handling in continuous systems for iron production by liquid-phase reduction is investigated. The quantity of lime powder most suitable for the drying of concentrate with different initial moisture contents is determined. A system is proposed for the use of wet batch in continuous industrial systems for iron production.     

打造新包钢的原料采购战略之管见

在铁矿粉供不应求的今天,打造千万吨级新包钢,铁精矿粉的采购战略应有所改变.提高铁精矿粉的自给率是打造新包钢的第一措施,改变过去竞争采购为战略性采购,保持稳定的原料来源是当前首要的战略措施.     

电解铁粉的制备及压缩烧结性能

摘要：以电解铁片为原料制备了电解铁粉并且研究了其纯度及硬度，同时以某电解厂生产的电解铁粉为原料，研究了电解铁粉的压缩及烧结性能。结果表明，最佳因素组合下电解得到的电解铁片及电解铁粉纯度(质量分数)分别达到99.98%和99.99%；电解铁粉压坯密度随着压制压力的增加而增大，粒径大的铁粉更利于压制成型，但会导致孔隙尺寸大变大且分布不均匀；铁粉烧结坯密度随着烧结温度的升高而增大，同时随保温时间增加增长缓慢，因此在实际生产中应通过适当提高烧结温度和缩短烧结时间，进而提高烧结效率。     

高线斯太尔摩风冷线冷却模型

摘要：以电解铁片为原料制备了电解铁粉并且研究了其纯度及硬度，同时以某电解厂生产的电解铁粉为原料，研究了电解铁粉的压缩及烧结性能。结果表明，最佳因素组合下电解得到的电解铁片及电解铁粉纯度(质量分数)分别达到99.98%和99.99%；电解铁粉压坯密度随着压制压力的增加而增大，粒径大的铁粉更利于压制成型，但会导致孔隙尺寸大变大且分布不均匀；铁粉烧结坯密度随着烧结温度的升高而增大，同时随保温时间增加增长缓慢，因此在实际生产中应通过适当提高烧结温度和缩短烧结时间，进而提高烧结效率。     

武钢铁矿石质量价值分析

介绍了当前国内常用的铁矿石评价方法,对武钢外购铁矿石的质量价值进行分析研究,得出用于烧结配矿最经济的矿粉是澳粉、加拿大粉、委粉以及FMG矿粉等,提出适合当前武钢铁矿石的质量价值评估方法,以此用来优化武钢外购铁矿石矿种,降低铁矿石成本。     

铁焦初始反应温度的降低及其机理

 在铁矿粉配比为10%的条件下,系统地研究了加矿粉、澳矿粉和鄂矿粉对铁焦的反应性、初始反应温度和活化能等的影响。试验结果表明,与传统焦炭相比,加矿铁焦、澳矿铁焦和鄂矿铁焦的初始反应温度明显降低,降低的幅度取决于铁矿粉的种类和性质;其原因是铁矿粉的催化作用使铁焦的活化能降低,也致使焦炭的反应性提高;初始反应温度、活化能和反应性三者之间具有良好的相关性。     

利用高生坯强度润滑剂开发无线通讯装置用PM软磁零件

软磁烧结铁框是无线通讯装置中的一个重要零件，用其来防止电子元件间的电磁干扰和对人有害的电磁辐射。铁框结构复杂且轻巧，依据电子电路的具体设计，壁厚可薄至0.8mm。传统的金属冲压成形因零件挠曲而不能满足尺寸公差与平直度的要求。用粉末冶金工艺制造铁框面临的难题是因壁薄，截面处易碎而使生坯难以搬运。用常规的硬脂酸锌或EBS蜡之类润滑剂混粉，生坯的废品率高达50％。因此，采取了用新近开发的高生坯强度润滑剂，制造烧结铁框的方法。为使开发的烧结铁框能达到磁性要求，选用了添加0.45%磷的高纯铁粉ATOMET 1001HP。采用冷压、温压及在压制后进行和不进行固化的不同工艺，测试了几种高生坯强度润滑剂纱列，从中选出了一种使压坯强度满足粉末冶金铁框压坯搬运要求的润滑剂系列，从而大大降低了生产成本。     

羰基铁粉的应用、生产和工程设计

全面介绍了羰基铁粉的应用领域、生产现状和生产特点,鉴于羰基铁粉生产过程中危险性较高的特点,提出了工业化装置的工程设计要点,可供相关人员参考。     

Properties and sintering behaviour of fine spherical iron powders produced by new hydrogen reduction process

Abstract

The most important use of fine spherical iron powders is for metal injection moulding (MIM). For many applications, the high costs of powder based on the carbonyl or atomising production route are a limiting factors. An alternative two-step hydrogen reduction process using a granulated hematite powder, which is a recycling product from steelmaking, has been developed to produce <25 µm spherical powder. The morphology and properties of the powder have been found to depend strongly on the second temperature step of the reduction process. A further important step is enclosed powder processing by milling and sieving to remove agglomerates. The powder properties and sintering behaviour as a function of heat treatment and processing parameters are reported and discussed.     

Mixed State and High Effective Utilization of Pilbara Blending Iron Ore Powder

 Pilbara blending iron ore powder (PB powder) is blending ores with good and poor quality iron ores, so how to use PB power effectively is a problem. The self-characteristics of PB powder and its single-components were studied respectively, such as the macroscopic properties, microscopic properties, and high-temperature properties; the behavior and effect in the sintering were mastered. Then based on the new ore-proportioning idea of iron ores sintering characteristics complementary, the principles on the effective use of PB powder were discussed, and was further validated through the sintering pot test and industrial production. The results show that: PB powder is composed of three kinds of iron ore, and the sintering characteristics of different iron ores are obviously discrepant. With the ore-proportioning optimization based on the iron ores sintering characteristics complementary, the proportion of PB iron ore powder can be increased to more than 45%.     

Effect of Binder Composition on Rheology of Iron Powder Injection Moulding Feedstocks: Experimental Design

Abstract

A statistical analysis based on the McLean-Anderson design method was conducted to study the influence of each binder component on the flow properties of iron feed stocks for powder injection moulding. The formulations were composed of carbonyl iron powder (FE), polyethylene resin (PE), polyethylene wax (PEW), and stearic acid (SA). The viscosities of 15 different formulations were measured using a capillary viscometer. Fluidity and pseudoplasticity were evaluated and the effect of each component on these properties was analysed. The studied composition ranges of FE, PE, PEW, and SA were 90—92, 3—4·5, 2—4, and 0—1·5 wt—% respectively. It was found that lower iron powder content or higher binder content improved the fluidity of the feedstock. The relative effectiveness of binder ingredients in increasing fluidity is SA>PEW>PE and in enhancing pseudoplasticity PE > PEW > SA. Feedstocks with binder phases containing about 50 wt-%PE have the greatest fluidity with flow index n in the range 0·6—0·8. PM/0699     

铁精矿还原铁粉的质量稳定性

根据铁精矿还原铁粉主要质量指标的统计数据,分析了铁粉质量稳定性,其酸不溶物(AIC)含量≤0.22%,氢损(HL)为～0.1%,碳含量<0.02%。文中讨论了铁精矿粉两个阶段的还原过程,第一阶段用隧道窑还原成海绵铁,此阶段宜于过还原终点,精矿粉应被充分还原,略有渗碳,降低海绵铁的氢损值十分重要,其值应～0.8%,甚至更低,碳含量可控制于～0.3%,甚至更高。第二阶段用带式炉进行精还原,即所谓"二次还原",经破碎和合批得到合格的铁粉,该阶段的实质是脱碳还原。水是良好的脱碳剂,高温区通入少量水,形成水蒸气,是一个有效的脱碳方法。在冷却段通入干氢,控制气氛露点,将铁粉表面氧化膜还原,可以得到低碳和低氢损的还原铁粉。     

Strength of Unsintered Powder Compacts with Axial and Radial Loading

Cohesion and the internal friction angle characterizing the fracture region for the contour of Drucker-Prager limiting states are determined by experiment for green copper and iron powder compacts. With an increase in density the increase in cohesion is more marked for iron compacts. With an increase in compaction density the internal friction angle increases from 67° to 70° for copper compacts and it decreases from 70.5° to 69.9° for iron powder specimens.     

单种铁矿性能评价体系的设计与开发

针对国内外各种铁矿石性能差异较大的现状,为了更合理有效地评价和利用各种铁矿资源,将单种铁矿分为块矿、球团矿、富矿粉和精矿粉4种类型,并根据提供的铁矿数据设计了简易型和科学型2种评价模型,建立单种铁矿性能综合评价体系。结合某钢厂的烧结、炼铁生产实际参数,采用Visual Studio开发模型软件,对各种铁矿石做出快速、定量的综合评价,直接计算出最佳的采购参考价格。经企业应用表明,模型计算结果准确度高,为降低炼铁成本,提高生产效率提供了理论和技术依据。     

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。     

… as QMP offers new high-strength grades

Canadian-based QMP Metal Powders will be promoting a high-strength diffusion-bonded molybdenum steel powder at PM2003 in Valencia later this month. ATOMET DB49 is a newly developed grade that allows the manufacture of PM parts with a tensile strength of more than 850MPa using normal sintering conditions in belt furnaces equipped with a rapid cooling zone. The company will also be exhibiting their own polymeric HGS lubricating system that, they say, “drastically enhances the strength of green parts to the point where they can withstand the stresses applied by cutting tools during machining. QMP will also be showing off a new sponge-type iron powder, ATOMET 24, for high green strength applications that can be used to facilitate the production of more complex parts.This is a short news story only. Visit www.metal-powder.net for the latest powder metallurgy industry news.