DISPERSION-STRENGTHENED ALUMINIUM POWDER PRODUCTS FOR NUCLEAR APPLICATION

Abstract

The main properties of sintered aluminium products (SAP) of interest when consideringtheir application in nuclear technology are strength, elongation, corrosion-resistance, homogeneity, purity, compatibility with fuel, and resistance to irradiation damage. These properties are discussed briefly in connection with commercial products.

Sintered aluminium products consist of oxide particles finely dispersed in aluminium, normally subdivided into grains. The effect on tensile and creep properties of parameters such as size and volume fraction of the oxide particles and the grain size of the aluminium, is considered in relation to both commercial and experimental materials. Examination of low-oxide material in the as-extruded and in the recrystallized state shows that the oxide particles are mainly responsible for the high strength and low elongation found in sintered aluminium products at elevated temperatures. The matrix grain size contributes to the tensile strength, in reasonable agreement with the behaviour found in pure aluminium, whereas an effect on elongation has not been observed.     

雾化轴承钢粉制造滚动轴承的研究

研究了用水雾化轴承钢料头、车屑制造滚动轴承套圈的工艺过程,研究了粉末中含氧量的控制及影响。测试了各项机械、物理性能。进行了接触疲劳、轴承寿命试验。其材料利用率为70%以上,外圈寿命为计算寿命的3倍。采用本工艺可以生产圆锥滚子轴承外圈。     

流化床还原碳化法制备超细WC－Co复合粉末

介绍了一种制备超细ＷＣ－Ｃｏ复合粉末的新工艺─—流化床还原碳化法。ＸＲＤ分析结果表明，该法制备的粉末由ＷＣ和Ｃｏ两相组成。Ｘ－射线小角衍射测定粉末的平均颗粒度为０．１２μｍ。将该粉末压制成形的样品在１２８０℃真空烧结１ｈ获得９９．７％理论密度的试块。     

DISPERSION-STRENGTHENED IRON BY GEL PRECIPITATION

Abstract

Metastable iron oxide particles containing calcium, magnesium, or zirconium in solid solution were produced by the gel precipitation method. These were reduced to metal with hydrogen/nitrogen mixtures in a fluidized-bed furnace at 800°C to yield iron powders containing dispersed oxide phases within each iron particle. The oxide phases were either 2CaO.Fe₂O₃, a solid solution of MgO and FeO, or ZrO₂, which appeared to be free from iron. Consolidation by compacting the powders into cans, sealing under vacuum, and hot extrusion yielded bars in which the oxide particles were dispersed. Hardness and tensile-test data for material heated to 1000°C for up to 100 h suggest that the oxides containing iron coarsen rapidly and contribute to strengthening only by maintaining a small matrix grain size. The iron-free ZrO₂ appears to be a true dispersion hardener and to restrain grain growth more than do the other oxides investigated.     

粉末冶金铝合金

本文概述了粉末冶金铝合金的发展现状和前景。较详细地介绍了普通粉末冶金铝合金和高性能粉末冶金铝合金的组成、制备工艺、性能和应用。     

氧化铝增强铜基复合材料机械合金化粉末的制备

对机械合金化制备氧化铝弥散强化铜粉末的工艺进行了研究,通过观察合金化后材料的微观形貌,确定了机械合金化的工艺参数。     

FEASIBILITY OF PRODUCING DISPERSION-STRENGTHENED CHROMIUM BY BALL-MILLING IN HYDROGEN HALIDES

Abstract

Chromium, with and without 4 vol.-% thoria, and nickel powders were ground to fine powder sizes by ball-milling in gaseous hydrogen halides. After reducing the milled chromium in flowing hydrogen under pulsating pressure at ～680°C, submicron-size powders with 4–500 ppm residual halogens were obtained. The compacted chromium–thoria alloys had interparticle spacings ranging from 2·1 to 6·5 μm. After 100 h at 1318°C the interparticle spacing of the 2·1-μm alloy increased to 5·2 μm. Submicron-size chromium and nickel powders were also obtained by pulsating hydrogen reduction of their chlorides.     

粉末冶金产品的快速开发与生产

快速响应市场需求是新世纪制造企业必需的能力之一 ,文章详述了快速响应制造技术在粉末冶金工业中的应用与前景 ,强调了该技术对粉末冶金产品的快速开发与生产以及快速响应市场需求的重要作用     

粉末冶金制品在纺织机械上的应用

回顾了企业的发展历史。阐述了粉末冶金零件在纺织机械上的应用。通过对粉末冶金产品链块技术进步的介绍和摇架结构零件的经济效果分析, 表明粉末冶金零件质量可靠, 技术经济效益显著, 从而说明粉末冶金工艺是开发生产纺机新产品的可靠方法。     

铝型材喷涂砂纹粉末生产工艺技术的改进

本文介绍了对铝型材喷涂普通粉末的生产工艺技术进行改进的方法，确定了铝型材喷涂砂纹粉末的工艺技术参数。生产实践证明，这种改进取得良好的效果，满足了客户的需求。     

特殊环境对硅酸铝制品使用效果的影响

硅酸铝纤维制品虽有明显的保温节能效果,但生产及试验表明,不同应用环境对最终使用效果均有影响。     

降低CSP低碳铝镇静钢成品酸溶铝含量实践

邯钢三炼钢厂结合生产实际,优化转炉、精炼操作工艺,使CSP低碳铝镇静钢成品酸溶铝由0．0299％降至0．0260％以下。     

提高粉末制品压制精度的机构设计

本文介绍了一种可有效提高粉末制品压制精度的机构设计方案。它采用机械定位机构与液压缸结构有机结合,组成一套完整的液压缸可调式行程刚性定位系统。通过该系统的调整,能方便的实现液压机主液压缸、下拉缸行程的高精度可靠定位。解决了由于液压控制精度差而引起的压坯高度尺寸偏差大等技术问题。并就其结构图论述了该系统的工作原理,展望了其应用前景。     

焦油渣制型煤回配炼焦工艺的应用

介绍了焦油渣作为粘结剂生产型煤炼焦的工艺流程,对工艺中配比可控化、自动除铁系统、联锁控制系统、专用回收装置、间接蒸汽加热等技术措施进行了阐述。实际应用情况表明,焦油渣配置型煤炼焦具备工业化条件,不但对焦炭质量基本无影响,同时还能创造一定经济和环保效益。     

钠还原钽粉的显微结构

用扫描电子显微镜观察了钠还原氟钽酸钾制得的钽粉的微观结构,其特征是:不同的钠还原方式生产的钽粉有相似的微观结构;同一钠还原工艺,不同工艺参数生产的钽粉,其原生粒子粒径从小于0.2μm到数μm;同一工艺条件生产的不同粒度的钽粉,其原生粒子大小一样。钽粉的原生粒子大小反映了比表面积的大小即比容的高低。     

用热分解法制备纳米级铁粉

用热分解法制备纳米级铁粉,通过改变热分解温度、Ｆｅ（ＣＯ）５的蒸发温度和稀释比,可以控制粉末的平均粒度;同时探讨了表面活性剂对粉末平均粒度的影响,指出在特定的热分解条件和选择适宜的表面活性剂的情况下,可以制备平均粒度＜１０ｎｍ的铁粉。     

机械合金化制取Ni－Fe－Mo粉

机械合金化可使在室温下部分互溶体系Ｎｉ－Ｆｅ－Ｍｏ形成ｆｃｃ固溶态粉末，Ｎｉ、Ｆｅ、Ｍｏ三种元素在粉末颗粒表面及内部均匀分布存在，固溶态粉末的液相生成温度的为１７１０Ｋ。     

采用变流量技术降低混匀料粒度偏析

为提高原料的混匀效果,采用了变流量技术降低混匀料的粒度偏析,建立了逐层变流量堆料系统的数学模型,并在此基础上开发了控制系统。使用本系统后原料混匀效果明显改善,混匀料质量提高,烧结产量和质量指标有了明显改善。     

THE EFFECT OF INTERPARTICLE CONTACT AREA ON THE STRENGTH OF COLD-PRESSED ALUMINIUM POWDER COMPACTS

Abstract

Measurements of the tensile strength of spherical cold-pressed aluminium powder, pressed to various densities up to the theoretical maximum, have shown that compaction is a two-stage process. At some high, intermediate pressure, interparticle sliding occurs in a way that does not itself increase densification but makes it easier for further deformation to occur. It is likely that the pressure at which this sliding takes place is dependent on the work-hardening rate of the powder as well as the powder size and morphology. In any case, it is shown to be important to the densification and strength reached by the compact.

It is concluded that the strength of a green compact is dependent upon the interparticle metallic contacts made during compaction. However,the green strength is well below that of wrought aluminium, probably due to the presence of broken-up oxides,which act as stress-concentrators at the interparticle boundaries.