金属粉末注射成形粘结剂的发展

概括了金属注射成形粘结剂的功能与发展过程，并对几种典型粘结剂及其脱除工艺进行了适用性与经济性分析。     

金属注射成形中碳控制的重要判别分析

金属注射成形(MIM)中碳难以控制,对其工艺的发展有很大的影响,最明显的是在MIM工艺发展早期对材料的选择。而且,适当地控制碳一直都十分重要,是影响MIM最终零件质量的一个重要因素。美国圣地亚哥洲立大学(San Diego State University,USA)的Randall German教授述评了MIM工艺发展中控制碳的历史,并考察了烧结气氛与黏结剂系统的重要性,还述评了在MIM生产过程中发生的相关反应。     

钨电极的金属注射成形工艺研究

以W-1.5%La2O3合金粉末为原料,采用金属注射成形技术,通过粉末和喂料的制备、注射、脱脂和烧结等工序,制造了一种薄壁、大长径比的杯状电极材料。研究了不同粒度的钨粉对于喂料制备和烧结工艺的影响,以及采用传统的烧结工艺和Ni元素活化烧结工艺对烧结坯的密度的影响。采用亚微米钨粉或活化烧结得到的镧钨电极的致密度达到98.3%,可以满足使用要求。     

增塑粉末挤压成形用新成形剂的研制

研制出了一种适用于增塑粉末挤压成形技术的新成形剂体系。通过优化成形剂配方设计与制备方式及工艺条件，制得了性能优良、分布均匀的成形剂。研究了成形剂的热脱脂机理，考察了成形剂的挤压、脱脂特性。用新开发出的成形剂制备出了高质量的大直径硬质合金挤压棒。     

高比重钨合金注射成形工艺研究

对高比重钨合金的注射成形工艺进行了研究,包括粉末的预处理,喂料制备、注射、脱脂和烧结工艺,并对材料的微观组织和机械性能进行了分析。研究表明:预处理后粉末的装载量可以达到58%,经过适当的注射工艺及热脱脂烧结工艺后,可以得到无缺陷的烧结坯。在一定的烧结温度范围内,烧结坯的密度、硬度等性能指标随着烧结温度的升高而增大。对95WNiFe材料而言,当烧结温度为1 450℃,烧结时间为120 min时,其密度可达18.02 g/cm~3,硬度为29 HRC,抗拉强度为792 MPa,屈服强度为612 MPa,延伸率为10%。     

金属粉末注射成形计算机模拟充模过程的数值求解

文章采用有限元方法对金属粉末注射成形计算机模拟充模过程给出的方程组和边界条件进行了详细的数学求解分析，并给出了采用有限元软件ANSYS进行具体求解的过程，同时逐项分析如何运用一般模拟求解的主要输出结果来指导粉末注射成形模具设计和参数优化。     

Fracture Features of Low-Alloy Steel Produced by Metal Injection Molding

Powder Metallurgy and Metal Ceramics - In the manufacture of sintered steels by metal injection molding (MIM), typical microstructural defects, such as pores and pore agglomerates, phase structure...     

低成本金属钛生产方法的研究与开发

简要分析限传统金属钛生产方法,指出依赖改进传统工艺无法改变钛生产成本高这一现状。系统总结了目前正在开发或改进的新的钛生产工艺,指出以氯化钛还原为基础的连续生产工艺最为希望作为一种新的提炼技术取代的Ｋｒｏｌｌ和Ｈｕｎｔｅｒ工艺。     

金属注射成形石蜡基粘结剂主体聚合物的研究

聚乙烯－醋酸乙烯酯（EVA）为主体聚合物的石蜡基粘结剂在金属注射成形技术中得到了广泛的应用。这种粘结剂体系有很好的流动性，但存在保形性较差的缺点，采用甲基丙烯酸甲醋和醋酸乙烯酸为单体进行溶液聚合和悬浮聚合，并重点考察了各种因素对聚合结果的影响，发现改变单体组成，引发剂用量，分子量调节剂用量和其它一些条件，可以得到理想的主体聚合物。     

中高密度系列钨镍合金粉末注射成形喂料的流变性能研究

利用XLY-Ⅱ型毛细管流变仪研究3种不同密度(分别为10g/cm3、14 g/cm3、17g/cm3)的钨镍合金粉末注射成形喂料的流变行为,分析了剪切速率、温度以及钨镍成分配比对喂料流变性能的影响。实验结果表明,钨镍合金喂料是一种假塑性流体,其表观粘度随剪切速率的增大、温度的升高而减小;非牛顿指数随温度的升高而增大;钨在合金中所占比重越大,喂料对剪切速率的变化及温度的变化越敏感。     

金属粉末增塑挤压与注射成型

系统地阐述和分析了粉末增塑挤压技术和金属注射成型技术中的应用、原料、工艺原理等，并对两种技术的异同进行了分析比较。     

金属粉末注射成形复杂模腔计算机充模模拟研究

利用有限元分析软件ANSYS，对金属粉末注射成形计算机复杂模腔充模过程进行了模拟，模拟结果与Cro—cher等用商业软件Polymold算出的结果相似，证明了所建模型和分析计算方法的可行性。同时通过分析模拟结果中流体前沿、压力场和温度场的分布，预测了部分常见注射缺陷产生的条件，讨论了如何利用模拟结果指导注射工艺参数的选择，展示了其实用前景。     

High-Temperature Oxidation Behavior of Two Nickel-Based Superalloys Produced by Metal Injection Molding for Aero Engine Applications

For different high-temperature applications like aero engines or turbochargers, metal injection molding (MIM) of superalloys is an interesting processing alternative. For operation at high temperatures, oxidation behavior of superalloys produced by MIM needs to match the standard of cast or forged material. The oxidation behavior of nickel-based superalloys Inconel 713 and MAR-M247 in the temperature interval from 1073 K to 1373 K (800 °C to 1100 °C) is investigated and compared to cast material. Weight gain is measured discontinuously at different oxidation temperatures and times. Analysis of oxidized samples is done via SEM and EDX-measurements. MIM samples exhibit homogeneous oxide layers with a thickness up to 4 µm. After processing by MIM, Inconel 713 exhibits lower weight gain and thinner oxide layers than MAR-M247.     

铁水预脱硫喷吹系统的优化设计

根据铁水预脱硫工艺和喷吹技术发展状况,结合实践经验,从铁水预脱硫喷吹系统垢角度出发,对铁水预脱硫工艺、脱硫剂喷吹方式、操作方式、敢比大小及喷吹控制方式的优化设计做一些有益的探讨。实践表明,铁水预脱硫喷吹系统的优化设计取得了良好的效果。     

浅谈冷轧无取向电工钢涂层的发展

介绍了冷轧无取向电工铜涂层即有机涂层、无机涂层和半无机涂层需满足的性能要求及其应用发展趋势;国内外电工铜厂家硅铜涂层的应用状况,涂有环保涂层的硅铜片将会占领整个电工铜市场。因此,各企业均投入大量人力物力进行研究开发。     

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     

铁水脱硫喷枪技术的发展综述

综述了铁水脱硫及其喷枪技术研究现状与发展。     

Molding Properties and Causes of Deterioration of Recycled Powder Injection Molding Feedstock

To lower the manufacturing cost of powder injection molded products, the gate, runner, sprue, and green parts with defects are usually recycled. Unfortunately, these feedstocks deteriorate as the number of recycling iterations increases. This study presents an investigation of the molding properties and the causes of the deterioration of the recycled feedstocks by monitoring changes in melting points, in-situ strength changes during solvent debinding, spiral length, and viscosity. The oxygen content measurements indicate that serious oxidation occurs after recycling, particularly in the paraffin wax (PW). The results of the molecular weight from gel-permeation chromatography (GPC) also show that the polyethylene (PE) deteriorates during recycling. The viscosity of the 1R (recycled once) feedstock was slightly lower than that of the fresh material. However, as the number of recycling iterations increased, the viscosity increased again. As a result, the spiral length decreased and the required injection pressure increased. It was also noticed that more defects developed along the molding and debinding process.     

CFD Modelling and Analysis of Pulverized Coal Injection in Blast Furnace: An Overview

In order to understand the complicated phenomena of pulverized coal injection (PCI) process in blast furnace (BF), several mathematical models have been developed by the UNSW and BSR cooperation. These models are featuring from coal combustion in a pilot‐scale test rig, to coal combustion in a real BF, and then to coal/coke combustion in a real BF, respectively. This paper reviews these PCI models in aspects of model developments and model applicability. The model development is firstly discussed in terms of model formulation, their new features and geometry/regions considered. The model applicability is then discussed in terms of main findings followed by the model evaluation on their advantages and limitations. It is indicated that the three PCI models are all able to describe PCI operation qualitatively. The model of coal/coke combustion in a real BF is more reliable for simulating in‐furnace phenomena of PCI operation qualitatively and quantitatively. Such model gives a more reliable burnout prediction over the raceway surface, which could better represent the amount of unburnt char entering the coke bed. These models are useful for understanding the flow‐thermo‐chemical behaviours and then optimising the PCI operation in practice.