粉末冶金零件的锻造与挤压成形

一、粉末冶金结构零件的锻造成形 1.概况粉末结构零件锻造成形技术的研究与应用近年发展迅速。据报导,在北美、欧洲和日本,该工艺已广泛用于生产汽车、拖拉机、电站设备、农林机具、钻探机械、工业轴承以及航空发动机等多种高强度零件。     

高密度粉末冶金零件制备技术现状

近年来,随着零件成形技术的不断改进,粉末冶金工业得到了快速发展。本文主要介绍了温压技术、动力磁性压制技术、爆炸压制技术、粉末锻造技术、快速全向压制技术、轧制成形和高速压制技术的基本原理、特点和应用情况,指出高速压制技术是粉末冶金工业寻求低成本高密度材料加工技术的又一次新突破,具有广阔的应用前景。     

剖析别克轿车，展望汽车零件发展

概述了粉末冶金零件在汽车工业中的巨大市场，以别克轿车为例，介绍了在别克轿车中粉末锻造连杆、组合凸轮轴、错位双联齿轮等几种典型汽车零件及其应用情况，指出粉末锻造、温压、高密度烧结、注射成形等先进技术将在我国工业生产中实施。     

2003年国际粉末冶金零件生产企业动态

20 0 3年GKN烧结金属公司以精确近成形技术制造的零件的产量增加了,粘接材料和在汽车中应用的金属注射成形制品的产量也在增长,GKN烧结金属公司的副总裁Arnhold先生认为在未来的5 - 10年里,应用于汽车制造领域的铝粉末冶金制品会有较大的发展。Arnhold先生认为使用粉末锻造技术生产高强度、高精度零件的数量会增加,将会开发出一些新型的粉末锻造用粉,钛粉末冶金制品的应用也会增加。CapstanAtlantic公司主管工程的副总裁RobertSlattery先生表示:CapstanAtlantic公司的齿轮制造业务继续保持增长,按客户需要制造的高精度齿轮使CapstanA…     

粉末冶金温压成形技术的研究现状

粉末冶金温压成形,在得到较高致密度零件的同时,可以较铸造和锻造显著的降低原料成本,缩短零件的研制周期,具有重要的研究价值。本文概述了国内外温压成形技术的应用、发展现状及温压成形工艺的关键技术,指出了粉末冶金温压成形技术的发展方向。     

温压工艺最新进展--流动温压技术

流动温压技术兼有温压技术和金属注射成形技术的优点,既克服了传统粉末冶金技术在成形方面的不足,又避免了注射成形技术的高成本.由于微细粉末的加入和较多的润滑剂含量而使混合粉末在温压时转变成一种具有良好流动性和充填能力的黏流体,从而可以直接成形零件的复杂几何形状如侧凹、螺纹孔等而不需要其后的二次机加工,具有很大的应用潜力.     

国外粉末冶金期刊一览

1. International Journal of Powder Metallurgy and Powder Technology.1974(as International Journal of Powder Metallurgy 1965-) 《国际粉末冶金与粉末工艺》是美国粉末冶金学会的季刊,是一份国际性的粉末冶金杂志。刊载关于金属粉末、粉末成形、烧结、粉末冶金制品、硬质合金及耐热合金、粉末锻造及热成形、粉末冶金工艺设备等     

从PM2004看世界粉末冶金的发展现状

详细介绍了2004年粉末冶金世界大会的基本情况, 概述了国际粉末冶金工业现状, 并按照类别阐述了粉末冶金各技术领域以及材料产品, 如粉末烧结钢、粉末注射成形、粉末制备技术、粉末压制技术、粉末烧结理论与技术、粉末多孔材料、硬质合金、粉末轻金属、粉末零件后续处理加工技术、粉末冶金过程模拟与标准化以及粉末功能材料等的发展趋势。世界粉末冶金的发展现状和趋势表明粉末冶金技术是工业化集成技术, 而不仅仅是一种高技术。     

中国成为全球粉末冶金汽车零件最大的集散地之一

<正>目前,粉末冶金已经被业界公认为是一种绿色、可持续的制造技术。例如在持续性功能方面,粉末冶金的最终成形能力与材料利用率很高,可使全部能源消耗最小化。与传统工艺(热加工+冷加工)的铸造或锻造+切削加工相比,粉末冶金工艺制造同一零件只需要采用较少的几道工序,即能完成工序较多、较复杂的工艺。在材料可持续性方面,粉末冶金的最终成形能力是其主要优势。例如成形一个齿状零件,传统切     

日本汽车用粉末冶金材料的动向

粉末冶金制品,由于具有材料利用率高,能够进行大量生产的优点,因而在汽车零件的制造上得到了广泛的应用。1974—1978年间,汽车生产量增加约1.6倍,而粉末冶金机械零件的增长达3倍。达到如此高的增长率,是由于有效地利用了粉末冶金经济效益高的优点,以及1975年间汽车液压转向装置、自动变速箱、空气调节器等新装置的普及。为了扩大粉末冶金零件的应用范围,必须开发新的粉末冶金技术。作为结构零件用的烧结技术,如以提高强度为目标的烧结锻造技术及高强度材料用合金粉末的开发,为了降低成本进行的铸铁切屑利用技术的开发,以及烧结冷锻、复合成形等新技术的研究等正在进行并逐渐被应用。随着对汽车的轻型化要求越来越高,烧结铝材料的应用研究也很盛行,但由于成本方面的原因,目前     

粉末冶金高致密化成形技术的新进展

本文针对粉末冶金行业近十年来出现的提高制品致密化的新途径新方法, 简要介绍了其中的温压技术,流动温压技术、模壁润滑技术、高速压制技术、动力磁性压制技术、爆炸压制技术、放电等离子烧结技术的原理、特点、发展和应用情况。指出发展粉末冶金高效高致密化成形技术是粉末冶金的发展方向和研究重点, 产品致密化程度的提高将大大促进性能的改进。粉末冶金新技术、新工艺、新材料的不断出现, 必将促进高技术产业的快速发展, 也必将带给材料工程和制造技术以光明的前景。     

热等静压近净成形数值模拟的研究进展

热等静压近净成形工艺具有材料利用率高、坯料组织均匀性好的突出优势,是镍基粉末高温合金、粉末钛合金等复杂形状部件的重要成形工艺。介绍了热等静压近净成形的工艺特点和生产流程、热等静压近净成形技术在国内外的发展和应用以及粉末热等静压致密化的微观模型和宏观模型,通过对比分析不同模型的热等静压数值模拟和试验验证结果,总结了不同模型的优缺点,分析了影响数值模拟准确性的因素。     

粉末冶金高强度锥齿轮成形模具结构

本文主要介绍在普通国产液压机的上-下二模架上压制高强度锥齿轮的模具结构。高强度锥齿轮由于其力学性能要求高，用粉末冶金方法生产时对压机要求较高，本厂通过将压制阴模放任浮动模板上的模具结构改进，利用同产压机浮动模板的移粉和上模后压功能，在普通国产液压机上，实现了产品的双向压制并且成形位置精确可控，满足通过进口机械压机才能达刊的密度均匀和控制精度高的成形效果，使零件的齿部密度与整体密度仅相差0．03g／cm^3左右。使刚安装在国产普通液压式粉未冶金成形压机上的该模具结构，可批量压制高强度的粉末冶金锥齿轮，使高强度粉术冶金锥齿轮成形可靠，结构简单，操作方便且成本低廉。     

Study of warm compaction of Alumix 123 L

Abstract

Although powder metallurgy (PM) material is dominated by ferrous alloys, there is a growing interest in Al PM. The usage of Al PM in automotive applications depends on the development of higher density and improved dynamic properties. Several approaches have been proposed to increase density of sintered parts. Warm compaction process of Al powder was used to achieve high density. In this study the authors focused on the effect of warm compaction on Alumix 123 L (ECKA Granules) powder blend. It has been found that warm compaction at 110°C led to a reduction in the ejection force by 27·9%, increased green density to 94% of theoretical density and increased sintered strength to 315 MPa as compared to those pressed at room temperature.     

Mechanisms of lysis by activated cytotoxic cells expressing perforin and granzyme-B genes and the protein TIA-1 in muscle biopsies of myositis

OBJECTIVE: Polymyositis (PM) and cermatomyositis (DM) are inflammatory muscle diseases of autoimmune origin. A chronic mononuclear cell infiltrate is always present around PM and DM muscle damage. In PM, the predominant cells are activated cytotoxic cells, natural killer, and CD8+ T lymphocytes. Cytotoxic cells can kill the target cells via 2 mechanisms. Both pathways induce target cell death by releasing the molecules (granule exocytosis) perforin (PF), which attacks the target cell membrane and causes cell death by necrosis, and TIA-1 protein and granzyme-B (GZB), possibly responsible for apoptosis. We studied the mechanisms of lysis in muscle biopsies of myositis. METHODS: We used a panel of monoclonal antibodies to determine the phenotypes of reactive lymphocyte subsets, in situ hybridization to study the expression of PF and GZB genes, and immunohistochemistry to evaluate TIA-1 protein production in muscle biopsies from 14 patients with myositis (11 PM/3 DM). Results were compared to those obtained from muscle biopsies of 12 control patients with muscle weakness, including patients with muscle dystrophy and vasculitis, but without myositis. RESULTS: Abundant CD8+ cells, especially in endomysial sites in PM, formed the predominant phenotype. The predominant mononuclear cells observed in DM were CD4+ T cells and CD22+ B lymphocytes, in perivascular sites. The GZB and PF genes and the TIA-1 protein were expressed simultaneously in muscle samples from patients with myositis. GZB, PF, and TIA-1 positive cells were predominantly located in endomysial sites of PM, in the nonnecrotic muscle fibers. In DM, these positive cells were rare. CONCLUSION: In myositis, especially PM, cytotoxic cells may cause muscle damage and muscle cell necrosis and/or apoptosis by releasing several proteins (PF, GZB, and TIA-1 proteins) responsible for the lysis of these stimulating target cells. Some drugs (prednisone and cyclosporine) inhibit the release of GZB and PF. Their efficacy may be due in part to this inhibitory effect.     

Selected Problems of Die‐Forging of PM Steel Products

The paper discusses the selected technological and material problems of closed‐die forging of PM steel preforms. The first part presents technological variants of hot forging routs of PM materials. In the second part the influence of hot forging parameters on the density, mechanical properties and structure are discussed. The influence of the size of powder particles, powder manufacturing method, chemical composition and heat treatment conditions on mechanical properties after forging is shown. The research on thermomechanical forging of PM preforms has resulted in potential possibilities of shortening of the manufacturing route to obtain products with high density and good mechanical properties from one heating before forming.     

粉末冶金温压工艺的研究进展及展望

温压是一项以较低的成本制造高性能粉末冶金零件的新型成形技术，本文综述并讨论了温压工艺的粉末原料、聚合物、温度、压力、烧结环节及致密化机理。在此基础上，介绍了温压工艺的新发展——流动温压、高压温压等，并对其应用前景进行了展望。     

快速凝固铝硅合金的制备、组织特征及断裂行为

快速凝固Al-Si合金是一种高性能结构材料,目前主要通过快速凝固/粉末冶金(RS/PM)和喷射沉积(SF)两种方法进行制备;此类合金具有超细化显微组织、成分均匀分布、非平衡亚稳相和过饱和固溶体及高密度位错等组织特征;其断裂方式主要呈脆性断裂。本文主要对上述内容进行综合评述     

Raw Material and Energy Conservation in Production of Sintered PM Parts

Abstract

It can be regarded as proven that the PM production of structural parts for the processing industry is a forming method involving minimum utilization of energy and material. In the present paper, data on energy consumption are examined using industrial examples for the individual stages in the process. These stages are the production of the raw material, shaping, sintering, and secondary forming. On the subject of single and double sintering, two examples are given in each case of the economies attainable through the use of PM processes, and some ideas for further reductions in energy consumption are put forward. PM/0239